An in vivo Study of Basic Fibroblast Growth Factor on Activation and Proliferation of Retinal Progenitor Cells in RCS Rat

Purpose: To investigate the effect of intravitreal injection of basic fibroblast growth factor(bFGF) on activation and proliferation of endogenous retinal progenitor cells in the Royal College of Surgeons(RCS) rat. Methods: Twenty-four rats were studied after the 30th postnatal day(≥30). Eighteen RCS-p+/LAV rats were divided into 3 groups: bFGF-treated, vehicle-treated and untreated groups randomly, and 6 RCS-ray+p+/Lav respectively rats were used as normal controls. 6 μl of bFGF (5 μg/10 μl) or vehicle was injected into the vitreous on day 31, 33 and 35 after birth (P31, P33, P35) in the bFGF group and vehicle group respectively, and no injections were administered in the untreated and control groups. All the rats were euthanized, and their eyes were enucleated, hemisected and fixed at 50 d ays after birth for immunohistochemistry and measurement of outer nuclear layer thickness. Results:Nestin and Chx10 were positive in all retinal layers, intravitreal injection of bFGF in retina-dystrophic RCS(RCS-p+/Lav) rats induced intense labeling for the retinal progenitor cell markers Chx10 and Nestin, which were highly colocalized. Fluorescence intensity for both labels was somewhat less in the control rats, and much less in the vehicle-injected rats as well as in the untreated RCS rats. The outer nuclear layer(ONL) was significantly thicker in bFGF group than that in vehicle-treated or untreated group(P<0.01), but thinner than that of the control group(P<0.01). No significant difference was observed in the ONL thickness between the vehicle group and untreated group(P>0.05). Conclusion:bFGF may contribute to the activation of retinal progenitor cells in RCS rats,thus counteract degeneration by promoting the proliferation of the progenitor cells.