Abstract
Purpose::
To investigate if stimulation of specific cell types with growth factors can up-regulate markers considered typical of stem cells.
Methods::
Stem cells are identified using markers that belong to different functional classes of proteins. These markers are often taken as unequivocal proof for the identity of stem cells. D407, a well characterized retinal pigment epithelial cell line, RGC-5, a retinal ganglion cell line, and mouse embryonic fibroblasts were grown in culture media containing 20ng/ml basic fibroblast growth factor and 20ng/ml epidermal growth factor. Stimulated cells were examined by light microscopy and for the expresion of nestin, notch, and sox2 by immunohistochemistry for up to 4 passages. Expression of these markers was compared with controls (cells treated similarly, but without growth factors).
Results::
RGC showed distinctive morphological changes in response to growth factors. No significant changes were noticed in D407 and mouse fibroblasts. Notch immunoreactivity was more intense in cells stimulated with growth factors as compared to controls. Differences in nestin and sox2 expression was not significant.
Conclusions::
Our results suggest that cells other than stem/progenitor cells, when exposed to growth factors, may show markers considered typical of stem cells. If confirmed by quantitative methods, they may have significant impact on criteria for identifying stem/progenitor cells
Keywords: growth factors/growth factor receptors • immunohistochemistry • retinal culture