Enhancement of nerve healing with the combined use of amniotic membrane and granulocyte-colony-stimulating factor.

Healing of a transected nerve is not always optimal even if it is repaired with an ideal microsurgical technique. We studied the effects of solitary and combined usage of amniotic membrane (AM) wrapping and granulocyte-colony-stimulating factor (GCSF) injections after primary repairs of transected sciatic nerves of Wistar rats. No repair was performed in group 1, primary nerve repairs were performed in group 2, AMs were wrapped around repair sites in group 3, in addition to AM wrapping G-CSF injections were performed in group 4, and only G-CSF injections were performed in group 5. Nerve regeneration was assessed by clinical tests at the 4th, 8th, and 12th weeks and by electrophysiological studies and histological evaluations at the end of the 12th week. Group 4 rats gave earlier responses to clinical tests that showed a stable increase throughout the study. In electrophysiological studies, the mean amplitude values were higher in group 4 whereas mean latency and duration values were higher in group 1. At the end of the 12th week, the morphology of the distal nerve segment was similar to healthy nerves in the absence of fibrosis in group 4. The comparison of mean scores of axonal counting under the light microscope revealed that scores of group 4 were higher than the other groups in a statistically significant manner. Electron microscopy revealed that samples from groups 3 and 4 had high numbers of axons possessing myelin sheaths of normal thickness, as well as less inter-axonal fibrosis. In terms of both axonal diameter and myelin thickness, groups 2, 3, and 4 had higher values than groups 1 and 5. As a conclusion, both AM wrapping and G-CSF injection have a supportive effect on nerve regeneration, and this effect is further potentialized by their combined use.