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1.  Stress-Mediated Increases in Systemic and Local Epinephrine Impair Skin Wound Healing: Potential New Indication for Beta Blockers 
PLoS Medicine  2009;6(1):e1000012.
Stress, both acute and chronic, can impair cutaneous wound repair, which has previously been mechanistically ascribed to stress-induced elevations of cortisol. Here we aimed to examine an alternate explanation that the stress-induced hormone epinephrine directly impairs keratinocyte motility and wound re-epithelialization. Burn wounds are examined as a prototype of a high-stress, high-epinephrine, wound environment. Because keratinocytes express the β2-adrenergic receptor (β2AR), another study objective was to determine whether β2AR antagonists could block epinephrine effects on healing and improve wound repair.
Methods and Findings
Migratory rates of normal human keratinocytes exposed to physiologically relevant levels of epinephrine were measured. To determine the role of the receptor, keratinocytes derived from animals in which the β2AR had been genetically deleted were similarly examined. The rate of healing of burn wounds generated in excised human skin in high and low epinephrine environments was measured. We utilized an in vivo burn wound model in animals with implanted pumps to deliver β2AR active drugs to study how these alter healing in vivo. Immunocytochemistry and immunoblotting were used to examine the up-regulation of catecholamine synthetic enzymes in burned tissue, and immunoassay for epinephrine determined the levels of this catecholamine in affected tissue and in the circulation. When epinephrine levels in the culture medium are elevated to the range found in burn-stressed animals, the migratory rate of both cultured human and murine keratinocytes is impaired (reduced by 76%, 95% confidence interval [CI] 56%–95% in humans, p < 0.001, and by 36%, 95% CI 24%–49% in mice, p = 0.001), and wound re-epithelialization in explanted burned human skin is delayed (by 23%, 95% CI 10%–36%, p = 0.001), as compared to cells or tissues incubated in medium without added epinephrine. This impairment is reversed by β2AR antagonists, is absent in murine keratinocytes that are genetically depleted of the β2AR, and is reproduced by incubation of keratinocytes with other β2AR-specific agonists. Activation of the β2AR in cultured keratinocytes signals the down-regulation of the AKT pathway, accompanied by a stabilization of the actin cytoskeleton and an increase in focal adhesion formation, resulting in a nonmigratory phenotype. Burn wound injury in excised human skin also rapidly up-regulates the intra-epithelial expression of the epinephrine synthesizing enzyme phenylethanolamine-N-methyltransferase, and tissue levels of epinephrine rise dramatically (15-fold) in the burn wounded tissue (values of epinephrine expressed as pg/ug protein ± standard error of the mean: unburned control, 0.6 ± 0.36; immediately postburn, 9.6 ± 1.58; 2 h postburn, 3.1 ± 1.08; 24 h post-burn, 6.7 ± 0.94). Finally, using an animal burn wound model (20% body surface in mice), we found that systemic treatment with βAR antagonists results in a significant increase (44%, 95% CI 27%–61%, p < 0.00000001) in the rate of burn wound re-epithelialization.
This work demonstrates an alternate pathway by which stress can impair healing: by stress-induced elevation of epinephrine levels resulting in activation of the keratinocyte β2AR and the impairment of cell motility and wound re-epithelialization. Furthermore, since the burn wound locally generates epinephrine in response to wounding, epinephrine levels are locally, as well as systemically, elevated, and wound healing is impacted by these dual mechanisms. Treatment with beta adrenergic antagonists significantly improves the rate of burn wound re-epithelialization. This work suggests that specific β2AR antagonists may be apt, near-term translational therapeutic targets for enhancing burn wound healing, and may provide a novel, low-cost, safe approach to improving skin wound repair in the stressed individual.
Rivkah Isseroff and colleagues describe how stress-induced elevation of epinephrine levels can impair the healing of burns in mice and suggest that β2 adrenergic receptor antagonists may have a role in improving skin wound repair.
Editors' Summary
Skin—the largest organ in the human body—protects the rest of the body against infection by forming an impervious layer over the whole external body surface. Consequently, if this layer is damaged by rubbing, cutting, or burning, it must be quickly and efficiently repaired. Wound repair (healing) involves several different processes. First, the clotting cascade stops bleeding at the wound site and immune system cells attracted into the site remove any bacteria or debris in the wound. Various factors are released by the immune cells and the other cells in and near the damaged area that encourage the migration of several different sorts of cells into the wound. These cells proliferate and prepare the wound for “re-epithelialization.” In this process, keratinocytes (a type of epithelial cell that makes a tough, insoluble protein called keratin; epithelial cells cover all the surfaces of the body) migrate into the wound site and form a new, intact epithelial layer. If any of these processes fail, the result can be a chronic (long-lasting) nonhealing wound. In particular, if the wound does not re-epithelialize, it remains open and susceptible to infection and loss of body fluids.
Why Was This Study Done?
One factor that impairs the repair of skin wounds is stress. In stressful situations (including situations in which wounds are likely to occur), the human body releases several chemicals that prepare the body for “fight or flight,” including cortisol and epinephrine (also called adrenaline). Most scientists ascribe the effects of stress on wound healing to stress-induced increases in cortisol, but might stress-induced epinephrine also affect wound healing? In this study, the researchers test whether epinephrine impairs keratinocyte migration and re-epithelialization of burn wounds (keratinocytes have a receptor for epinephrine called the β2 adrenergic receptor [β2AR] on their cell surface that allows them to respond to epinephrine). They chose to study burn wounds for two reasons. First, major burns cause a massive release of stress chemicals into the bloodstream that raises blood levels (systemic levels) of cortisol and epinephrine for days or weeks after the initial trauma. Second, despite recent therapeutic advances, many people still die from major burns (4,000 every year in the USA alone) so there is a pressing need for better ways to treat this type of wound.
What Did the Researchers Do and Find?
The researchers investigated the effects of epinephrine on wound healing in three types of experiments. First, they looked at the effect of epinephrine on keratinocytes growing in dishes (in vitro experiments). Levels of epinephrine similar to those in the blood of stressed individuals greatly inhibited the motility and migration of human keratinocytes (isolated from the foreskin of newborn babies) and of mouse keratinocytes. It also inhibited the repair of scratch wounds made in monolayers of keratinocytes growing on dishes. Treatment of the cultures with a β2AR antagonist (a chemical that prevents epinephrine activating the β2AR) reversed the effects of epinephrine. In addition, the migration of mouse keratinocytes that had been genetically altered so that they did not express β2AR was not inhibited by epinephrine. Next, the researchers investigated the healing of burn wounds made in small pieces of human skin growing in dishes (ex vivo experiments). Burn injuries rapidly increased the amount of epinephrine in these tissue explants, they report, and treatment of the explants with a βAR antagonist (an inhibitor of all types of βARs) greatly increased wound re-epithelialization. Finally, the researchers report that the re-epithelialization of burn wounds in living mice was improved when the mice were treated with a β2AR antagonist.
What Do These Findings Mean?
These findings reveal a second pathway by which stress can impair wound healing. They show that stress-induced increases in systemic and local epinephrine activate β2ARs on keratinocytes and that this activation inhibits keratinocyte motility and wound re-epithelialization. Although results obtained in animals do not always reflect what happens in people, the finding that the treatment of mice with β2AR antagonists improves the rate of burn wound re-epithelialization, suggests that beta blockers—drugs that inhibit all βARs and that are widely used to treat high blood pressure and to prevent heart disease—or specific β2AR antagonists might provide a new therapeutic approach to the treatment of burns and, perhaps, chronic nonhealing wounds.
Additional Information.
Please access these Web sites via the online version of this summary at
Wikipedia has pages on wound healing, burn injuries, and epinephrine (Note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
The MedlinePlus Encyclopedia has a page on burns (in English and Spanish)
MedlinePlus provides links to other information on burns (in English and Spanish)
PMCID: PMC2621262  PMID: 19143471
2.  Bupivacaine causes cytotoxicity in mouse C2C12 myoblast cells: involvement of ERK and Akt signaling pathways 
Acta Pharmacologica Sinica  2010;31(4):493-500.
The adverse effects of local anesthetics (LAs) on wound healing at surgical sites have been suggested, and may be related to their cytotoxicity. This study was aimed to compare the cellular toxicity of bupivacaine and lidocaine (two well-known LAs), and to explore the molecular mechanism(s).
