Predominant fusion of bone marrow-derived cardiomyocytes

Abstract

Here we address the capacity of bone marrow-derived cells (BMDCs) to trans-differentiate into mature myocytes under the physiological stimulus of exercise training. For this purpose, we have transplanted bone marrow from mice ubiquitously expressing enhanced green fluorescence protein (eGFP) into host mice that have been subjected to a prolonged program of exercise. In all successful bone marrow reconstitutions (greater than 80%), we observed rare but consistent events of bone marrow-derived cardiomyocytes, the frequency of which was unchanged upon exercise training. We have further determined whether these recruited myocytes are a product of trans-differentiation or fusion by the use of a genetic system that distinguishes cell fusion from trans-differentiation in a single-cell assay. We concluded that both in the unchallenged mouse and in the trained specimens, fusion is the most prominent mechanism by which bone marrow-derived cells are observed in the myocyte compartment.