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1.  Differential Regulation of Pericyte Function by the CXC Receptor 3 
Pericytes are mural cell that have been found to play important roles in promoting blood vessel development and regulating blood flow. The signals that attract pericytes to maturing vessels during the resolution phase of wound healing are unknown. In this study, we examine the role of the chemokine receptor CXC receptor 3 (CXCR3) ligands, as they are produced by maturing endothelial cells. Pericytes isolated from muscle and retina were found to by and large only express the B-isoform of CXCR3 (CXCR3B), with expression being independent of the mitotic state of the cells. Pericyte stimulation with the CXCR3 ligands Mig (CXCL9), IP-9/I-TAC (CXCL11) or IP-10 (CXCL10) resulted in the activation of ERK but not AKT. Treatment with Mig or IP-9, but not IP-10, enhanced p38MAPK phosphorylation. Interestingly, while cAMP is generated downstream of CXCR3B in other cells, PKA activation was not observed in these pericytes when treated with these three CXCR3 ligands. The increase in ERK activity resulted in a slight increase in cell transmigration, with the inhibition of ERK leading to a decrease in CXCR3B mediated migration and inhibition of p38MAPK reducing transmigration through small pores. These ligands did not affect proliferation. These data are the first to characterize CXCR3B as the predominant isoform expressed on pericytes, and was found on these diverse cells isolated from both muscle and eye. We also show that CXCR3B signaling stimulates transmigration of barrier pores in pericytes as opposed to its inhibitory affects on endothelial cells and fibroblasts. These findings characterize a novel role for the B-isoform of CXCR3 in regulating cellular function. Taken together these data demonstrate a role for CXCR3B in regulating pericyte function.
PMCID: PMC4662923  PMID: 26207932
pericytes; CXC receptor 3; Erk; AKT; p38MAPK; migration
2.  The murine excisional wound model: Contraction revisited 
Rodent models of healing are considered limited because of the perception that rodent wounds heal by contraction while humans heal by re-epithelialization. The purpose of this report is to present evidence that simple murine excisional wounds provide a valid and reproducible wound model that heals by both contraction and re-epithelialization. Previous studies have shown that, although rodent wounds contract by up to 80%, much of this contraction occurs only after epithelial closure. To confirm these previous findings, we measured re-epithelialization and contraction in three separate mouse strains, (BALB/c, db/+ and db/db); re-epithelialization and contraction each accounted for ~40-60% of the initial closure of full thickness excisional wounds. After closure, the wound continues to contract and this provides the impression of dominant closure by contraction. In conclusion, the simple excisional rodent wound model produces a well-defined and readily identifiable wound bed over which the process of re-epithelialization is clearly measurable.
PMCID: PMC5094847  PMID: 26136050
wound healing; contraction; mouse; skin
3.  Injury, inflammation and the emergence of human‐specific genes 
Wound Repair and Regeneration  2016;24(3):602-606.
In light of the central role of inflammation in normal wound repair and regeneration, we hypothesize that the preponderance of human‐specific genes expressed in human inflammatory cells is commensurate with the genetic versatility of inflammatory response and the emergence of injuries associated with uniquely hominid behaviors, like a bipedal posture and the use of tools, weapons and fire. The hypothesis underscores the need to study human‐specific signaling pathways in experimental models of injury and infers that a selection of human‐specific genes, driven in part by the response to injury, may have facilitated the emergence of multifunctional genes expressed in other tissues.
PMCID: PMC5021143  PMID: 26874655
4.  Use of 16S rRNA sequencing and quantitative PCR to correlate venous leg ulcer bacterial bioburden dynamics with wound expansion, antibiotic therapy, and healing 
Clinical diagnosis of infection in chronic wounds is currently limited to subjective clinical signs and culture-based methods that underestimate the complexity of wound microbial bioburden as revealed by DNA-based microbial identification methods. Here, we use 16S rRNA next generation sequencing and quantitative polymerase chain reaction to characterize weekly changes in bacterial load, community structure, and diversity associated with a chronic venous leg ulcer over the 15-week course of treatment and healing. Our DNA-based methods and detailed sampling scheme reveal that the bacterial bioburden of the wound is unexpectedly dynamic, including changes in the bacterial load and community structure that correlate with wound expansion, antibiotic therapy, and healing. We demonstrate that these multidimensional changes in bacterial bioburden can be summarized using swabs taken prior to debridement, and therefore, can be more easily collected serially than debridement or biopsy samples. Overall, this case illustrates the importance of detailed clinical indicators and longitudinal sampling to determine the pathogenic significance of chronic wound microbial dynamics and guide best use of antimicrobials for improvement of healing outcomes.
