Human Skin Allografts Research Articles

Evaluation ofTopical Off-the-Shelf Therapies to Reduce the Need to Evacuate Battlefield-Injured Warfighters.

Immediate evacuation of burn casualties can be challenging in austere environments, and it is predicted to be even more difficult in future multi-domain battlespaces against near-peer foes. Therefore, a need exists to treat burn wounds at the point of injury to protect the exposed injury for an extended period. In this study, we compare two commercially available FDA-approved therapies to the current gold standard of care (GSOC), excisional debridement followed by the application of split-thickness skin graft, and the standard for prolonged field care, silver sulfadiazine (SSD) cream. The shelf-stable therapies evaluated were irradiated human skin (IHS) allograft and polylactic acid (PLA). Our objective was to study whether they have the potential capability to reduce the need for evacuation to a burn center for surgical intervention so that the combat power can be preserved in the field. Sixteen burns (50 cm2) were created on the dorsum of four anesthetized swine. All materials were sterile, but a sterile field was not utilized in order to simulate the prolonged field care setting. The wounds were then treated with PLA, IHS, and SSD cream, and the remaining wounds (designated GSOC) were also treated with SSD cream. On post-operative day (POD) 3, sterile surgical debridement and skin grafting (1:4) were performed on the GSOC wounds. Burn healing was followed for either PODs 10, 14, 21, or 28, wherein one animal was humanely euthanized at each time point; each represented a time point of the healing process. A full-thickness excisional biopsy was taken from each wound immediately after euthanasia to give a cross-section view of the wound edge to edge. Wound healing was determined by the histological analysis of wound re-epithelialization, epidermal thickness, rete ridges, and scar elevation index and macroscopically using noninvasive imaging systems. The PLA and IHS treatments did not need to be reapplied to the wounds during the course of the experiment, unlike SSD, which was reapplied at each assessment time point. In terms of re-epithelialization, on POD 10, IHS and SSD were similar to the GSOC; on POD 14, all treatments were similar; on POD 21, PLA and IHS were similar to SSD; finally, on POD 28, re-epithelialization was similar in all groups. On POD 28, scar elevation index and rete ridges/mm were similar to all groups, and epidermal and dermal thickness for PLA and IHS were similar to GSOC. This preclinical study demonstrated that the use of the PLA and the IHS dressings resulted in similar outcomes to the GSOC-treated burns in several key metrics of wound healing. These therapies represent a potentially useful tool in current and future battlespaces, where surgical intervention is not possible. The products are lightweight and, more importantly, stable at room temperature for their entire shelf lives. This would allow for easy storage and transport by medical practitioners in the field.

722 Select Survey of Human Cadaver Skin Allograft Utilization by 21 Senior Academic Burn Surgeons

Abstract Introduction As of 2022, cryopreserved human cadaver skin allograft remains the gold standard by which all other skin substitutes used for burn care are compared. The 2015 Taiwan Color Dust Explosion burn mass casualty engendered the transfer of emergency tranches of skin allograft from reserves in both the US and EU to Taiwan. HHS/ASPR/BARDA/CBRN led an after-action fact-finding mission to Taiwan and concluded that skin allograft would still play a central role as a safety net in US national burn care preparedness, even as BARDA invested in the development of other burn medical countermeasures that would be part of the preparedness strategy. However, before investments in a skin allograft based national strategy could be built, it was critical that the leaders of the Disaster Committee and Organization and Delivery of Burn Care (ODBC) Committee of the American Burn Association (ABA) commission a survey to verify current practice patterns of senior academic burn surgeons on the use of skin allograft. Methods The committee chairs curated a list of 21 leading academic burn surgeons in North America. These surgeons’ credentials included having been an ABA president, a member of the ABA Board of Trustees, or having chaired a standing committee of the ABA. All 21 surgeons were actively practicing burn care daily. The survey contained 18 questions and was intentionally kept brief (Survey to be provided as Appendix). Results Of the 21 surgeons selected, there was 100% participation and completion of the survey. Most were in practice >15 years (62%) and manage >200 patients surgically per year (71%). The predominant use of allograft is to temporize the wound bed when there are inadequate donor sites (48% “Almost Always”). It is “Often” (48%) used to temporize wound beds prior to autografting. However, most are looking for alternatives to allograft (43% “Sometimes”, 43% “Often”). With ongoing development of skin substitutes, most indicated their allograft use will likely decrease, with only 19% indicating “Probably Not”. Conclusions Human skin allograft continues to play a central role in surgical burn care management. For the foreseeable future, new technologies are not likely to displace allograft use but rather blend with its use. This brief, select survey is not powered but provides a snapshot of the current role of skin allograft. In the future, we may conduct a broader survey to obtain a validated and more granular view of the use of allograft in modern burn care. Applicability of Research to Practice Armed with this information, the US Federal Government acted to increase preparedness after a burn mass casualty. In February 2022, a Request for Proposals for a large vendor-managed inventory of human cryopreserved skin allograft was answered by two separate tissue banks. As of September 2022, $38M was awarded to two partners for procurement and expansion of a vendor managed inventory of cryopreserved human skin allograft to ensure preparedness for rapid response to a burn mass casualty incident.

