miR-222 is necessary for exercise-induced cardiac growth and protects against pathological cardiac remodeling.

Isolated primary neonatal rat ventricular cardiomyocytes were plated in 6 cm BD Primaria tissue culture dishes. Transfection of microRNA precursors or scramble control (0.4 µM) was carried out using Lipofectamine RNAiMAX (Invitrogen) as recommended by the manufacturer. Forty-eight hours after transfection, RNAs from cultured cells and tissues were isolated with Tryzol (Invitrogen) following the manufactures’ manuals. Total RNA was harvested and submitted to the Dana-Farber Cancer Institute Molecular Diagnostics Laboratory for assay. These results revealed miR-222 regulated gene expression in primary neonatal rat ventricular cardiomyocytes.