 In vivo reprogramming using October 3, 4, SOX2, KLF4, and CMYC, OSKM, has been shown to be effective in generating pluripotent stem cells from adult, fully differentiated cells. However, some studies have reported the formation of teratomas due to prolonged exposure to OSKM. Recently, a study by the Espigior Belmonti lab demonstrated a cyclical approach to in vivo OSKM expression that prevents full reprogramming and tumoragesis. This study provides evidence that in vivo reprogramming can be used to enhance tissue regeneration without the risk of teratoma formation. Further research into this area may lead to new applications in regenerative medicine. This article was authored by Irene de la Zaro, Giulio Cosso, and Costas Costarellos.