Abstract
Introduction: :
Retinal detachment (RD) is a severe condition with poor functional recovery even after successful surgical reattachment. Undesired outcomes reflect both retinal remodeling and growth of epi- and sub-retinal membranes. Astrocytes, Müller cells, microglia and retinal pigment epithelial (RPE) can contribute to membranes. However, membrane development is not completely understood. Here, we report the appearance of minichromosome protein 2 (MCM2), a marker of cycling cells during G1 phase, after experimental RD.
Methods: :
5-week old Balb-c mice received general and topical anesthesia, following the ARVO Statement for the Use of Animals. A nasal RD was produced by sub-retinal injection of hyaluronic acid. 2, 3 or 5 days after surgery, animals were anesthetized for examination of the eye fundus and perfusion fixation. Cryosections were incubated with antibodies against MCM2, the macrophage/microglia marker F4/80, and the intermediate filament nestin. They were studied with immunoenzymatic or immunofluorescent procedures.Resultados: In control animals, neither the neural retina nor the RPE showed MCM+ nuclei. Some labeled nuclei appeared in the ciliary body. F4/80+ cells were very few, and Müller cell endfeet showed low nestin immunostaining.Numerous MCM2+ nuclei appeared in the detached retina, the detached RPE and the nasal ciliary body. Within the detached retina, MCM2+ nuclei occupied random positions. Their distribution resembled that of F4/80+ cells appearing after RD. Nestin immunostaining of Müller cells increased after RD, but co-localization with MCM2 nuclear labeling was not observed.The nasal ciliary body displayer a large increase of MCM2+ nuclei. Lower numbers of MCM2+ nuclei appeared in the temporal region of the ciliary body, distant from the detached retina. MCM2+ ciliary cells also showed cytoplasmic nestin.Sub-retinal membranes were found in about 30% of RD eyes. These membranes usually showed an anatomical conection with the ciliary body and contained numerous MCM2+ and nestin+ cells.
Conclusions: :
Nuclear MCM2+ immunoreactivity detected cycling G1 cells. These cells appeared in regions that are known to be involved in epi- and sub-retinal membrane formation. Proliferation in the ciliary body, together with nestin expression in ciliary MCM2+ cells, suggests that RD would also activate putative retinal progenitors. In addition, anatomical connections between the ciliary body and sub-retinal membranes indicate that cells derived from the ciliary body could perhaps contribute to membrane formation.
Keywords: retinal degenerations: cell biology • retinal detachment • retinal glia