Embryonic Stem Cell-Derived Neural Progenitor-Endothelial Cell Interactions in Vitro

In cell replacement therapies, transplanted cells stimulate repair of diseased or damaged tissue and can become fully integrated within the local environment. This implies that grafted cells will participate in the routine exchange of signals and form physical connections with host cells, facilitating the formation of a single cohesive tissue. Studies using transplantation into the brain have demonstrated a close physical association between transplanted neural stem cells (NSCs) and the local neurovasculature. Several groups have investigated these NSC-vascular interactions in vitro by co-culturing NSCs derived from neural tissue (tissue-specific NSCs) with brain endothelial cells (BECs). They note differences between tissue-specific NSCs cultured alone and those cultured with BECs, including BEC-induced multicellular aggregation and inhibited differentiation. They also document a role for integrins in enabling the physical attachments between NSCs and BECs. Here, we report the first studies of BEC-NSC interactions using NSCs derived from a human embryonic stem cell line (ESNPs). In co-culture we note the formation of multicellular ESNP aggregates, similar to those observed with tissue-specific NSCs. We find differences in neuronal morphology between co-cultured and monocultured ESNPs that may be explained by BEC inhibition of ESNP differentiation. We also demonstrate that α6β1 integrin mediates adhesion of ESNPs to a BEC monolayer, presumably through contacts with BEC-specific laminin. Information gained from studying the adhesive