Carvacrol ameliorates skin allograft rejection through modulating macrophage polarization by activating the Wnt signalling pathway.

Post-transplantation immune rejection remains an important factor for transplant patients. However, conventional immunosuppressants are associated with substantial adverse effects. Natural immunosuppressants present a promising alternative to conventional counterparts, boasting exceptional biological activity, minimal toxicity and reduced side effects. We identified carvacrol as a prospective immunosuppressive agent following T cell proliferation experiment and validated carvacrol's immunosuppressive efficacy in the murine allogeneic skin graft model. T cell proliferation assay was used to screen natural small molecule compounds and the immunosuppressive effect of compounds was evaluated in MHC-mismatched murine allogeneic skin graft model. H&E and immunohistochemical staining were applied to evaluate the pathological grade. Furthermore, flow cytometry was uitlized to analyse the immunophenotype changes of immune cells. Western blotting and q-PCR were used to detect the expression of key molecules in macrophages. In vitro, carvacrol demonstrates significant inhibition of the proliferation of CD4+ T and CD8+ T cells. It notably reduces inflammatory factor expression within the allografts, suppresses T cell differentiation toward Th1 phenotype and expansion. Furthermore, carvacrol prominently hinders M1-type macrophages polarization by activating Wnt signaling. Notably, the anti-rejection efficacy of carvacrol was significantly weakened upon the removal of macrophages in mice using chlorophosphate liposomes. Carvacrol could significantly inhibit T cell proliferation, alleviate graft rejection and has outstanding toxicological safety. The molecular mechanism of the anti-rejection effect of carvacrol is closely related to its mediating activation of macrophage Wnt pathway, inhibiting M1 polarization and inducing T cell differentiation.

Combined Use of Tocilizumab and Mesenchymal Stem Cells Attenuate the Development of an Anti-HLA-A2.1 Antibody in a Highly Sensitized Mouse Model.

Sensitization to HLA can result in allograft loss for kidney transplantation (KT) patients. Therefore, it is required to develop an appropriate desensitization (DSZ) technique to remove HLA-donor-specific anti-HLA antibody (DSA) before KT. The aim of this research was to investigate whether combined use of the IL-6 receptor-blocking antibody, tocilizumab (TCZ), and bone-marrow-derived mesenchymal stem cells (BM-MSCs) could attenuate humoral immune responses in an allo-sensitized mouse model developed using HLA.A2 transgenic mice. Wild-type C57BL/6 mice were sensitized with skin allografts from C57BL/6-Tg (HLA-A2.1)1Enge/J mice and treated with TCZ, BM-MSC, or both TCZ and BM-MSC. We compared HLA.A2-specific IgG levels and subsets of T cells and B cells using flow cytometry among groups. HLA.A2-specific IgG level was decreased in all treated groups in comparison with that in the allo-sensitized control (Allo-CONT) group. Its decrease was the most significant in the TCZ + BM-MSC group. Regarding the B cell subset, combined use of TCZ and BM-MSC increased proportions of pre-pro B cells but decreased proportions of mature B cells in BM (p < 0.05 vs. control). In the spleen, an increase in transitional memory was observed with a significant decrease in marginal, follicular, and long-lived plasma B cells (p < 0.05 vs. control) in the TCZ + BM-MSC group. In T cell subsets, Th2 and Th17 cells were significantly decreased, but Treg cells were significantly increased in the TCZ+BM-MSC group compared to those in the Allo-CONT group in the spleen. Regarding RNA levels, IL-10 and Foxp3 showed increased expression, whereas IL-23 and IFN-γ showed decreased expression in the TCZ + BM-MSC group. In conclusion, combined use of TCZ and BM-MSC can inhibit B cell maturation and up-regulate Treg cells, finally resulting in the reduction of HLA.A2-specific IgG in a highly sensitized mouse model. This study suggests that the combined use of TCZ and BM-MSC can be proposed as a novel strategy in a desensitization protocol for highly sensitized patients.

Natural Compound 2,2',4'-Trihydroxychalcone Suppresses T Helper 17 Cell Differentiation and Disease Progression by Inhibiting Retinoid-Related Orphan Receptor Gamma T.

