Immunosuppressive Potential of Activated Human Amniotic Cells in an Experimental Murine Model of Skin Allo- and Xenotransplantation

Isolated human amniotic cells (hAC) could be used as a source of immunomodulatory factors in regenerative medicine and transplantation. However, in previous experimental studies, native hAC administered to skin graft recipients did not induce graft immunotolerance. To strengthen the immunomodulatory properties of hAC prior to administration to the recipient, we activated them ex vivo using pro-inflammatory cytokines. In this study, we compared the transplantation efficiency of skin allografts (mouse to mouse) and xnografts (rat to mouse) in recipient mice divided into three main groups receiving: 1. Placebo (control group); 2. Cyclosporine A (CsA) [10 or 50 mg/kg body weight (bw)]; 3. suspension of hAC activated ex vivo by IL-1β and INFγ, administered into a tail vein or subcutaneously. During 15 days of observation, hAC administered intravenously or subcutaneously after allotransplantation appeared to be as safe and efficient as CsA at the dose of 10 mg/kg bw in preventing rejection of skin allo- and xenografts. After xenotransplantation, however, only hAC administered intravenously prevented rejection to an extent comparable to CsA. Both CsA (10 mg/kg bw) and activated hAC reduced inflammatory infiltration in the skin (after intravenous injection) and did not increase the concentration of the inflammation marker SAP in serum or percentage of leukocytes in blood. Finally, we concluded that administration of activated hAC is safe and efficient in the presented animal model of skin allo- and xenotransplantation in a route-dependent manner. Activated hAC injected intravenously exhibit an immunosuppressive effect comparable to CsA administered at the dose of 10 mg/kg bw in both allo- and xenotransplantation.

Procurement and Use of Cryopreserved Total Skin Allograft in Complex Wounds

Cryopreserved total skin allografts are a new therapeutic alternative for the management of complex wounds. Their properties allow them to be classified as a temporary coverage for some patients and as definitive in others. And they can be an alternative option to the use of dermal regeneration templates.

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.

Usage of intermingled skin allografts and autografts in a senior patient with major burn injury

Mortality rate in older adults following extensive burn injury is extremely high, and management of these patients is challenging. One of the main problems is that autologous split-thickness skin grafts are scarce and the wounds cannot be covered quickly and effectively. Intermingled skin grafting is a low-tech and economic method, which not only maximizes the use of precious autologous skin but also prevents the wounds from infection and consumption. Herein we present a case of extensive burn injury in a 68-year-old female successfully treated with intermingled skin grafting. The patient was accidentally burned by gas flame, resulting in a major burn injury covering 80% of her total body surface area. Early burn wound excision was performed and the wound was temporarily covered with irradiated porcine skin in the first week after injury. Autologous stamp-like skin grafts were applied to the wound bed 4 weeks after injury. In this operation, the results were not satisfactory. The take rate of the skin grafts is only about 50%. We covered the wounds with intermingled skin allografts and autografts 8 weeks after injury: autografts (0.5 cm × 0.5 cm) + fresh close relative’s allografts (1 cm × 1 cm) + cryopreserved allografts (2 cm × 2 cm).

537 Transplantation of Fresh Scalp Allograft in Repairing Extensive Deep Burn Wounds in Children

Introduction It is difficult to treat pediatric extensive burns, which contribute to high mortality rates, partly because of the lack of large allogeneic skin to close wound in China. Therefore, we innovatively used fresh scalp as thin split thickness skin allografts to cover the burn wounds of pediatric patients. Methods Fresh scalp allografts were harvested from voluntary donors who were patients’ relatives. The median total burn area in the major burns was of 40% TBSA, in depth of deep second to third degree. The fresh scalp allografts were transplanted on the wounds post tangential excision or escharectomy in the way of mere fresh scalp allografts coverage or mixed coverage with autografts and fresh scalp allografts. Results All the patients survived without serious complications during the treatment period. The median healing time was 47 days; the average healing time of the donors’ scalps was (7.6±1.08) days with no scar formation, alopecia areata or folliculitis post operation. Conclusions The use of fresh scalp allografts in the treatment of pediatric major burns is an effective and feasible method in protecting wounds and promoting wound healing as well as in reducing scar formation in the donor sites of burned children. The high ratio of fresh scalp areas to pediatric burn wound areas ensures high efficiency of wound coverage; and healthy relative skin donors have more initiatives and favorable healing results. Applicability of Research to Practice This is a clinical research which is highly applicable in practice.

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.

Increased frequency of myeloid-derived suppressor cells facilitating skin allograft survival in aged mice

Background More and more aged people have organ transplantation recently. Aging process may have an influence on immunity, which conducts an adjustment of immunosuppressive agents to prevent adverse effects. Understanding of aging effects on immunity will be helpful for post-transplant care of aged recipients. Results A mouse model using C3H mice as donors and aged/young C57BL/10J mice as recipients was employed to study the aging effects on immunity. The frequency of CD4 + , CD8 + and native CD4 + foxp3 + regulatory T-cells in the spleen were not different between aged and young mice. However, the frequency of CD11b + Gr-1 + myeloid-derived suppressor cells (MDSC) was higher in aged mice (4.4 ± 1.4% versus 1.6 ± 1.1%, p=0.026). To measure cytokines in the serum, the level of TGF-β was higher in aged mice than in young mice (21.04 ± 3.91ng/ml versus 15.26 ± 5.01ng/ml, p = 0.026). In vitro, enriched T-cells from aged mice had lower proliferation capacity (0.350±0.003 O.D. versus 0.430±0.017 O.D. at responders/stimulatory cells = 100/1) and lower Ag-specific cytotoxic ability (21.2 ± 3.0% versus 39.3 ± 4.8% at target cell/effector cells = 1/100, p=0.003) than T-cells from young mice. In vivo, the skin allografts survived on aged recipients was 19.7 ± 5.2 days, compared 11.9 ± 4.1 days on young mice (p = 0.005). When entinostat was applied to aged mice to block MDSC, the survival of skin allografts was shorten to 13.5 ± 4.7 days which was not different from the survival on young mice (p = 0.359). Conclusion The allogeneic immunity was lower in aged than in young mice evidenced by a higher frequency of MDSC, higher serum level of TGF-β, decreased function of T-cells, and easy-to-induced regulatory T-cells in aged mice. Blocking the function of MDSC reversed the low immunity in aged mice and cause skin allograft rejection similar to young recipients.