Characterization of the Ependymal Barrier due to Human Aging and Injury in Murine Models

Ventriclulomegaly, or the expansion of the ventricles in the brain, is a phenomenon associated with age and injury to the brain. The ependymal layer that encases the ventricles displays certain degrees of plasticity and regenerative ability due to its associated stem cell niche, the subventricular zone (SVZ). Previous research in the Conover Lab has shown that in the mouse, which maintains an actively proliferating SVZ into adulthood, there is an intact ependymal monolayer throughout normal aging, with maintained lateral ventricle size with some degree of stretching. In contrast, the human SVZ declines in proliferative capacity after infancy, and age-related changes to the ventricular lining can be seen. Here, we confirm that ventriculomegaly, or the expansion in ventricle volume, is consistent in human brains, particularly after the age of 60. We found that extensive formation of gliosis is associated with ventriculomegaly, possibly compensating for the loss of ependymal cell coverage along the ventricle wall. In addition, we looked at the effects of injury in the form of repeated traumatic brain injury (rmTBI) on the ventricular lining. Results confirm that in mice, there is an increase in ependymal cell size correlated with increased ventricular size, along with an increased expression of astrocytes along the apical surface of the ventricles. These studies show the importance of the ventricular system in the brain, and further research could elucidate how it is implicated in neurodegeneration