PMCID: PMC5007860  PMID: 25902876
5.  Inhibition of Pseudomonas aeruginosa biofilm formation on wound dressings 
Chronic non-healing skin wounds often contain bacterial biofilms that prevent normal wound healing and closure and present challenges to the use of conventional wound dressings. We investigated inhibition of Pseudomonas aeruginosa biofilm formation, a common pathogen of chronic skin wounds, on a commercially available biological wound dressing. Building upon prior reports, we examined whether the amino acid tryptophan would inhibit P. aeruginosa biofilm formation on the 3-dimensional surface of the biological dressing. Bacterial biomass and biofilm polysaccharides were quantified using crystal violet staining or an enzyme linked lectin, respectively. Bacterial cells and biofilm matrix adherent to the wound dressing were visualized through scanning electron microscopy. D-/L-tryptophan inhibited P. aeruginosa biofilm formation on the wound dressing in a dose dependent manner and was not directly cytotoxic to immortalized human keratinocytes although there was some reduction in cellular metabolism or enzymatic activity. More importantly, D-/L-tryptophan did not impair wound healing in a splinted skin wound murine model. Furthermore, wound closure was improved when D-/L-tryptophan treated wound dressing with P. aeruginosa biofilms were compared with untreated dressings. These findings indicate that tryptophan may prove useful for integration into wound dressings to inhibit biofilm formation and promote wound healing.
PMCID: PMC4980578  PMID: 26342168
Biofilm; Wound Dressing; Tryptophan
6.  Pseudomonas aeruginosa uses T3SS to inhibit diabetic wound healing 
Diabetic foot ulcers are responsible for more hospitalizations than any other complication of diabetes. Bacterial infection is recognized as an important factor associated with impaired healing in diabetic ulcers. Pseudomonas aeruginosa is the most frequently detected Gram-negative pathogen in diabetic ulcers. P. aeruginosa infection has been shown to impair healing in diabetic wounds in a manner that correlates with its ability to form biofilm. While the majority of infections in diabetic ulcers are biofilm associated, 33% of infections are nonbiofilm in nature. P. aeruginosa is the most prevalent Gram-negative pathogen in all diabetic wound types, which suggests that the deleterious impact of P. aeruginosa on healing in diabetic wounds goes beyond its ability to form biofilm and likely involves other factors. The Type III Secretion System (T3SS) virulence structure is required for the pathogenesis of all P. aeruginosa clinical isolates, suggesting that it may also play a role in the inhibition of wound repair in diabetic skin ulcers. We evaluated the role of T3SS in mediating P. aeruginosa–induced tissue damage in the wounds of diabetic mice. Our data demonstrate that P. aeruginosa establishes a robust and persistent infection in diabetic wounds independent of its ability to form biofilm and causes severe wound damage in a manner that primarily depends on its T3SS.
PMCID: PMC4690211  PMID: 25912785
7.  Health literacy and diabetic foot ulcer healing 
The adherence by patients to diabetic foot ulcer therapy is often difficult. The goal of this study was to begin to understand how a patient’s health literacy affects their foot ulcer management decisions. Initially using a cross-sectional study design, we evaluated diabetics with foot ulcers within 4 weeks of being asked to participate in a longitudinal study. We assessed health literacy using measures of general health literacy, diabetes health literacy, diabetes self-efficacy, and diabetes numeracy. Individuals enrolled in the study had higher health literacy based on the Short Test of Functional Health Literacy in Adults (33.8 (SD 2.3) versus 27.3 (SD 9.6); p=0.009) as compared to individuals who previously declined an invitation to enroll in the study. Furthermore, patients with lower Short Test of Functional Health Literacy in Adults scores had larger (p=0.04) and older (p=0.125) wounds (markers for poorer prognosis). Other measures of literacy showed similar results. In conclusion, those with diminished health literacy were less likely to enroll in an investigational study and had wounds that were less likely to heal.
