the effect of extracellular matrix on choronotropic characteristics of cardiomyocytes drived from embryonic stem cells

introduction: extracellular matrix (ecm) components significantly influence the growth characteristics of cell, development of spontaneous contractile activity, andmorphologic differentiation. the present study evaluates the effect of ecm ongenotypic and physiologic characteristics of cardiomyocytes derived from embryonic stem (es) cells. material and methods: embryoid bodies derived from mouse es cells line royan b1 (c57bl/6) were cultured on commercial ecm (matrigel), a cardiac fibroblast-derived extracellular matrix (cardiogel), and control media (without ecm)for 21 days. the growth characteristics of cardiomyocytes were assessed by immunocytochemistery, rt-pcr, and chronotropic drugs. results: the beating frequency of cardiomyocytes cultured on cardiogel increasedin comparison with cardiomyocytes cultured on matrigel and/or control during days 7-9(p<0.05) the spontaneously beating cells expressed markers characteristic ofcardiomyocytes including α-actinin, desmin, tropnin-i, sarcomeric myosin heavy chain (mhc), pan-cadherin, connexin 43, cardiac α-mhc, cardiacβ-mhc, myosin light chain isoform-2v, and atrial natriuretic factor. in addition,spontaneousness of cardiomyocytes on both ecms was enhanced by treatment of cells with isopernaline, while reduced more on matrigel and carbacol when compared with control and cardiogel. however, the change in beating was similar in all groups upon treatment with phenylephrine, propranolol and for bay-k. conclusions: we conclude that the ecm influences es-derived cardiomyocytes, in terms of chronotropic characteristics.