Abstract
Abstract: :
Purpose:We have previously reported that transplanted human neural stem cells (HNSCs) displayed extensive migration and positional incorporation into the aged rat brain associated with cognitive function improvements (Qu et al., 2001). These HNSCs are also capable of spontaneously differentiating into neurons and glia in vitro after long-term cell proliferation under a non-serum defined condition (Brannen et al., 2000). Because of the multipotency of HNSCs, we hypothesized that HNSCs can be differentiated into retinal cells that may be used to treat retinal degeneration. Methods:We treated HNSCs with pleiotropic factors; transforming growth factor-beta3 (TGFbeta3, 10-100 ng/ml), insulin-like growth factor-1 (IGF-1, 2-20 ng/ml), Ciliary NeuroTrophic Factor (CNTF, 1-10 ng/ml), or vascular endothelial cell growth factor (VEGF, 10-100 ng/ml) during differentiation under a serum free condition in Lab-Teck II chamber slides (Nalge Nunc). After 3-5days differentiation, HNSCs were fixed and double-immuno-fluorescent-stained with anti-opsin (Chemicon) and anti-human glial fibrillary acidic protein (GFAP, Research Diagnostics). The stained slides were coverslipped using VECTASIELD mounting medium (Vector) with DAPI. Results:We found opsin-positive and GFAP-positive cells in TGFbeta3-, IGF-1-, and CNTF-treated HNSCs, indicating the presence of photoreceptor and glial cells, where as VEGF-treated HNSCs did not show opsin immunoreactivity. IGF-treated HNSCs showed the most abundant amount of opsin- or GFAP-positive cells. CNTF-treated cells also differentiated into opsin- or GFAP-positive cells, but many non-labeled cells were also observed. TGFbeta3-treated HNSCs differentiated into a few opsin-positive and many non-labeled cells. Since opsin and GFAP are not colocalized, glially differentiated cells did not express opsin. Conclusion:Here we report, for the first, the differentiation of HNSCs into opsin-immuno-positive cells in vitro, indicating that HNSCs possess the possibility of differentiating into retinal cells. Although we have yet to confirm the physiological function of opsin-expressed cells, or to investigate whether other retinal cell markers are expressed by differentiated HNSCs, our results suggest a new and effective treatment for retinal degenerative diseases, i.e. transplantation of HNSCs.
Keywords: 554 retina • 560 retinal culture • 434 immunohistochemistry