Retinoid-related orphan receptor γt (RORγt), a vital transcription factor for the differentiation of the pro-inflammatory Th17 cells, is essential to the inflammatory response and pathological process mediated by Th17 cells. Pharmacological inhibition of the nuclear receptor RORγt provides novel immunomodulators for treating Th17-driven autoimmune diseases and organ transplant rejection. Here, we identified 2,2',4'-trihydroxychalcone (TDC), a natural chalcone derivant, binds directly to the ligand binding domain (LBD) of RORγt and inhibited its transcriptional activation activity. Using three mice models of Th17-related diseases, it was found that the administration of TDC effectively alleviated the disease development of experimental autoimmune encephalomyelitis (EAE), experimental colitis, and skin allograft rejection. Collectively, these results demonstrated TDC targeting RORγt to suppress Th17 cell polarization, as well as its activity, thus, indicating the potential of this compound in treating of Th17-related autoimmune disorders and organ transplant rejection disorders.

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.

BAFF Inhibition Effectively Suppresses the Development of Anti-HLA.A2 Antibody in the Highly Sensitized Mouse Model.

B cell activating factor (BAFF) is a cytokine that plays a role in the survival, proliferation and differentiation of B cells. We proposed to observe the effects of BAFF inhibition on the humoral immune responses of an allosensitized mouse model using HLA.A2 transgenic mice. Wild-type C57BL/6 mice were sensitized with skin allografts from C57BL/6-Tg (HLA-A2.1)1Enge/J mice and were treated with anti-BAFF monoclonal antibody (mAb) (named Sandy-2) or control IgG1 antibody. HLA.A2-specific IgG was reduced in BAFF-inhibited mice compared to the control group (Δ-13.62 vs. Δ27.07, p < 0.05). BAFF inhibition also resulted in increased pre-pro and immature B cell proportions and decreased mature B cells in the bone marrow (p < 0.05 vs. control). In the spleen, an increase in transitional B cells was observed with a significant decrease in marginal and follicular B cells (p < 0.05 vs. control). There was no significant difference in the proportions of long-lived plasma and memory B cells. Microarray analysis showed that 19 gene probes were significantly up- (>2-fold, p < 0.05) or down-regulated (≤2-fold, p < 0.05) in the BAFF-inhibited group. BAFF inhibition successfully reduced alloimmune responses through the reduction in alloantibody production and suppression of B cell differentiation and maturation. Our data suggest that BAFF suppression may serve as a useful target in desensitization therapy.

Bacterial contamination of human skin allografts and antimicrobial resistance: a skin bank problem.

BACKGROUND: Bacterial contamination remains the major problem in skin banks, even after antimicrobial treatment, and results in high rates of tissue discarding. This study aimed to analyze bacterial contamination in 32 human skin allografts from the skin bank of Dr. Roberto Corrêa Chem from the Hospital Complex Santa Casa de Misericórdia de Porto Alegre. These samples were already discarded due to microbial contamination. The identification of the bacteria isolated from skin allografts was performed by matrix assisted laser desorption ionization-time of flight. The antimicrobial susceptibility of the isolates to six different classes of antimicrobials was determined using the disk-diffusion agar method, and the evaluation of the inhibitory potential was determined by the minimal inhibitory concentration (50/90) of antimicrobials already used in the skin bank and those that most isolates were susceptible to. RESULTS: A total of 21 (65.6%) skin samples were contaminated with Gram-positive bacteria: 1 (4.7%) with Paenibacillus sp., 12 (61.9%) with Bacillus sp., 6 (28.5%) with Staphylococcus sp., and 2 (9.5%) with Bacillus sp. and Staphylococcus sp. Several resistance profiles, including multiresistance, were found among the isolates. Most of the isolates were susceptible to at least one of the antimicrobials used in the skin bank. All isolates were susceptible to amikacin, gentamicin, and tetracycline, which demonstrated the best inhibitory activities against the isolates and were considered as potential candidates for new antimicrobial treatments. CONCLUSIONS: Bacillus, Paenibacillus, and Staphylococcus were isolated from the skin allografts, thus demonstrating the predominance of Gram-positive bacteria contamination. Other factors not related to the resistance phenotype may also be involved in the persistence of bacterial isolates in the skin allografts after antibiotic treatment. Gentamicin, amikacin, and tetracycline can be considered as an option for a more effective treatment cocktail.

