EFFECTS OF BASIC FIBROBLAST GROWTH-FACTOR ON THE RETINAL DEGENERATIONOF THE MI(VIT) MI(VIT) (VITILIGO) MOUSE - A MORPHOLOGIC AND ELECTROPHYSIOLOGIC STUDY/

Basic fibroblast growth factor (bFGE) has been shown to rescue dying p hotoreceptor cells in the RCS rat, a model with a genetic defect of th e RPE that impairs outer segment phagocytosis. The purpose of the pres ent study was to determine whether intravitreal injection of bFGF woul d have a similar effect on photoreceptor cell death in the vitiligo (C 57BL/6-mi(vit)/mi(vit)) mouse. This mutant mouse loses photoreceptor c ells slowly over many months. Experimental evidence suggests that the primary cellular site of the defect is the RPE. In the present study, bFGF was prepared with and without heparin in PBS and injected intravi treally into vitiligo mice at ages 2, 4, 6, 8 and 13 weeks, surroundin g the onset of photoreceptor cell death. Non-injected, PBS-injected an d heparin/PBS injected mice served as controls. Scotopic ERG's were pe rformed on one group of mice prior to killing. Mice were killed 4, 6 o r 10 weeks following the injection and the eyes were processed for his tology and analysed. The amplitude of the b-wave was significantly sma ller in mice injected with bFGP/PBS than in PBS-injected and non-injec ted eyes regardless of the time of injection or duration following inj ection. Histological examination revealed that the number of rows of p hotoreceptor cells did not differ significantly between bFGF-injected, vehicle- or non-injected mice. Although slight improvement in the att achment of outer segments to RPE was observed in 4 week mutants inject ed with bFGF/heparin/PBS, a similar result was obtained in heparin/PBS injected mutants. In mice injected with bFGF without heparin, detachm ent was severe and gross disruption of neural retina was observed. The re were significantly more macrophages and photoreceptor cells in the subretinal space in bFGF injected mice. It appears that at the dosages and times administered, bPGF does not improve the electrophysiologica l functioning of the retina nor retard the degeneration of the retina in the vitiligo mouse as it does in the RCS rat. (C) 1996 Academic Pre ss Limited