Deciphering the beta-adrenergic response in human embryonic stem cell-derived-cardiac myocytes: closer to clinical use?

Cardiomyocyte marker expression in a human lymphocyte cell line using mouse cardiomyocyte extract

Cell transplantation shows potential for the treatment of cardiac diseases. Embryonic stem cells, cord blood and mesenchymal stem cells have been suggested as sources for transplantation therapy. Because of some technical limitations with the use of stem cells, transdifferentiation of fully differentiated cells is a potentially useful alternative. We investigated whether human peripheral blood cells could transdifferentiate into cardiomyocyte. Transdifferentiation was induced in a human B lymphocyte cell line (Raji). Cardiomyocyte extract was prepared from adult mouse cardiomyocytes. The cells were treated with 5-aza-2-deoxycytidine and trichostatin A, permeabilized with streptolysin O, and exposed to the mouse cardiomyocyte extract. They were cultured for 10 days, 3 weeks and 4 weeks. Cardiomyocyte markers were detected with immunohistochemistry and flow cytometry. Immunocytochemistry revealed that some cells expressed myosin heavy chain, α-actinin and cardiac troponin T after 3 and 4 weeks. Flow cytometry confirmed these data. In cells exposed to trichostatin A and 5-aza-2-deoxycytidine and permeabilized in the presence of the cardiomyocyte extract, troponin T expression was seen in 3.53% of the cells and 3.11% of them expressed α-actinin. After exposure to the cardiomyocyte extract, some permeabilized cells adhered to the plate loosely; however, the morphology did not change significantly, and they continued to show a rounded shape after 4 weeks. Our treated lymphocytes expressed cardiomyocyte markers. Our results suggest that lymphocytes may be useful in future research as a source of cells for reprogramming procedures.

GPCR theme editorial

This themed section of BJP includes 11 reviews on the biology of G-protein coupled receptors (GPCRs) and the drug targets that these present, 21 research papers on the pharmacology of a range of GPCRs and Commentaries on four of the papers. Areas reviewed include molecular interactions, particular in respect of hetero-dimerisation between receptors and other membrane-located proteins and other key signalling molecules including cAMP and G12/13 proteins and recently de-orphanised receptors including the Neuromedins U & S and the Free Fatty Acid receptors FFA2 & FFA3. The research papers cover the pharmacology of a range of agents acting at GPCRs, including adrenoceptors, purinoceptors, 5HT, opioid, cannabinoid & PAR-2 receptors. A group of papers is concerned with the interesting and rapidly developing pharmacology of drugs acting at beta(2)-adrenoceptors. The reach of GPCRs is illustrated by the range of physiological systems and therapeutic applications involved, including pain, cancer, cardiovascular, gastrointestinal, visual and respiratory and central nervous systems.