Comparison between cryopreserved and glycerol-preserved allografts in a partial-thickness porcine wound model.

Human skin allografts are one of the best temporary biological coverings for severely burned patients. Cryopreserved (CPA) and glycerol-preserved (GPA) allografts are the most widely used types. This study compared the allograft efficiency of both preservation methods under the same conditions. To simulate actual clinical conditions, we used a porcine wound model. In addition, we evaluated the macroscopic and microscopic scoring of graft performance for each method. Porcine cadaver skin 1 mm thick was obtained from one pig. Cryopreserved skin cell viability was 20.8 %, glycerol-preserved skin was 9.08 %, and fresh skin was 58.6 %. We made ten partial-thickness wounds each in two pigs. The take rates on day 2 were 96.23 and 82.65 % in the GPA and CPA group (both n = 9), respectively. After 1 week, the take rates of both groups were nearly equal. The removal rate at week 5 was 98.87 and 94.41 % in the GPA and CPA group, respectively. On microscopic findings at week 2, inflammation was greater in the CPA group. Other findings such as fibroblast hyperplasia and neovascularization were not significantly different between both groups. At week 5, the score of collagen fiber synthesis was 2.67 ± 0.47 and 2.33 ± 0.47 in the GPA and CPA group, respectively. The epidermal-dermal junction was 2.22 ± 0.79 and 2.00 ± 0.47 in the GPA and CPA group, respectively. These findings suggest that wound healing takes longer in the CPA group. The preservation method of allografts is not a absolute factor in the wound healing process in this wound model.

Hypercapnic acidosis prolongs survival of skin allografts.

BACKGROUND: Evidence reveals that hypercapnic acidosis (HCA) modulates immune responses. However, the effect of HCA on allogenic skin graft rejection is unknown. We examined whether HCA might improve skin graft survival in a mouse model of skin transplantation. METHODS: A major histocompatibility-complex-incompatible BALB/c to C57BL/6 mouse skin transplantation model was used. Animals were divided into sham control, air, and HCA groups. Mice in the HCA group were exposed daily to 5% CO2 in air for 1 h. Skin grafts were harvested for histologic analyses. Nuclear factor (NF)-κB activation was determined in harvested draining lymph nodes. Spleen weights and serum levels of tumor necrosis factor-α and chemokine (C-X-C motif) ligand 2 were serially assessed after skin transplantation. RESULTS: Skin allografts survived significantly longer in the HCA group of mice than those in the air group. Allografted mice in the air group underwent a 2.1-fold increase in spleen weight compared with a 1.1-fold increase in the mice with HCA on day 3. There were increased inflammatory cell infiltration, folliculitis, focal dermal-epidermal separation, and areas of epidermal necrosis in the air group that were reduced with HCA treatment. In the HCA group, CD8(+) T cell infiltration at day 7 decreased significantly but not CD4(+) T cell infiltration. In addition, HCA significantly suppressed serum tumor necrosis factor-α on days 1 and 3 and chemokine (C-X-C motif) ligand 2 on days 1 and 10. Furthermore, the HCA group had remarkably suppressed NF-κB activity in draining lymph nodes. CONCLUSIONS: HCA significantly prolonged the survival of incompatible skin allografts in mice by reducing proinflammatory cytokine production, immune cell infiltration, and NF-κB activation.

MicroRNA 26a prolongs skin allograft survival and promotes regulatory T cell expansion in mice.