Toxicity of bupivacaine and lidocaine was assessed in cultured mouse C2C12 myoblasts by cell viability and apoptosis assays. Effects of LAs on extracellular signal-regulated kinase (ERK) and protein kinase B (Akt) activation, which are essential for cell proliferation and survival, were evaluated by immunoblotting.
Both LAs, especially bupivacaine, prevented cell growth and caused cell death in a dose-dependent manner. The half maximal inhibitory concentrations (IC50) for bupivacaine and lidocaine were 0.49±0.04 and 3.37±0.53 mmol/L, respectively. When applied at the same dilutions of commercially available preparations, the apoptotic effect induced by bupivacaine was more severe than that of lidocaine in C2C12 cells. Furthermore, bupivacaine significantly diminished the ERK activation, which may underlie its anti-proliferative actions. Both LAs suppressed Akt activation, which correlated with their effects on apoptosis.
Our study demonstrated that, when used at the same dilutions from clinically relevant concentrations, bupivacaine is more cytotoxic than lidocaine in vitro. Anti-proliferation and cell death with concomitant apoptosis mediated by bupivacaine may offer an explanation for its adverse effects in vivo (eg slowing wound healing at the surgical sites). A less toxic, long-acting anesthetic may be needed.
PMCID: PMC4007657  PMID: 20228829
local anesthetic; cytotoxicity; cell proliferation; apoptosis; extracellular signal-regulated kinase; Akt
3.  Effect of wound infiltration with bupivacaine or lower dose bupivacaine/magnesium versus placebo for postoperative analgesia after cesarean section 
The authors examined the analgesic effect of wound infiltration with bupivacaine or lower dose bupivacaine and magnesium versus normal saline for postoperative analgesia after cesarean section.
Materials and Methods:
A total of 120 patients, American Society of Anesthesiologists (ASA) I-II were prepared for elective cesarean section. At the end of the surgery, the wound was continuously infiltrated at a rate of 5 ml/h for 24 h post-operatively by one of the following solutions: 0.25% bupivacaine, a mixture of 0.125% bupivacaine and 5% magnesium sulphate or normal saline (0.9%). Total opioid consumption, Visual Analogue Scale (VAS) at rest and movement, incidence of opioid side-effects and signs of wound inflammation were assessed during the period of the study (24 h post-operatively). Three months later, residual pain, surgical wound infection, need for extra-antibiotic therapy and wound healing impairment were assessed.
Post-operative pain scores at rest were statistically significant higher in the control group than those in the both wound infiltration groups from 4th h and onwards (P < 0.0001). Meanwhile, post-operative pain was higher in bupivacaine group versus magnesium group (P < 0.0001, P < 0.0001, 0.0012, respectively). There was statistically significant increase in VAS during movement in the control group versus others at 2, 4, 12, 24 h post-operatively (P < 0.0001). However, patients received magnesium plus bupivacaine wound infiltration showed a significant decrease in post-operative pain scores than whom received bupivacaine from 4th h and onward (P < 0.0001, 0.0054, 0.0001, respectively). Morphine consumption was significantly reduced in the magnesium group, (P < 0.0001). Incidence of residual pain was comparable in the three groups. The incidence of sedation and urine retention were noted to be significantly higher in the control group in comparison to other groups, (P <0.0001). The incidence of post-operative nausea and vomiting was reduced in patients received magnesium plus bupivacaine block versus others (P < 0.0001).
Continuous wound infiltration with a mixture of bupivacaine and magnesium sulphate after cesarean section showed an effective analgesia and reduced post-operative Patient Controlled Analgesia (PCA) requirements as compared to continuous wound infiltration with local anesthetic only or placebo with fewer incidences of opioid adverse effects.
PMCID: PMC4173540  PMID: 25885979
Analgesia; cesarean section; magnesium sulphate; wound infiltration
4.  Episodic Binge Ethanol Exposure Impairs Murine Macrophage Infiltration and Delays Wound Closure by Promoting Defects in Early Innate Immune Responses 
Exacerbation of cutaneous wound infections and delayed wound closure are frequent complications seen in alcohol exposed subjects who sustain injuries. We previously reported that acute alcohol exposure alters the early dermal inflammatory phase of wound healing and also several parameters of the proliferative wound healing phase in wounds from ethanol-treated mice for several days or weeks after ethanol exposure. Hence, it is likely that the cumulative defects arising in the early phases of the wound healing process directly contribute to the increased complications observed in intoxicated patients at the time of injury.
C57BL/6 mice were given intraperitoneal ethanol (2.2g/kg body weight) or vehicle (saline) ethanol using our episodic binge ethanol exposure protocol (3 days ethanol, 4 days off, 3 days ethanol) to yield a blood alcohol concentration (B.A.C.) of 300 mg/dl at the time of wounding. Mice were subjected to six 3 mm full-thickness dorsal wounds and immediately treated topically with 10 μl of sterile saline (control) or diluted Staphylococcusaureus corresponding to 1 × 10^4 CFU/wound. Wounds were harvested at 24 hours post-injury to evaluate wound area, neutrophil and macrophage accumulation, and the protein levels of cytokines, interleukin (IL) IL-6, IL-1β, IL-6, and IL-10, and chemokines, macrophage inflammatory proteins (MIP), MIP-2 and MIP-1α, monocyte chemotactic protein-1 (MCP-1) and KC. The abundance and localization of cathelicidin-related antimicrobial peptide (CRAMP) and the kallikrein epidermal proteases (KLK5 and KLK7) were also determined.
Compared to control mice, ethanol-treated mice exhibited delayed wound closure, decreased macrophage accumulation and impaired production of MIP-1α. Furthermore, skin from ethanol-treated mice demonstrated a reduction in the abundance of epidermal CRAMP and KLK7.
These findings suggest that ethanol exposure hinders several distinct components of the innate immune response, including phagocyte recruitment and chemokine/cytokine and AMP production. Together, these effects likely contribute to delayed wound closure and enhanced infection severity observed in intoxicated patients.
PMCID: PMC4001884  PMID: 24689549
Antimicrobial peptides; proteases; wound healing; macrophages; cathelicidin; inflammation
5.  Dermal wound transcriptomic responses to Infection with Pseudomonas aeruginosa versus Klebsiella pneumoniae in a rabbit ear wound model 
Bacterial infections of wounds impair healing and worsen scarring. We hypothesized that transcriptome analysis of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) would indicate host-responses associated with the worse healing of P.a.- than K.p.-infected wounds.
Wounds created on post-operative day (POD) 0 were infected during the inflammatory phase of healing on POD3 and were harvested on POD4 for microarray and transcriptome analysis. Other wounds received topical antibiotic after infection for 24 hours to promote biofilm development, and were harvested on POD6 or POD12.
Wounds infected for 24 hours, relative to uninfected wounds, elevated transcripts of immune-response functions characteristic of infiltrating leukocytes. But P.a.-infected wounds elevated many more transcripts and to higher levels than K.p.-infected wounds. Coincidently, suppressed transcripts of both wounds enriched into stress-response pathways, including EIF2 signaling; however, this was more extensive for P.a.-infected wounds, including many-fold more transcripts enriching in the ‘cell death’ annotation, suggesting resident cutaneous cell toxicity in response to a more damaging P.a. inflammatory milieu. The POD6 wounds were colonized with biofilm but expressed magnitudes fewer immune-response transcripts with no stress-response enrichments. However, elevated transcripts of P.a.-infected wounds were inferred to be regulated by type I interferons, similar to a network unique to P.a.-infected wounds on POD4. On POD12, transcripts that were more elevated in K.p.-infected wounds suggested healing, while transcripts more elevated in P.a.-infected wounds indicated inflammation.
An extensive inflammatory response of wounds was evident from upregulated transcripts 24 hours after infection with either bacterium, but the response was more intense for P.a.- than K.p.-infected wounds. Coincidently, more extensive down-regulated transcripts of P.a.-infected wounds indicated a stronger “integrated stress response” to the inflammatory milieu that tipped more toward cutaneous cell death. Unique to P.a.-infected wounds on POD4 and POD6 were networks inferred to be regulated by interferons, which may result from intracellular replication of P.a. These data point to specific downregulated transcripts of cells resident to the wound as well as upregulated transcripts characteristic of infiltrating leukocytes that could be useful markers of poorly healing wounds and indicators of wound-specific treatments for improving outcomes.
