Post-injury regeneration in rat sciatic nerve facilitated by neurotrophic factors secreted by amniotic fluid mesenchymal stem cells

Amniotic fluid mesenchymal stem cells have the ability to secrete neurotrophic factors that are able to promote neuron survival in vitro. The purpose of this study was to evaluate the effects of neurotrophic factors secreted by rat amniotic fluid mesenchymal stem cells on regeneration of sciatic nerve after crush injury. Fifty Sprague–Dawley rats weighing 250–300 g were used. The left sciatic nerve was crushed with a vessel clamp. Rat amniotic fluid mesenchymal stem cells embedded in fibrin glue were delivered to the injured nerve. Enzyme-linked immunosorbent assay (ELISA) and immunocytochemistry were used to detect neurotrophic factors secreted by the amniotic fluid mesenchymal stem cells. Nerve regeneration was assessed by motor function, electrophysiology, histology, and immunocytochemistry studies. Positive CD29/44, and negative CD11b/45, as well as high levels of expression of brain-derived neurotrophic factor, glia cell line-derived neurotrophic factor, ciliary neurotrophic factor (CNTF), nerve growth factor, and neurotrophin-3 (NT-3) were demonstrated in amniotic fluid mesenchymal stem cells. Motor function recovery, the compound muscle action potential, and nerve conduction latency showed significant improvement in rats treated with amniotic fluid mesenchymal stem cells. ELISA measurement in retrieved nerves displayed statistically significant elevation of CNTF and NT-3. The immunocytochemical studies demonstrated positive staining for NT-3 and CNTF in transplanted cells. The histology and immunocytochemistry studies revealed less fibrosis and a high level of expression of S-100 and glial fibrillary acid protein at the crush site. Rat amniotic fluid mesenchymal stem cells may facilitate regeneration in the sciatic nerve after crush injury. The increased nerve regeneration found in this study may be due to the neurotrophic factors secreted by amniotic fluid mesenchymal stem cells.