Development of acellular porcine peripheral nerves

Peripheral nerve injuries can lead to a major loss of function and affect quality of life. Current autologous treatments and commercially available products such as nerve guide conduits all have limitations. The aim of this study was to develop biocompatible, non-immunogenic nerve grafts using low concentration SDS to decellularise porcine peripheral nerves. Initially the porcine nerve anatomy was defined. Acellular nerves were then used as the basis for an in vitro study of perfused flow within the tissue for the introduction of Schwann cells - as the delivery of these cells is reported to stimulate axon regeneration. Furthermore, an in vivo study using a rat sciatic nerve injury model was conducted to evaluate the regenerative capacity of acellular porcine grafts. Histology confirmed an absence of cells and retention of the native nerve histioarchitecture. DNA levels were reduced by >95 % throughout the decellularised tissue. Immunohistochemistry showed retention of important extracellular matrix proteins such as collagen, laminin and fibronectin. In vitro biocompatibility studies indicated the acellular nerves were not cytotoxic to human dermal fibroblasts and primary rat Schwann cells. Uniaxial tensile testing showed a significant increase in ultimate tensile strength (UTS) and strain between native and acellular nerve tissues. In addition, mechanical testing of the nerves revealed porcine peroneal nerves to have a higher UTS value in comparison to the porcine tibial nerves. Analysis of the nerves using transmission electron microscopy concluded that the mechanical properties of nerves could not be determined exclusively by their ultrastructure or collagen fibril diameter. Porcine acellular nerve grafts were used as an in vitro and in vivo model for the introduction of primary rat Schwann cells. The in vitro nerve model confirmed that reseeded Schwann cells under perfusion maintained their phenotype and had a lower rate of cell death when compared to static conditions. A rat sciatic nerve in vivo gap injury model demonstrated that porcine grafts were able to promote axonal regeneration; however, they were not as effective as the autologous graft. In summary, acellular peripheral nerve tissue was found to have excellent potential for development of a tissue engineered graft to aid peripheral nerve regeneration.