PMCID: PMC4101837  PMID: 25035691
6.  Delayed Wound Healing in Diabetic (db/db) Mice with Pseudomonas aeruginosa Biofilm Challenge – A Model for the Study of Chronic Wounds 
Chronic wounds are a major clinical problem that leads to considerable morbidity and mortality. We hypothesized that an important factor in the failure of chronic wounds to heal was the presence of microbial biofilm resistant to antibiotics and protected from host defenses. A major difficulty in studying chronic wounds is the absence of suitable animal models. The goal of this study was to create a reproducible chronic wound model in diabetic mice by application of bacterial biofilm. Six millimeter punch biopsy wounds were created on the dorsal surface of diabetic (db/db) mice, subsequently challenged with Pseudomonas aeruginosa (PAO1) biofilms two days post-wounding, and covered with semi-occlusive dressings for two weeks. Most of the control wounds were epithelialized by 28 days post-wounding. In contrast, none of biofilm challenged wounds were closed. Histological analysis showed extensive inflammatory cell infiltration, tissue necrosis and epidermal hyperplasia adjacent to challenged wounds- all indicators of an inflammatory non-healing wound. Quantitative cultures and transmission electron microscopy demonstrated that the majority of bacteria were in the scab above the wound bed rather than in the wound tissue. The model was reproducible, allowed localized cutaneous wound infections without high mortality and demonstrated delayed wound healing following biofilm challenge. This model may provide an approach to study the role of microbial biofilms in chronic wounds as well as the effect of specific biofilm therapy on wound healing.
PMCID: PMC2939909  PMID: 20731798
wound matrix; bacteria; scab; immunohistology; electron microscopy
7.  Delayed Wound Repair in Sepsis Is Associated with Reduced Local Pro-Inflammatory Cytokine Expression 
PLoS ONE  2013;8(9):e73992.
Sepsis is one of the main causes for morbidity and mortality in hospitalized patients. Moreover, sepsis associated complications involving impaired wound healing are common. Septic patients often require surgical interventions that in-turn may lead to further complications caused by impaired wound healing. We established a mouse model to the study delayed wound healing during sepsis distant to the septic focus point. For this reason cecal ligation and puncture (CLP) was combined with the creation of a superficial wound on the mouse ear. Control animals received the same procedure without CPL. Epithelialization was measured every second day by direct microscopic visualization up to complete closure of the wound. As interplay of TNF-α, TGF-β, matrix metalloproteinases (MMP), and tissue inhibitors of metalloproteinases (TIMP) is important in wound healing in general, TNF-α, TGF-β, MMP7, and TIMP1 were assessed immunohistochemical in samples of wounded ears harvested on days 2, 6, 10 and 16 after wounding. After induction of sepsis, animals showed a significant delay in wound epithelialization from day 2 to 12 compared to control animals. Complete wound healing was attained after mean 12.2± standard deviation (SD) 3.0 days in septic animals compared to 8.7± SD 1.7 days in the control group. Septic animals showed a significant reduction in local pro-inflammatory cytokine level of TNF-α on day 2 and day 6 as well as a reduced expression of TGF-β on day 2 in wounds. A significant lower expression of MMP7 as well as TIMP1 was also observed on day 2 after wounding. The induction of sepsis impairs wound healing distant to the septic focus point. We could demonstrate that expression of important cytokines for wound repair is deregulated after induction of sepsis. Thus restoring normal cytokine response locally in wounds could be a good strategy to enhance wound repair in sepsis.
PMCID: PMC3783436  PMID: 24086305
8.  Morphine-induced early delays in wound closure: involvement of sensory neuropeptides and modification of neurokinin receptor expression 
Biochemical pharmacology  2009;77(11):1747-1755.
Dose-limiting side effects of centrally-acting opioid drugs have led to the use of topical opioids to reduce the pain associated with chronic cutaneous wounds. However, previous studies indicate that topical morphine application impairs wound healing. This study was designed to elucidate the mechanisms by which morphine delays wound closure. Rats were depleted of sensory neuropeptides by treatment with capsaicin, and full-thickness 4 mm diameter wounds were excised from the intrascapular region. Wounds were treated topically twice daily with 5 mM morphine sulfate, 1 mM substance P, 1 mM neurokinin A, or 5 mM morphine combined with 1 m M substance P or neurokinin A and wound areas assessed. During closure, wound tissue was taken 1, 3, 5, and 8 days post-wounding from control and morphine-treated rats and immunostained for neurokinin receptors and markers for macrophages, myofibroblasts, and vasculature. Results obtained from capsaicin-treated animals demonstrated a significant delay in the early stages of wound contraction that was reversed by neuropeptide application. Treatment of capsaicin-treated rats with topical morphine did not further delay wound closure, suggesting that topical opioids impair wound closure via the inhibition of peripheral neuropeptide release into the healing wound. Morphine application altered neurokinin-1 and neurokinin-2 receptor expression in inflammatory and parenchymal cells essential for wound healing in a cell-specific manner, demonstrating a direct effect of morphine on neurokinin receptor regulation within an array of cells involved in wound healing. These data provide evidence indicating a potentially detrimental effect of topical morphine application on the dynamic wound healing process.
PMCID: PMC4159122  PMID: 19428329
substance P; neurokinin A; primary afferent neuron; skin; macrophage; myofibroblast
9.  Multi-modal-analgesia for pain management after Hallux Valgus surgery: a prospective randomised study on the effect of ankle block 
Pain and emesis are the two major complaints after day case surgery. Local anaesthesia has become an important part of optimizing intra and post-operative pain treatment, but is sometimes not entirely sufficient. The aim of the present study was to study the effect of adding an ankle block to a multi-modal analgesic approach on the first 24-hour-need for rescue analgesia in patients undergoing elective Hallux Valgus surgery.
Type of study
Prospective, randomized patient-blind study comparing ankle block with levo-bupivacaine, lidocaine and Saline placebo control.
Ninety patients were studied comparing ankle block (15 cc) using levo-bupivacaine 2.5 mg/ml, lidocaine 10 mg/ml or placebo (saline) on day-case elective Hallux Valgus surgery, supported by general anaesthesia in all cases. Primary study endpoint was number of patient's requiring oral analgesics during the first 24 post-operative hours.
Ankle block had no effect on need for rescue analgesia and pain ratings during the 1st 24 postoperative hours, there was no difference seen between placebo and any of the two active local anaesthesia studied. The only differences seen was that both lidocaine and levo-bupivacaine reduced the intra-operative need for anaesthetic (sevoflurane) and that levo-bupivacaine patients had a lower need as compared to the lidocaine patients for oral analgesics during the afternoon of surgery.
Adding a single shot ankle block to a multi-modal pain management strategy reduces the need for intra-operative anaesthesia but has no major impact of need of rescue analgesics or pain during the first 24-hour after surgery.
PMCID: PMC2175499  PMID: 18088436
10.  Ala42S100A8 Ameliorates Psychological-Stress Impaired Cutaneous Wound Healing 
Brain, behavior, and immunity  2009;23(6):755-759.
Although wound healing is generally a successful, carefully orchestrated and evolutionary sound process, it can be disregulated by extrinsic factors such as psychological stress. In the SKH-1 restraint stress model of cutaneous wound healing, the rate of wound closure is approximately 30% slower in stressed mice. Delay in healing is associated with exaggerated acute inflammation and deficient bacterial clearance at the wound site. It has been suggested that wound hypoxia may contribute to the mechanisms of impaired cutaneous wound healing in the mouse SKH-1 model.
Optimal healing of a cutaneous wound is a stepwise repair program. In its early phase, an inflammatory oxidative burst generated by neutrophils is observed. 40% of neutrophils cytosolic protein weight is comprised of two calcium binding proteins S100A8 and S100A9. Our previous work has shown that S100A8 act as an oxidation sensitive repellent of human neutrophils in-vitro. Ala42S100A8, a site-directed mutant protein is resistant to oxidative inhibition and inhibits neutrophil recruitment in-vivo.
Accordingly, we tested the hypothesis that S100A8 may ameliorate wound healing in this model. We examined the effect of wild type and ala42S100A8 for their ability to ameliorate wound closure rates. The data indicated that a single local application of ala42S100A8 ameliorated the decreased rate of wound closure resulting from stress. This occurred without significantly affecting wound bacterial clearance. Wild type S100A8 only had a partial beneficial effect on the rate of wound closure. Those findings support further translational studies of S100 based intervention to ameliorate impaired wound healing.
