Skin graft expansion techniques (mesh and micrograft) are widely used, but there is ample evidence that skin graft meshers do not provide their claimed expansion rates. Although this finding might not be new for the majority of surgeons, less is known about surgeons’ actual knowledge of expansion rates. The aim of this study was to evaluate the true expansion rates of commonly used expansion techniques with regard to claimed, achieved, and polled results. In the first part of the study, 54 surgeons were polled during an annual burns meeting regarding the most commonly used expansion techniques and expansion ratios; in the second step the true (achievable) expansion rates of the most widely used meshers and micrografts were analysed; and in third step, a poll involving 40 surgeons was conducted to estimate the true expansion rates of the most frequently used skin expansion techniques. The skin meshers (1:1.5 / 1:3) did not achieve their claimed values: (1:1.5) 84.7% of the claimed expansion (mean ± SD: 1:1.27 ± 0.15) and (1:3) 53.1% of the 1:3 (1:1.59 ± 0.15) mesher. The use of the micrografting technique resulted in 99.8% of the 1:3 (1:2.99 ± 0.09), 93.6% of the 1:4 (1:3.74 ± 0.12) and 93.8% of the 1:6 (1:5.63 ± 0.12) claimed expansion rates, respectively. In general the surgeons overestimated the achievable expansion rates. In general the achieved expansion rate was lower than the estimated and claimed expansion rates. The micrografting technique provided reliable and valid expansion rates compared to the skin meshers. We recommend using the micrograft technique when large expansion ratios are required, for example in severe extensive burns.
skin transplantation; skin graft; mesh; micrografting; Meek’s technique
Successful treatment of wounds relies on precise control and continuous monitoring of the wound-healing process. Wet or moist treatment of wounds has been shown to promote re-epithelialization and result in reduced scar formation, as compared to treatment in a dry environment.
By treating wounds in a controlled wet environment, delivery of antimicrobials, analgesics, other bioactive molecules such as growth factors, as well as cells and micrografts, is allowed. The addition of growth factors or transplantation of cells yields the possibility of creating a regenerative wound microenvironment that favors healing, as opposed to excessive scar formation.
Although several manufacturers have conceived products implementing the concept of moist wound healing, there remains a lack of commercial translation of wet wound-healing principles into clinically available products. This can only be mitigated by further research on the topic.
The strong evidence pointing to the favorable healing of wounds in a wet or moist environment compared to dry treatment will extend the clinical indications for this treatment. Further advances are required to elucidate by which means this microenvironment can be optimized to improve the healing outcome.
Acute burn wounds often require early excision and adequate coverage to prevent further hypothermia, protein and fluid losses, and the risk of infection. Meshed autologous skin grafts are generally regarded as the standard treatment for extensive full-thickness burns. Graft take and rate of wound healing, however, depend on several endogenous factors. This paper describes a standardized reproducible porcine model of burn and skin grafting which can be used to study the effects of topical treatments on graft take and re-epithelialization.
Procedures provide a protocol for successful porcine burn wound experiments with special focus on pre-operative care, anesthesia, burn allocation, excision and grafting, postoperative treatment, dressing application, and specimen collection. Selected outcome measurements include percent area of wound closure by planimetry, wound assessment using a clinical assessment scale, and histological scoring.
The use of this standardized model provides burn researchers with a valuable tool for the comparison of different topical drug treatments and dressing materials in a setting that closely mimics clinical reality.
Burn; Burn excision; Wound healing; Reconstruction; Autograft
There are a wide variety of dressing techniques and materials available for management of both acute wounds and chronic non-healing wounds. The primary objective in both the cases is to achieve a healed closed wound. However, in a chronic wound the dressing may be required for preparing the wound bed for further operative procedures such as skin grafting. An ideal dressing material should not only accelerate wound healing but also reduce loss of protein, electrolytes and fluid from the wound, and help to minimize pain and infection. The present dictum is to promote the concept of moist wound healing. This is in sharp contrast to the earlier practice of exposure method of wound management wherein the wound was allowed to dry. It can be quite a challenge for any physician to choose an appropriate dressing material when faced with a wound. Since wound care is undergoing a constant change and new products are being introduced into the market frequently, one needs to keep abreast of their effect on wound healing. This article emphasizes on the importance of assessment of the wound bed, the amount of drainage, depth of damage, presence of infection and location of wound. These characteristics will help any clinician decide on which product to use and where,in order to get optimal wound healing. However, there are no ‘magical dressings’. Dressings are one important aspect that promotes wound healing apart from treating the underlying cause and other supportive measures like nutrition and systemic antibiotics need to be given equal attention.
