INFLAMMATION MEASUREMENT AND IMMUNOCHARACTERIZATION OF CELL-PROLIFERATION IN AN EXPERIMENTAL-MODEL OF PROLIFERATIVE VITREORETINOPATHY

An experimental model of proliferative vitreoretinopathy was developed in the rabbit eye by injecting a solution of human platelet-rich plas ma. In this model we evaluated the progression with time of intraocula r inflammation and the rate and origin of cell proliferation. A steril e solution adjusted to 10(7) platelets was injected into the right eye of a total of 46 pigmented and 14 albino rabbits. Animals were sequen tially sacrificed at days 7, 14, 21 and 1 month after injection, Clini cal evaluation of vitreoretinal proliferation, using a classification in six grades, and of anterior segment inflammation assessed by a Lase r Flare Meter, were done for 1 month after injection, before histopath ological analysis. Eighty percent of eyes developed tractional retinal detachment in 1 month. Histopathology showed intense cell migration a nd proliferation in the area of the ciliary body, as early as the seve nth day, then further increasing rapidly. Infiltrates were composed of cytokeratin- and vimentin-expressing cells. Abnormal expression of vi mentin was also found in ciliary and retinal epithelia and in Muller c ells. Inflammation measured by the Laser Flare Meter was maximal at da y 11 and then reached a plateau at significantly higher levels than co ntrols. Albino rabbits showed significantly lower grades of proliferat ion, as compared to pigmented rabbits. This study thus clarified some characteristics of experimental vitreoretinal proliferations that prov ed similar to those in human diseases, such as the involvement of cili ary body and retinal pigment epithelium, the existence of inflammatory reactions preceding cell proliferation and strong changes in intermed iate filaments, This may provide a simple and valuable model for antip roliferative assays and shed some light on the pathogenesis of intraoc ular proliferative disorders.