Mesenchymal stem cells (MSCs) can be isolated from the bone marrow and may be used for regenerative medicine applications because they can differentiate into fat, cartilage and bone cells. However, MSCs constitute less than 1% of the bone marrow mononuclear cell population, which presents challenges for their isolation and characterization. Moreover, these stem cells are heterogeneous, displaying variable potential for proliferation and differentiation, which complicates studies with conventional assays. In this project, we use a microfluidic cell trap device to array large numbers of MSCs for single-cell optical imaging. Immunolabelling of surface markers will be used to identify MSC subpopulations, while exposure to signalling pathway activators will yield information on the differentiation potential of specific MSC sub-types. The ultimate aim is to formulate drug carriers that are able to trigger the differentiation of susceptible stem cells into desired tissue, for example to enhance bone mass to reduce fracture risk, or to facilitate bone fracture healing.