Recent advances in artificial nerve conduit design: Strategies for the delivery of luminal fillers

Artificial nerve conduits offer an attractive alternative to nerve autografts for the repair of peripheral nerve injuries and several commercially-available conduits are currently on the market. However, at present, utilization of these conduits is limited to the repair of nerve gaps less than 3 cm in length. Thus, current research is focused on how best to design artificial conduits with improved nerve regeneration potential over longer distances. Successful nerve regeneration necessitates that the cells, extracellular matrix components, and growth factors involved interact in a highly specific manner that is tightly coordinated. Combinatorial approaches that take into account these interactions and conduits that utilize supportive factors, such as neurotrophins and stem cells, may be key components of the next generation of artificial conduits. Additionally, design strategies that combine physical cues for contact guidance and biochemical signals to enhance cellular function have shown promise. This review highlights recent advances in artificial nerve conduit design, focusing on the use of luminal fillers, with special focus on the various techniques for accessory cell and/or growth factor delivery into artificial nerve conduits.