The Role of Wnt/β-Catenin Signaling Pathway in Early Dopaminergic Differentiation of Trabecular Meshwork-Derived Mesenchymal Stem Cells

Parkinson’s disease is the second most common neurodegenerative disorder. Degeneration of dopaminergic neurons in the Substansia nigra causes the loss of dopaminergic function. It has been shown that Wnt/β-catenin signaling pathway is involved in differentiation of dopaminergic neurons. Our preliminary study showed that the neural crest-derived trabecular meshwork MSCs (TM-MSCs) could be anappropriate source of stem cells to differentiate into neurons. Therefore, the aim of this study was to examine neural differentiation potential of these cells compared to two other sources of MSCs including adiposederived and bone marrow MSCs and to determinethe role of Wnt/β-catenin signaling pathway in early dopaminergic differentiation. Materials and Methods: To address these questions, the cells were cultured in the presence and absence of neural induction medium for six days and were analyzed by Real time PCR andimmunofluorescence staining. Results: Morphometric analysis showed that TM-MSCs exhibited a better neural characteristic morphology than the other two sources of cells. Real time PCR studies revealed the expression of neural markers, Nurr1 and Map2, were upregulated inneural induced TM-MSCs compared to cells cultured at the absence of it. Plus, we studied the expression of Nurr1 in TM-MSCs after dopaminergic differentiation by immunofluorescence staining, and it was upregulated in treated samples. CHIR was used to induce Wnt/β-catenin signaling pathway. In the presence of both CHIR (3μM) and neural induction medium, the expression of neural markers was increased compared to cells cultured only at the presence of neural induction medium. Expressions of Wnt/β-catenin signaling target genes, c-Myc and CyclinD1, were increased in CHIR treated TM-MSCs, indicating the activation of Wnt/β-catenin signaling in these cells. Conclusion: Our results suggest that TM-MSCs are a better candidate for dopaminergic differentiation than the other commonly used MSCs and Wnt/β-catenin Signaling pathway has an important role during this differentiation.