From ancient Egypt to the dermatologic office: An overview of skin substitutes and modern-day applications in dermatologic surgery.

Skin grafting (specifically xenografting) dates back to as early as 1500 before Christ (BC)in the Ebers papyrus, an Egyptian medical papyrus.In 1503, the use of human skin allograft was described in the manuscript of Branca of Sicily, and among the Hindu Tilemaker Caste approximately 2500-3000 years ago, surgeons repaired defects secondary to nose amputations of those who committed adultery and thievery. Over the years, many advancements in skin grafts/substitutes and their applications have propelled the field to focus on better graft survival, contracture prevention, cosmesis, and quality of life.We provide a general overview of skin substitutes (SS) with a particular focus on placental SS and their current applications in dermatologic surgery.

Human Umbilical Cord Lining-Derived Epithelial Cells: A Potential Source of Non-Native Epithelial Cells That Accelerate Healing in a Porcine Cutaneous Wound Model.

Human umbilical cord lining epithelial cells [CLECs) are naïve in nature and can be ethically recovered from cords that are routinely discarded. The success of using oral mucosal epithelial cells for cornea defects hints at the feasibility of treating cutaneous wounds using non-native CLECs. Herein, we characterized CLECs using flow cytometry (FC) and skin organotypic cultures in direct comparison with skin keratinocytes (KCs). This was followed by wound healing study to compare the effects of CLEC application and the traditional use of human skin allografts (HSGs) in a porcine wound model. While CLECs were found to express all the epidermal cell markers probed, the major difference between CLECs and KCs lies in the level of expression (in FC analysis) as well as in the location of expression (of the epithelium in organotypic cultures) of some of the basal cell markers probed. On the pig wounds, CLEC application promoted accelerated healing with no adverse reaction compared to HSG use. Though CLECs, like HSGs, elicited high levels of local and systemic immune responses in the animals during the first week, these effects were tapered off more quickly in the CLEC-treated group. Overall, the in vivo porcine data point to the potential of CLECs as a non-native and safe source of cells to treat cutaneous wounds.

IL-34 deficiency impairs FOXP3+ Treg function in a model of autoimmune colitis and decreases immune tolerance homeostasis.

BackgroundImmune homeostasis requires fully functional Tregs with a stable phenotype to control autoimmunity. Although IL‐34 is a cytokine first described as mainly involved in monocyte cell survival and differentiation, we recently described its expression by CD8+ Tregs in a rat model of transplantation tolerance and by activated FOXP3+ CD4+ and CD8+ Tregs in human healthy individuals. However, its role in autoimmunity and potential in human diseases remains to be determined.MethodsWe generated Il34 −/− rats and using both Il34 −/− rats and mice, we investigated their phenotype under inflammatory conditions. Using Il34 −/− rats, we further analyzed the impact of the absence of expression of IL‐34 for CD4+ Tregs suppressive function. We investigated the potential of IL‐34 in human disease to prevent xenogeneic GVHD and human skin allograft rejection in immune humanized immunodeficient NSG mice. Finally, taking advantage of a biocollection, we investigated the correlation between presence of IL‐34 in the serum and kidney transplant rejection.ResultsHere we report that the absence of expression of IL‐34 in Il34 −/− rats and mice leads to an unstable immune phenotype, with production of multiple auto‐antibodies, exacerbated under inflammatory conditions with increased susceptibility to DSS‐ and TNBS‐colitis in Il34 −/− animals. Moreover, we revealed the striking inability of Il34 −/− CD4+ Tregs to protect Il2rg−/− rats from a wasting disease induced by transfer of pathogenic cells, in contrast to Il34 +/+ CD4+ Tregs. We also showed that IL‐34 treatment delayed EAE in mice as well as GVHD and human skin allograft rejection in immune humanized immunodeficient NSG mice. Finally, we show that presence of IL‐34 in the serum is associated with a longer rejection‐free period in kidney transplanted patients.ConclusionAltogether, our data emphasize on the crucial necessity of IL‐34 for immune homeostasis and for CD4+ Tregs suppressive function. Our data also shows the therapeutic potential of IL‐34 in human transplantation and auto‐immunity.Highlights –Absence of expression of IL‐34 in Il34−/− rats and mice leads to an unstable immune phenotype, with a production of multiple auto‐antibodies and exacerbated immune pathology under inflammatory conditions.– Il34−/− CD4+ Tregs are unable to protect Il2rg−/− rats from colitis induced by transfer of pathogenic cells.–IL‐34 treatment delayed EAE in mice, as well as acute GVHD and human skin allograft rejection in immune‐humanized immunodeficient NSG mice.