Moist healing; topical wound care; wet dressings
Diabetic foot ulcerations are historically difficult to treat despite advanced
therapeutic modalities. There are numerous modalities described in the literature ranging
from noninvasive topical wound care to more invasive surgical procedures such as
primary closure, skin flaps, and skin grafting. While skin grafting provides faster time to
closure with a single treatment compared to traditional topical wound treatments, the
potential risks of donor site morbidity and poor wound healing unique to the diabetic
state have been cited as a contraindication to its widespread use. In order to garner
clarity on this issue, a literature review was undertaken on the use of split-thickness skin
grafts on diabetic foot ulcers. Search of electronic databases yielded four studies that
reported split-thickness skin grafts as definitive means of closure. In addition, several
other studies employed split-thickness skin grafts as an adjunct to a treatment that was
only partially successful or used to fill in the donor site of another plastic surgery
technique. When used as the primary closure on optimized diabetic foot ulcerations,
split-thickness skin grafts are 78% successful at closing 90% of the wound by eight weeks.
Proper care must be taken even for a clean wound in normal body to heal earlier with a minimum scar. Various scientific and technological advancement taking place from time to time the problem wound healing is still under evolution process, till now there are many research works have been undertaken on Chronic wounds. As Dustavrana is vitiated by various doshas so it needs proper care in proper time. Hence in present concept all efforts are directed to keep the wound clean and also to enhance the wound healing. To manage the Dustavrana different type of treatment modalities explained in the classics, Bala Taila is one among them. Objective of study: To assess the effectiveness of BalaTaila Application in wound healing. To assess the healing of wound (Vrana ropana).
30 patients were selected according to inclusion criteria and divided into two groups of 15 each. Viz Group I: Trail group, were treated by Bala Taila local application once daily & Group II: Control group, were treated by the application of Hydrogen Peroxyde, sterile dry gauze were used for dressing.
Results were assessed with the help of prefixed assessment criteria, and favorable results obtained on, Vedana as 85%, Swelling 80%, Varna 84.44%, Srava 82.92% Granulation 86.66% and size of wound 79.41%. The result of Bala Taila is found to be statically significant in the process of wound healing
The Bala Taila proves a vital role in the healing of Dustavrana.
Local and regional flap failure can be a major complication in head and neck surgery,
which continue to be prevalent for a number of reasons including poor flap design, improper surgical technique, and poor tissue vascularity. Dealing with these failures can
be quite difficult.
Surgical debridement, flap revisions, and complex wound regimens are necessitated to
reestablish appropriate tissue coverage. Traditional use of wet to dry dressing to enable
proper wound granulation and possible closure with additional flaps or skin grafts is a
laborious process. Such treatments place great time burdens on the patient, physicians, and nurses.
Because the face and neck possess a complex three-dimensional topography,
wound dressings are inherently complex to design and change. Many patients also require postoperative
treatments such as radiation and chemotherapy to treat aggressive malignancies, and delay in
wound healing leads to a delay in adjuvant treatment. Recently, advances in regenerative medicine,
specifically xenogeneic extracellular matrix compounds, have been shown to promote tissue growth while limiting
scar tissue formation (Badylak 2004). To our knowledge, this paper is the first case series using the porcine
extracellular matrix bioscaffold (MatriStem ACell, Columbia, MD, USA) to salvage flaps with extensive wound breakdown on the face and neck.
