Human Periapical-cysts Mesenchymal Stem Cells Differentiate into Dopaminergic Neuromelanin-Producing Neurons

Objectives: Parkinson's disease (PD) is a neurodegenerative disease characterized by the degeneration of dopaminergic (DA) neurons at midbrain; the absolute concentration of neuromelanin (NM) is dramatically decreased in PD patients. DA cells replacement could represent a promising approach for treating PD. The objective of the investigation was to assess the ability of Human Periapical-Cysts Mesenchymal Stem Cells (hPCy-MSCs) to differentiate into dopaminergic neuromelanin-producing neurons. Methods: The hPCy-MSCs and Dental Pulp Stem Cells (DPSCs) were isolated and cultured as previously described. DPSCs and hPCy-MSCs were both seeded in different conditions. A group was seeded on poly-L-ornithine/laminin coated 6-well plates (coated group) and exposed to neurogenic medium. Another group was cultured on plates without poly-L-ornithine/laminin coating (uncoated group) and exposed to neurogenic medium. Both groups were also grown in a control medium with α-MEM containing 10% FBS then supplemented with L-DOPA. The quantitative analysis of NM content was performed in coated and uncoated groups, as previously described with some modifications. Results: Flow cytometry and immunofluorescence analysis already showed that hPCy-MSCs and DPSCs spontaneously express the neuron-specific protein β-III tubulin and the neural stem-/astrocyte-specific protein glial fibrillary acidic protein (GFAP) in their basal state. After exposure to neurogenic differentiation conditions, the hPCy-MSCs showed enhanced expression of dopaminergic neuron-specific transcription factors Nuclear Receptor related protein 1 (Nurr1) and paired-like homeodomain transcription factor 3 (Pitx3) at the transcript level. Moreover, immunofluorescence and flow cytometry analysis showed enhanced expression of dopaminergic-neuronal markers as dopamine-related genes tyrosine hydroxylase (TH), En1, Nurr1, and Pitx3. We found NM levels in the neuro-differentiated cells medium significantly higher with respect to the NM levels detected in the control cells. Conclusions: We demonstrated that hPCy-MSCs can differentiate into morphologically and functionally dopaminergic neuromelanin-producing neurons when exposed to neuronal conditions. This research identifies hPCy-MSCs as optimal source of DA cells for cell-based therapies to treat PD.