PMCID: PMC2710400  PMID: 19336252
Wound healing; calprotectin; S100A8; oxidation; psychological stress; neutrophils; bacterial clearance; cutaneous; translational
11.  MMP-8 overexpression and persistence of neutrophils relate to stress-impaired healing and poor collagen architecture in mice 
Brain, behavior, and immunity  2012;28:10.1016/j.bbi.2012.10.016.
Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) are critical for tissue remodeling during wound repair. Psychological stress has been found to impair wound healing in humans and animals. The objective of this study was to assess MMP and TIMP gene expression during stress-impaired healing. Female SKH-1 mice (n = 299) were divided into control and stress groups (13 h restraint/day for 3 days prior to and 5 days post-wounding). Two 3.5 mm cutaneous full-thickness wounds were placed on the dorsum of each mouse and wound measurements were performed daily. RTPCR for gene expression of MMP-2, MMP-8, MMP-9, TIMP-1 and TIMP-2 was performed at days 1, 3 and 5. Immunohistochemical analyses of the healed wounds were performed at days 15 and 28. As expected, wounds healed more slowly in restraint-stressed mice compared to controls. Stressed mice exhibited MMP-8 overexpression and lower TIMP-1 levels during healing, and poorer collagen organization once healed. MMP-8 overexpression may have stemmed from a higher level of neutrophils, observed in wound tissue on days 3 and 5. These findings implicate higher neutrophil numbers, MMP-8 overexpression, and TIMP-1 under-expression, as mechanisms that may compromise wound outcomes such as scarring under conditions of stress.
PMCID: PMC3878435  PMID: 23103444
Wound healing; Psychological stress; Mifepristone; RU486; Collagen; MMP; TIMP; Remodeling; Scarring
12.  p38 MAPK inhibition reduces diabetes-induced impairment of wound healing 
In healthy tissue, a wound initiates an inflammatory response characterized by the presence of a hematoma, infiltration of inflammatory cells into the wound and, eventually, wound healing. In pathological conditions like diabetes mellitus, wound healing is impaired by the presence of chronic nonresolving inflammation. p38 mitogen-activated protein kinase (MAPK) inhibitors have demonstrated anti-inflammatory effects, primarily by inhibiting the expression of inflammatory cytokines and regulating cellular traffic into wounds. The db/db mouse model of type 2 diabetes was used to characterize the time course of expression of activated p38 during impaired wound healing. The p38α-selective inhibitor, SCIO-469, was applied topically and effects on p38 activation and on wound healing were evaluated. A topical dressing used clinically, Promogran™, was used as a comparator. In this study, we established that p38 is phosphorylated on Days 1 to 7 post-wounding in db/db mice. Further, we demonstrated that SCIO-469, at a dose of 10 μg/wound, had a positive effect on wound contraction, granulation tissue formation, and re-epithelialization, and also increased wound maturity during healing. These effects were similar to or greater than those observed with Promogran™. These results suggest a novel approach to prophylactic and therapeutic management of chronic wounds associated with diabetes or other conditions in which healing is impaired.
PMCID: PMC3048002  PMID: 21437122
p38 MAPK ihibition; diabetic wound healing; db/db mouse; nonresolving healing; Promogran™
13.  Therapy of acute wounds with water-filtered infrared-A (wIRA) 
Water-filtered infrared-A (wIRA) as a special form of heat radiation with a high tissue penetration and with a low thermal load to the skin surface acts both by thermal and thermic as well as by non-thermal and non-thermic effects. wIRA produces a therapeutically usable field of heat in the tissue and increases tissue temperature, tissue oxygen partial pressure, and tissue perfusion. These three factors are decisive for a sufficient tissue supply with energy and oxygen and consequently as well for wound healing and infection defense.
wIRA can considerably alleviate the pain (with remarkably less need for analgesics) and diminish an elevated wound exudation and inflammation and can show positive immunomodulatory effects. wIRA can advance wound healing or improve an impaired wound healing both in acute and in chronic wounds including infected wounds. Even the normal wound healing process can be improved.
A prospective, randomized, controlled, double-blind study with 111 patients after major abdominal surgery at the University Hospital Heidelberg, Germany, showed with 20 minutes irradiation twice a day (starting on the second postoperative day) in the group with wIRA and visible light VIS (wIRA(+VIS), approximately 75% wIRA, 25% VIS) compared to a control group with only VIS a significant and relevant pain reduction combined with a markedly decreased required dose of analgesics: during 230 single irradiations with wIRA(+VIS) the pain decreased without any exception (median of decrease of pain on postoperative days 2-6 was 13.4 on a 100 mm visual analog scale VAS 0-100), while pain remained unchanged in the control group (p<0.001). The required dose of analgesics was 57-70% lower in the subgroups with wIRA(+VIS) compared to the control subgroups with only VIS (median 598 versus 1398 ml ropivacaine, p<0.001, for peridural catheter analgesia; 31 versus 102 mg piritramide, p=0.001, for patient-controlled analgesia; 3.4 versus 10.2 g metamizole, p=0.005, for intravenous and oral analgesia). During irradiation with wIRA(+VIS) the subcutaneous oxygen partial pressure rose markedly by approximately 30% and the subcutaneous temperature by approximately 2.7°C (both in a tissue depth of 2 cm), whereas both remained unchanged in the control group: after irradiation the median of the subcutaneous oxygen partial pressure was 41.6 (with wIRA) versus 30.2 mm Hg in the control group (p<0.001), the median of the subcutaneous temperature was 38.9 versus 36.4°C (p<0.001). The overall evaluation of the effect of irradiation, including wound healing, pain and cosmesis, assessed on a VAS (0-100 with 50 as indifferent point of no effect) by the surgeon (median 79.0 versus 46.8, p<0.001) or the patient (79.0 versus 50.2, p<0.001) was markedly better in the group with wIRA compared to the control group. This was also true for single aspects: Wound healing assessed on a VAS by the surgeon (median 88.6 versus 78.5, p<0.001) or the patient (median 85.8 versus 81.0, p=0.040, trend) and cosmetic result assessed on a VAS by the surgeon (median 84.5 versus 76.5, p<0.001) or the patient (median 86.7 versus 73.6, p=0.001). In addition there was a trend in favor of the wIRA group to a lower rate of total wound infections (3 of 46, approximately 7%, versus 7 of 48, approximately 15%, p=0.208) including late infections after discharge, caused by the different rate of late infections after discharge: 0 of 46 in the wIRA group and 4 of 48 in the control group. And there was a trend towards a shorter postoperative hospital stay: 9 days in the wIRA group versus 11 days in the control group (p=0.037). The principal finding of this study was that postoperative irradiation with wIRA can improve even a normal wound healing process.
A prospective, randomized, controlled, double-blind study with 45 severely burned children at the Children’s Hospital Park Schönfeld, Kassel, Germany, showed with 30 minutes irradiation once a day (starting on the first day, day of burn as day 1) in the group with wIRA and visible light VIS (wIRA(+VIS), approximately 75% wIRA, 25% VIS) compared to a control group with only VIS a markedly faster reduction of wound size. On the fifth day (after 4 days with irradiation) decision was taken, whether surgical debridement of necrotic tissue was necessary because of deeper (second degree, type b) burns (11 of 21 in the group with wIRA, 14 of 24 in the control group) or non-surgical treatment was possible (second degree, type a, burns). The patients treated conservatively were kept within the study and irradiated till complete reepithelialization. The patients in the group with wIRA showed a markedly faster reduction of wound area: a median reduction of wound size of 50% was reached already after 7 days compared to 9 days in the control group, a median reduction of wound size of 90% was already achieved after 9 days compared to 13 days in the control group. In addition the group with wIRA showed superior results till 3 months after the burn in terms of the overall surgical assessment of the wound, cosmesis, and assessment of effects of irradiation compared to the control group.
