Genetically-engineered mesenchymal stem cells transfected with human HCN1 gene to create cardiac pacemaker cells

Objective To test the proof-of-principle that genetically-engineered mesenchymal stem cells (MSCs) transfected with the human hyperpolarization-activated cyclic nucleotide-gated channel 1 (hHCN1) gene can be modified to become cardiac pacemaker cells. Methods MSCs were transfected with the hHCN1 gene using lentiviral-based transfection. The expressed pacemaker current (I-f) in hHCN1-transfected MSCs was recorded using whole-cell patch-clamp analysis. The effect of the hHCN1-transfected MSCs on cardiomyocyte excitability was determined by coculturing the MSCs with neonatal rabbit ventricular myocytes (NRVM). The spontaneous action potentials of the NRVM were recorded by whole-cell current-clamp analysis. Results A high level time- and voltage-dependent inward hyperpolarization current that was inhibited by 4mM caesium chloride was detected in hHCN1-transfected MSCs, suggesting that the HCN1 proteins acted as I-f channels in MSCs. The meanSE beating frequency in NRVMs cocultured with control MSCs transfected with the pcDNA3 plasmid control was 82 +/- 8 beats/min (n=5) compared with 129 +/- 11 beats/min (n=5) in NRVMs cocultured with hHCN1-transfected MSCs. Conclusions Genetically-engineered MSCs transfected with the hHCN1 gene can be modified to become cardiac pacemaker cells.