Objective: Certain cytokines, especially those known as growth factors, have been demonstrated to mediate or modulate burn wound healing. Experimental and clinical evidence suggests that there are therapeutic advantages to the wound healing process when these agents are utilized. Positive effects have been reported for 4 types of wounds seen in the burn patient: partial-thickness wounds, full-thickness wounds, interstices of meshed skin grafts, and skin graft donor sites. Methods: A comprehensive literature search was performed using the MEDLINE, Ovid, and Web of Science databases to identify pertinent articles regarding growth factors and other cytokines in burns and wound healing. Results: The current knowledge about cytokine growth factors and their potential therapeutic applications in burn wound healing are discussed and reviewed. Conclusions: Platelet-derived growth factor, fibroblast growth factors, epidermal growth factors, transforming growth factor alpha, vascular endothelial growth factor, insulin-like growth factor I, nerve growth factor, transforming growth factor beta, granulocyte-macrophage colony-stimulating factor, and amnion-derived cellular cytokine solution have all been suggested to enhance the rate and quality of healing in 1 or more of these wounds encountered in burn care.
Quantum leap advancements in hair transplantation have occurred in the past 10 to 15 years, particularly the use of micrografts (one- to two-hair follicular unit grafts) and minigrafts (three- to four-hair follicular unit grafts) used in large numbers (> 1000 grafts) in a single session (megasession). This was initially described for the treatment of male pattern baldness. Since that time I have found many other applications, particularly in facial and scalp reconstruction. Common causes for aesthetic reconstructive hair restoration in my experience include: hair loss due to facelift and forehead lift procedures, revision of unsatisfactory results from previous hair transplantation, burn alopecia, congenital reasons, postoncological resections, and idiopathic. The basic technique is described in detail, including the variations for each of the challenging anatomic areas including sideburns and temporal hairline, eyebrows, eyelashes, mustache, beard, and remaining scalp. Especial attention is given to the direction of hair growth, texture, aesthetic planning, and absence of detectable scars, so as to mimic nature. The use of micrografts and minigrafts in the aesthetic reconstruction of the face and scalp has been found to be safe and predictable and has provided a high level of patient satisfaction.
Reconstructive; hair transplantation; micrografting; minigrafting
Successful wound care involves optimizing patient local and systemic conditions in conjunction with an ideal wound healing environment. Many different products have been developed to influence this wound environment to provide a pathogen-free, protected, and moist area for healing to occur. Newer products are currently being used to replace or augment various substrates in the wound healing cascade. This review of the current state of the art in wound-healing products looks at the latest applications of silver in microbial prophylaxis and treatment, including issues involving resistance and side effects, the latest uses of negative pressure wound devices, advanced dressings and skin substitutes, biologic wound products including growth factor applications, and hyperbaric oxygen as an adjunct in wound healing. With the abundance of available products, the goal is to find the most appropriate modality or combination of modalities to optimize healing.
The role of the wet environment in wound healing has been investigated in various studies. The current study explores the role of the wet wound environment in promoting healing of skin grafts. We hypothesized that survival of the skin grafts is not only dependent on the orientation of transplantation, but also on the environment into which the skin is transplanted.
The study included 72 full-thickness (2.5×2.5cm) wounds in 6 Yorkshire pigs. The wounds were grafted with autologous split-thickness skin grafts (meshed or sheet), placed either regularly (dermal-side-down) or inverted (dermal-side-up), and treated in wet or dry environment. Behavior of the skin grafts and healing were analyzed in histologies collected on days 4, 6, 9 and 12 postwounding. Wound contraction was quantified by photoplanimetry.
In the wet environment, not only did inverted meshed skin grafts survive, but also they proliferated to accelerate reepithelialization. In this environment, wounds transplanted with inverted and regular meshed grafts showed no significant difference in reepithelialization rate and contraction. In contrast, in the dry environment, wounds transplanted with inverted meshed grafts showed a significantly lower reepithelialization and higher contraction than wounds transplanted with regular grafts. Inverted meshed grafts in dry environment and inverted sheet grafts did not survive.
The wound environment has an important role in the survival and proliferation of skin grafts, as demonstrated by survival of inverted meshed grafts in the wet environment and their contribution to accelerated reepithelialization, equal to the regularly placed grafts.
