The Rho-associated kinase inhibitor fasudil hydrochloride enhances neural regeneration after axotomy in the peripheral nervous system

Background: The Rho family of small GTPases is responsible for various processes involving actin cytoskeleton in eukaryotic cells, including neurite outgrowth. Several substances found at the peripheral nerve injury site were shown to activate one member of this family, Rho. The activation of Rho leads to neurite outgrowth inhibition and the development of posttraumatic neuropathic pain. The authors used the clinically tested Rho-associated kinase inhibitor fasudil hydrochloride to enhance the functional recovery of the peripheral nerve in the rat. Methods: In the peroneal nerve interpositional graft model, the authors administered fasudil (experimental groups) or saline (control groups) (1) intraperitoneally and (2) directly into the graft by microinjection (n = 6 animals per experimental condition). Neural recovery was assessed during postoperative follow-up lasting 80 days by peroneal functional index, electrophysiologic, and histomorphometric analyses. Results: The peroneal functional index returned to values not significantly different from preoperative values on days 55 (fasudil injected into the graft) and 60 (fasudil injected intraperitoneally) in the experimental groups. In the control groups, this took 70 (saline injected intraperitoneally) and 75 days (saline injected into the graft). These results are supported by electrophysiologic and histomorphologic assessments. Conclusions: The authors determined that fasudil hydrochloride was capable of accelerating the functional regeneration after peripheral nerve axotomy, which is consistent with the results of reports about Rho cascade disruption in the central nervous system. Because fasudil hydrochloride is a clinically tested drug, it could be used to enhance neural regeneration in human patients as well.