Clinical Impact of Cryopreservation on Split Thickness Skin Grafts in the Porcine Model

Skin Grafting, Cryopreservation, and Diseases: A Review Article

Food supplements may be consumed through diet and have been shown to modify skin functions, making them helpful in the management of skin aging. However, there are not many clinical trials that back up these assertions. The stratum corneum, which acts as the organism's contact with its environment, is the principal function of the epidermis of land vertebrates. Antioxidants are chemicals that slow down or prevent other molecules from oxidizing. In people's diets, their use has considerably expanded in recent years. Due to their benefits for health, nutrition, and therapy, natural antioxidants are increasingly being used in place of synthetic antioxidant components. A popular component thought to be an antioxidant is hydrolyzed collagen. With aging comes a steady loss of physiological integrity, capacity to handle stress from the inside out, and function. This is a byproduct of several intricate biological processes that are affected by diseases both local and systemic as well as constitutive and environmental variables. Systemic and constitutive (genetic) variables influence skin aging and its phenotypic manifestation. The biological process of skin aging is complicated and impacted by both external and endogenous causes. The primary contributor to skin cancer is sun exposure. Ultraviolet radiation from the sun can kill skin cells by directly absorbing DNA damage. The skin's hydration is a crucial factor that affects its mechanical and physical characteristics. This study looks at how the stratum corneum's molecular and macroscopic characteristics interact and change with skin wetness. Although there is little information written about them and even less is understood about them, moisturizers are a crucial component of a dermatologist's toolkit. There is a plethora of anticipated skin products on the market, but their true scientific function is yet unknown. These items play a well-known part in many skin problems, while occasionally being dismissed as simple cosmetics.

The MHC-characterized Miniature Swine: Lessons Learned From a 40-Year Experience in Transplantation

Over the last 40 y, a specialized herd of miniature swine has been intentionally bred to develop lines of animals homozygous for the swine major histocompatibility complex (MHC), which have facilitated transplantation studies across reproducible MHC and minor antigen mismatch barriers. These MHC-characterized miniature swine (Mc-MS) have been used for the study of novel surgical techniques, various approaches to tolerance induction of solid organ and vascularized composite allografts, as well as studies of the immunobiology of allografts and xenografts. Mc-MS possess characteristics that are highly advantageous to these studies, and their continued use will likely continue to play an important role in bridging "bench-to-cage-to bedside" therapies in the field of transplantation. In this review, we highlight the seminal contributions of the Mc-MS model to the field and analyze their role in the broader context of large animal models in transplantation research.

Skin xenotransplantation: technological advances and future directions

PURPOSE OF REVIEW

To summarize the evolution of skin xenotransplantation and contextualize technological advances and the status of clinically applicable large animal research as well as prospects for translation of this work as a viable future treatment option.

RECENT FINDINGS

Porcine xenografts at the start of the millennium were merely biologic dressings subject to rapid rejection. Since then, numerous important advances in swine to nonhuman primate models have yielded xenotransplant products at the point of clinical translation. Critical genetic modifications in swine from a designated pathogen-free donor herd have allowed xenograft survival reaching 30 days without preconditioning or maintenance immunosuppression. Further, xenograft coverage appears not to sensitize the recipient to subsequent allograft placement and vice versa, allowing for temporary coverage times to be doubled using both xeno and allografts.

SUMMARY

Studies in large animal models have led to significant progress in the creation of living, functional skin xenotransplants with clinically relevant shelf-lives to improve the management of patients with extensive burns.

Immunological response in cynomolgus macaques to porcine α-1,3 galactosyltransferase knockout viable skin xenotransplants-A pre-clinical study

BACKGROUND

Allogeneic skin recovered from human deceased donors (HDD) has been a mainstay interim treatment for severe burns, but unfortunately risk of infectious disease and availability limitations exist. Genetically engineered ɑ-1,3 galactosyltransferase knockout (GalT-KO) porcine source animals for viable skin xenotransplants may provide a promising clinical alternative.

METHODS

Four cynomolgus macaque recipients received full-thickness surgical wounds to model the defects arising from excision of full-thickness burn injury and were treated with biologically active skin xenotransplants derived from GalT-KO, Designated Pathogen Free (DPF) miniature swine. Evaluations were conducted for safety, tolerability, and recipient immunological response.

RESULTS

All skin xenotransplants demonstrated prolonged survival, vascularity, and persistent dermal adhesion until the study endpoint at post-operative day 30. No adverse outcomes were observed during the study. Varying levels of epidermolysis coincided with histologic detection of CD4+ and CD8+ T cells, and other cellular infiltrates in the epidermis. Recipient sera IgM and IgG demonstrated significant antibody immune response to non-α-1,3-galactose porcine xenoantigens. Separately, specific wound healing mediators were quantified. Neither porcine cell migration nor PERV were detected in circulation or any visceral organs.

CONCLUSIONS

These results provide a detailed analysis of vital skin xenotransplants utilizing a non-human primate model to predict the anticipated immunological response of human patients. The lack of adverse rejection even in the presence of elevated Ig indicates this is a prospective therapeutic option. The findings reported here directly supported regulatory clearance for a first-in-man, Phase I xenotransplantation clinical trial.