Abstract: Provided is a system for regulating expression of a gene of interest in a target cell, including a recombinant first RNA molecule with (i) a coding sequence for a translation-suppressor protein and (ii) a first microRNA (miR) recognition element in its 3? UTR, wherein the first miR recognition element recognizes a first miR and binding of a first miR to the first miR recognition element reduces translation of the translation suppressor, and a recombinant second RNA molecule, with (i) a coding sequence for the gene of interest, (ii) a recognition sequence for the translation-suppressor, wherein binding of the translation-suppressor to the recognition sequence for the translation-suppressor reduces translation of the gene of interest, and, optionally, (iii) a second miR recognition element in its 3? UTR, wherein the second miR recognition element recognizes one or more second miR and binding of one or more of the one or more second miR to the second miR recognition element reduces translation of the gene of int

Abstract: The present disclosure relates to compositions including molecules of modified mRNA encoding GATA Binding Protein 4, modRNA encoding Myocyte Enhancer Factor 2C, modRNA encoding T-box 5, modRNA encoding Heart- and neural crest derivatives-expressed protein 2, modRNA encoding dominant negative transforming growth factor beta, and modRNA encoding domimant negative Wingless-related integration site 8a, wherein said molecules of modRNAs are present in said composition in a ratio. The present disclosure further relates to pharmaceutical compositions, methods for increasing a ratio of a number of cardiomyocytes to a number of non-cardiomyocytes within a population of cells, methods for treating cardiac injury, methods for stimulating vascular regeneration, methods for treating of stroke, and methods for enhancing wound healing.