خصوصيات ضرباهنگي (كرونوتروپي ) سلولهاي عضله قلبي مشتق از بن ياخته هاي جنيني

Chronotropic Characteristics of Cardiomyocytes Differentiated From Mouse Embryonic Stem Cells

Objective: The study of mammalian cardiac tissue development is hampered by the lack of a suitable in vitro model. Embryonic stem (ES) cells are piuripotent cells able to differentiate into derivatives of the three primary germ layers including cardiomyocytes. The aim of the present study was to investigate whether ES-derived cardiomyocytes react in respect to the chronotropic activities of adrenergic and cholinergic agents. Materials and Methods: Embryonic stern cells of line Royan BI were cultivated to produce embryoid bodies in hanging drops for 2 days and in bacterial dish for 5 days, then in tissue culture dish for 14 days. Chronotropic characteristics of spontaneously differentiated cardiomyocytes evaluated by isoprenulinc (Beta1- adrenergic receptor agonist), phenylephrine (alpha1-adrenergic reaptor agonist). propanolol, (Beta -aderergic receptor antagonist), carbacol (muscarinic receptor agonist) and Bay K (Ca^+2` channel activator) during 3 steps of differentiation (early, intermediate and terminal stages). Inimunocytochemistry evaluated with antibodies against (alpha-actinin, desmin, troponin I, and connexin 43. Results: Isopernalin, phenylephrine and Bay K increased the beats/min^-1 and carbacol and propanolol reduced the beats/min during different steps. lmmunocvtochemistry of the cells showed alpha-actinin, desmin, troponin I and gap junction proteins. Conclusion: These results showed this system can he useful as a test procedure for investigating the action of chrotropic drugs thus avoiding the use of alive animals for the prepartion of primary cultures of neonatal cardiac myocytes and a suitable system for developmental biology studies.