Assistant Professor Mahidol University Bangkok, Krung Thep, Thailand
Abstract: Neurodegenerative diseases are caused by dysfunction of neuronal cells, determining clinical presentation. Exploring alternative cell sources that have the neuronal differentiation’s potential should be investigated for further transplantation. Human stem cells from apical papilla (hSCAPs) are derived from ectomesenchyme origin that exhibited the potential for neuronal differentiation. Quercetin is defined as a natural flavonoid compound that can promote neuronal differentiation. Therefore, this study aims to demonstrate the potential effect of Quercetin on neuronal differentiation of hSCAPs. The hSCAPs were isolated from extracted human-impact third molars of Thai patients and characterized as mesenchymal stem cells (MSCs). Consequently, the cell viability of Quercetin pre-treatment (0-80 µM) on hSCAPs was performed by using a colorimetric (MTT) assay. The non-cytotoxic concentrations were selected to investigate neuronal gene expression (NES, TUBB3) by using qRT-PCR and determined the highest potential concentrations. Neurogenic induction was sequentially performed to completely induce neuronal differentiation. The characterization of neuronal-like cells was evaluated by cell morphology, β-III tubulin immunofluorescence staining, and Cresyl violet staining. The results demonstrated that the pre-treatment of Quercetin at 0-40 µM showed non-cytotoxicity for 24 hours and cell morphology presented a fibroblasts-like shape to indicate the undifferentiated cells. The highest expression of NES and TUBB3 was observed at 2.5 µM of Quercetin, which was determined as the optimal concentration (Quercetin-hSCAPs). Under neurogenic induction, hSCAPs and Quercetin-hSCAPs differentiated into neuronal-like cells, which positively expressed β-III tubulin by immunofluorescence staining. Cresyl violet staining demonstrated that neuronal-like cells revealed round cell bodies with neurite outgrowth and intensely expressed Nissl substance (a typical neuronal hallmark). Whereas, the undifferentiated cells still presented fibroblast-like morphology. Interestingly, the highest percentage of Cresyl violet positive cells was detected at optimal concentration of Quercetin with neurogenic induction that indicated the potential of Quercetin on neuronal differentiation.
