Fig. 7: Summary of in vitro and in vivo experimental results.

A The co-culture of OPCs with platelets leads to increased levels of differentiation towards myelin-forming oligodendrocytes. B The co-culture of NSPCs with different densities of platelets leads to a dichotomous effect on the expression of Ki67, with a significant reduction in Ki67+ cells at low platelet densities, an increase in Ki67 mRNA at middle densities, and an increase in Ki67+ cells at high densities. Another effect is the increased presence of Sox2+ cells, across all tested densities of platelets. C, D A demyelinating lesion (area in green characterized by loss of oligodendrocytes) was induced in the CC proximal to the SEZ (area in yellow) by injecting lysolecithin, and the effects on OPCs (C) and NSPCs (D) were investigated. The reduction in the numbers of circulating platelets, in Nbeal2-KO mice, did not result in any changes compared to wild-type (WT) mice, both in the CC and the SEZ. The more severe, chemical, depletion of platelets led to the extravasation of platelets in the brain parenchyma, possibly due to micro-hemorrhages. This was accompanied by a significant increase in the presence of oligodendrocytes in the CC and of OPCs in the SEZ. E The increased accumulation of platelets within the vasculature of the SEZ, observed in response to neuraminidase-induced damage of ependymal cells, did not lead to changes in NSPCs. F The intracerebral injection of platelets in the striatum led to the emergence of mitotic Sox2+ cells. [The illustration is not in scale and only the necessary cell types are depicted].