Transplanted neural stem cells promote regeneration of peripheral nerve

Abstract

Purpose of study: The purposes of this study are to investigate the characters of neural stem cells in collagen medium and to achieve the peripheral nerve regeneration after neural stem cell transplantation.Methods used: Neural stem cells were harvested from hippocampus of embryo rat. The cells were floated and cultured in medium containing bFGF (20 ng/ml) and collagen gel (1%). To investigate whether these cells in collagen medium could maintain the undifferentiated condition, cells were stained with anti-nestin antibody, which is specific for undifferentiated neural cells. Thereafter we removed bFGF to investigate whether these cells could differentiate into neurons and whether the axon could extend in the collagen medium. A 15-mm defect was made of the sciatic nerves of inbred Fischer 344 adult rats. The defects were bridged by silicone tubes (20 mm in length, 1.5 mm in diameter) filled inside with neural stem cells in collagen gel. In the control rats, silicone tubes were filled with collagen gel without neural stem cells. We counted the numbers and diameters of axons at the regenerative nerves in the silicone tubes 8 weeks after transplantation. The regenerative nerves were stimulated electrically to investigate whether the descending nerve action potential (NAP) could be recognized.of findings: 1) Neural stem cells started to proliferate within 48 hours in the collagen medium, and neurospheres were recognized after 8 days. On immunostains with anti-nestin antibody, positive findings were observed in the cytoplasm. In medium without bFGF, these cells differentiated into neurons and gradually extended axons. 2) Eight weeks after neural stem cells were transplanted, regenerative nerves were visible in the silicone tube. The mean number of myelinated fibers was 7,064 and the mean diameter of myelinated fibers was 3.51 μm in the neural stem cell transplantation group, but these values were 293 and 1.51 μm in control group. NAPs were recognized in all regenerative nerves. Mean latency was 7.92 ms, and mean amplitude was 1.38 mV. The mean latency was almost the same as the normal control nerve, but mean amplitude was 38% of the normal control nerve.Relationship between findings and existing knowledge: For the peripheral nerve regeneration, several kinds of cells were used for the source of transplantation. This is the first report of neural stem cells being transplanted to a nerve injury site, and definite regeneration was recognized.Overall significance of findings: Neural stem cells from the hippocampus of fetal rats maintained the potentials of proliferate and their undifferentiated condition and ability to differentiate into neurons. Transplanted neural stem cells could supply regenerative myelinated fiber at nerve injury site.Disclosures: No disclosures.Conflict of interest: No conflicts.