Thrombin causes the Enrichment of Rat Brain Primary Cultures with Ependymal Cells Via Protease-Activated Receptor 1

Ependymal cell culture models from rat have been developed over the last 20 years to facilitate biochemical studies on this least-studied glial cell type. The cell culture protocol calls for the presence of thrombin, which is essential for obtaining a high proportion of multiciliated ependymal cells. The serine protease appears to act via protease-activated receptor 1 to prevent the apoptosis of ependymal precursors and enhance their proliferation without affecting contaminating cells. Unciliated precursors differentiate into polyciliated ependymocytes by passing through a stage of monociliation. The message for protease-activated receptor (PAR) 1 is initially abundant in the cultures, but its level declines as the cells differentiate. Besides PAR 1, signalling through PAR 2 also promotes ciliation in rat brain primary cultures, albeit to a lesser degree than the thrombin receptor. Thrombin and other proteases may be involved in the regulation of ventricular wall development. This action would be mediated mainly by PAR1.