The induced pluripotent stem cell (iPSC) technology has been profoundly advanced the area of stem cell regenerative medicine. iPSCs can be generated by overexpression of a cocktail of transcription factors. However, iPSC induction is very inefficient with all existing approaches, forming barriers to translate this technology into clinical studies. In the second grant year, we have made significant progresses by engineering iPSC-inducing factors. We optimized factor proteins based on the local chromatin loop structure, a barrier that needs to be overcome for activation of stem cell-related genes. We found that this mechanism-based engineering significantly enhanced iPSC formation. Most importantly, we demonstrated that iPSCs were able to be generated by a single engineered factor, instead of using conventional four factors. The resulting iPSCs exhibited the same potency as embryonic stem cells to differentiate into various tissue types. We believe this system will ultimately become a valuable tool for the stem cell research community in developing of patient-based stem cell regenerative therapies.