Mesenchymal stem cells transfected with HCN2 genes by LentiV can be modified to be cardiac pacemaker cells

Pacemaker cells differ from common cardiomyocytes for the presence of a spontaneous depolarization process during the diastolic phase of the cardiac cycle, which is due to the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel genes, providing the presence of an inward current. With this in mind, we embarked on a study to test proof-of-principle if genetically engineered mesenchymal stem cells (MSCs) transfected with HCN2 genes can be modified to be cardiac pacemaker cells. In addition to expressing an anticipated high level of hHCN2 gene, MSCs transfected with HCN2 genes by LentiV in our study also expressed characteristic hHCN2 protein, the I(f)-like current and were capable of increasing the spontaneous beating rate of cocultured cardiac myocytes. Control MSCs did not exert these effects. Thus, the electrical effects of the MSCs transfected with the hHCN2 gene were similar to the effects of overexpression of the same gene in the myocytes in vitro system. For stable genetic modification, we used the self-inactivating HIV1-based lentiviral vector (LentiV) for transgene delivery in our study, which can integrate transgene into the host genome. This unique property makes LentiV ideal for modifying MSCs, which allows persistent transgene expression. With these findings, we hypothesize that genetically engineered MSCs transfected with HCN2 genes by LentiV can be modified to be cardiac pacemaker cells.