Therapeutic improvement of Parkinson’s disease transplantation therapy through modulating the immune system.

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Abstract We report clinically the implantation of patient-derived midbrain dopaminergic progenitor cells (mDAPs), differentiated in vitrofrom autologous iPSCs, in a patient with idiopathic Parkinson's disease (PD). The patient-specific mDAPs were produced under Good Manufacturing Practice conditions and characterized as having the phenotypic properties of substantia nigra pars compacta neurons; testing in a humanized mouse model indicated an absence of immunogenicity to these cells. The cells were implanted into the putamen (left hemisphere followed by right hemisphere, 6 months apart) of a patient with PD, without the need for immunosuppression. Clinical measures of symptoms of PD after surgery stabilized or improved at 18 to 24 months after implantation. Although our previous data (Schweitzer*, Park* et al., NEJM, 382(20) p1926–1932, 2020) showed that using autologous mDAPs can avoid graft rejection, cell survival and functional recovery in the first patient as assessed by 18F-DOPA PET scan analysis and clinical motor assessments was modest, suggesting that survival of mDA neurons may have been suboptimal even in autologous implantation. We have developed a safer and more effective treatment by not only increasing mDA neuron survival by simultaneously controlling the causative immune response, but also by modulating the problematic proliferative property, which is a characteristic of progenitor cells after implantation. In conclusion, our new study suggests that initial, specific mDA neuron survival in these grafts is strongly affected by the host innate immune response, while long-term graft survival is subject to the adaptive immune response, elucidating a two-phase involvement of the immune system for graft survival. This work was supported by NIH grants (NS070577 and OD024622), the Parkinson’s Cell Therapy Research Fund at McLean Hospital and Massachusetts General Hospital, and the Masson Family Endowed Scholar in Neurosurgery, and the George A. Lopez, MD Endowed Chair in Neurosurgery.