Restoration of Contractile Function in Isolated Cardiomyocytes From Failing Human Hearts by Gene Transfer of SERCA2a

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Abstract
Background—Failing human myocardium is characterized by abnormal relaxation, a deficient sarcoplasmic reticulum (SR) Ca2+ uptake, and a negative frequency response, which have all been related to a deficiency in the SR Ca2+ ATPase (SERCA2a) pump. Methods and Results—To test the hypothesis that an increase in SERCA2a could improve contractile function in cardiomyocytes, we overexpressed SERCA2a in human ventricular myocytes from 10 patients with end-stage heart failure and examined intracellular Ca2+ handling and contractile function. Overexpression of SERCA2a resulted in an increase in both protein expression and pump activity and induced a faster contraction velocity (26.7±6.7% versus 16.6±2.7% shortening per second, PP2+ was decreased in failing cardiomyocytes overexpressing SERCA2a (270±26 versus 347±30 nmol/L, P2+ was increased (601±38 versus 508±25 nmol/L, PConclusions—These results support the premise that gene-based therapies and targeting of specific pathways in human heart failure may offer a new modality for the treatment of this disease.