PMCID: PMC4519401  PMID: 25923608
8.  Using a continuum model to predict closure time of gaps in intestinal epithelial cell layers 
A two-dimensional continuum model of collective cell migration is used to predict the closure of gaps in intestinal epithelial cell layers. The model assumes cell migration is governed by lamellipodia formation, cell-cell adhesion, and cell-substrate adhesion. Model predictions of the gap edge position and complete gap closure time are compared with experimental measures from cell layer scratch assays (also called scratch wound assays). The goal of the study is to combine experimental observations with mathematical descriptions of cell motion to identify effects of gap shape and area on closure time and to propose a method that uses a simple measure (e.g., area) to predict overall gap closure time early in the closure process. Gap closure time is shown to increase linearly with increasing gap area; however, gaps of equal areas but different aspect ratios differ greatly in healing time. Previous methods that calculate overall healing time according to the absolute or percent change in gap area assume that the gap area changes at a constant rate and typically underestimate gap closure time. In this study, data from scratch assays suggest that the rate of change of area is proportional to the first power or square root power of area.
PMCID: PMC4895899  PMID: 23421747
cell migration; wound healing; intestinal epithelial cells; continuum mechanics mathematical model
9.  Arachidonic acid-derived signaling lipids and functions in impaired healing 
Very little is known about lipid function during wound healing, and much less during impaired healing. Such understanding will help identify what roles lipid signaling plays in the development of impaired/chronic wounds. We took a lipidomics approach to study the alterations in lipid profile in the LIGHT−/− mouse model of impaired healing which has characteristics that resemble those of impaired/chronic wounds in humans, including high levels of oxidative stress, excess inflammation, increased extracellular matrix degradation and blood vessels with fibrin cuffs. The latter suggests excess coagulation and potentially increased platelet aggregation. We show here that in these impaired wounds there is an imbalance in the arachidonic acid (AA) derived eicosonoids that mediate or modulate inflammatory reactions and platelet aggregation. In the LIGHT−/− impaired wounds there is a significant increase in enzymatically derived breakdown products of AA. We found that early after injury there was a significant increase in the eicosanoids 11-, 12-, and 15-hydroxyeicosa-tetranoic acid, and the proinflammatory leukotrienes (LTD4 and LTE) and prostaglandins (PGE2 and PGF2α). Some of these eicosanoids also promote platelet aggregation. This led us to examine the levels of other eicosanoids known to be involved in the latter process. We found that thromboxane (TXA2/B2), and prostacyclins 6kPGF1α are elevated shortly after wounding and in some cases during healing. To determine whether they have an impact in platelet aggregation and hemostasis, we tested LIGHT−/− mouse wounds for these two parameters and found that, indeed, platelet aggregation and hemostasis are enhanced in these mice when compared with the control C57BL/6 mice. Understanding lipid signaling in impaired wounds can potentially lead to development of new therapeutics or in using existing nonsteroidal anti-inflammatory agents to help correct the course of healing.
PMCID: PMC4837701  PMID: 26135854
10.  Hyaluronan enhances wound repair and increases collagen III in aged dermal wounds 
Age-related changes in the extracellular matrix contribute to delayed wound repair in aging. Hyaluronan, a linear nonsulfated glycosaminoglycan, promotes synthesis and assembly of key extracellular matrix components, such as the interstitial collagens, during wound healing. The biological effects of hyaluronan are mediated, in part, by hyaluronan size. We have previously determined that dermal wounds in aged mice, relative to young mice, have deficits in the generation of lower molecular weight hyaluronan (defined as <300 kDa). Here, we tested the effect of exogenous hyaluronan of 2, 250, or 1,000 kDa sizes on full-thickness excisional wounds in aged mice. Only wounds treated with 250 kDa hyaluronan (HA250) were significantly improved over wounds that received carrier (water) alone. Treatment with HA250 was associated with increased expression of transcripts for the hyaluronan receptors CD44 and RHAMM, as well as collagens III and I. Analyses of dermal protein content by mass spectrometry and Western blotting confirmed significantly increased expression of collagen III in wounds treated with HA250 relative to control wounds. In summary, we find that HA250 improves wound repair and increases the synthesis of collagen III in aged dermal wounds.
PMCID: PMC4822517  PMID: 25041621
11.  Clinical Application of Growth Factors and Cytokines in Wound Healing 
Wound healing is a complex and dynamic biological process that involves the coordinated efforts of multiple cell types and is executed and regulated by numerous growth factors and cytokines. There has been a drive in the past two decades to study the therapeutic effects of various growth factors in the clinical management of non-healing wounds (e.g. pressure ulcers, chronic venous ulcers, diabetic foot ulcers). For this review, we conducted a nonline search of Medline and Pub Medical and critically analyzed the literature regarding the role of growth factors and cytokines in the management of these wounds. We focused on currently approved therapies, emerging therapies and future research possibilities. In this review we discuss four growth factors and cytokines currently being used on and off label for the healing of wounds. These include: granulocyte-macrophage colony stimulating factor (GM-CSF), platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF). While the clinical results of using growth factors and cytokines are encouraging, many studies involved a small sample size and are disparate in measured endpoints. Therefore, further research is required to provide definitive evidence of efficacy.