MicroRNA 26a (Mir-26a) has been reported to play functions in cellular differentiation, cell growth, cell apoptosis, and metastasis. However, the role of Mir-26a in transplant rejection has never been investigated. Full-thickness skin grafts 1-2 cm in diameter were obtained from the tail-skin CBA/J donor mice and transplanted onto the back of wild-type C57Bl/6 recipient mice. Vectors encoding pre-Mir-26a (LV-26a) and an empty lentiviral vector (LV-Con) delivered approximately 2 × 10(7) transforming units of recombinant lentivirus were injected to mice once through the tail vein. Mir-26a overexpression results in prolonged skin allograft survival (MST = 9.5 days in LV-Con mice; MST = 22 days in LV-26a mice. P < 0.01) and promoted regulatory T cells (Tregs) expansion. The prolonged skin allograft survival induced by LV-26a was abrogated by depletion of Tregs with anti-CD25 antibodies. Mir-26a significantly promoted IL-10 expression and suppressed the expression of IL-6, IL-17, and IFN-γ. Furthermore, IL-6 overexpression led to complete suppression of the Mir-26a-induced upregulation of Foxp3. The prolonged allograft survival induced by LV-Mir-26a was also completely abrogated by IL-6 overexpression. In conclusion, Mir-26a prolongs skin allograft survival and promotes Tregs expansion in part through inhibition of IL-6 expression.

Anti-HLA sensitization in extensively burned patients: extent, associated factors, and reduction in potential access to vascularized composite allotransplantation.

Extensively burned patients receive iterative blood transfusions and skin allografts that often lead to HLA sensitization, and potentially impede access to vascularized composite allotransplantation (VCA). In this retrospective, single-center study, anti-HLA sensitization was measured by single-antigen-flow bead analysis in patients with deep, second- and third-degree burns over ≥40% total body surface area (TBSA). Association of HLA sensitization with blood transfusions, skin allografts, and pregnancies was analyzed by bivariate analysis. The eligibility for transplantation was assessed using calculated panel reactive antibodies (cPRA). Twenty-nine patients aged 32 ± 14 years, including 11 women, presented with a mean burned TBSA of 54 ± 11%. Fifteen patients received skin allografts, comprising those who received cryopreserved (n = 3) or glycerol-preserved (n = 7) allografts, or both (n = 5). An average 36 ± 13 packed red blood cell (PRBC) units were transfused per patient. In sera samples collected 38 ± 13 months after the burns, all patients except one presented with anti-HLA antibodies, of which 13 patients (45%) had complement-fixing antibodies. Eighteen patients (62%) were considered highly sensitized (cPRA≥85%). Cryopreserved, but not glycerol-preserved skin allografts, history of pregnancy, and number of PRBC units were associated with HLA sensitization. Extensively burned patients may become highly HLA sensitized during acute care and hence not qualify for VCA. Alternatives to skin allografts might help preserve their later access to VCA.

Comparative study of two antimicrobial dressings in infected leg ulcers: a pilot study.

OBJECTIVE: The aim of the study was to compare the efficacy of a microorganism-binding (MB) dressing with a silver-containing hydrofiber (SCH) dressing in controlling the bacterial loads of heavily colonised or locally infected chronic venous leg ulcers, before surgical management with homologous skin grafts. METHOD: A randomised comparative single centre study recruited patients presenting with hard-to-heal critically colonised or locally infected leg ulcers, who could be treated with skin grafting. Inclusion criteria included; ulcers of vascular aetiology, over 18 years old, a wound duration ≥6 months and ankle brachial index (ABPI) >0.6. Patients were randomly assigned to treatment with SCH dressings (Aquacel Ag) or MB dressing (Cutimed Sorbact). Dressings were changed daily over a four-day observation period, after which they were taken for a skin grafting procedure. Swab samples from ulcer beds were taken in order to quantify the bacterial load at inclusion (D0) and at the end of the observation period day 4 (D4). No antibiotics were administered before or during the evaluation period. RESULTS: Both groups (n=20 SCH, n=20 MB) were similar in gender, age, pathophysiology (both had 15 patients with venous leg ulcers and 5 with arterial leg ulcers), ulcer surface, ulcer duration, treatment-related pain and initial bacterial load. Analysing bacterial load variation showed a significant reduction of bacterial burden at D4 in both groups. In the SCH group, we found an average bacterial load reduction of 41.6%, with an average reduction of 73.1% in the MB group (p< 0.00001). No serious adverse events were reported. CONCLUSION: Our evaluation confirmed that MB and SCH dressings are effective in reducing the bacterial burden in critically colonised or locally infected chronic leg ulcers, without inducing adverse events, with MB dressings significantly more effective. DECLARATION OF INTEREST: There were no external sources of funding for this study. The authors have no conflicts of interest to declare.