In a prospective, randomized, controlled study with 12 volunteers at the University Medical Center Charité, Berlin, Germany, within each volunteer 4 experimental superficial wounds (5 mm diameter) as an acute wound model were generated by suction cup technique, removing the roof of the blister with a scalpel and a sterile forceps (day 1). 4 different treatments were used and investigated during 10 days: no therapy, only wIRA(+VIS) (approximately 75% wIRA, 25% VIS; 30 minutes irradiation once a day), only dexpanthenol (= D-panthenol) cream once a day, wIRA(+VIS) and dexpanthenol cream once a day. Healing of the small experimental wounds was from a clinical point of view excellent with all 4 treatments. Therefore there were only small differences between the treatments with slight advantages of the combination wIRA(+VIS) and dexpanthenol cream and of dexpanthenol cream alone concerning relative change of wound size and assessment of feeling of the wound area. However laser scanning microscopy with a scoring system revealed differences between the 4 treatments concerning the formation of the stratum corneum (from first layer of corneocytes to full formation) especially on the days 5-7: fastest formation of the stratum corneum was seen in wounds treated with wIRA(+VIS) and dexpanthenol cream, second was wIRA(+VIS) alone, third dexpanthenol cream alone and last were untreated wounds. Bacterial counts of the wounds (taken every 2 days) showed, that wIRA(+VIS) and the combination of wIRA(+VIS) with dexpanthenol cream were able to inhibit the colonisation with physiological skin flora up to day 5 when compared with the two other groups (untreated group and group with dexpanthenol cream alone). At any investigated time, the amount of colonisation under therapy with wIRA(+VIS) alone was lower (interpreted as more suppressed) compared with the group with wIRA(+VIS) and dexpanthenol cream.
During rehabilitation after hip and knee endoprosthetic operations the resorption of wound seromas and wound hematomas was both clinically and sonographically faster and pain was reduced by irradiation with wIRA(+VIS).
wIRA can be used successfully for persistent postoperative pain e.g. after thoracotomy.
As perspectives for wIRA it seems clinically prudent to use wIRA both pre- and postoperatively, e.g. in abdominal and thoracic operations. wIRA can be used preoperatively (e.g. during 1-2 weeks) to precondition donor and recipient sites of skin flaps, transplants or partial-thickness skin grafts, and postoperatively to improve wound healing and to decrease pain, inflammation and infections at all mentioned sites. wIRA can be used to support routine pre- or intraoperative antibiotic administration or it might even be discussed to replace this under certain conditions by wIRA.
PMCID: PMC2831241  PMID: 20204084
water-filtered infrared-A (wIRA); wound healing; acute wounds; prospective, randomized, controlled, double-blind studies; reduction of pain; problem wounds; wound infections; infection defense; wound exudation; inflammation; thermal and non-thermal effects; thermic and non-thermic effects; energy supply; oxygen supply; tissue oxygen partial pressure; tissue temperature; tissue blood flow; visual analog scales (VAS); quality of life
14.  Improved diabetic wound healing through topical silencing of p53 is associated with augmented vasculogenic mediators 
Diabetes is characterized by several poorly understood phenomena including dysfunctional wound healing and impaired vasculogenesis. P53, a master cell cycle regulator, is upregulated in diabetic wounds and has recently been shown to play regulatory roles in vasculogenic pathways. We have previously described a novel method to topically silence target genes in a wound bed with siRNA. We hypothesized that silencing p53 results in improved diabetic wound healing and augmentation of vasculogenic mediators. Paired 4-mm stented wounds were created on diabetic db/db mice. Topically applied p53 siRNA, evenly distributed in an agarose matrix, was applied to wounds at post-wound day 1 and 7 (matrix alone and nonsense siRNA served as controls). Animals were sacrificed at post-wound days 10 and 24. Wound time to closure was photometrically assessed, and wounds were harvested for histology, immunohistochemistry, and immunofluorescence. Vasculogenic cytokine expression was evaluated via western blot, RT-PCR, and ELISA. ANOVA/t-test was used to determine significance (p<=0.05). Local p53 silencing resulted in faster wound healing with wound closure at 18 ± 1.3d in the treated group versus 28 ± 1.0d in controls. The treated group demonstrated improved wound architecture at each time point while demonstrating near complete local p53 knockdown. Moreover, treated wounds showed a 1.92 fold increase in CD31 endothelial cell staining over controls. Western blot analysis confirmed near complete p53 knockdown in treated wounds. At day 10, VEGF secretion (ELISA) was significantly increased in treated wounds (109.3 ± 13.9 pg/ml) versus controls (33.0 ± 3.8 pg/ml) while RT-PCR demonstrated a 1.86 fold increase in SDF-1 expression in treated wounds versus controls. This profile was reversed after treated wounds healed and prior to closure of controls (day 24). Augmented vasculogenic cytokine profile and endothelial cell markers are associated with improved diabetic wound healing in topical gene therapy with p53 siRNA.
PMCID: PMC3145486  PMID: 20955346
siRNA; wound; diabetes; p53
15.  Wound Administration of M2-Polarized Macrophages Does Not Improve Murine Cutaneous Healing Responses 
PLoS ONE  2014;9(7):e102994.
Macrophages play a crucial role in all stages of cutaneous wound healing responses and dysregulation of macrophage function can result in derailed wound repair. The phenotype of macrophages is influenced by the wound microenvironment and evolves during healing from a more pro-inflammatory (M1) profile in early stages, to a less inflammatory pro-healing (M2) phenotype in later stages of repair. The aim of the current study was to investigate the potential of exogenous administration of M2 macrophages to promote wound healing in an experimental mouse model of cutaneous injury. Bone marrow derived macrophages were stimulated in-vitro with IL-4 or IL-10 to obtain two different subsets of M2-polarized cells, M2a or M2c respectively. Polarized macrophages were injected into full-thickness excisional skin wounds of either C57BL/6 or diabetic db/db mice. Control groups were injected with non-polarized (M0) macrophages or saline. Our data indicate that despite M2 macrophages exhibit an anti-inflammatory phenotype in-vitro, they do not improve wound closure in wild type mice while they delay healing in diabetic mice. Examination of wounds on day 15 post-injury indicated delayed re-epithelialization and persistence of neutrophils in M2 macrophage treated diabetic wounds. Therefore, topical application of ex-vivo generated M2 macrophages is not beneficial and contraindicated for cell therapy of skin wounds.
PMCID: PMC4113363  PMID: 25068282
16.  Heme Oxygenase-1 Accelerates Cutaneous Wound Healing in Mice 
PLoS ONE  2009;4(6):e5803.
Heme oxygenase-1 (HO-1), a cytoprotective, pro-angiogenic and anti-inflammatory enzyme, is strongly induced in injured tissues. Our aim was to clarify its role in cutaneous wound healing. In wild type mice, maximal expression of HO-1 in the skin was observed on the 2nd and 3rd days after wounding. Inhibition of HO-1 by tin protoporphyrin-IX resulted in retardation of wound closure. Healing was also delayed in HO-1 deficient mice, where lack of HO-1 could lead to complete suppression of reepithelialization and to formation of extensive skin lesions, accompanied by impaired neovascularization. Experiments performed in transgenic mice bearing HO-1 under control of keratin 14 promoter showed that increased level of HO-1 in keratinocytes is enough to improve the neovascularization and hasten the closure of wounds. Importantly, induction of HO-1 in wounded skin was relatively weak and delayed in diabetic (db/db) mice, in which also angiogenesis and wound closure were impaired. In such animals local delivery of HO-1 transgene using adenoviral vectors accelerated the wound healing and increased the vascularization. In summary, induction of HO-1 is necessary for efficient wound closure and neovascularization. Impaired wound healing in diabetic mice may be associated with delayed HO-1 upregulation and can be improved by HO-1 gene transfer.
PMCID: PMC2686151  PMID: 19495412
17.  The alarmin HMGB-1 influences healing outcomes in fetal skin wounds 
In mice, cutaneous wounds generated early in development (embryonic day 15, E15) heal scarlessly, while wounds generated late in gestation (embryonic day 18, E18) heal with scar formation. Even though both types of wounds are generated in the same sterile uterine environment, scarless fetal wounds heal without inflammation but a strong inflammatory response is observed in scar-forming fetal wounds. We hypothesized that altered release of alarmins, endogenous molecules that trigger inflammation in response to damage, may be responsible for the age-related changes in inflammation and healing outcomes in fetal skin. The purpose of this study was to determine whether the alarmin high-mobility group box -1 (HMGB-1) is involved in fetal wound repair. Immunohistochemical analysis showed that in unwounded skin, E18 keratinocytes expressed higher levels of HMGB-1 compared to E15 keratinocytes. After injury, HMGB-1 was released to a greater extent from keratinocytes at the margin of scar-forming E18 wounds compared to scarless E15 wounds. Furthermore, instead of healing scarlessly, E15 wounds healed with scars when treated with HMGB-1. HMGB-1-injected wounds also had more fibroblasts, blood vessels, and macrophages compared to control wounds. Together, these data suggest that extracellular HMGB-1 levels influence the quality of healing in cutaneous wounds.
