Some embodiments of the invention comprise methods, systems, and compositions to selectively induce, whether in vitro or in vivo, the neuronal differentiation of multipotent stromal cells through the application of microRNAs, including but not limited to miRNA-124, miRNA-137 and/or miRNA-9* expression products of those miRNAs, and molecules and compositions containing functional elements of those miRNAs. Some embodiments of the invention also comprise the therapeutic administration and use of such induced cells to treat mammalian injuries and diseases, including but not limited to, nervous system injuries or diseases that may otherwise result in decreased cell or system function.