A system to control the differentiation of human mesenchymal stem cells (hMSCs) using RNAi methods is being investigated. Through this delivery system, we aim to induce the differentiation of stem cells for a variety of regenerative medicine applications. In these preliminary studies, we have characterized both the cytotoxicity and uptake of our polymeric system relative to commercial siRNA delivery systems. These ongoing studies also indicate that this system has the ability to alter gene expression in hMSCs, and therefore may present a means to control differentiation for regenerative medicine purposes.