Real-time three-dimensional imaging of epidermal splitting and removal by high-definition optical coherence tomography.

While real-time 3-D evaluation of human skin constructs is needed, only 2-D non-invasive imaging techniques are available. The aim of this paper is to evaluate the potential of high-definition optical coherence tomography (HD-OCT) for real-time 3-D assessment of the epidermal splitting and decellularization. Human skin samples were incubated with four different agents: Dispase II, NaCl 1 M, sodium dodecyl sulphate (SDS) and Triton X-100. Epidermal splitting, dermo-epidermal junction, acellularity and 3-D architecture of dermal matrices were evaluated by High-definition optical coherence tomography before and after incubation. Real-time 3-D HD-OCT assessment was compared with 2-D en face assessment by reflectance confocal microscopy (RCM). (Immuno) histopathology was used as control. HD-OCT imaging allowed real-time 3-D visualization of the impact of selected agents on epidermal splitting, dermo-epidermal junction, dermal architecture, vascular spaces and cellularity. RCM has a better resolution (1 µm) than HD-OCT (3 µm), permitting differentiation of different collagen fibres, but HD-OCT imaging has deeper penetration (570 µm) than RCM imaging (200 µm). Dispase II and NaCl treatments were found to be equally efficient in the removal of the epidermis from human split-thickness skin allografts. However, a different epidermal splitting level at the dermo-epidermal junction could be observed and confirmed by immunolabelling of collagen type IV and type VII. Epidermal splitting occurred at the level of the lamina densa with dispase II and above the lamina densa (in the lamina lucida) with NaCl. The 3-D architecture of dermal papillae and dermis was more affected by Dispase II on HD-OCT which corresponded with histopathologic (orcein staining) fragmentation of elastic fibres. With SDS treatment, the epidermal removal was incomplete as remnants of the epidermal basal cell layer remained attached to the basement membrane on the dermis. With Triton X-100 treatment, the epidermis was not removed. In conclusion, HD-OCT imaging permits real-time 3-D visualization of the impact of selected agents on human skin allografts.

Single-cell RNA sequencing revealed the role of the Th17 pathway in the development of anti- human leukocyte antigen antibodies in a highly sensitized mouse model.

Background: The aim of this study is to investigate the specific pathway involved in human leukocyte antigen (HLA) sensitization using single-cell RNA-sequencing analysis and an allo-sensitized mouse model developed with an HLA.A2 transgenic mouse. Methods: For sensitization, wild-type C57BL/6 mouse received two skin grafts from C57BL/6-Tg(HLA-A2.1)1Enge/J mouse (allogeneic mouse, ALLO). For syngeneic control (SYN), skin grafts were transferred from C57BL/6 to C57BL/6. We performed single-cell RNA-sequencing analysis on splenocytes isolated from ALLO and SYN and compared the gene expression between them. Results: We generated 9,190 and 8,890 single-cell transcriptomes from ALLO and SYN, respectively. Five major cell types (B cells, T cells, natural killer cells, macrophages, and neutrophils) and their transcriptome data were annotated according to the representative differentially expressed genes of each cell cluster. The percentage of B cells was higher in ALLO than it was in SYN. Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that the highly expressed genes in the B cells from ALLO were mainly associated with antigen processing and presentation pathways, allograft rejection, and the Th17 cell differentiation pathway. Upregulated genes in the T cells of ALLO were involved in the interleukin (IL)-17 signaling pathway. The ratio of Th17 cluster and Treg cluster was increased in the ALLO. On flow cytometry, the percentage of Th17 (IL-17+/CD4+ T) cells was higher and regulatory T cells (FOXP3+/CD4+ T) was lower in the ALLO compared to those in the SYN. Conclusion: Our results indicate that not only the B cell lineage but also the Th17 cells and their cytokine (IL-17) are involved in the sensitization to HLA.