PMCID: PMC4812574  PMID: 24942811
Growth factors; cytokines; wounds
12.  Negative pressure wound therapy limits downgrowth in percutaneous devices 
Maintenance of a soft tissue seal around percutaneous devices is challenged by the downgrowth of periprosthetic tissues—a gateway to potential infection. As negative pressure wound therapy (NPWT) is used clinically to facilitate healing of complex soft tissue pathologies, it was hypothesized that NPWT could limit downgrowth of periprosthetic tissues. To test this hypothesis, 20 hairless guinea pigs were randomly assigned into four groups (n = 5/group). Using a One-Stage (Groups 1 and 3) or a Two-Stage (Groups 2 and 4) surgical procedure, each animal was implanted with a titanium-alloy subdermal device porous-coated with commercially pure, medical grade titanium. Each subdermal device had a smooth titanium-alloy percutaneous post. The One-Stage procedure encompassed insertion of a fully assembled device during a single surgery. The Two-Stage procedure involved the implantation of a subdermal device during the first surgery, and then three weeks later, insertion of a percutaneous post. Groups 1 and 2 served as untreated controls and Groups 3 and 4 received NPWT. Four weeks postimplantation of the post, the devices and surrounding tissues were harvested, and histologically evaluated for downgrowth. Within the untreated control groups, the Two-Stage surgical procedure significantly decreased downgrowth (p = 0.027) when compared with the One-Stage procedure. Independent of the surgical procedures performed, NPWT significantly limited downgrowth (p ≤ 0.05) when compared with the untreated controls.
PMCID: PMC4805517  PMID: 26487170
13.  Postoperative wound dehiscence: predictors and associations 
The Agency for Healthcare Research and Quality (ARHQ) patient safety indicators (PSI) were developed as a metric of hospital complication rates. PSI-14 measures postoperative wound dehiscence and specifically how often a surgical wound in the abdominal or pelvic area fails to heal after abdominopelvic surgery. Wound dehiscence is estimated to occur in 0.5–3.4% of abdominopelvic surgeries, and carries a mortality of up to 40%. Postoperative wound dehiscence has been adopted as a surrogate safety outcome measure since it impacts morbidity, length of stay, healthcare costs and readmission rates. Postoperative wound dehiscence cases from the Nationwide Inpatient Sample demonstrate 9.6% excess mortality, 9.4 days of excess hospitalization and $40,323 in excess hospital charges relative to matched controls.
The purpose of the current study was to investigate the associations between PSI-14 and measurable medical and surgical co-morbidities by using the Explorys technology platform to query electronic health record (EHR) data from a large hospital system serving a diverse patient population in the Washington DC and Baltimore, MD metropolitan areas. The study population included 25,636 eligible patients who had undergone abdominopelvic surgery between January 1, 2008 and December 31, 2012. Of these cases, 786 (2.97%) had post-operative wound dehiscence. Patient-associated co-morbidities were strongly associated with PSI-14, suggesting that this indicator may not solely be an indicator of hospital safety. There was a strong association between PSI-14 and opioid use after surgery and this finding merits further investigation.
PMCID: PMC4587566  PMID: 25683272
Explorys; post-operative wound dehiscence; AHRQ; PSI-14
14.  Healing of Grafted Adipose Tissue: Current Clinical Applications of Adipose-Derived Stem Cells for Breast and Face Reconstruction 
Since their isolation and characterization nearly a decade ago, adipose-derived stem cells (ASCs) have become one of the most popular adult stem cell populations for soft tissue engineering and regenerative medicine applications. Compared to other stem cell sources, ASCs offer several advantages including abundant autologous source, minor invasive harvesting (liposuction), significant proliferative capacity in culture, and multi-lineage potential. In this mini-review, wefocus on some of the more salient published clinical and pre-clinical data to date regarding ASC treatmentfor breast andfacial soft tissue reconstruction.