Evaluation of Topical Off-The-Shelf Therapies to Improve Prolonged Field Care of Burn-Injured Service Members.

Burns are common injuries on the battlefield. Given austere environments, surgical debridement of injured service members is often not feasible in these settings. Delays in surgical debridement create a risk of infection and deranged healing for burn patients. As such, this study attempts to identify the best commercially available off-the-shelf (OTS) therapies with field-deployable potential to improve prolonged field care (PFC) of burn-injured soldiers. Deep partial-thickness (DPT) burns (25 cm2) were created on the dorsum of 5 anesthetized pigs utilizing a thermocouple burn device at 100°C for 15 seconds. Nonsurgical debridement was done 1-hour after burn creation using sterile saline water and gauze to remove excess eschar tissue. Animals were then randomized into 5 experimental groups, and OTS therapies were applied to 6 of the 12 created DPT burns. The remaining 6 burns were treated with 1% silver sulfadiazine cream (Ascend Laboratories, LLC, Parsippany, NJ) as the PFC standard of care (SOC) controls. The 5 randomized OTS therapies were: irradiated sterile human skin allograft (IHS), biodegradable temporizing matrix (BTM), polylactic acid skin substitute, hyaluronic acid ester matrix (HAM), and decellularized fish skin graft (FSG). Wounds were serially assessed on post-burn days 3, 7, 14, 21, and 28. Assessments were conducted using a combination of photographs, histology, and quantitative bacteriology. Endpoints included burn wound progression, re-epithelialization, wound contraction, scar elevation index, and colony-forming units (CFU). The analysis demonstrated that by day 3, the FSG prevented burn wound progression the most efficiently. In terms of wound healing, the results showed re-epithelialization percentages close to 100% by day 28 for all treatment groups. No statically significant differences were observed. Quality of healing analyses demonstrated that the BTM-treated wounds had contracted less and the difference to the IHS-treated wounds was statistically significant (P < .05). As regards to antimicrobial properties, the CFU results showed no statistically significant differences between the OTS therapies and the SOC on days 3, 7, and 14. The impact of Food and Drug Administration-approved OTS therapies was compared to the current PFC SOC for the treatment of DPT burns in a porcine model. Several topical options exist for the management of burns prior to definitive treatment in the operating room and warrant further evaluation. These therapies are actively used on civilian burn counterparts and have far-forward, field-deployable potential for use at the point of injury so that injured service members may not need evacuation to higher roles of care and combat power may be preserved. Our results demonstrated that all the studied OTS therapies performed well when compared to the SOC in terms of burn wound progression, wound healing, quality of healing, and quantitative bacteriology.

