Formation of Cell-To-Cell Connection between Bone Marrow Cells and Isolated Rat Cardiomyocytes in a Cocultivation Model

Aims: Limited regenerative potential of cardiomyocytes (CMs) causes irreversible changes in heart tissue during pathological processes. However bone marrow mononuclear cells (BM-MNCs) can migrate to this tissue, incorporate to the area of dead or missing myocytes, and improve the global heart function. The mechanism of BMMSCs’ incorporation and interaction with CMs is not clear. Our aim was to create an in vitro model which would enable to study the interaction of BM-MNCs with CMs and to make a microscopy description of these interactions. Methods and Results: CMs were isolated from adult and newborn rats. BM-MNCs were isolated from bone marrow. BM-MNCs were added to the myocyte culture. Cell-to-cell adherence and Cx43 expression were evaluated by fluorescence microscopy, Ca2+ transients were evaluated in cardiomyocyte-BMC communication under electrical stimulation by fluo-4 fluorescence measurement. Analysis of calcein transport from BM-MNCs to CMs was performed using fluorescence microscopy. Conclusions: The adherence of BM-MNCs to CMs occurred quickly and was stable. Cx43 was detected in contact zones between BM-MNCs and CMs; pairs which displayed Cx43 positivity represented less than 1% from all BM-MNC-cardiomyocyte pairs in the coculture. Conductive structures between CMs and BM-MNCs were formed and verified by imaging calcein transfer and synchronous Ca2+ transients.