Nerve Allotransplantation as it Pertains to Composite Tissue Transplantation

Abstract

Nerve allografts provide a temporary scaffold for host nerve regeneration and allow for the repair of significant segmental nerve injuries. From rodent, large animal, and nonhuman primate studies, as well as clinical experience, nerve allografts, with the use of immunosuppression, have the capacity to provide equal regeneration and function to that of an autograft. In contrast to solid organ transplantation and composite tissue transfers, nerve allograft transplantation requires only temporary immunosuppression. Furthermore, nerve allograft rejection is difficult to assess, as the nerves are surgically buried and are without an immediate functional endpoint to monitor. In this article, we review what we know about peripheral nerve allograft transplantation from three decades of experience and apply our current understanding of nerve regeneration to the emerging field of composite tissue transplantation.

Scaffolds for Peripheral Nerve Regeneration, the Importance of In Vitro and In Vivo Studies for the Development of Cell-Based Therapies and Biomaterials: State of the Art

“…However, autografts sacrifice a functioning nerve, usually a sensory nerve, to substitute a more important injured motor nerve. Therefore, sensory loss and scarring at the donor site, where neuroma and pain phenomena, are expected [30,63,77]. Autologous nerve graft undergoes Wallerian degeneration and therefore just provides support and guidance for the ingrowing axon.…”

“…Also, fascicle mismatch, scarring and fibrosis of the repair site is unavoidable and is caused by the injury, tissue handling and suture itself. [30,63,77]. An alternative to autologous nerve grafting is the use of nerve allografts.…”

“…The advantages of allografts are no donor supply limitations or donor-site morbidity, accessibility and unlimited supply of neuronal tissue. However, there are significant costs and complexity with their use, such as immunosuppression [30,63,72,73,77]. Several techniques have been used to reduce allograft antigenicity, such as cold preservation, irradiation and lyophilization and certainly patients' immunosuppressive therapy.…”

Biofabrication and testing of a fully cellular nerve graft

“…These show good functional repair in clinical applications for small gaps [9], especially when combined with muscle tissue [8] or nerve slices [9]. In the absence of autografts, allografts (a nerve segment transplanted from a genetically non-identical donor of the same species) have been used with satisfactory outcome, but they require immunosuppression therapy to avoid rejection [2, 10]. …”

Hand transplantation: current challenges and future prospects

“…This effect is applied to nerve transection with primary repair as well as grafts. [59][60][61] In an attempt to decrease systemic immunosuppression and focus on the antigenic nature of skin, topical steroids and tacrolimus have also been trialed. 7 Moreover, novel approaches have been applied to adapt the immune system to tolerate the coexistence of donor and recipient immune cells through chimerism.…”