615 Evaluation of Topical Off-The-Shelf Therapies to Improve Burn Wound Healing During Prolonged Field Care

IntroductionBurns are common injuries in the battlefield. Given austere environments, prolonged field care (PFC) is often necessary. Delays in surgical debridement create a risk of infection and deranged healing for burn patients. As such, this study attempts to identify the best commercially available off-the-shelf (OTS) dressings with field-deployable potential.MethodsDeep-partial thickness burns (1" diameter) were created on the dorsum of 3 anesthetized pigs utilizing a thermocoupled burn device at 100°C for 15s. Non-surgical debridement was done 1-h post-burn creation and either an OTS dressing or standard-of-care (SOC) treatment (Silver Sulfadiazine) was applied to the wound in order to simulate a PFC environment. OTS dressings were randomized and included irradiated sterile human skin allograft (ISHSA), alloplastic absorbable skin substitute (AASS), and synthetic polyurethane dermal matrix (SPDM). Wounds were serially assessed on post-burn days 3, 7, 14, 21, and 28. Assessments were conducted using a combination of photographs, histology, and quantitative bacteriology. Endpoints included burn wound progression, re-epithelialization, wound contraction, scar elevation index (SEI), and colony forming units (CFU).ResultsNo statistically significant differences in burn wound progression were seen on days 3 and 7 for the ISHSA or SPDM and the SOC. The differences between the AASS and the SOC were statistically significant on both days (p≤0.05). Day 21 re-epithelialization results for the ISHSA, AASS, SPDM and SOC treated wounds were 30%, 85%, 95%, and 78% re-epithelialized, respectively. The difference between the AASS and the SOC was statistically significant (p≤0.05). Results showed that by day 28, wound contraction for the ISHSA, AASS, SPDM and SOC treated wounds were 65%, 80%, 82%, and 78%, respectively. No statistically significant differences in wound contraction were seen for any of the OTS dressings and the SOC. SEI showed no statistically significant difference in scar hypertrophy between the OTS dressings and the SOC on day 28. CFU results showed no statistically significant differences between the OTS dressings and the SOC on days 3 and 7.ConclusionsThree OTS dressings were compared to the SOC for use in the PFC setting. Generally, all the dressings performed well when compared to the SOC in terms of burn wound progression, re-epithelialization, wound contraction, SEI, and CFU. Although significant differences in burn progression and re-epithelialization for burns treated with AASS were seen. In the future, we hope to continue to discover and test various OTS dressings to determine their appropriateness for use in the PFC setting.

Multi‐centre prospective randomised controlled clinical trial to evaluate a bioactive split thickness skin allograft vs standard of care in the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) pose a significant risk for infection and limb loss. Advanced wound therapies including human skin allografts have shown promise in resolving these challenging wounds. The primary objective of this randomised, prospective study was to compare the response of 100 subjects with non‐healing DFUs of which 50 were treated with a cryopreserved bioactive split thickness skin allograft (BSA) (TheraSkin; Misonix,Inc., Farmingdale, NY) compared with 50 subjects treated with standard of care (SOC, collagen alginate dressing) at 12 weeks. Both groups received standardised care that included glucose monitoring, weekly debridement's as appropriate, and an offloading device. The primary endpoint was proportion of full‐thickness wounds healed at 12 weeks, with secondary endpoints including differences in percent area reduction (PAR) at 12 weeks, changes in Semmes‐Weinstein monofilament score, VAS pain, and w‐QoL. The result illustrated in the intent‐to‐treat analysis at 12 weeks showed that 76% (38/50) of the BSA‐treated DFUs healed compared with 36% (18/50) treated with SOC alone (adjusted P = .00056). Mean PAR at 12 weeks was 77.8% in the BSA group compared with 49.6% in the SOC group (adjusted P = .0019). In conclusion, adding BSA to SOC appeared to significantly improve wound healing with a lower incidence of adverse events related to treatment compared with SOC alone.

Clinical Efficacy of Human Split-thickness Skin Allograft in Patients With Pyoderma Gangrenosum: A Case Series

Pyoderma gangrenosum (PG) is an uncommon inflammatory skin disease that is characterized clinically by the development of painful pustules that subsequently progress to large cutaneous ulcers. There is no universally effective treatment for PG, and a combination of local and systemic therapies is often used to manage it. Biologically active, cryopreserved human skin allograft (BSA) has become a standard part of the treatment algorithm for complex nonhealing wounds. These allografts facilitate the wound healing cascade by delivering the essential biologically active compounds of fresh skin to the wound bed and promoting wound bed revascularization. The purpose of this case series was to illustrate how the use of human split-thickness allografts positively contributes to wound healing in patients with PG. Five cases highlighting the efficacy of a BSA in achieving clinical wound healing in patients with complex PG ulcerations are presented. Clinical findings appear to indicate that the positive effect of BSA in combination with systemic therapies on wound beds in patients with PG is because of a combination of both the unique alterations in the patient's immune system in addition to the possible delays in clearance of cellular components of the allograft, which promote the strong inosculation and revascularization necessary for wound healing. The BSA studied herein appears to aid in wound healing because it has natural components found in human skin that facilitate wound healing, and it eliminates the potential for pathergy because no graft harvesting from the host is performed. These allografts can be applied numerous times, and each has the major essential components of human skin wound healing for a more rapid and complete epithelialization.

Glycerolised Skin Allografts for Extensive Burns in Low- and Middle-income Countries.

