Engineered Aligned Endothelial Cell Structures in Tethered Collagen Hydrogels Promote Peripheral Nerve Regeneration

Abstract

Vascularisation is important in nerve tissue engineering to provide blood supply and nutrients for long-term survival of implanted cells. Furthermore, blood vessels in regenerating nerves have been shown to serve as tracks for Schwann cells to migrate along and thus form Bands of Bungner which promote axonal regeneration. In this study, we have developed tissue‑engineered constructs containing aligned endothelial cells, or co-cultures of both endothelial cells and Schwann cells to test whether these structures could promote regeneration across peripheral nerve gaps. Type I rat tail collagen gels containing HUVECs (Human Umbilical Vein Endothelial Cells, 4×106 cells/ml) were cast in perforated tethering silicone tubes to facilitate cellular self-alignment and tube formation for 4 days of culture. For co-culture constructs, optimal tube formation and cellular alignment was achieved with a ratio of 4:0.5×106 cells/ml (HUVECs:Schwann cells). An in vivo test of the engineered constructs to bridge a 10 mm gap in rat sciatic nerves for 4 weeks revealed that constructs containing only HUVECs significantly promoted axonal regeneration and vascularisation across the gap, as compared to conventional aligned Schwann cell constructs and those containing co-cultured HUVECs and Schwann cells. Our results suggest that tissue-engineered constructs containing aligned endothelial cells within collagen matrix could be good candidates to treat peripheral nerve injury.