Morphology, Dynamic Behavior and Biomarkers of Repopulated Retinal Microglia

Science Center, Bent Corridor

Microglia are a class of neuron-promoting cells that exist throughout the Central Nervous System(CNS). Microglia function as the resident immune cells of the CNS, acting as the first responders to inflammation. Currently, microglia and their mechanics of homeostasis are not well understood. This project sought to better elucidate these mechanisms and to determine whether microglia could regenerate a population through chemical depopulation in mice retina, and observation of the population’s regeneration. Microglia were observed with regards to morphology, biomarkers and behavior using confocal microscopy at several time points before and after depopulation. Microglia at an early time point after depopulation were found to have a more simplified morphology compared to control microglia but were indistinguishable by the later time point. The presence of biomarkers for microglia activation and proliferation decreased significantly between an early time point and a later time point after depopulation. Microglia behavior (motility and ATP response) at a later time point was found to be statistically indistinguishable from control microglia. However, the distributions of the behavior populations were significantly different. In conclusion, it seems that microglia are able to establish a functional population within two months. Not all microglia seem to be fully mature with regards to behavior, but it seems that other microglia work to pick up the slack. Lastly the initial presence of biomarkers and their decline in expression over time suggest that microglia activation and proliferation may be relevant factors in their reestablishment of homeostasis.