PMCID: PMC3594575  PMID: 23438257
alarmins; Damage associated molecular patterns (DAMPs); danger signals; fetal wound healing; high-mobility group box-1 (HMGB-1); scarless repair; skin
18.  Elevation of hemopexin-like fragment of matrix metalloproteinase-2 tissue levels inhibits ischemic wound healing and angiogenesis 
Journal of Vascular Surgery  2011;54(5):1430-1438.
Matrix metalloproteinase-2 (MMP-2) degrades type IV collagen and enables endothelial cell (EC) migration during angiogenesis and wound healing. PEX2 is a byproduct of activated MMP-2 autocatalysis and competitively inhibits newly activated MMP-2 from EC surface binding and migration. We hypothesize that PEX2 is elevated during limb ischemia, contributing to poor wound healing by interfering with angiogenesis. We aim to identify elevated PEX2 in ischemic murine hindlimb muscle and demonstrate poor healing with decreased capillary density.
Western blot was used to identify PEX2 in hindlimbs of FVB/NJ mice with surgically induced ischemia. The PEX2 effect on healing was evaluated by calculating area of exposed muscle after wounding the dorsum of mice and performing daily injections with recombinant PEX2 (hrPEX2). Additionally, wounds were injected with lentivirus expressing PEX2 (PEX2-LV), harvested on post operative day 7 (POD 7), fixed and sectioned for staining with hematoxylin and eosin (H&E). Epithelial gap was assessed with light microscopy. Capillary density was evaluated after wounding Tie2-GFP+ transgenic FVB mice (ECs labeled green) and viral transduction with PEX2-LV. Wounds were harvested on POD 7, frozen in liquid nitrogen, sectioned and stained with Hoechst. Vessel density was assessed via fluorescence microscopy as average number of capillaries per ten high powered fields (HPF). Paired Student’s t-test was used to assess differences between the groups.
PEX2 was elevated 5.5-fold (±2.0, P= .005) on POD 2 and 2.9-fold (±0.69, P= .004) on POD 4 in gastrocnemius muscles of ischemic hindlimbs. The wound surface area, or lack of granulation tissue and exposed muscle, decreased daily in all mice, but was greater in the hrPEX mice by 12% to 16% (P< .004). Wounds in the control group were completely covered with granulation tissue by POD 3, whereas wounds injected with hrPEX2 were not completely covered by POD 7, but continued to have exposed muscle. Microscopic examination of wounds after PEX2-LV viral transduction, demonstrated an average epithelial gap of 1.6±0.3μm versus 0.64±0.3 μm in control wounds (P< .04). Wounds from Tie-2-GFP mice had an average number of 3.8±1.1 capillaries versus 6.9±1.2 in control wounds (P< .007).
Our study is the first report linking elevated PEX2 to ischemia and poor wound healing. We demonstrate comparative PEX2 elevation in ischemic murine hindlimbs. Wounds subjected to hrPEX2 or viral transduction with PEX2-LV produce less granulation tissue and retarded healing. Microscopic evaluation of the wounds exhibit fewer capillaries, supporting the hypothesis that PEX2 decreases angiogenesis.
PMCID: PMC3384519  PMID: 21903356
19.  Sex Hormones and Mucosal Wound Healing 
Brain, behavior, and immunity  2008;23(5):629-635.
Wound healing studies, which have chiefly examined dermal tissues, have reported a female advantage in healing rates. Recently our laboratory demonstrated women heal mucosal wounds more slowly than men. We hypothesized sex hormones influence wound healing rates, possibly through their modulating effects on inflammation. This study involved 329 younger subjects aged 18-43 (165 women, 164 men) and 93 older subjects aged 50-88 (60 women, 33 men). A 3.5mm diameter wound was created on the hard oral palate and videographed daily to assess wound closure. Blood collected at the time of wounding was used to assess circulating testosterone, progesterone and estradiol levels, and in vitro cytokine production in response to LPS. No strong associations were observed between healing times and estradiol or progesterone levels. However, in younger subjects, lower testosterone levels related to faster wound closure. Conversely, in older women higher testosterone levels related to 1) lower inflammatory responses; and 2) faster healing times. No such relationships were seen in older men, or in women taking oral contraceptives or hormone replacement therapy [HRT]. Older women (50-54 years) not yet experiencing menopause healed similarly to younger women and dissimilarly from age-matched post-menopausal women. This suggests that the deleterious effects of aging on wound healing occur secondary to the effects of menopause. Supporting this, there was evidence in post-menopausal women that HRT augmented wound closure. Overall, this study suggests that human mucosal healing rates are modulated by testosterone levels. Based upon when between-group differences were observed, testosterone may impact upon the proliferative phase of healing which involves immune processes such as re-epithelialization and angiogenesis.
PMCID: PMC2746088  PMID: 19111925
Testosterone; estradiol; progesterone; follicular; luteal; menopause; inflammation; cytokines; aging; menstrual cycle
20.  Low-Intensity Vibration Improves Angiogenesis and Wound Healing in Diabetic Mice 
PLoS ONE  2014;9(3):e91355.
Chronic wounds represent a significant health problem, especially in diabetic patients. In the current study, we investigated a novel therapeutic approach to wound healing – whole body low-intensity vibration (LIV). LIV is anabolic for bone, by stimulating the release of growth factors, and modulating stem cell proliferation and differentiation. We hypothesized that LIV improves the delayed wound healing in diabetic mice by promoting a pro-healing wound environment. Diabetic db/db mice received excisional cutaneous wounds and were subjected to LIV (0.4 g at 45 Hz) for 30 min/d or a non-vibrated sham treatment (controls). Wound tissue was collected at 7 and 15 d post-wounding and wound healing, angiogenesis, growth factor levels and wound cell phenotypes were assessed. LIV increased angiogenesis and granulation tissue formation at day 7, and accelerated wound closure and re-epithelialization over days 7 and 15. LIV also reduced neutrophil accumulation and increased macrophage accumulation. In addition, LIV increased expression of pro-healing growth factors and chemokines (insulin-like growth factor-1, vascular endothelial growth factor and monocyte chemotactic protein-1) in wounds. Despite no evidence of a change in the phenotype of CD11b+ macrophages in wounds, LIV resulted in trends towards a less inflammatory phenotype in the CD11b− cells. Our findings indicate that LIV may exert beneficial effects on wound healing by enhancing angiogenesis and granulation tissue formation, and these changes are associated with increases in pro-angiogenic growth factors.
PMCID: PMC3950202  PMID: 24618702
21.  Negative Pressure Wound Therapy 
Executive Summary
This review was conducted to assess the effectiveness of negative pressure wound therapy.
Clinical Need: Target Population and Condition
Many wounds are difficult to heal, despite medical and nursing care. They may result from complications of an underlying disease, like diabetes; or from surgery, constant pressure, trauma, or burns. Chronic wounds are more often found in elderly people and in those with immunologic or chronic diseases. Chronic wounds may lead to impaired quality of life and functioning, to amputation, or even to death.
The prevalence of chronic ulcers is difficult to ascertain. It varies by condition and complications due to the condition that caused the ulcer. There are, however, some data on condition-specific prevalence rates; for example, of patients with diabetes, 15% are thought to have foot ulcers at some time during their lives. The approximate community care cost of treating leg ulcers in Canada, without reference to cause, has been estimated at upward of $100 million per year.
Surgically created wounds can also become chronic, especially if they become infected. For example, the reported incidence of sternal wound infections after median sternotomy is 1% to 5%. Abdominal surgery also creates large open wounds. Because it is sometimes necessary to leave these wounds open and allow them to heal on their own (secondary intention), some may become infected and be difficult to heal.
Yet, little is known about the wound healing process, and this makes treating wounds challenging. Many types of interventions are used to treat wounds.
Current best practice for the treatment of ulcers and other chronic wounds includes debridement (the removal of dead or contaminated tissue), which can be surgical, mechanical, or chemical; bacterial balance; and moisture balance. Treating the cause, ensuring good nutrition, and preventing primary infection also help wounds to heal. Saline or wet-to-moist dressings are reported as traditional or conventional therapy in the literature, although they typically are not the first line of treatment in Ontario. Modern moist interactive dressings are foams, calcium alginates, hydrogels, hydrocolloids, and films. Topical antibacterial agents—antiseptics, topical antibiotics, and newer antimicrobial dressings—are used to treat infection.
