Counteracting neuroinflammation in experimental Parkinson’s disease favors recovery of function. Effects of Er-NPCs administration

INTRODUCTION: Parkinson's disease (PD) is the second most common neurodegenerative disease, caused by midbrain dopaminergic neurons degeneration. A growing number of study show that inflammation-derived oxidative stress and cytokine-dependent toxicity may contribute to PD pathogenesis. Cell therapies have long been considered a feasible regenerative approach to compensate for cellular loss. Erythropoietin-releasing Neural Precursors (Er-NPCs) are a subclass of SVZ-derived neural progenitors with high neural differentiation features and able to survive in an unfavorable microenvironment. Our aim was to characterize the therapeutic potential of Er-NPCs in PD. METHODS: The degeneration was obtained by the intraperitoneal administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in C57BL/6 male mice. 2.5x105 GFP-labeled Er-NPCs were administered by stereotaxic injection unilaterally in the left striatum. Functional recovery was assessed by two independent behavioral tests. Neuroinflammation was investigated measuring the mRNAs levels of pro-inflammatory and anti-inflammatory cytokines and immunohistochemistry studies were performed to evaluate markers of inflammation. RESULTS: Our results show that animals grafted with Er-NPCs present a remarkable behavioral improvement beginning the third day after transplantation. We found that transplanted Er-NPCs were vital, able to migrate ventrally and caudally from the injection site, and reach the Striatum and Substantia Nigra pars compacta. Morphological analyses revealed that Er-NPCs can differentiate into dopaminergic (40%), cholinergic (60%), and gabaergic neurons (20%). Furthermore, Er-NPCs administration promoted a rapid anti-inflammatory effect that was already evident 24h after transplant with a decreased expression of pro-inflammatory and increased anti-inflammatory cytokines. Er-NPCs transplant also reduces macrophages infiltration, directly counteracting the M1 pro-inflammatory response of primary murine activated microglia and inducing M2 pro-regeneration traits. Moreover, we show that Er-NPCs-derived Erythropoietin (EPO) mediates this activity, since the co-injection of precursors with an anti-EPO antibody neutralizes the effect of the Er-NPCs treatment. DISCUSSION & CONCLUSIONS: We suggest that Er-NPCs represent good candidates for cellular therapy in PD for their differentiation capabilities and their anti-inflammatory properties. ACKNOWLEDGEMENTS: The authors are deeply grateful to Professor Alfredo Gorio (University of Milan, Italy) for his scientific support and unswerving encouragement to the work. Dr. Zuzanna Gombalova participated in the research when she was visiting a student in the Laboratory of Pharmacology, Department of Health Sciences, University of Milan, supported by the Erasmus Program for PhD students. Dr. Federica Rey and Maria Carlotta F. Gorio are PhD student in the Nutritional Sciences, University of Milan. Federica Rey is supported by theFondazione F.lli Confalonieri.