PMCID: PMC4756904  PMID: 24813358
Adipose derived stem cells; Autologous fat grafting; Cell-assisted lipotransfer; Stem cells; Adipogenesis
15.  Chronic Wound Repair and Healing in Older Adults: Current Status and Future Research 
The incidence of chronic wounds is increased among older adults, and the impact of chronic wounds on quality of life is particularly profound in this population. It is well established that wound healing slows with age. However, the basic biology underlying chronic wounds and the influence of age-associated changes on wound healing are poorly understood. Most studies have used in vitro approaches and various animal models, but observed changes translate poorly to human healing conditions. The impact of age and accompanying multi-morbidity on the effectiveness of existing and emerging treatment approaches for chronic wounds is also unknown, and older adults tend to be excluded from randomized clinical trials. Poorly defined outcomes and variables, lack of standardization in data collection, and variations in the definition, measurement, and treatment of wounds also hamper clinical studies. The Association of Specialty Professors, in conjunction with the National Institute on Aging and the Wound Healing Society, held a workshop, summarized in this paper, to explore the current state of knowledge and research challenges, engage investigators across disciplines, and identify key research questions to guide future study of age-associated changes in chronic wound healing.
PMCID: PMC4414710  PMID: 25486905
chronic wound; pressure ulcer; diabetic foot ulcer; venous leg ulcer; wound repair; wound healing
16.  A Modified Collagen Gel Dressing Promotes Angiogenesis in a Pre-Clinical Swine Model of Chronic Ischemic Wounds 
We recently performed proteomic characterization of a modified collagen gel (MCG) dressing and reported promising effects of the gel in healing full-thickness excisional wounds. In this work, we test the translational relevance of our aforesaid findings by testing the dressing in a swine model of chronic ischemic wounds recently reported by our laboratory. Full thickness excisional wounds were established in the center of bi- pedicle ischemic skin flaps on the backs of animals. Ischemia was verified by Laser Doppler imaging and MCG was applied to the test group of wounds. Seven days post- wounding, macrophage recruitment to the wound was significantly higher in MCG- treated ischemic wounds. In vitro, MCG up-regulated expression of Mrc-1 (a reparative M2 macrophage marker) and induced the expression of anti-inflammatory cytokine IL-10 and of β-FGF. An increased expression of CCR2, a M2 macrophage marker, was noted in the macrophages from MCG treated wounds. Furthermore, analyses of wound tissues 7 days post wounding showed up-regulation of TGF-β, VEGF, vWF, and collagen type I expression in MCG-treated ischemic wounds. At 21 days post-wounding, MCG-treated ischemic wounds displayed higher abundance of proliferating endothelial cells that formed mature vascular structures and increased blood flow to the wound. Fibroblast count was markedly higher in MCG-treated ischemic wound-edge tissue. In addition, MCG-treated wound-edge tissues displayed higher abundance of mature collagen with increased collagen type I:III deposition. Taken together, MCG helped mount a more robust inflammatory response which resolved in a timely manner, followed by an enhanced proliferative phase, angiogenic outcome and post-wound tissue remodeling. Findings of the current study warrant clinical testing of MCG in a setting of ischemic chronic wounds.
PMCID: PMC4380279  PMID: 25224310
17.  A Novel Immune Competent Murine Hypertrophic Scar Contracture Model: A Tool to Elucidate Disease Mechanism and Develop New Therapies 
Hypertrophic scar contraction (HSc) following burn injury causes contractures. Contractures are painful and disfiguring. Current HSc therapies are marginally effective. To study pathogenesis and develop new therapies, a murine model is needed. We have created a validated immune-competent murine HSc model. A third-degree burn was created on the dorsum of C57BL/6 mice. Three days post-burn, tissue was excised and grafted with ear skin. Graft contraction was analyzed by computer planimetry and tissue harvested on different time points. Outcomes were compared to human condition to validate the model. To confirm graft survival, green fluorescent protein mice (GFP) were used and histologic analysis was performed to differentiate between ear and back skin. Role of panniculus carnosus (PC) in contraction was analyzed. Cellularity was assessed with DAPI. Collagen maturation was assessed with Picro-sirius red. Mast cells were stained with Toluidine blue. Macrophages were detected with F4/80 immune. Vascularity was assessed with CD31 immune. RNA for contractile proteins was detected by qRT-PCR. Elastic moduli of human and murine skin and scar tissue were analyzed using a microstrain analyzer. Grafts contracted to ~45% of their original size by day 14 and maintained their size. Grafting of GFP mouse skin onto wild type mice and vice-versa and analysis of dermal thickness and hair follicle density, confirmed graft survival. Interestingly, hair follicles disappeared after grafting and regenerated in ear skin configuration by day 30. Radiological analysis revealed the PC does not contribute to contraction. Microscopic analyses demonstrated that grafts show increase in cellularity. Granulation tissue formed after day 3. Collagen analysis revealed increases in collagen maturation over time. CD31 stain revealed increased vascularity. Macrophages and mast cells were increased. qRT-PCR demonstrated upregulation of TGF-β, ASMA, NMMII, and ROCK2 in HSc. Tensile testing revealed that human skin and scar tissues are tougher than mouse skin and scar tissues.
