Methods for maturing cardiomyocytes and uses thereof
Described herein are methods and compositions useful for inducing maturation of a cardiomyocyte to a mature (e.g., adult) phenotype, such that the function and morphology of the mature cardiomyocyte matches or more closely mimics that of the adult heart. The methods and compositions use Let-7 miRNAs and modified forms thereof. Such methods and compositions permit the study and treatment of adult-onset cardiac diseases, disorders or injuries with mature cardiomyocytes that mimic the heart function of an adult. Methods of using cardiomyocytes matured in this manner for drug identification and drug cardiotoxicity testing are also provided.
1. A method for inducing maturation of a cultured cardiomyocyte comprising contacting in vitro a cultured cardiomyocyte derived from a pluripotent stem cell or an induced pluripotent stem cell (iPS cell) with an isolated microRNA from the let-7 family, or with a vector that expresses said miRNA of the let-7 family, thereby inducing maturation of the cultured cardiomyocyte.
2. The method of claim 1 , wherein the miRNA from the let-7 family is selected from the group consisting of: let-7a-1, let-7a-2, let-7b, let-7c, let-7d, let-7e, let-7f-1, let-7f-2, let-7g, and let-7i.
3. The method of claim 2 , wherein the miRNA is let-7g or let-7i.
4. The method of claim 1 , wherein the miRNA from the let-7 family is resistant to inhibition by Lin28.
5. The method of claim 1 , wherein the cardiomyocyte expresses the fetal isoform of myosin heavy chain (MHC), troponin 1, or carnitine palmitoyl transferase 1 (CPT-1) prior to contacting with the miRNA.
6. The method of claim 1 , wherein the maturation of the cardiomyocyte comprises a shift in the primary source of energy from glycolysis to fatty acid oxidation.
7. The method of claim 1 , wherein the resulting mature cardiomyocyte expresses at least one of: cardiac troponin (cTnT), myosin heavy chain-7 (MYH7), sacrcoendoplasmic reticulum ATPAse (SERCA2a), gap junction protein alpha 1 (GJA1), or ryanodine receptor 2 (RYR2).
8. The method of claim 1 , further comprising a step of administering the resulting mature cardiomyocyte to a subject in need thereof, wherein the subject has cardiac tissue damage as a result of an acute myocardial infarction, ischemia/reperfusion injury, autophagy, cardiomyopathy, dilated cardiomyopathy, heart failure, restenosis, apoptosis, or necrosis.
9. The method of claim 1 , wherein the cultured cardiomyocyte is a human cardiomyocyte.