Compositions, kits, cells and methods for treating cardiovascular (e.g., myocardial ischemia and heart failure), immunological, and inflammatory diseases or disorders involve the use of the mature and precursor sequences of microRNAs 142-5p, 142-3p, 17-5p, 17-3p, 374, and 20a, and of antisense molecules complementary to these sequences, to manipulate processes relevant to, for example, the cardiac response to stress, including survival signaling, angiogenesis, stem cell differentiation along muscle or vascular lineages, and repression or promotion of cardiac myocyte growth. Also described are methods to treat cardiovascular, immunological and inflammatory diseases by engineering cells containing specific micro-RNAs or antagomirs against specific mRNAs. The engineered cells can then be used to treat patients with such diseases by autologous stem cell therapy.