Abstract
Purpose: :
To create and characterize a novel, cone-rich retinal detachment (RD) animal model using the chick.
Methods: :
Retinal detachments were created in White Leghorn chicks (Gallus, gallus, n=22) between P7-P21 with subretinal injections of saline or hyaluronic acid (10mg/ml, Healon, AMO). Injections were performed through a dilated pupil with assistance of an operating microscope. The fellow eye was used as a control. Immunohistochemical analyses were performed at days 1, 3, 7, 10 and 14 after detachment to evaluate the responses of photoreceptors, Muller glia, microglia and nonastrocytic inner retinal glial (NIRG). Cell proliferation was detected with BrdU-incorporation and PCNA-expression, and photoreceptor apoptosis was detected with TUNEL.
Results: :
Similar to mammalian models of retinal detachment, there is shortening of photoreceptor outer segments and mis-trafficking of cone photoreceptor opsins in areas of RD. Photoreceptor apoptosis begins within 1 day of RD and is maximal at day 3. Muller glia up-regulate glial fibriliary acidic protein, and proliferate, undergoing interkinetic nuclear migration, in areas of detachment. Microglia become reactive, up-regulate CD45, acquire ameboid morphology, and migrate toward the outer retina in areas of RD. In contrast to chemically-induced retinal detachments produced with NMDA and IGF1 injections, there is no significant up-regulation of NIRG cells in detached areas.
Conclusions: :
Subretinal delivery of hyaluronic acid in the chick eye results in an acute retinal detachment that is similar to several mammalian models of retinal detachment. Given the relatively large eye size and low cost, the chick model of RD may offer advantages for high-throughput studies.
Keywords: retinal detachment • retinal glia • photoreceptors