In this period, we were able to transplant engineered human embryonic stem cells expressing an immune tolerance gene into mice with a human immune system to determine whether they survive immune rejection. We observed no rejection of these engineered human embryonic stem cells. The engineered hESCs also were observed to maintain their pluripotency into all 3 germ layers. Histological studies showed that the engineered gene is expressed in all 3 germ layers within the teratomas that formed. Current experiments remain underway to answer whether epidermal stem cells derived from these engineered cells will be rejected in the same animal model.