Enhanced rat sciatic nerve regeneration through silicon tubes filled with pyrroloquinoline quinone

Pyrroloquinoline quinone (PQQ) is an antioxidant that also stimulates nerve growth factor (NGF) synthesis and secretion. In an earlier pilot study in our laboratory, Schwann cell growth was accelerated, and NGF mRNA expression and NGF secretion were promoted. The present study was designed to explore the possible nerve-inducing effect of PQQ on a nerve tube model over a 1-cm segmental deficit. An 8-mm sciatic nerve deficit was created in a rat model and bridged by a 1-cm silicone tube. Then,10 mul of 0.03 mmol/l PQQ were perfused into the silicone chamber in the PQQ group. The same volume of normal saline was delivered in the control group. Each animal underwent functional observation (SFI) at 2-week intervals and electrophysiological studies at 4-week intervals for 12 weeks. Histological and morphometrical analyses were performed at the end of the experiment, 12 weeks after tube implantation. Using a digital image-analysis system, thickness of the myelin sheath was measured, and total numbers of regenerated axons were counted. There was a significant difference in SFI, electrophysiological index (motor-nerve conduct velocity and amplitude of activity potential), and morphometrical results (regenerated axon number and thickness of myelin sheath) in nerve regeneration between the PQQ group and controls (P < 0.05). More mature, high-density, newly regenerated nerve was observed in the PQQ group. We conclude that PQQ is a potent enhancer for the regeneration of peripheral nerves.