Successful storage of peripheral nerve before transplantation using green tea polyphenol: an experimental study in rats

Abstract

Green tea polyphenol is known to act as a buffer, reducing biological responses to oxidative stress. Several effects of polyphenol have been reported, such as protection of tissue from ischemia, antineoplasmic and anti-inflammatory effects, and suppression of arteriosclerosis. In this study, we investigated whether peripheral nerve segments could be kept viable in a polyphenol solution for 1 month. Sciatic nerve segments, 20 mm long, were harvested from Lewis rats and treated in three different ways before transplanting to recipient Lewis rats to bridge sciatic nerve gaps created by removal of 15-mm-long nerve segments. Group F: nerve segments were transplanted immediately after harvesting. Group P: nerve segments were transplanted after they had been stored in Dulbecco's Modified Eagle's Medium (DMEM) containing polyphenol for 7 days at 4°C and then in DMEM for 21 days at 4°C. Group M: nerve segments were stored in DMEM solution alone for 28 days at 4°C. Viability of the nerve segments was assessed by vital staining (calcein-AM/ethidium homodimer), by electron microscopy and by genomic studies before transplantation. Nerve regeneration was evaluated using electrophysiological and morphological studies 12 and 24 weeks after transplantation. Neural cell viability of the preserved nerve segments was confirmed in group P, in which the nerve regeneration was similar to that in group F and superior to that in group M. Peripheral nerve segments can be successfully preserved for 1 month using green tea polyphenol.