The Technology Being Reviewed
Negative pressure wound therapy is not a new concept in wound therapy. It is also called subatmospheric pressure therapy, vacuum sealing, vacuum pack therapy, and sealing aspirative therapy.
The aim of the procedure is to use negative pressure to create suction, which drains the wound of exudate (i.e., fluid, cells, and cellular waste that has escaped from blood vessels and seeped into tissue) and influences the shape and growth of the surface tissues in a way that helps healing. During the procedure, a piece of foam is placed over the wound, and a drain tube is placed over the foam. A large piece of transparent tape is placed over the whole area, including the healthy tissue, to secure the foam and drain the wound. The tube is connected to a vacuum source, and fluid is drawn from the wound through the foam into a disposable canister. Thus, the entire wound area is subjected to negative pressure. The device can be programmed to provide varying degrees of pressure either continuously or intermittently. It has an alarm to alert the provider or patient if the pressure seal breaks or the canister is full.
Negative pressure wound therapy may be used for patients with chronic and acute wounds; subacute wounds (dehisced incisions); chronic, diabetic wounds or pressure ulcers; meshed grafts (before and after); or flaps. It should not be used for patients with fistulae to organs/body cavities, necrotic tissue that has not been debrided, untreated osteomyelitis, wound malignancy, wounds that require hemostasis, or for patients who are taking anticoagulants.
Review Strategy
The inclusion criteria were as follows:
Randomized controlled trial (RCT) with a sample size of 20 or more
Human study
Published in English
Summary of Findings
Seven international health technology assessments on NPWT were identified. Included in this list of health technology assessments is the original health technology review on NPWT by the Medical Advisory Secretariat from 2004. The Medical Advisory Secretariat found that the health technology assessments consistently reported that NPWT may be useful for healing various types of wounds, but that its effectiveness could not be empirically quantified because the studies were poorly done, the patient populations and outcome measures could not be compared, and the sample sizes were small.
Six RCTs were identified that compared NPWT to standard care. Five of the 6 studies were of low or very low quality according to Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. The low and very low quality RCTs were flawed owing to small sample sizes, inconsistent reporting of results, and patients lost to follow-up. The highest quality study, which forms the basis of this health technology policy assessment, found that:
There was not a statistically significant difference (≥ 20%) between NPWT and standard care in the rate of complete wound closure in patients who had complete wound closure but did not undergo surgical wound closure (P = .15).
The authors of this study did not report the length of time to complete wound closure between NPWT and standard care in patients who had complete wound closure but who did not undergo surgical wound closure
There was no statistically significant difference (≥ 20%) in the rate of secondary amputations between the patients that received NPWT and those that had standard care (P = .06)
There may be an increased risk of wound infection in patients that receive NPWT compared with those that receive standard care.
Based on the evidence to date, the clinical effectiveness of NPWT to heal wounds is unclear. Furthermore, saline dressings are not standard practice in Ontario, thereby rendering the literature base irrelevant in an Ontario context. Nonetheless, despite the lack of methodologically sound studies, NPWT has diffused across Ontario.
Discussions with Ontario clinical experts have highlighted some deficiencies in the current approach to wound management, especially in the community. Because NPWT is readily available, easy to administer, and may save costs, compared with multiple daily conventional dressing changes, it may be used inappropriately. The discussion group highlighted the need to put in place a coordinated, multidisciplinary strategy for wound care in Ontario to ensure the best, continuous care of patients.
PMCID: PMC3379164  PMID: 23074484
22.  Local Toxicity from Local Anesthetic Polymeric Microparticles 
Anesthesia and analgesia  2013;116(4):794-803.
Local tissue injury from sustained release formulations for local anesthetics can be severe. There is considerable variability in reporting of that injury. We investigated the influence of the intrinsic myotoxicity of the encapsulated local anesthetic (lidocaine, low; bupivacaine, high) on tissue reaction in rats.
Cytotoxicity from a range of lidocaine and bupivacaine concentrations was measured in C2C12 myotubes over 6 days. Rats were given sciatic nerve blocks with 4 microparticulate formulations of lidocaine and bupivacaine: 10% (w/w) lidocaine poly-lactic-co-glycolic acid (PLGA), 10% (w/w) bupivacaine PLGA, 50% (w/w) lidocaine PLGA, and 50% (w/w) bupivacaine PLGA. Effectiveness of nerve blockade was assessed by a modified hotplate test and weight-bearing measurements. Myotoxicity was scored in histologic sections of injection sites. Bupivacaine and lidocaine release kinetics from the particles were measured.
Median sensory blockade duration for 50% (w/w) lidocaine was 255 (90–540) min versus 840 (277–1215) min for 50% (w/w) bupivacaine (P=0.056). All microparticulate formulations resulted in myotoxicity. The choice of local anesthetic did not influence the severity of myotoxicity. Median myotoxicity scores for 50% (w/w) lidocaine compared to 50% (w/w) bupivacaine at 4 days was 3.4 (2.1–4.2) vs. 3.3 (2.9–3.5)(P=0.44) and at 14 days 1.9 (1.8–2.4) versus 1.7 (1.3–1.9)(P=0.23) respictively.
Lidocaine and bupivacaine PLGA microspheres resulted in similar degrees of myotoxicity, irrespective of drug loading. Intrinsic myotoxicity did not predict tissue injury from sustained release of these anesthetics. Caution is warranted in the use of such devices near muscle and nerve.
PMCID: PMC3606664  PMID: 23460564
23.  Plasminogen initiates and potentiates the healing of acute and chronic tympanic membrane perforations in mice 
Most tympanic membrane (TM) perforations heal spontaneously, but approximately 10-20% remain open as chronic TM perforations. Chronic perforations can lead to an impaired hearing ability and recurrent middle ear infections. Traditionally, these perforations must be surgically closed, which is costly and time consuming. Therefore, there is a need for simpler therapeutic strategies. Previous studies by us have shown that plasminogen (plg) is a potent pro-inflammatory regulator that accelerates cutaneous wound healing in mice. We have also shown that the healing of TM perforations is completely arrested in plg-deficient (plg-/-) mice and that these mice develop chronic TM perforations. In the present study, we investigated the therapeutic potential of local plg injection in acute and chronic TM perforation mice models.
Plg-/- mice and wild-type mice were subjected to standardized TM perforations followed by local injection of plg into the soft tissue surrounding the TM. TM perforations with chronic characteristics were induced by leaving TM perforations in plg-/- mice untreated for 9 days before treatment. The healing process was observed through otomicroscope and finally confirmed by immunostaining. The quality of TM healing was evaluated based on the morphology of the TM.
Daily local injections of plg into the soft tissue surrounding the TM restored the ability to heal TM perforations in plg-/- mice in a dose-dependent manner, and potentiated the healing rate and quality in wild-type mice. A single local injection of plg initiated the healing of the chronic-like TM perforations in these mice, resulting in a closed TM with a continuous but rather thick outer keratinocyte layer. However, three plg injections led to a completely healed TM with a thin keratinizing squamous epithelium covering a connective tissue layer.
Our data suggests that plg is a promising drug candidate for the treatment of chronic TM perforations in humans.
PMCID: PMC3895791  PMID: 24393366
Plasminogen; Wound healing; Tympanic membrane perforations
24.  Management of Chronic Pressure Ulcers 
Executive Summary
In April 2008, the Medical Advisory Secretariat began an evidence-based review of the literature concerning pressure ulcers.
Please visit the Medical Advisory Secretariat Web site, to review these titles that are currently available within the Pressure Ulcers series.
Pressure ulcer prevention: an evidence based analysis
The cost-effectiveness of prevention strategies for pressure ulcers in long-term care homes in Ontario: projections of the Ontario Pressure Ulcer Model (field evaluation)
Management of chronic pressure ulcers: an evidence-based analysis
The Medical Advisory Secretariat (MAS) conducted a systematic review on interventions used to treat pressure ulcers in order to answer the following questions:
Do currently available interventions for the treatment of pressure ulcers increase the healing rate of pressure ulcers compared with standard care, a placebo, or other similar interventions?
Within each category of intervention, which one is most effective in promoting the healing of existing pressure ulcers?
