Current Status in Peripheral Nerve Xenotransplantation

Abstract

Nerve grafts are used to repair segmental defects in peripheral nerves. However, autografts and even allografts are limited for clinical use. Xenotransplantation offers a potentially unlimited source for tissue transplantation. We have conducted a systematic review of the literature, aiming to clarify the latest and more appealing proposals and discoveries in nerve xenotransplantation. A total of 22 articles were retrieved, all of them experimentally controlled studies in animals. There are no current studies in humans. Fresh xenografts provoke an immune response that leads to graft rejection. Immunosuppressive drugs or pretreatment of the grafts are the preferred methods against immune rejection. Recently, investigative groups have proposed the use of acellular nerve xenografts, which do not elicit immune rejection while they do allow and promote axonal regeneration. The addition of human stem cells increases nerve growth. Limits to the analyzed studies are the absence of trials in humans and the short length of the nerve defects that have been successfully repaired. Further investigations and clinical trials are needed before nerve xenografting is accepted as a valid method of nerve repair.