Differentiation induction of mouse cardiac stem cells into sinus node-like cells by co-culturing with sinus node.

Sinus nodal cells can generate a diastolic or "pacemaker" depolarization at the end of an action potential driving the membrane potential slowly up to the threshold for firing the next action potential. It has been proved that adult cardiac stem cells (CSCs) can differentiate into sinus nodal cells by demethylating agent. However, there is no report about adult CSCs-derived sinus nodal cells with pacemaker current (the funny current, I f). In this study, we isolated the mouse adult CSCs from mouse hearts by the method of tissue explants adherence. The expression of c-kit protein indicated the isolation of CSCs. Then we co-cultured mouse CSCs with mouse sinus node tissue to induce the differentiation of these CSCs into sinus node-like cells, which was proved by identifying the enhanced expression of marker proteins cTnI, cTnT and α-Actinin with Immunofluorescence staining. At the same time, with whole-cell patch-clamp we detected the I f current, which can be blocked by CsCl, in these differentiated cells. In conclusion, by confirming specific I f current in the induced node-like cells, our work shows a method inducing differentiation of CSCs into sinus node-like cells, which can provide helpful information for the further research on sick sinus syndrome.