Effect of ex vivo culture density on CXCR7 expression in human mesenchymal stem cells

The ability of Mesenchymal stem cells (MSCs) to migrate into host tissues is crucial to their potential use in cell therapies. Here, we evaluated whether ex vivo culture conditions affect the expression of C-X-C chemokine receptor type 7 (CXCR7), which plays pivotal roles in the survival and migration of MSCs to injured tissues, in MSCs. CXCR7 was up-regulated in BM-MSCs harvested at a high density (~90% confluent) in comparison to BM-MSCs harvested at a low density (~50% confluent). Furthermore, following their injection, high-density MSCs expressing CXCR7 were found in small intestinal tissues of graft-versus-host disease mice. In addition, MSCs derived from three different umbilical cord blood samples highly expressed CXCR7 in high-density culture. Collectively, culture conditions such as cell confluency at harvest are important for CXCR7 expression in MSCs; therefore, the results of this study may provide useful guidelines for the harvest of MSCs that can migrate to injured tissues.