In the first two years of the New Faculty Physician Scientist award, my colleagues and I have made progress on all 3 Aims. The majority of our focus in accordance with our planned timeline has been on Aim 1, where we have made the most significant progress and have completed the Aim. Aim 1 focuses on identification of appropriate donor muscles for human muscle stem cell applications. We have characterized and transplanted human muscle stem cells from diverse muscles and have evaluated their ability to engraft into recipient muscle. As human muscle stem cells have not previously been definitively characterized or transplanted, the initial main focus of this CIRM grant is to do so with stem cells from diverse muscles and, combined with our clinical understanding of expendability of different muscles, choose human muscles that will be appropriate to harvest stem cells from in future applications. We have now accomplished this and are positioned to complete the remaining Aims of the grant. For the experiments in Aim 2, we are testing injury and transplantation methods for human muscle stem cells that could potentially be used clinically and are testing the effects of human muscle stem cell transplantation on muscle function. We have also begun work on Aim 3, developing preclinical models in which to test human muscle stem cell transplantation.