The recently acquired ability to reprogram human adult somatic cells to induced pluripotent stem cells (iPSCs) in culture [6] has raised the possibility that not only could we provide allogenic dopaminergic neurons but also now provide an unlimited source of personalized cells for replacement therapy. Human iPSCs thus may allow us to bypass the immunorejection issue faced with allogenic cell transplants and may also solve bioethical concerns surrounding hESCs. As PD may be either hereditary or acquired, iPSC lines derived from such patients could also serve as a unique tool for drug discovery or therapeutic cell replacement or gene delivery applications. Several key issues, however, need to be addressed before iPSC-based therapy can become prevalent. This requires extending the development of defined cell culture systems developed for hESC-derived dopaminergic neurons, confirming that iPSC lines are overall similar to hESCs, and developing zero footprint iPSC induction technology and efficient gene delivery as well as retargeting methodologies.