Introduction:There has been a significant improvement in the outcome of treatment of large surface area burns in developed countries. A major contributory factor is an early excision and skin grafting of burn wounds. The initial coverage of large surface area deep burn wounds requires the use of temporary skin substitutes such as allografts due to limited skin autografts. Cadaveric skin allografts are the commonest source of skin allografts in use; however, there may be religious, cultural, cost, or other factors mitigating its availability and routine use in low- and middle-income countries (LMICs). Human skin allografts may be used fresh or stored in tissue banks to ensure its ready availability. The purpose of this review is to promote glycerolised skin allografts as a means of skin preservation in low-resource countries above other modalities cryopreservation due to its cost advantages and relative ease of operation.Materials and Methods:A literature search for articles related to human skin allograft use in burn care, skin banks, and glycerolised skin allografts in LMICs was done using PubMed, EMBASE, and Web of Science databases. The key words used were ‘allograft’ and ‘burn’ with a filter in the search for human studies. The relevant references in the articles obtained were also searched for and included in the reviewResults:Sixty-three journal articles were reviewed for contents in line with the objectives of this study.Conclusion:Glycerolised skin graft is a viable option for coverage of extensive burns in LMICs.

135 Vital, Porcine Skin Xenotransplants Provide Safe and Efficacious Temporary Wound Closure of Severe Burns in a First-in-Human Phase I Clinical Trial

Abstract Introduction Temporary wound closure with human allograft skin is considered the gold standard after early excision of a large burn injury. Limitations of allograft include availability, cost, and safety; thus, an alternative that provides the same quality with enhanced safety would be a valuable surgical adjunct to the clinical options currently available to treat severe and extensive full thickness burn wounds. A live cell skin xenotransplant from a clinical grade porcine donor is one candidate. Advantages of this alternative include retention of 70% or more of the innate metabolic activity following cryopreservation, vascularly favorable dermal thickness, and genetic modifications that eliminate hyperacute graft rejection. Combined, these result in pliability, strength, survivability, and function that far exceed those of conventional xenografts and mirror those of human allograft. Methods Split-thickness skin xenotransplants containing vital dermal and epidermal cells were aseptically procured from alpha-galactosyltransferase knockout porcine donors from a closed, Designated Pathogen Free, colony. They were then processed to achieve both sterility and cellular viability and cryopreserved for long term storage. In 2018, the FDA authorized a first-in-human Phase I clinical trial to evaluate the safety and tolerability of a genetically modified skin xenotransplant to treat severe and extensive burn wounds. A two cohort, open-label, dose-escalation study evaluated 6 consenting patients with severe burns requiring allograft. Each received surgical grafting with a skin xenotransplant and human allograft skin in a side-by-side, in-situ comparison. Results The skin xenotransplant was well tolerated by all patients, resulting in zero adverse events or safety issues, and without zoonotic disease transmission. In all cases, the skin xenotransplant appeared indistinguishable from the human allograft comparator and at the time of autografting, both were vascularized and fully adherent. These findings build upon the series of preclinical studies reported by these authors and presented at the ABA in 2019. Conclusions These highly promising patient outcomes demonstrate a potential treatment for complicated burns, especially when human allograft skin is unavailable. Further study of the efficacy of the porcine skin xenotransplants is warranted. As such, a multi-center, Phase II efficacy trial is planned for 2021.

How to improve donor skin availability: Pragmatic procedures to minimize the discard rate of cryopreserved allografts in skin banking

BackgroundMicrobial contamination of human skin allografts is a frequent cause of allograft discard. Our purpose was to evaluate the discard rate of skin bank contaminated allografts and specific procedures used to reduce allograft contamination without affecting safety. MethodsWe conducted at the Lille Tissue Bank a retrospective study of all deceased donors (n = 104) harvested from January 2018 to December 2018. Skin procurement was split into 3 zones: the back of the body and the two legs that were processed separately. It represented 433 cryopreserved skin allograft pouches of approximatively 500 cm² each. Donors were almost equally split between brain-dead (53%, 55/104) and cadaveric (47%, 49/104) donors. ResultsOut of all donors, 42 (40.5%) had at least one sampling zone with a positive microbiological test resulting in 106 (24%) contaminated skin pouches. The contamination rate did not vary according to the harvested zone or type of donor. Traumatic deaths showed significantly less contamination rates than other death types (p < 0.05). Contamination rate decreased with time spent in the antibiotic solution. The risk of having contaminated allografts was five-fold higher when the skin spent less than 96 h in the antibiotic cocktail (p < 0.05). According to our validation protocol, most donors (32/42, 76%) had skin allografts contaminated with bacteria (mainly Staphylococcus spp) compatible with clinical use. No recipient infection was recorded as a result of skin graft contaminated with saprophytic or non-pathogenic germs. By harvesting 3 separate zones per donor, the total surface area for clinical use increased by 53% for contaminated donors. Overall, the proportion of contamination-related discarded allografts was 3.2% (14/433 of pouches). ConclusionFew simple pragmatic measures (including skin incubation in the antibiotic bath for at least 96 h at 4 °C, splitting the skin harvesting areas to minimize the risk of cross-infection and clinical use of allografts contaminated with saprophytic and non-pathogenic germs) can reduce the discard rate of contaminated allografts without affecting clinical safety.

