Differentiation of human adipose-derived stem cells towards cardiomyocytes is facilitated by laminin.

Adipose-derived stem cells (ASCs) are promising candidates for therapy in myocardial infarction (MI). However, the frequency of human ASCs that differentiate towards cardiomyocytes is low. We hypothesized that adherence to extracellular matrix molecules that are upregulated after MI might increase human stem cell differentiation towards cardiomyocytes. We analysed putative ASC differentiation on fibronectin-coated, laminin-coated and uncoated culture plates. Expression of cardiac markers in cells was analysed 1, 3 and 5 weeks after stimulation with 5-aza-2-deoxycytidine. After 1 week, mRNA expression of myosin light chain-2alpha (MLC-2alpha), an early marker in cardiomyocyte development, was increased significantly in treated cells, independent of coating. At 5 weeks, however, mRNA expression of the late cardiomyocyte development marker SERCA2alpha was only significantly increased in 5-aza-2-deoxycytidine-treated cells cultured on laminin. Significantly higher numbers of cells were immunopositive for MLC-2alpha in cultures of treated cells grown on laminin-coated wells, when compared with cultures of treated cells grown on uncoated wells, both at 1 week and at 5 weeks. Furthermore, after 3 weeks, significantly more alpha-actinin- and desmin-positive cells were detected after treatment with 5-aza-2-deoxycytidine, but only in uncoated wells. After 5 weeks, however, the number of desmin-positive cells was only significantly increased after treatment of cells with 5-aza-2-deoxycytidine and culture on laminin (61% positive cells). Thus, we have found that a high percentage of human ASCs can be differentiated towards cardiomyocytes; this effect can be improved by laminin, especially during late differentiation.