Minor postoperative bleeding is the most common complication of cutaneous surgery. Because of the commonality of this complication, hemostasis is an important concept to address when considering dermatologic procedures. Patients that have a bleeding diathesis, an inherited/acquired coagulopathy, or who are on anticoagulant/antiplatelet medications pose a greater risk for bleeding complications during the postoperative period. Knowledge of these conditions preoperatively is of the utmost importance, allowing for proper preparation and prevention. Also, it is important to be aware of the various hemostatic modalities available, including electrocoagulation, which is among the most effective and widely used techniques. Prompt recognition of hematoma formation and knowledge of postoperative wound care can prevent further complications such as wound dehiscence, infection, or skin-graft necrosis, minimizing poor outcomes.
The treatment of extensive thermal injuries with insufficient autologous skin remains a great challenge to burn surgeons. In this study, we investigated the influence of the ratio of autologous and allogeneic tissue in mixed microskin grafts on wound healing in order to develop an effective method for using limited donor skin to cover a large open wound. Four different mixtures were tested: autologous microskin at an area expansion ratio of 10∶1 with allogeneic microskin at an area expansion ratio of 10∶1 or 10∶3 and autologous microskin at an expansion ratio of 20∶1 with allogeneic microskin at an expansion ratio of 20∶3 or 20∶6. Wound healing, wound contraction, and integrin β1 expression were measured. Mixed microskin grafting facilitated wound healing substantially. The mixture of autologous microskin at an expansion ratio of 10∶1 with the same amount of allogeneic microskin achieved the most satisfactory wound healing among the 4 tested mixtures. Histological examination revealed the presence of obviously thickened epidermis and ectopic integrin β1 expression. Keratinocytes expressing integrin β1 were scattered in the suprabasal layer. Higher levels of integrin β1 expression were associated with faster wound healing, implying that ectopic expression of integrin β1 in keratinocytes may play a pivotal role in wound healing. In conclusion, this study proves that this new skin grafting technique may improve wound healing.
Enterocutaneous fistulas represent a challenging situation with respect to wound care and stoma therapy. An understanding of the principles of wound care and the various techniques and materials that are available is of vital importance to enhance patient comfort and recovery as well as facilitate fistula healing. Skin barriers, adhesives, dressings, pouches, and negative pressure dressings are all materials that are available in the armamentarium of the enterostomal therapist. Proper utilization of these items and appropriate modifications to their application requires an intimate knowledge of the characteristics of the fistula being treated. Wound care management is a key element in the overall care and healing of the enterocutaneous fistula.
Enterocutaneous fistula; wound management; skin barriers; pouches; negative pressure dressings
Donor site wounds after split-skin grafting are rather 'standard' wounds. At present, lots of dressings and topical agents for donor site wounds are commercially available. This causes large variation in the local care of these wounds, while the optimum 'standard' dressing for local wound care is unclear. This protocol describes a trial in which we investigate the effectiveness of various treatment options for these donor site wounds.
A 14-center, six-armed randomized clinical trial is being carried out in the Netherlands. An a-priori power analysis and an anticipated dropout rate of 15% indicates that 50 patients per group are necessary, totaling 300 patients, to be able to detect a 25% quicker mean time to complete wound healing. Randomization has been computerized to ensure allocation concealment. Adult patients who need a split-skin grafting operation for any reason, leaving a donor site wound of at least 10 cm2 are included and receive one of the following dressings: hydrocolloid, alginate, film, hydrofiber, silicone dressing, or paraffin gauze. No combinations of products from other intervention groups in this trial are allowed. Optimum application and changes of these dressings are pursued according to the protocol as supplied by the dressing manufacturers. Primary outcomes are days to complete wound healing and pain (using a Visual Analogue Scale). Secondary outcomes are adverse effects, scarring, patient satisfaction, and costs. Outcome assessors unaware of the treatment allocation will assess whether or not an outcome has occurred. Results will be analyzed according to the intention to treat principle. The first patient was randomized October 1, 2009.