Novel approach for enhancing skin allograft survival by bioadhesive nanoparticles loaded with rapamycin.

Skin graft rejection is a significant challenge in skin allografts for skin defects, particularly in extensive burn injury patients when autografts are insufficient. Enhancing the survival duration of allogeneic skin grafts can improve the success rate of subsequent autologous skin grafting, thereby promoting the therapeutic efficacy for wound healing. Rapamycin (Rapa), a potent immunosuppressant with favorable efficacy in organ transplantation, is limited by its systemic administration-associated toxicity and side effects. Therefore, addressing the short survival time of allogeneic skin grafts and minimizing the toxicity related to systemic application of immunosuppressive agents is an urgent requirement. Here, we present a topical formulation based on bioadhesive poly (lactic acid)-hyperbranched polyglycerol nanoparticles (BNPs) with surface-modified encapsulation of Rapamycin (Rapa/BNPs), applied for local immunosuppression in a murine model of allogeneic skin grafts. Our Rapa/BNPs significantly prolong nanoparticle retention, reduce infiltration of T lymphocytes and macrophages, decrease the level of pro-inflammatory cytokines and ultimately extend skin allograft survival with little systemic toxicity compared to free Rapa or Rapamycin-loaded non-bioadhesive nanoparticles (Rapa/NNPs) administration. In conclusion, Rapa/BNPs effectively deliver local immunosuppression and demonstrate potential for enhancing skin allograft survival while minimizing localized inflammation, thus potentially increasing patient survival rates for various types of skin defects.

Skin Bank Establishment in Treatment of Severe Burn Injuries: Overview and Experience with Skin Allografts at the Vienna Burn Center.

Depending on their extent, burn injuries require different treatment strategies. In cases of severe large-area trauma, the availability of vital skin for autografting is limited. Donor skin allografts are a well-established but rarely standardized option for temporary wound coverage. Ten patients were eligible for inclusion in this retrospective study. Overall, 202 donor skin grafts obtained from the in-house skin bank were applied in the Department of Plastic and Reconstructive and Aesthetic Surgery, Medical University of Vienna. Between 2017 and 2022, we analysed the results in patient treatment, the selection of skin donors, tissue procurement, tissue processing and storage of allografts, as well as the condition and morphology of the allografts before application. The average Abbreviated Burn Severity Index (ABSI) was 8.5 (range, 5-12), and the mean affected total body surface area (TBSA) was 46.1% (range, 20-80%). In total, allograft application was performed 14 times. In two cases, a total of eight allografts were removed due to local infection, accounting for 3.96% of skin grafts. Six patients survived the acute phase of treatment. Scanning electron microscope images and histology showed no signs of scaffold decomposition and intact tissue layers of the allografts. The skin banking program and the application of skin allografts at the Vienna Burn Center can be considered successful. In severe burn injuries, skin allografts provide time by serving as sufficient wound coverage after early necrosectomy. Having an in-house skin banking program at a dedicated burn centre is particularly advantageous since issues of availability and distribution can be minimized. Skin allografts provide a reliable treatment option in patients with extensive burn injuries.

Successful Treatment of Lower Limb Burn Wounds With Long-Term Survived Human Skin Allograft in an Immunosuppressed Patient: A Case Report.

Early excision and autografting have been the principles in managing acute burn wounds. Despite the known benefits of early autografting, there are situations in which the placement of autograft is unsafe or even unavailable. In these clinical situations, skin substitutes like artificial dressings and human skin allografts are considered as useful for temporary wound coverage. We present an immunosuppressed patient with deep lower limb burn wound who received human skin allograft for wound management. The applied human skin allograft persisted for a longer period without infection or rejection and successfully improved her wound healing. Large and well-designed prospective studies are needed to confirm the encouraging results of the present case report.

Fast protocol for the processing of split-thickness skin into decellularized human dermal matrix.