A pressure ulcer is a localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in conjunction with shear and/or friction. Many areas of the body, especially the sacrum and the heel, are prone to the development of pressure ulcers. People with impaired mobility (e.g., stroke or spinal cord injury patients) are most vulnerable to pressure ulcers. Other factors that predispose people to pressure ulcer formation are poor nutrition, poor sensation, urinary and fecal incontinence, and poor overall physical and mental health.
The prevalence of pressure ulcers in Ontario has been estimated to range from a median of 22.1% in community settings to a median of 29.9% in nonacute care facilities. Pressure ulcers have been shown to increase the risk of mortality among geriatric patients by as much as 400%, to increase the frequency and duration of hospitalization, and to decrease the quality of life of affected patients. The cost of treating pressure ulcers has been estimated at approximately $9,000 (Cdn) per patient per month in the community setting. Considering the high prevalence of pressure ulcers in the Ontario health care system, the total cost of treating pressure ulcers is substantial.
Wounds normally heal in 3 phases (inflammatory phase, a proliferative phase of new tissue and matrix formation, and a remodelling phase). However, pressure ulcers often fail to progress past the inflammatory stage. Current practice for treating pressure ulcers includes treating the underlying causes, debridement to remove necrotic tissues and contaminated tissues, dressings to provide a moist wound environment and to manage exudates, devices and frequent turning of patients to provide pressure relief, topical applications of biologic agents, and nutritional support to correct nutritional deficiencies. A variety of adjunctive physical therapies are also in use.
Health technology assessment databases and medical databases were searched from 1996 (Medline), 1980 (EMBASE), and 1982 (CINAHL) systematically up to March 2008 to identify randomized controlled trials (RCTs) on the following treatments of pressure ulcers: cleansing, debridement, dressings, biological therapies, pressure-relieving devices, physical therapies, nutritional therapies, and multidisciplinary wound care teams. Full literature search strategies are reported in appendix 1. English-language studies in previous systematic reviews and studies published since the last systematic review were included if they had more than 10 subjects, were randomized, and provided objective outcome measures on the healing of pressure ulcers. In the absence of RCTs, studies of the highest level of evidence available were included. Studies on wounds other than pressure ulcers and on surgical treatment of pressure ulcers were excluded. A total of 18 systematic reviews, 104 RCTs, and 4 observational studies were included in this review.
Data were extracted from studies using standardized forms. The quality of individual studies was assessed based on adequacy of randomization, concealment of treatment allocation, comparability of groups, blinded assessment, and intention-to-treat analysis. Meta-analysis to estimate the relative risk (RR) or weighted mean difference (WMD) for measures of healing was performed when appropriate. A descriptive synthesis was provided where pooled analysis was not appropriate or not feasible. The quality of the overall evidence on each intervention was assessed using the grading of recommendations assessment, development, and evaluation (GRADE) criteria.
Findings from the analysis of the included studies are summarized below:
There is no good trial evidence to support the use of any particular wound cleansing solution or technique for pressure ulcers.
There was no evidence that debridement using collagenase, dextranomer, cadexomer iodine, or maggots significantly improved complete healing compared with placebo.
There were no statistically significant differences between enzymatic or mechanical debridement agents with the following exceptions:
Papain urea resulted in better debridement than collagenase.
Calcium alginate resulted in a greater reduction in ulcer size compared to dextranomer.
Adding streptokinase/streptodornase to hydrogel resulted in faster debridement.
Maggot debridement resulted in more complete debridement than conventional treatment.
There is limited evidence on the healing effects of debridement devices.
Hydrocolloid dressing was associated with almost three-times more complete healing compared with saline gauze.
There is evidence that hydrogel and hydropolymer may be associated with 50% to 70% more complete healing of pressure ulcers than hydrocolloid dressing.
No statistically significant differences in complete healing were detected among other modern dressings.
There is evidence that polyurethane foam dressings and hydrocellular dressings are more absorbent and easier to remove than hydrocolloid dressings in ulcers with moderate to high exudates.
In deeper ulcers (stage III and IV), the use of alginate with hydrocolloid resulted in significantly greater reduction in the size of the ulcers compared to hydrocolloid alone.
Studies on sustained silver-releasing dressing demonstrated a tendency for reducing the risk of infection and promoting faster healing, but the sample sizes were too small for statistical analysis or for drawing conclusions.
Biological Therapies
The efficacy of platelet-derived growth factors (PDGFs), fibroblast growth factor, and granulocyte-macrophage colony stimulating factor in improving complete healing of chronic pressure ulcers has not been established.
Presently only Regranex, a recombinant PDGF, has been approved by Health Canada and only for treatment of diabetic ulcers in the lower extremities.
A March 2008 US Food and Drug Administration (FDA) communication reported increased deaths from cancers in people given three or more prescriptions for Regranex.
Limited low-quality evidence on skin matrix and engineered skin equivalent suggests a potential role for these products in healing refractory advanced chronic pressure ulcers, but the evidence is insufficient to draw a conclusion.
Adjunctive Physical Therapy
There is evidence that electrical stimulation may result in a significantly greater reduction in the surface area and more complete healing of stage II to IV ulcers compared with sham therapy. No conclusion on the efficacy of electrotherapy can be drawn because of significant statistical heterogeneity, small sample sizes, and methodological flaws.
The efficacy of other adjunctive physical therapies [electromagnetic therapy, low-level laser (LLL) therapy, ultrasound therapy, ultraviolet light therapy, and negative pressure therapy] in improving complete closure of pressure ulcers has not been established.
Nutrition Therapy
Supplementation with 15 grams of hydrolyzed protein 3 times daily did not affect complete healing but resulted in a 2-fold improvement in Pressure Ulcer Scale for Healing (PUSH) score compared with placebo.
Supplementation with 200 mg of zinc three times per day did not have any significant impact on the healing of pressure ulcers compared with a placebo.
Supplementation of 500 mg ascorbic acid twice daily was associated with a significantly greater decrease in the size of the ulcer compared with a placebo but did not have any significant impact on healing when compared with supplementation of 10 mg ascorbic acid three times daily.
A very high protein tube feeding (25% of energy as protein) resulted in a greater reduction in ulcer area in institutionalized tube-fed patients compared with a high protein tube feeding (16% of energy as protein).
Multinutrient supplements that contain zinc, arginine, and vitamin C were associated with a greater reduction in the area of the ulcers compared with standard hospital diet or to a standard supplement without zinc, arginine, or vitamin C.
Firm conclusions cannot be drawn because of methodological flaws and small sample sizes.
Multidisciplinary Wound Care Teams
The only RCT suggests that multidisciplinary wound care teams may significantly improve healing in the acute care setting in 8 weeks and may significantly shorten the length of hospitalization. However, since only an abstract is available, study biases cannot be assessed and no conclusions can be drawn on the quality of this evidence.
PMCID: PMC3377577  PMID: 23074533
25.  Effect of Hominis Placenta on cutaneous wound healing in normal and diabetic mice 
Nutrition Research and Practice  2014;8(4):404-409.
The number of diabetic patients has recently shown a rapid increase, and delayed wound healing is a major clinical complication in diabetes. In this study, the wound healing effect of Hominis placenta (HP) treatment was investigated in normal and streptozotocin-induced diabetic mice.
Four full thickness wounds were created using a 4 mm biopsy punch on the dorsum. HP was injected subcutaneously at the middle region of the upper and lower wounds. Wounds were digitally photographed and wound size was measured every other day until the 14th day. Wound closure rate was analyzed using CANVAS 7SE software. Wound tissues were collected on days 2, 6, and 14 after wounding for H/E, immunohistochemistry for FGF2, and Masson's trichrome staining for collagen study.
Significantly faster wound closure rates were observed in the HP treated group than in normal and diabetes control mice on days 6 and 8. Treatment with HP resulted in reduced localization of inflammatory cells in wounded skin at day 6 in normal mice and at day 14 in diabetic mice (P < 0.01). Expression of fibroblast growth factor (FGF) 2 showed a significant increase in the HP treated group on day 14 in both normal (P < 0.01) and diabetic mice (P < 0.05). In addition, HP treated groups showed a thicker collagen layer than no treatment groups, which was remarkable on the last day, day 14, in both normal and diabetic mice.
Taken together, HP treatment has a beneficial effect on acceleration of cutaneous wound healing via regulation of the entire wound healing process, including inflammation, proliferation, and remodeling.
PMCID: PMC4122712  PMID: 25110560
Diabetes; wound; Hominis placenta; inflammation; fibroblast growth factor 2

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