This study will provide comprehensive data on the effectiveness of different treatment options for donor site wounds. The dressing(s) that will prevail in effectiveness, satisfaction and costs will be promoted among clinicians dealing with such patients. Thus, we aim to contribute a well-designed trial, relevant to all clinicians involved in the care for donor site wounds, which will help enhance uniformity and quality of care for these patients.
http://www.trialregister.nl, NTR1849. Date registered: June 9, 2009
Wound care is constantly evolving with the advances in medicine. Search for the ideal dressing material still continues as wound care professionals are faced with several challenges. Due to the emergence of multi-resistant organisms and a decrease in newer antibiotics, wound care professionals have revisited the ancient healing methods by using traditional and alternative medicine in wound management. People's perception towards traditional medicine has also changed and is very encouraging. The concept of moist wound healing has been well accepted and traditional medicine has also incorporated this method to fasten the healing process. Several studies using herbal and traditional medicine from different continents have been documented in wound care management. Honey has been used extensively in wound care practice with excellent results. Recent scientific evidences and clinical trials conducted using traditional and alternative medicine in wound therapy holds good promise in the future.
Alternative medicine; complementary medicine; traditional medicine; wound healing; wound management
I first presented micrografts for hair restoration surgery in 1982, combining to hide the anterior hairline of the temporo-parieto-occipital (TPO) flaps. Later, in 1986 and 1991 respectively, I introduced megasessions with micrografts and minigrafts. At that point, I created my own surgical routine, introducing a “stick-and-place” method, named the punctiform technique, which was published in several magazines, Congressional annals, and books. Hair-micrografting is a simple, yet refined, technique that requires three assistants and lasts 2 to 3 hours; the result is a natural-looking transplant with small incidence of risk or postoperative complications.
Punctiform technique; hair restoration; micrograft; minigraft
In covering wounds, efforts should include utilization of the safest and least invasive methods with goals of achieving optimal functional and cosmetic outcome. The recent development of advanced wound healing technology has triggered the use of cells to improve wound healing conditions. The purpose of this review is to provide information on clinically available cell-based treatment options for healing of acute and chronic wounds. Compared with a variety of conventional methods, such as skin grafts and local flaps, the cell therapy technique is simple, less time-consuming, and reduces the surgical burden for patients in the repair of acute wounds. Cell therapy has also been developed for chronic wound healing. By transplanting cells with an excellent wound healing capacity profile to chronic wounds, in which wound healing cannot be achieved successfully, attempts are made to convert the wound bed into the environment where maximum wound healing can be achieved. Fibroblasts, keratinocytes, adipose-derived stromal vascular fraction cells, bone marrow stem cells, and platelets have been used for wound healing in clinical practice. Some formulations are commercially available. To establish the cell therapy as a standard treatment, however, further research is needed.
Cell-and Tissue-based Therapy; Wounds and Injuries; Tissue Engineering
Plant grafting techniques have deepened our understanding of the signals facilitating communication between the root and shoot, as well as between shoot and reproductive organs. Transmissible signalling molecules can include hormones, peptides, proteins and metabolites: some of which travel long distances to communicate stress, nutrient status, disease and developmental events. While hypocotyl micrografting techniques have been successfully established for Arabidopsis to explore root to shoot communications, inflorescence grafting in Arabidopsis has not been exploited to the same extent. Two different strategies (horizontal and wedge-style inflorescence grafting) have been developed to explore long distance signalling between the shoot and reproductive organs. We developed a robust wedge-cleft grafting method, with success rates greater than 87%, by developing better tissue contact between the stems from the inflorescence scion and rootstock. We describe how to perform a successful inflorescence stem graft that allows for reproducible translocation experiments into the physiological, developmental and molecular aspects of long distance signalling events that promote reproduction.
Wedge grafts of the Arabidopsis inflorescence stem were supported with silicone tubing and further sealed with parafilm to maintain the vascular flow of nutrients to the shoot and reproductive tissues. Nearly all (87%) grafted plants formed a strong union between the scion and rootstock. The success of grafting was scored using an inflorescence growth assay based upon the growth of primary stem. Repeated pruning produced new cauline tissues, healthy flowers and reproductive siliques, which indicates a healthy flow of nutrients from the rootstock. Removal of the silicone tubing showed a tightly fused wedge graft junction with callus proliferation. Histological staining of sections through the graft junction demonstrated the differentiation of newly formed vascular connections, parenchyma tissue and lignin accumulation, supporting the presumed success of the graft union between two sections of the primary inflorescence stem.
