Impact of Extracellular Matrix Protein Supplementation on Morphology and Functionality of Müller Glial Cells in the rd1 Mouse Model of Retinal Degeneration

VALLESE MAURIZI, H.; VIERA, S.; COLÓ, G.; GERMAN, O. L.

Simposio; Simposio Frontiers in Neuroscience 4; 2023

Purpose:Müller glial cells (MGC) are specialized retinal cells that support photoreceptor (PR) survival. Inthe retinal degeneration mouse model (rd1) MGC exhibit a reduced regenerative potential andlamellipodia formation compared to the wild type (wt) cells. Changes in MGC morphology andcellular adhesion may contribute to PR death in the retina diseased. The impact of extracellularmatrix (ECM) on MGC adhesion, morphology, and functionality in rd1 retinas remains unclear.The aim of this study was to investigate the ECM protein expression and localization in rd1 retinasprior to the peak of PR degeneration and assesses whether ECM pretreatment can restore themorphology and functionality of rd1 MGC in vitro.Methods:Neuron-glial cultures from rd1 and wt mouse retinas were prepared from postnatal day 2. Weanalyzed by immunocytochemistry the expression of SPARC and Fibronectin (ECM proteins),Paxillin (focal adhesions, FA), and actin. The neuron-glial cluster area was measured using ImageJ software based on phase contrast images. To obtain ECM-enriched SPARC conditional media(CM), we used the retinoblastoma RN22 cell line. Furthermore, rd1 cultures were supplementedwith ECM-CM to evaluate the effects on the neuroglial cluster area, cell proliferation measuredthrough BrdU nucleotide incorporation, and cell death assessed via DAPI staining.Results:SPARC expression was significantly lower, while fibrillary fibronectin expression was higher inrd1 neuro-glial cultures compared to wt cultures. Moreover, rd1 MGC exhibited a reducednumber and length of FA, mainly with a cortical distribution, contrary to the wt condition. In rd1,the actin cytoskeleton also displayed a cortical distribution, with higher fluorescence intensitycompared to wt cultures. Furthermore, our findings demonstrated that supplementation withECM restored lamellipodia extensions in rd1 cultures, improved MGC proliferation, andenhanced PR survival.Conclusion:Enhancement of ECM in rd1 retinas might restore MGC functionality, thus contributing to PRsurvival