Müller and macrophage-like cell interactions in an organotypic culture of porcine neuroretina

To analyze the in vitro Müller cell modifications in an organotypic culture of porcine neuroretina in response to the addition of a blood-derived mononuclear fraction (MNF; monocytes and lymphocytes) as a source of macrophages. Control and MNF-stimulated neuroretinal explants were examined at 3, 6, and 9 days of culture. Specimens were processed for epoxy-resin embedding and cryosectioning. Light and immunofluorescence microscopy were performed, using toluidine blue staining and antibodies against glial fibrillary acidic protein (GFAP), as a reactive gliosis marker, and cellular retinaldehyde-binding protein (CRALBP), as a Müller cell marker. Compared to controls, explants cocultured with MNF displayed increased cellular disorganization and larger tissue invasion of the subretinal space at 9 days of culture. Immunostaining of the MNF-treated explants revealed evidence of more reactive gliosis and greater number of GFAP-immunoreactive Müller cells that had increased width and processes extending into the subretinal space and forming a multilayer tissue. Astrocytes also responded to the MNF addition, producing extensions that invaded the neuroretinal outer layers. Addition of MNF stimulates modifications of Müller cells, producing a wider intraretinal reactive gliosis and tissue proliferation at the subretinal space (outer layers of the retina). These findings emphasize the role of macrophage-like cells in the production of changes in retinal structure observed after retinal detachment in humans.