PMCID: PMC4304906  PMID: 25327261
Hypertrophic Scar; burn; wound healing; contracture; fibrosis
18.  Normalizing dysfunctional purine metabolism accelerates diabetic wound healing 
Diabetic patients exhibit dysfunction of the normal wound healing process, leading to local ischemia by vascular occlusive disease as well as sustained increases in the proinflammatory cytokines and overproduction of reactive oxygen species (ROS). Of the many sources of ROS, the enzyme xanthine oxidase (XO) has been linked to overproduction of ROS in diabetic environment, and studies have shown that treatment with XO inhibitors decreases XO overactivity and XO-generated ROS. This study evaluates the role of XO in the diabetic wound and the impact of specifically inhibiting its activity on wound healing. Treatment of diabetic wounds with siXDH (xanthine dehydrogenase siRNA) decreased XDH mRNA expression by 51.6%, XO activity by 35.9%, ROS levels by 78.1%, pathologic wound burden by 31.5%, and accelerated wound healing by 7 days (23.3%). Polymerase chain reaction analysis showed that increased XO activity in wild-type wound may be due to XDH to XO conversion and/or XO phosphorylation, but not to gene transcription, whereas increased XO activity in diabetic wounds may also be from gene transcription. These results suggest that XO may be responsible for large proportion of elevated oxidative stress in the diabetic wound environment and that normalizing the metabolic activity of XO using targeted delivery of siXDH may decrease overproduction of ROS and accelerate wound healing in diabetic patients.
PMCID: PMC4637936  PMID: 25571764
19.  Role of salivary vascular endothelial growth factor (VEGF) in palatal mucosal wound healing 
The mucosa of alimentary tract heals more rapidly than cutaneous wounds. The underlying mechanisms of this enhanced healing have not been completely elucidated. Constant exposure to salivary growth factors has been shown to play a critical role in mucosal homeostasis and tissue repair. Angiogenesis also has an essential role in successful wound repair. One of the main angiogenic growth factors, vascular endothelial growth factor (VEGF), has a pleiotropic role in tissue repair via neovascularization, reepithelialization, and regulation of extracellular matrix. We have previously reported a critical role for salivary VEGF in bowel adaptation after small bowel resection. We hypothesize that salivary VEGF is an essential stimulus for oral mucosal tissue repair, and use the murine palatal wound model to test our hypothesis. In a loss-of-function experiment, we removed the primary source of VEGF production through selective submandibular gland (SMG) sialoadenectomy in a murine model and observed the effects on wound closure and neovascularization. We then performed a selective loss-of-function experiment using the protein VEGF-Trap to inhibit salivary VEGF. In a gain-of-function experiment, we supplemented oral VEGF following SMG sialoadenectomy. After SMG sialoadenectomy, there was significant reduction in salivary VEGF level, wound closure, and vessel density. Lower levels of salivary VEGF were correlated with impaired neovascularization and reepithelialization. The selective blockade of VEGF using VEGF-Trap resulted in a similar impairment in wound healing and neovascularization. The sole supplementation of oral VEGF after SMG sialoadenectomy rescued the impaired wound healing phenotype and restored neovascularization to normal levels. These data show a novel role for salivary-VEGF in mucosal wound healing, and provide a basis for the development of novel therapeutics aimed at augmenting wound repair of the oral mucosa, as well as wounds at other sites in the alimentary tract.