We describe a simple and reliable method for grafting sections of an Arabidopsis inflorescence stem. This step-by-step protocol facilitates laboratories without grafting experience to further explore the molecular and chemical signalling which coordinates communications between the shoot and reproductive tissues.
Grafting; Wedge; Plant development; Inflorescence stem; Systemic; Signal; Molecule; Transmission; Arabidopsis; Scion
AIMS--To establish the structural changes that occur in deep surgical wounds engrafted with allogeneic sheets, their time course and inter-relation. METHODS--Deep surgical wounds following shave excision of tattoos (down to deep dermis/subcutaneous fat) were treated with sheets of sex mismatched allogeneic keratinocytes in 19 patients and then biopsied weekly until wound healing was complete. More superficial surgical wounds--that is, 20 standard skin graft donor sites, were biopsied at seven to 10 days (all healed) following application of keratinocyte allografts. All biopsy specimens were examined with a large panel of monoclonal antibodies to keratins, envelope proteins, basement membrane components, and to extracellular matrix components. RESULTS--The hyperproliferative keratin pair K6/16 was expressed in all wounds, for up to six weeks in keratinocyte grafted deep wounds, and up to six months in split thickness skin grafted wounds. CONCLUSIONS--Keratins 6 and 16 have not been detected in normal skin, although the relevant mRNA has. This raises the possibility of regulation at a post-transcriptional level allowing a rapid response to injury with cytoskeletal changes that may aid cell migration. This keratin pair offers the most sensitive marker for altered epidermis following wounding.
With the advent of several innovative wound care management tools, the choice of products and treatment modalities available to clinicians continues to expand. High costs associated with wound care, especially diabetic foot wounds, make it important for clinician scientists to research alternative therapies and optimally incorporate them into wound care protocols appropriately. This article reviews using sugar as a treatment option in diabetic foot care and provides a guide to its appropriate use in healing foot ulcers. In addition to a clinical case study, the physiological significance and advantages of sugar are discussed.
diabetic foot ulcers; sugar; wound healing
Wound healing involves complex mechanisms, which, if properly chaperoned, can enhance patient recovery. The abilities of platelets and keratinocytes may be harnessed in order to stimulate wound healing through the formation of platelet clots, the release of several growth factors and cytokines, and cell proliferation. The aim of the study was to test whether autologous keratinocyte suspensions in platelet concentrate would improve wound healing. The study was conducted at the Lausanne University Hospital, Switzerland in 45 patients, randomized to three different topical treatment groups: standard treatment serving as control, autologous platelet concentrate (PC) and keratinocytes suspended in autologous platelet concentrate (PC + K). Split thickness skin graft donor sites were chosen on the anterolateral thighs of patients undergoing plastic surgery for a variety of defects. Wound healing was assessed by the duration and quality of the healing process. Pain intensity was evaluated at day five.
Healing time was reduced from 13.9 ± 0.5 days (mean ± SEM) in the control group to 7.2 ± 0.2 days in the PC group (P < 0.01). An addition of keratinocytes in suspension further reduced the healing time to 5.7 ± 0.2 days. Pain was reduced in both the PC and PC + K groups. Data showed a statistically detectable advantage of using PC + K over PC alone (P < 0.01).
The results demonstrate the positive contribution of autologous platelets combined with keratinocytes in stimulating wound healing and reducing pain. This strikingly simple approach could have a significant impact on patient care, especially critically burned victims for whom time is of the essence.
Clinical trial registry information
Protocol Record Identification Number: 132/03
Registry URL: http://www.clinicaltrials.gov
Background: Moist wound treatment improves healing of skin graft donor site wounds. Microbial colonised wounds represent an increased risk of wound infection; while antimicrobially active, topical antiseptics may impair epithelialization. Objectives: The aim of this prospective randomised controlled clinical trial was to examine the influence of an Octenidine-dihydrochloride (OCT) hydrogel on bacterial colonisation and epithelialization of skin graft donor sites. Methods: The study was designed as a randomised, double-blinded, controlled clinical trial. Skin graft donor sites from a total of 61 patients were covered either with 0.05% OCT (n=31) or an OCT-free placebo wound hydrogel (n=30). Potential interaction with wound healing was assessed by measuring the time until 100% re-epithelialization. In addition, microbial wound colonisation was quantitatively determined in all skin graft donor sites. Results: There was no statistically significant difference in the time for complete epithelialization of skin graft donor sites in the OCT and the placebo group (7.3±0.2 vs. 6.9±0.2 days; p=0.236). Microbial wound colonisation was significantly lower in the OCT group than in the placebo group (p=0.014). Conclusions: The OCT-based hydrogel showed no delay in wound epithelialization and demonstrated a significantly lower bacterial colonisation of skin graft donor site wounds.
