Effect of cell genome editing on the outcome of neurotransplantation in experimental parkinsonism

Abstract

The aim of the study was to evaluate the effect of genome editing on the outcome of experimental transplantation of neuronal precursors obtained from a patient with the hereditary form of Parkinson’s disease. Materials and Methods. Parkinsonian syndrome was modeled in Wistar rats (n=24) by unilateral administration (into the substantia nigra) of the neurotoxin 6-hydroxydopamine, that selectively destroy dopaminergic neurons. The neural progenitors were differentiated from induced pluripotent stem cells (iPSCs) derived from a patient with the PARK8 form of Parkinson’s disease carrying the G2019S mutation in the LRRK2 gene. In two series of experiments, the cells containing the mutated gene and the isogenic “normalized” cells (that underwent genome editing using the artificial endonuclease system CRISP/Cas9) were used for neurotransplantation. The neuronal precursors were transplanted via a unilateral injection into the brain striatum of rats. We then monitored changes in the behavior of experimental animals using the open field test and the passive avoidance response (PAR) test. The data was processed using the Statistica 7.0 software with the single-factor analysis of variance (ANOVA). Results. The administration of neuronal precursors into the rat brain striatum led to a gradual restoration of motor activity in the experimental animals of both groups, i.e., those transplanted with either mutant or “normalized” cells. In the PAR test, the rats transplanted with mutant cells failed to reproduce the conditioned responses, whereas the rats transplanted with “normalized” cells were able to reproduce the avoidance responses in the way similar to that in intact rats. The latent period before entering the dark box differed between the two groups of animals with a high degree of statistical significance. Conclusion. The study confirms the possibility of correcting motor and cognitive impairments in experimental parkinsonian rats by replenishing the pool of dopaminergic neurons with neuronal precursors produced from iPSCs derived from somatic cells (fibroblasts). Using genome editing to correct the causal mutation in iPSCs before transplantation significantly improves the treatment results. This study, therefore, provides the rationale for further development of this promising technique and its eventual use in patients with genetically determined forms of Parkinson’s disease.