PMCID: PMC4528184  PMID: 23758212
20.  S-nitrosylation of caspase-3 is the mechanism by which adhesion fibroblasts manifest lower apoptosis 
We have previously found that adhesion fibroblasts exhibit lower apoptosis and higher protein nitration as compared with normal peritoneal fibroblasts. In this study, we sought to determine whether the decreased apoptosis observed in adhesion fibroblasts is caused by lower caspase-3 activity due to an increase in caspase-3 S-nitrosylation. For this study, we have utilized primary cultures of fibroblasts obtained from normal peritoneum and adhesion tissues of the same patient(s). Cells were treated with increasing concentrations of peroxynitrite and cell lysates were immunoprecipitated with anti-caspase-3 polyclonal antibody. The biotinylated proteins were detected using a nitrosylation detection kit. Caspase-3 activity and apoptosis were measured by colorimetric and TUNEL assays, respectively. Our results showed that caspase-3 S-nitrosylation is significantly higher in adhesion fibroblasts as compared with normal peritoneal fibroblasts. This increase in S-nitrosylation resulted in a 30% decrease in caspase-3 activity in adhesion fibroblasts. Peroxynitrite treatment resulted in a dose response increase in caspase-3 S-nitrosylation, leading to a decrease in caspase-3 activity and apoptosis in normal peritoneal fibroblasts. We conclude that S-nitrosylation of caspase-3 is the reason for its decreased activity and subsequent decrease in apoptosis of adhesion fibroblasts. The mechanism by which caspase-3 S-nitrosylation occurs is not fully understood. However, the role of hypoxia in the formation of peroxynitrite via superoxide production may suggest a possible mechanism.
PMCID: PMC4529118  PMID: 19320891
21.  Local blockade of glucocorticoid activation reverses stress- and glucocorticoid-induced delays in cutaneous wound healing 
Stress slows cutaneous wound healing (WH) in an endogenous glucocorticoid (GC)-dependent fashion. We investigated whether stress/GC-induced delays in WH require further intracutaneous activation of endogenous GC; and whether blockade or down-regulation of peripheral activation normalizes WH in the face of stress. Delayed WH in our motion-restricted murine model of stress could be attributed to elevated systemic GC, because blockade of GC production (using corticotropin-releasing factor inhibitor, antalarmin), or of peripheral binding to the GC receptor [GCr], with an antagonist, Ru-486, normalized WH. We next investigated whether local blockade or down-regulation of the peripheral GC-activating enzyme, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), accelerates cutaneous WH. Topical applications of nonspecific (carbenoxolone) as well as an isoform-specific 11β-HSD1 inhibitor overcame stress and exogenous GC-induced delays in WH. Moreover, two liver X receptor ligands, TO901317 and GW3695, down-regulated expression of 11β-HSD1, attenuating stress-induced delays in WH. Combined inhibitor and liver X receptor ligand applications accelerated WH in the face of stress/systemic GC. Thus: (1) intracutaneous conversion of inactive-to-active GC accounts for stress (GC)-induced delays in WH; and (2) blockade or down-regulation of 11β-HSD1 and/or GCr normalize cutaneous WH in the face of stress/GC. Local blockade or down-regulation of cutaneous GC activation could help enhance WH in various clinical settings.
PMCID: PMC4507432  PMID: 23927023
22.  Topical Administration of a Connexin43-based peptide Augments Healing of Chronic Neuropathic Diabetic Foot Ulcers: A Multicenter, Randomized Trial 
Nonhealing neuropathic foot ulcers remain a significant problem in individuals with diabetes. The gap-junctional protein connexin43 (Cx43) has roles in dermal wound healing and targeting Cx43 signaling accelerates wound reepithelialization. In a prospective, randomized, multi-center clinical trial we evaluated the efficacy and safety of a peptide mimetic of the C-terminus of Cx43, ACT1, in accelerating the healing of chronic diabetic foot ulcers (DFUs) when incorporated into standard of care protocols. Adults with DFUs of at least four weeks duration were randomized to receive standard of care with or without topical application of ACT1. Primary outcome was mean percent ulcer reepithelialization and safety variables included incidence of treatment related adverse events and detection of ACT1 immunogenicity. ACT1 treatment was associated with a significantly greater reduction in mean percent ulcer area from baseline to 12 weeks (72.1% vs. 57.1%; p = 0.03). Analysis of incidence and median time-to-complete-ulcer closure revealed that ACT1 treatment was associated with a greater percentage of participants that reached 100% ulcer reepitheliazation and a reduced median time-to-complete-ulcer closure. No adverse events reported were treatment related, and ACT1 was not immunogenic. Treatment protocols that incorporate ACT1 may present a therapeutic strategy that safely augments the reepithelialization of chronic DFUs.
