Cell based therapies such as bone marrow and islet transplantation provides patients with functional cells to supplement disease- compromised cells. One major limitation of cell- based therapies is providing adequate numbers of functional cells to alleviate disease symptoms. Mesenchymal stem cells (MSCs) are multipotent progenitor cells used for cell- based therapies via bone marrow transplant, and more recently for cardiovascular and neurodegenerative diseases. Since MSCs are multipotent and easy to obtain, the aim of this study is to obtain large amounts of functional MSC derived cells for cell- based therapies via high throughput cell isolation and laser guided assembly for directed differentiation of cells. Successful cell therapy requires efficient cell isolation, maximal cell survival, and optimum differentiation environments. Efficient MSC isolation from adipose and bone marrow tissue is obtained through high throughput flow cytometry based cell sorting. After isolation, cells are placed in a polyethylene glycol diacrylate (PEGDA- based) hydrogel using arrays of optical traps to place single cells into an array. Mimicking the in vivo environment of the cells is important for successful differentiation, and the hydrogel provides a three- dimensional scaffold that allows the cell to rest in a matrix that is more like a tissue microenvironment than a liquid culture dish. Seeded in the hydrogel along with the cells are microspheres holding reagents that are used to stimulate lineage- specific induction of MSCs. The microspheres are thermally excited to release the contents in a controlled and time dependent manner, thus leading to control differentiation events. Placement of microspheres and concentration of reagents affect differentiation outcome and differentiation is observed in the hydrogel by confocal microscopy and cell surface markers. Currently, the laser- guided systems and microsphere placement are being optimized using U937 cells. Using high throughput flow cytometry in conjunction with optical trapping we plan to study directed differentiation of stem cells in vitro and provide large numbers of functional mesenchymal derived cells for cellbased therapies.