Harvesting human skin allografts for burn care in a developing country

The usage of fresh and glycerolized preserved human skin allograft in burn care is a challenge in a developing countries despites it’s benefits in improving morbidity and mortalities in burn patients. We present two case reports to demonstrates it’s usage. In our first case report, the skin harvested allograft was from a consented patient who was undergoing abdominoplasty. It was harvested as a full thickness skin graft from the panniculus. The harvested skin allograft underwent process of glycerolisation and was stored in 85% glycerol in a fridge at 4°C. The skin allografts were used on the donor site of a patient with 51 percent burns undergoing burn wound excision and skin grafting. The skin was secured with sutures and adherence of the skin allograft on the donor site was noted on the wound review on the third day. Evidence of rejection of some parts of the skin allograft (sloughing off of the skin) was noted by the 7th day post-surgery. The second case report, a two-year-old girl who presented with 37% total burn surface area predominantly deep dermal flame burn injury with suspected inhalation injury. She had tangential wound excision and split thickness skin grafting with both autograft and living donor allograft (donor was the mother). The donor was screened for human immunodeficiency virus (HIV) I and II, hepatitis B surface antigen (HBsAg) and hepatitis C virus (HCV). The autografts were meshed 6:1. Allografts were previously harvested from the thigh of the mother on the same day using a power dermatome and meshed 3:1. By the 12th day, there was a 60% loss of the allograft on the left thigh while there was 5% graft loss for the autograft. On the right thigh, there was a 50% graft loss for the allograft while there was a 2% graft loss for the autograft. Human Skin allograft can be used as an option for wound coverage in patients who have sustained burns.

The cadaveric human skin allograft as a paradigm shift for the management of a large wound of necrotizing soft tissue infection: an interesting case report

Necrotizing soft tissue infection (NSTI) is an uncommon but fatal and rapidly progressing disease which requires emergent recognition and prompt treatment. Patients of NSTI frequently suffer from large soft tissue defects, which require coverage of these defects by auto-skin graft or flap cover. It becomes a challenge to cover the soft tissue defects in an already sick patient. The patient of NSTI has a restricted skin graft donor site and a poor skin grafting bed. Here authors report a case of 50 years old female, known case of type 2 diabetes mellitus, who suffered from NSTI post intramuscular injection of the left gluteal region. Her left thigh, left gluteal region, lower back, pubic and perineal region were involved. She underwent multiple radical debridement’s followed by the use of Cadaveric human skin allografts to cover the raw area temporarily. Meanwhile, authors optimized the patient nutrition state and controlled the infections. Finally, raw areas were covered with an autologous skin graft, and the patient discharged in stable condition.

A real-world experience with the bioactive human split thickness skin allograft for venous leg ulcers.

Data collected from standardized clinical practices can be valuable in evaluating the real-world therapeutic benefit of skin substitutes in the treatment of venous leg ulcers (VLU). Utilizing such a dataset, this study aimed to validate the effectiveness of a bioactive human split-thickness skin allograft for the treatment of VLU in the real-world setting and to understand how certain variables impacted healing rates. From a pool of 1474 VLU treated with allograft, 862 ulcers in 742 patients were selected from a large wound EMR database and analyzed. All patients received standard wound care prior to allograft application. Impact of ulcer duration, number of applications, ulcer size, and time to application were analyzed. The VLU, on average, were of 189 days duration with a mean ulcer size of 19.3 cm2 . During treatment, 70.7% of wounds healed, with an average time to closure of 15 weeks (SD = 14.1 weeks). The percentage of VLU less than one-year duration that healed was significantly higher (72.3%) than the percentage of VLU with duration of greater than 1 years (51.5%) ( χ2 = 18.17; P < .001). Ulcers less than 10 cm2 in size were more likely to heal (73.9%) than those larger than 10 cm2 (67.9%) ( χ2 = 8.65, P = .03). VLU receiving allograft within 90 days of initial presentation are 1.4 times more likely to heal vs those receiving their first BSA application after 90 days of standard of care (95% CI: [1.05, 1.86], P = .02). Allograft used in wound clinics healed a majority of refractory VLU, even in large ulcers of long duration, which are more difficult to heal. Smaller wound, size, and shorter wound duration were associated with greater likelihood of healing. VLUs treated earlier with allograft had better healing outcomes. Clinicians may consider more aggressive and timely treatment with allograft for refractory VLU.