Octenidine; wound gel; antimicrobial compound; skin graft donor site; skin graft; acute wound; tolerability; antiseptic efficacy
Negative-pressure wound therapy (NPWT) has been used for to treat wounds for more than 15 years and, more recently, has been used to secure split-thickness skin grafts. There are some data to support this use of NPWT, but the actual mechanism by which NPWT speeds healing or improves skin graft take is not entirely known. The purpose of this project was to assess whether NPWT improved angiogenesis, wound healing, or graft survival when compared with traditional bolster dressings securing split-thickness skin grafts in a porcine model.
We performed two split-thickness skin grafts on each of eight 30 kg Yorkshire pigs. We took graft biopsies on postoperative days 2, 4, 6, 8, and 10 and submitted the samples for immunohistochemical staining, as well as standard hematoxylin and eosin staining. We measured the degree of vascular ingrowth via immunohistochemical staining for von Willenbrand's factor to better identify blood vessel epithelium. We determined the mean cross-sectional area of blood vessels present for each representative specimen, and then compared the bolster and NPWT samples. We also assessed each graft for incorporation and survival at postoperative day 10.
Our analysis of the data revealed that there was no statistically significant difference in the degree of vascular ingrowth as measured by mean cross-sectional capillary area (p = 0.23). We did not note any difference in graft survival or apparent incorporation on a macroscopic level, although standard hematoxylin and eosin staining indicated that microscopically, there seemed to be better subjective graft incorporation in the NPWT samples and a nonsignificant trend toward improved graft survival in the NPWT group.
We were unable to demonstrate a significant difference in vessel ingrowth when comparing NPWT and traditional bolster methods for split-thickness skin graft fixation. More studies are needed to elucidate the manner by which NPWT exerts its effects and the true clinical magnitude of these effects.
Level of Evidence
Negative-pressure wound therapy; split thickness skin graft
For patients suffering from catastrophic burns, few treatment options are available. Chimeric coculture of patient-derived autologous cells with a “carrier” cell source of allogeneic keratinocytes has been proposed as a means to address the complex clinical problem of severe skin loss.
Currently, autologous keratinocytes are harvested, cultured, and expanded to form graftable epidermal sheets. However, epidermal sheets are thin, are extremely fragile, and do not possess barrier function, which only develops as skin stratifies and matures. Grafting is typically delayed for up to 4 weeks to propagate a sufficient quantity of the patient's cells for application to wound sites.
Basic/Clinical Science Advances
Fully stratified chimeric bioengineered skin substitutes could not only provide immediate wound coverage and restore barrier function, but would simultaneously deliver autologous keratinocytes to wounds. The ideal allogeneic cell source for this application would be an abundant supply of clinically evaluated, nontumorigenic, pathogen-free, human keratinocytes. To evaluate this potential cell-based therapy, mixed populations of a green fluorescent protein-labeled neonatal human keratinocyte cell line (NIKS) and unlabeled primary keratinocytes were used to model the allogeneic and autologous components of chimeric monolayer and organotypic cultures.
Clinical Care Relevance
Relatively few autologous keratinocytes may be required to produce fully stratified chimeric skin substitute tissue substantially composed of autologous keratinocyte-derived regions. The need for few autologous cells interspersed within an allogeneic “carrier” cell population may decrease cell expansion time, reducing the time to patient application.
This study provides proof of concept for utilizing NIKS keratinocytes as the allogeneic carrier for the generation of bioengineered chimeric skin substitute tissues capable of providing immediate wound coverage while simultaneously supplying autologous human cells for tissue regeneration.