The purpose of the ET3RA is to establish an experimental model of stem cell transplantation that accomplishes two equally important goals: 1) to devise a strategy of protection of the child’s brain from the ravages of certain genetic diseases and 2) to devise a simultaneous strategy of transplantation that avoids immune system rejection. In our first year of work, we have shown that we can reliably produce the stem cells that we want to transplant into the brains of experimental animals (mice). We have also bred sufficient numbers of mice for the transplant experiments and have started the immune system-based strategy of transplantation. During the second and third years, we successfully finished our first round of transplantation experiments, we fully characterized the stem cells for brain transplantation, we showed that the cells have the desired biological effects in the culture dish, we completed installation of our Cell Production Facility, and we completed some, but not all of the final transplantation experiments. With a one year no-cost extension, we are on course to accomplishing our goals for this ET3RA and for eventual development of this strategy for the initiation of clinical trials.