Modulation of cardiomyocyte electrical properties using regulated bone morphogenetic protein-2 expression.

Because cardiomyocytes lose their ability to divide after birth, any subsequent cell loss or dysfunction results in pathologic cardiac rhythm initiation or impulse conduction. Strategies to restore and control the electrophysiological activity of the heart may, therefore, greatly affect the regeneration of cardiac tissue functionality. Using lentivirus-derived particles to regulate the bone morphogenetic protein-2 (BMP-2) gene expression in a pristinamycin- or gaseous acetaldehyde-inducible manner, we demonstrated the adjustment of cardiomyocyte electrophysiological characteristics. Complementary metal oxide semiconductor-based high-density microelectrode arrays (HD-MEAs) were used to monitor the electrophysiological activity of neonatal rat cardiomyocytes (NRCs) cultured as monolayers (NRCml) or as microtissues (NRCmt). NRCmt more closely resembled heart tissue physiology than did NRCml and could be conveniently monitored using HD-MEAs because of their ability to detect low-signal events and to sub-select the region of interest, namely, areas where the microtissues were placed. Cardiomyocyte-forming microtissues, transduced using lentiviral vectors encoding BMP-2, were capable of restoring myocardial microtissue electrical activity. We also engineered NRCmt to functionally couple within a cardiomyocyte monolayer, thus showing pacemaker-like activity upon local regulation of transgenic BMP-2 expression. The controlled expression of therapeutic transgenes represents a crucial advance for clinical interventions and gene-function analysis.