Abstract 15682: Role of Connexin 43 in Human Bone Marrow Derived Mesenchymal Stem Cell Cardiac Integration and Cardiac Stem Cell Niche Formation
Bone marrow-derived mesenchymal stem cells (MSCs) and cardiac progenitor stem cells (CPCs) have been used successfully as a cell-based approach for cardiac regeneration in animal model and in clinical trials. While MSCs and CPCs are effective, the mechanism underlying this ability remains controversial. Based on previous observations that MSCs and CPCs express connexin 43(Cx43) and form gap junctions with when administered to the injured heart, we hypothesized that Cx43 gap junctions are crucial for MSC and CPCs interaction, integration into cardiac tissue and cardiac stem cell niche formation.
Methods and Results: Human MSCs were co-cultured with neonatal rat ventricular cardiomyocytes (NRVMs). The ability of MSCs to form gap junctions was modulated using lentiviral constructs to either knockdown (Cx43KD) or overexpress (Cx43OE) Cx43. Co-culture of Cx43OE or control MSCs with NRVMs led to the formation of beating, three-dimensional tubes in 10-14 days whereas Cx43KD MSCs failed to form tubes (n=5, p<0.05). Furthermore, we replicated the cardiac stem cell niche by combining human CSCs and MSCs in an in vitro model using the same lentiviral constructs. As a result, MSCs and CPCs that expressed Cx43 coupled and formed organotypic three-dimensional structures similar to human MSCs and NRVMs, whereas the lack of Cx43 significantly affected the structure formation (n=6, p<0.05). In a single stem cell culture lack of Cx43 affected MSCs and CPCs proliferation (n=5, p<0.05) and culture phenotype (n=4, p<0.05). The angiogenic potential of MSCs and HUVEC was significantly decreased in Cx43 KD group compare to control affecting the tube length (n=5, p<0.05) on a Matrigel assay in vitro. Differentiation of MSCs and CPCs was evaluated by the change/onset of endothelial (KDR, PECAM-1, VE-cadherin), smooth muscle actin, and cardiomyocyte (Nkx2.5, Gata4, Troponin I, Na+ channel, K+ channel, Ca+ channel, Na+-Ca+ exchanger) gene expression. Only voltage ion channel genes was upregulated in control and Cx43OE groups by co-culture (n=5, p<0.05), but not affected in Cx43KD group.
Conclusion: These findings reveal that cell–cell contact mediated by Cx43 gap junctions enables MSCs to interact with CPCs, integrate and reconstitute cardiac stem cell niche.
- © 2013 by American Heart Association, Inc.