PMCID: PMC4472499  PMID: 25703647
ACT1 peptide; connexin 43; diabetic foot ulcer; wound healing
23.  Toll-like receptor 4 signaling regulates the acute local inflammatory response to injury and the fibrosis/neovascularization of sterile wounds 
The role of Toll-like receptor 4 (TLR4) in the regulation of inflammation and fibrosis in sterile wounds was investigated in TLR4 signal-deficient (C3H/HeJ or TLR4−/−) and control mice using the subcutaneously implanted polyvinyl alcohol sponge wound model. Total and differential wound cell counts 1, 3, and 7 days after injury did not differ between C3H/HeJ and C3H/HeOuJ animals. Blood monocytes from both strains expressed CCR2 equally. Day one wounds in C3H/HeJ mice contained fewer Gr-1high wound macrophages, CCL3, and CCL5, and more CCL17 than those in controls. The accumulation of CCL2, CX3CL1, tumor necrosis factor-α, interleukin (IL)-6, IL-10, IL-12, and interferon-γ in wound fluids was not TLR4 dependent. Wound macrophages from C3H/HeJ and C3H/HeOuJ mice expressed CCR4 and CCR5, but not CCR1 or CCR3. Wound macrophage recruitment was not altered in CCR5−/− mice or in C3H/HeOuJ animals injected with neutralizing anti-CCL3 and anti-CCL5 antibodies. Neutralization of the CCR4 ligand CCL17 in C3H/HeJ mice did not alter wound macrophage populations. There was a twofold increase in collagen content and number of neovessels in 21-day-old wounds in C3H/HeJ vs. C3H/HeOuJ mice. There were no differences between strains in the number of myofibroblasts in the wounds 7 or 21 days post-wounding. The increased fibrosis and angiogenesis in wounds from /HeJ mice correlated with higher concentrations of transforming growth factor-β and fibroblast growth factor 2 in wound fluids from these animals. Wound fluids did not contain detectable lipopolysaccharide and did not induce IκBα degradation in J774.A1 macrophages. Results support a role for endogenous ligands of TLR4 in the regulation of inflammation and repair in sterile wounds.
PMCID: PMC4469904  PMID: 23758142
24.  Wound Research Funding from Alternative Sources of Federal Funds in 2012 
Chronic wounds represent a major health care burden, costing $25 billion annually, and are associated with high mortality. We previously reported that cutaneous wound healing represented only 0.1% ($29.8 million) of the National Institutes of Health budget. This current study focuses on quantifying the contribution by federal agencies other than the National Institutes of Health for fiscal year 2012. Federal databases including USA spending, Veterans Affairs, Tracking Accountability in Government Grants Systems, Health Services Research Projects in Progress, and Patient-Centered Outcomes Research Institute, were searched for individual projects addressing wound healing. Twenty-seven projects were identified, totaling funding of $16,588,623 (median:$349,856). Four sponsor institutions accounted for 74% of awarded funds: Department of the Army, National Science Foundation, Department of Veterans Affairs, and Agency for Healthcare Research & Quality. Research projects and cooperative agreements comprised 44% and 37% of awarded grants. New applications and continuing projects represented 52% and 37%. Wound healing represented 0.15% of total medical research funded by the non-National Institutes of Health federal sector. Compared to potential impact on US public health, federal investment in wound research is exiguous. This analysis will draw attention to a disproportionately low investment in wound research and its perils to American public health.
PMCID: PMC4059782  PMID: 24844328
Wound research; federal; funding
25.  Digital imaging analysis to assess scar phenotype 
In order to understand the link between the genetic background of patients and wound clinical outcomes, it is critical to have a reliable method to assess the phenotypic characteristics of healed wounds. In this study, we present a novel imaging method that provides reproducible, sensitive and unbiased assessments of post-surgical scarring. We used this approach to investigate the possibility that genetic variants in orofacial clefting genes are associated with suboptimal healing. Red-green-blue (RGB) digital images of post-surgical scars of 68 patients, following unilateral cleft lip repair, were captured using the 3dMD image system. Morphometric and colorimetric data of repaired regions of the philtrum and upper lip were acquired using ImageJ software and the unaffected contralateral regions were used as patient-specific controls. Repeatability of the method was high with interclass correlation coefficient score > 0.8. This method detected a very significant difference in all three colors, and for all patients, between the scarred and the contralateral unaffected philtrum (P ranging from 1.20−05 to 1.95−14). Physicians’ clinical outcome ratings from the same images showed high inter-observer variability (overall Pearson coefficient = 0.49) as well as low correlation with digital image analysis results. Finally, we identified genetic variants in TGFB3 and ARHGAP29 associated with suboptimal healing outcome.
PMCID: PMC4411947  PMID: 24635173
wound healing; cleft palate; genes; genotype-phenotype; Tgfb3; Arhgap29; scar; imaging; digital

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