[Effects of tanshinone ⅡA sulfonate on nerve regeneration after cryopreserved sciatic nerve allograft in rats]

Abstract

In order to investigate the protective effect of tanshinone ⅡA sulfonate on the sciatic nerve activty in rats after cryopreservation as well as the nerve regeneration and functional recovery after allograft and its possible mechanism, Sprague-Dawley (SD) rats were divded into four groups at different doses of tanshinone ⅡA sulfonate (A 0 mg·L⁻¹, B 80 mg·L⁻¹, C 160 mg·L⁻¹, D 480 mg·L⁻¹) cryopreserved at -80 °C for 24 weeks. Fresh control group nerve segments were harvested without cryopreservation. The ultrastructure and the viable cells of the nerve segments after cryopreservation were observed by electron microscopy, calcein-AM/propidium iodide staining, respectively. The expression of Bax and Bcl-2 was detected by Western blot. After cryopreservation, the nerve segments were cultured in vitro for one week, the mRNA and protein level of NGF and GDNF were detected by PCR and Western blot respectively. In addition, the above four cryopreserved groups transplanted to the Wistar rats by allografting (A', B', C', D'). At 16-week postoperation, muscle compound action potential latency and nerve conduction velocity were examined by electrophysiological. The number and the thickness of myelinated nerve fibers were analyzed by toluidine blue staining. The ultrastructure of the sciatic nerve by electron microscopy was observed. According to the results, after the cryopreserved for 24 weeks, compared with groups A and B, the nerve demyelination and vacuolation were weak, and the more viable cells, the decreased Bax and increased Bcl-2, the increased NGF and GDNF in group C and D. At 16-week poseoperation, the results demonstrated that the more larger and thickly regenerated myelinated axons, the shorter latency of muscle compound action potentials and higher nerve conduction velocity in groups C' and D' compared with groups A' and B'. According to these results, tanshinone ⅡA sulfonate exerted a significant protective effect on the viability of the nerves during cryopreservation at -80 °C and promoted nerve regeneration and functional recovery after transplantation especially in middle- and high-dose of tanshinone ⅡA sulfonate.

Keywords: allograft; nerve regeneration; peripheral nerve cryopreservation; tanshinone ⅡA sulfonate.