Mitomycin‐C treatment during differentiation of induced pluripotent stem cell‐derived dopamine neurons reduces proliferation without compromising survival or function in vivo

Nongenetic methodologies to reduce undesirable proliferation would be valuable when generating dopamine neurons from stem cells for transplantation in Parkinson's disease (PD). To this end, we modified an established method for controlled differentiation of human induced pluripotent stem cells (iPSCs) into midbrain dopamine neurons using two distinct methods: omission of FGF8 or the in‐process use of the DNA cross‐linker mitomycin‐C (MMC). We transplanted the cells to athymic rats with unilateral 6‐hydroxydopamine lesions and monitored long‐term survival and function of the grafts. Transplants of cells manufactured using MMC had low proliferation while still permitting robust survival and function comparable to that seen with transplanted dopamine neurons derived using genetic drug selection. Conversely, cells manufactured without FGF8 survived transplantation but exhibited poor in vivo function. Our results suggest that MMC can be used to reduce the number of proliferative cells in stem cell‐derived postmitotic neuron preparations for use in PD cell therapy. In the present study, Kordower and colleagues offer evidence that, as an alternative to genetic selection methods, mitomycin‐C can be applied during the differentiation process of iPSC‐derived midbrain dopamine neurons as a means of removing proliferating cells without compromising graft health or function in the unilateral 6‐hydroxydopamine athymic rat model of Parkinson's disease.