A commentary from the SENS Foundation: "Rejuvenation biotechnology encompasses a suite of advanced medical therapies, each of which removes, repairs, replaces, or renders harmless one of the forms of cellular or molecular damage that accumulates in an aging tissue over time and impairs its function. Through the comprehensive abatement of all such aging damage to levels approximating those of younger adults, tissue structure and function can be made more youthful, restoring the health and vigor of aging persons to that of persons years or decades younger. This approach is most prominently under pursuit in the development of cell therapy and tissue engineering, of which the most striking success to date has been the use of fetal and embryonic mesencephalic tissue grafts to replace dopaminergic (DA) neurons lost to the age-related neurodegenerative processes driving Parkinson's disease (PD). ... The promise of this approach has been foreshadowed in murine models of PD, in which DA neurons derived from mouse [embryonic stem cells] have been found highly effective in reversing motor symptoms. But the performance of ostensibly DA neurons derived from human pluripotent stem cells in the same systems has so far been poor, due to uncertain and unstable differentiation of the cells. In a new study, a team of researchers [have] used their novel DA neuron differentiation strategy to resolve these difficulties, leading to robust and stable engraftment of human pluripotent stem cell-derived DA neurons into the striatum and substantial evidence of efficacy in two rodent models of the disease, and provided preliminary data on the viability of their approach in nonhuman primates."