Although stem cells have tremendous potential to regenerate damaged or diseased tissue, scientists must develop efficient methods to deliver the stem cells to the sites in the body where they are needed. Injection of stem cells through a syringe needle directly into the tissue site is a simple procedure to perform, but it exposes the stem cells to damaging mechanical forces that can injure the cells. In year 1 of this project, we developed a gel that encapsulates stem cells and protects them from these damaging mechanical forces. This gel was able to maintain excellent viability of transplanted stem cells for up to one week. In year 2 of the project, we further developed this new gel material with the goal of extending the lifetime of transplanted stem cells. In particular, we synthesized two new gel formulations. The first gel is able to co-encapsulate the stem cells together with pro-survival factors. The presence of these pro-survival factors was found to increase the retention of transplanted stem cells. The second gel is able to stiffen after it is injected into the body; thereby enabling it to last for longer times. Our long-term goal is to increase the percentage of stem cells that can survive the transplantation process and participate in the regeneration of damaged tissue.