Cardiac progenitor cells (CPCs) possess the insulin-like growth factor-1 (IGF-I)-IGF-I receptor system, and IGF-I can be tethered to self-assembling peptide nanofibers (NF-IGF-I), leading to prolonged release of this growth factor to the myocardium. Therefore, we tested whether local injection of clonogenic CPCs and NF-IGF-I potentiates the activation and differentiation of delivered and resident CPCs enhancing cardiac repair after infarction. Methods and Results-Myocardial infarction was induced in rats, and untreated infarcts and infarcts treated with CPCs or NF-IGF-I only and CPCs and NF-IGF-1 together were analyzed. With respect to infarcts exposed to CPCs or NF-IGF-1 alone, combination therapy resulted in a greater increase in the ratio of left ventricular mass to chamber volume and a better preservation of +dP/dt, -dP/dt, ejection fraction, and diastolic wall stress. Myocardial regeneration was detected in all treated infarcts, but the number of newly formed myocytes with combination therapy was 32% and 230% higher than with CPCs and NF-IGF-1, respectively. Corresponding differences in the volume of regenerated myocytes were 48% and 115%. Similarly, the length density of newly formed coronary arterioles with both CPCs and NF-IGF-1 was 73% and 83% greater than with CPCs and NF-IGF-1 alone, respectively. Importantly, activation of resident CPCs by paracrine effects contributed to cardiomyogenesis and vasculogenesis. Collectively, CPCs and NF-IGF-1 therapy reduced infarct size more than CPCs and NF-IGF-1 alone. Conclusions-The addition of nanofiber-mediated IGF-1 delivery to CPC therapy improved in part the recovery of myocardial structure and function after infarction.
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