New Treatment of Wound Healing With Allogenic Acellular Human Skin Graft: Preclinical Assessment and In Vitro Study

BackgroundNonhealing wounds can be a major clinical problem. Impaired wound healing is often related to massive tissue injury, concomitant wound healing deficiencies (chronic wounds), burn injury, or congenital conditions. We propose a novel biological dressing as an alternative surgical approach. The dressing is a form of an allogenic human skin graft equivalent with further use of allogeneic stem cells classified as an advanced therapy medicinal product. This new allogenic acellular human skin graft has been specifically developed to address the clinical indications for dressing wound lesions and promoting tissue repair in specific rare genetic diseases. MethodsThis case report illustrates the use of an acellular human skin allograft seeded with multipotent stem cells in the treatment of tissue injuries (burns), congenital conditions, and chronic wounds. Donor-tissue processing yields an acellular dermal matrix with integral collagen bundling and organization, as well as an intact basement membrane complex. ResultsPreclinical observations show prolonged viability of acellular human skin grafts with multipotent stem cells. This was confirmed with histological and electron-microscopic evaluation of biopsies, which demonstrated host-cell infiltration and neovascularization of the biological dressing. Moreover, the dressings were characterized by low immunogenicity, as confirmed by histology exam and T-cell proliferation assays in vitro. ConclusionOur data confirmed the safety and efficacy of the evaluated acellular human skin grafts, which may be used in patients with rare diseases, such as epidermolysis bullosa, burn injuries, and chronic wounds.

Cryopreserved human skin allografts promote angiogenesis and dermal regeneration in a murine model

Cryopreserved human skin allografts (CHSAs) are used for the coverage of major burns when donor sites for autografts are insufficiently available and have clinically shown beneficial effects on chronic non-healing wounds. However, the biologic mechanisms behind the regenerative properties of CHSA remain elusive. Furthermore, the impact of cryopreservation on the immunogenicity of CHSA has not been thoroughly investigated and raised concerns with regard to their clinical application. To investigate the importance and fate of living cells, we compared cryopreserved CHSA with human acellular dermal matrix (ADM) grafts in which living cells had been removed by chemical processing. Both grafts were subcutaneously implanted into C57BL/6 mice and explanted after 1, 3, 7, and 28 days (n = 5 per group). A sham surgery where no graft was implanted served as a control. Transmission electron microscopy (TEM) and flow cytometry were used to characterise the ultrastructure and cells within CHSA before implantation. Immunofluorescent staining of tissue sections was used to determine the immune reaction against the implanted grafts, the rate of apoptotic cells, and vascularisation as well as collagen content of the overlaying murine dermis. Digital quantification of collagen fibre alignment on tissue sections was used to quantify the degree of fibrosis within the murine dermis. A substantial population of live human cells with intact organelles was identified in CHSA prior to implantation. Subcutaneous pockets with implanted xenografts or ADMs healed without clinically apparent rejection and with a similar cellular immune response. CHSA implantation largely preserved the cellularity of the overlying murine dermis, whereas ADM was associated with a significantly higher rate of cellular apoptosis, identified by cleaved caspase-3 staining, and a stronger dendritic cell infiltration of the murine dermis. CHSA was found to induce a local angiogenic response, leading to significantly more vascularisation of the murine dermis compared with ADM and sham surgery on day 7. By day 28, aggregate collagen-1 content within the murine dermis was greater following CHSA implantation compared with ADM. Collagen fibre alignment of the murine dermis, correlating with the degree of fibrosis, was significantly greater in the ADM group, whereas CHSA maintained the characteristic basket weave pattern of the native murine dermis. Our data indicate that CHSAs promote angiogenesis and collagen-1 production without eliciting a significant fibrotic response in a xenograft model. These findings may provide insight into the beneficial effects clinically observed after treatment of chronic wounds and burns with CHSA.

Matched-cohort study comparing bioactive human split-thickness skin allograft plus standard of care to standard of care alone in the treatment of diabetic ulcers: A retrospective analysis across 470 institutions.

