Research ReportInvolvement of PI3K and ROCK signaling pathways in migration of bone marrow-derived mesenchymal stem cells through human brain microvascular endothelial cell monolayers

•MSC-induced tight junction disassembly in brain microvascular endothelial cells.•PI3K and ROCK signaling were involved in the MSC-induced increase in endothelial cell permeability.•Dominant negative PI3K mutations in MSC inhibited MSC transendothelial migration.•Interference with ROCK in MSC enhanced MSC transendothelial migration.

Bone marrow-derived mesenchymal stem cells (MSC) represent an important and easily available source of stem cells for potential therapeutic use in neurological diseases. The entry of circulating cells into the central nervous system by intravenous administration requires, firstly, the passage of the cells across the blood-brain barrier (BBB). However, little is known of the details of MSC transmigration across the BBB. In the present study, we employed an in vitro BBB model constructed using a human brain microvascular endothelial cell monolayer to study the mechanism underlying MSC transendothelial migration. Transmigration assays, transendothelial electrical resistance (TEER) and horseradish peroxidase (HRP) flux assays showed that MSC could transmigrate through human brain microvascular endothelial cell monolayers by a paracellular pathway. Cell fractionation and immunofluorescence assays confirmed the disruption of tight junctions. Inhibition assays showed that a Rho-kinase (ROCK) inhibitor (Y27632) effectively promoted MSC transendothelial migration; conversely, a PI3K inhibitor (LY294002) blocked MSC transendothelial migration. Interestingly, adenovirus-mediated interference with ROCK in MSC significantly increased MSC transendothelial migration, and overexpression of a PI3K dominant negative mutant in MSC cells could block transendothelial migration. Our findings provide clear evidence that the PI3K and ROCK pathways are involved in MSC migration through human brain microvascular endothelial cell monolayers. The information yielded by this study may be helpful in constructing gene-modified mesenchymal stem cells that are able to penetrate the BBB effectively for cell therapy.

Graphical abstractIn vitro studies of MSC transendothelial migration revealed that MSC transendothelial migration was associated with the PI3K and ROCK pathways. Interestingly, a ROCK inhibitor (Y27632) or adenovirus-mediated interference with ROCK expression in MSC significantly increased MSC transendothelial migration. These results indicate that genetically modified mesenchymal stem cells that are able to penetrate the BBB can be constructed for cell therapy of CNS disease.Download high-res image (138KB)Download full-size image