BACKGROUND: Dermal scaffolds for tissue regeneration are nowadays an effective alternative in not only wound healing surgeries but also breast reconstruction, abdominal wall reconstruction and tendon reinforcement. The present study describes the development of a decellularization protocol applied to human split-thickness skin from cadaveric donors to obtain dermal matrix using an easy and quick procedure. METHODS: Complete split-thickness donor was decellularized through the combination of hypertonic and enzymatic methods. To evaluate the absence of epidermis and dermal cells, and ensure the integrity of the extracellular matrix (ECM) structure, histological analysis was performed. Residual genetic content and ECM biomolecules (collagen, elastin, and glycosaminoglycan) were quantified and tensile strength was tested to measure the effect of the decellularization technique on the mechanical properties of the tissue. RESULTS: Biomolecules quantification, residual genetic content (below 50 ng/mg dry tissue) and histological structure assessment showed the efficacy of the decellularization process and the preservation of the ECM. The biomechanical tests confirmed the preservation of native properties in the acellular tissue. CONCLUSIONS: The acellular dermal matrix obtained from whole split-thickness skin donor with the newly developed decellualrization protocol, maintains the desired biomechanical and structural properties and represents a viable treatment option for patients.

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

BACKGROUND: Microbial 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. METHODS: We 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. RESULTS: Out 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). CONCLUSION: Few 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.

Review of the Latest Methods of Epidermolysis Bullosa and Other Chronic Wounds Treatment Including BIOOPA Dressing.

Epidermolysis bullosa (EB) is a hereditary genetic skin disorder, classified as a type of genodermatosis, which causes severe, chronic skin blisters associated with painful and potentially life-threatening complications. Currently, there is no effective therapy or cure for EB. However, over the past decade, there have been several important advances in treatment methods, which are now approaching clinical application, including gene therapy, protein replacement therapy, cell therapy (allogeneic fibroblasts, mesenchymal stromal cells), bone marrow stem cell transplant, culture/vaccination of revertant mosaic keratinocytes, gene editing/engineering, and the clinical application of inducible pluripotent stem cells. Tissue engineering scientists are developing materials that mimic the structure and natural healing process to promote skin reconstruction in the event of an incurable injury. Although a cure for EB remains elusive, recent data from animal models and preliminary human clinical trials have raised the expectations of patients, clinicians, and researchers, where modifying the disease and improving patients' quality of life are now considered attainable goals. In addition, the lessons learned from the treatment of EB may improve the treatment of other genetic diseases.

Contemporary reconstruction of a severe neuropathic foot burn injury.

The neuropathic foot in diabetic patients constitutes a special clinical entity that needs particular care and ministration. A burn on such a foot requires special care and attention in order to avoid amputation, especially when the burn is a deep partial or a full-thickness burn. The indication for early excision and coverage of a diabetic foot is taken under consideration in clinical practice. An 80-year-old male diabetic patient with deep partial and full-thickness burns on both his feet after a long hot footbath is presented. Even though feet appearance indicated the need for amputation of both feet, we performed gradual surgical debridement and primary coverage with human skin allografts. Both feet were finally covered with partial thickness skin grafts. Considering age, general condition and severity of the burn injuries, the final results were very satisfactory. We believe that the gamma-radiated allograft is another useful adjunct to the reconstructive armamentarium of the surgeon.

Les pieds du patient souffrant de neuropathie diabétique nécessitent des soins spécifiques. Le traitement d'une brûlure profonde de tels pieds a pour but d'en éviter l'amputation, l'indication d'excisiongreffe précoce étant systématiquement à évoquer. Nous présentant la cas d'une patiente diabétique de 80 ans ayant subi des brûlures profondes des 2 pieds du fait d'un bain trop chaud. Alors même que l'aspect des brûlures laissait craindre la nécessité d'une amputation, nous avons choisi des excisions réitérées avec couverture par allogreffe avant autogreffe dont les résultats, compte tenu de l'âge, de la comorbidité et de la profondeur de la brûlure, sont considérés comme satisfaisants. Les allogreffes irradiées représentent un élément utile dans l'arsenal thérapeutique du chirurgien brûlologue.