This retrospective, matched‐cohort study analyzed 1,556 patients with diabetic ulcers treated at 470 wound centers throughout the United States to determine the effectiveness of a cryopreserved bioactive split‐thickness skin allograft plus standard of care when compared to standard of care alone. There were 778 patients treated with the graft in the treatment cohort, who were paired with 778 patients drawn from a pool of 126,864 candidates treated with standard of care alone (controls), by using propensity matching to create nearly identical cohorts. Both cohorts received standard wound care, including surgical debridement, moist wound care, and offloading. Logistic regression analysis of healing rates according to wound size, wound location, wound duration, volume reduction, exposed deep structures, and Wagner grade was performed. Amputation rates and recidivism at 3 months, 6 months, and 1 year after wound closure were analyzed. Diabetic ulcers were 59% more likely to close in the treatment cohort compared to the control cohort (p = 0.0045). The healing rate with the graft was better than standard of care across multiple subsets, but the most significant improvement was noted in the worst wounds that had a duration of 90‐179 days prior to treatment (p = 0.0073), exposed deep structures (p = 0.036), and/or Wagner Grade 4 ulcers (p = 0.04). Furthermore, the decrease in recidivism was statistically significant at 3 months, 6 months, and 1 year, with and without initially exposed deep structures (p < 0.05). The amputation rate in the treatment cohort was 41.7% less than that of the control cohort at 20 weeks (0.9% vs. 1.5%, respectively). This study demonstrated that diabetic ulcers treated with a cryopreserved bioactive split‐thickness skin allograft were more likely to heal and remain closed compared to ulcers treated with standard of care alone.

The Health Economic Impact of Living Cell Tissue Products in the Treatment of Chronic Wounds: A Retrospective Analysis of Medicare Claims Data.

To investigate differences in wound-related costs; product waste; lower-extremity amputations; and number of applications, hospitalizations, and emergency room visits among patients treated with three cellular and/or tissue-based products. This retrospective intent-to-treat matched-cohort study analyzed the full Medicare claims dataset from 2011 to 2014. Patients who received either a bilayer cellular construct (BLCC), dermal skin substitute (DSS), or cryopreserved human skin allograft (CHSA) were concurrently matched for Charlson Comorbidity Index, age, sex, and region, resulting in 14,546 study patients. Key variables were reported at 60, 90, and 180 days after the first product application. There were no statistically significant differences in the distribution of Charlson Comorbidity Index, age, sex, and region among cohorts. Wound-related costs and product wastage were lower for CHSA patients relative to both BLCC and DSS patients at all time intervals (P < .05). Patients treated with CHSA received fewer product applications than DSS at 90 and 180 days (P < .05). Amputations were significantly higher among patients treated with DSS than either CHSA or BLCC (P < .0001). The data demonstrate that wound-related costs, product waste, amputations, and frequency of applications are lower for CHSA than DSS. Wound-related costs and product waste are lower for CHSA compared with BLCC. Further claims analysis and prospective clinical trials could help develop appropriate quality measures and reimbursement models to ensure smarter spending for the growing population of patients with chronic wounds.

The Effects of an IL-21 Receptor Antagonist on the Alloimmune Response in a Humanized Mouse Skin Transplant Model.

Interleukin 21 (IL-21) is involved in regulating the expansion and effector function of a broad range of leukocytes, including T cells and B cells. In transplantation, the exact role of IL-21 in the process of allograft rejection is unknown. To further explore this, the aim of this study is to test the effect of an IL-21 receptor (IL-21R) blocking antibody on the early phase of allograft rejection in a humanized skin transplantation model in mice reconstituted with human T and B cells. Immunodeficient Balb/c IL2rγRag2 mice were transplanted with human skin followed by adoptive transfer of human allogeneic splenocytes. Control animals were treated with a phosphate buffered saline vehicle while the other group was treated with a humanized anti-IL-21R antibody (αIL-21R). In the phosphate buffered saline-treated animals, human skin allografts were infiltrated with lymphocytes and developed a thickened epidermis with increased expression of the inflammatory markers Keratin 17 (Ker17) and Ki67. In mice treated with αIL-21R, these signs of allograft reactivity were significantly reduced. Concordantly, STAT3 phosphorylation was inhibited in this group. Of note, treatment with αIL-21R attenuated the process of T and B cell reconstitution after adoptive cellular transfer. These findings demonstrate that blockade of IL-21 signaling can delay allograft rejection in a humanized skin transplantation model.