New Artificial Nerve Conduits Made with Hyaluronic Acid for Peripheral Nerve Regeneration

+*Sakai, Y; * Matsuyama, Y; **Takahashi; **Sato, T; *Hattori, T; *Nakashima, S; *Ishiguro, N +* Nagoya University, Nagoya, Japan [email protected] Introduction: The achievement of peripheral nerve regeneration through biodegradable tubular conduits is at the frontier of nerve repair surgery. An ideal biodegradable conduit should maintain its structure integrity, nanostructured porous scaffold with pore and large surface area permitting cell adhesion and infiltration, and subsequent tissue ingrowth during nerve regenerative process. Thus many conduits using various bioresorbable materials, such as polyglycolic acid, collagens, chitosan, poly L-lactic acid and polycaprolactone have been developed, however, no biomaterials act as an agent to aid nerve growth and repair. We fabricated new artificial nerve conduits made with hyaluronic acid (HA) that facilitate a pathway for cellular and axonal ingrowth during peripheral nerve regeneration, identifying viability of disseminated Schwann cells and neuron cells into HA conduits in vitro. Materials and Methods: All procedures involving animals and their care were conducted in conformity with the institutional guidelines that are in compliance with the national and international laws and polices, and were approved by ethics committee of Nagoya University. Cell preparation: Schwann cells were harvested from dorsal root ganglia (DRG) and sciatic nerves of Sprague-Dawley (SD) female rat aged 6 weeks and weighing about 200g. The harvested DRG and sciatic nerves were cultured in DMEM supplemented with 10% fetal bovine serum for 1 week and following 1 week with serum-free medium. Total of 1.010 Schwann cells were obtained and examined with immunostaining for anti-S100 antibody. Neurospheres were prepared from the hippocampus of SD rat fetus at the specified gestational age of 16 days. The dissociated cells were cultured in DMEM/F12 replenished with N2 supplement and bFGF in 2 weeks. Total of 1.010 neurospheres were obtained and examined with immunostaining for anti-Nestin antibody. Fabrication of HA conduits: HA (810 molecular weight) purified from rooster comb (Seikagaku Corporation, Japan) was used to conjugate cinnamic acid during photo-crosslinking reaction. The photo-crosslinked HA was poured into mold and exposed to UV light. The product was lyophilized and stored with desiccant at –20 C. HA tubular conduit has porous nano-structure of 50m with inner diameter of 1.2mm. (Fig.1)