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Quantitative study on regenerated retinal pigment epithelium and the effects of growth factor.

PURPOSE
To evaluate the integrity of damaged retinal pigment epithelium (RPE) with normal neural retina in a rabbit model, and to examine the effects of basic fibroblast growth factor (bFGF) on the damaged RPE.


METHODS
A 3-port vitrectomy, a retinotomy, and a retinal detachment were made in pigmented rabbit eyes. The RPE was then abraded beneath the neural retina. In one group, 1 microgram(s) of bFGF was injected into the vitreous cavity (bFGF applied group). Zero, 7, 14, 21, and 28 days after the operation, fundus examination and fluorescein angiography were performed. Thereafter, the rabbits were killed, the eyes were enucleated, and the histological features were observed with light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The number of RPE cells in the treated area were counted in all experiments, and the effect of bFGF on the number of regenerated RPE cells was analyzed.


RESULTS
Regeneration of the RPE was observed in the treated area at postoperative day 14. The number of regenerated RPE cells showed a linear increase. Regenerated cells observed by TEM were smaller than those of the normal RPE. The difference in the number of regenerated RPE cells between the bFGF-applied and non-applied groups was statistically significant on postoperative days 7 and 21.


CONCLUSIONS
Repair of the RPE occurred in a short period of time. Similar RPE repair may be seen in humans. Intravitreal injection of bFGF increased the number of regenerated RPE in this model.