The Effect of Saffron Aquatic Extract and Crocin on the Differentiation of Neural Stem Cells Into Oligodendrocyte Precursor Cells

Abstract

Background: Oligodendrocytes are myelin-producing cells, which develop from oligodendrocyte precursor cells (OPCs) and may be damaged in multiple sclerosis (MS) and traumatic brain injuries. Promotion of neural stem cell (NSC) differentiation into oligodendrocytes in vivo is a viable strategy to replace the lost myelinating cells and restore motor functions in such debilitating diseases. Crocus sativus L. or saffron has been used as a spice since ancient times. Saffron and its major active component, crocin, are well-known for their medicinal and neuroprotective activities. The current study aimed at assessing the effect of saffron extract and crocin on the differentiation of NSCs into OPCs. Methods: To isolate NSCs, 14-day embryonic rats cortices were cultured, using the neurosphere assay. NSCs were cultured in a complete NSC medium under 4 different treatment conditions: 1, Negative control group, 10 ng/mL of basic fibroblast growth factor (bFGF); 2, Positive control group, 10 ng/mL of bFGF plus 30 ng/mL of platelet-derived growth factor-AA (PDGF-AA); 3, Crocin group, crocin extract plus 10 ng/mL of bFGF; and 4, Saffron group, saffron extract plus 10 ng/mL of bFGF in 2 or 5 days. The level of Olig2 protein, an early OPC marker, was evaluated by flow cytometry 2 days after the treatment. The level of sox10 mRNA expression, involving in OPC maturation processes, was assessed in the study groups via quantitative real-time polymerase chain reaction (PCR), 5 days after the treatment. All the experiments were done in triplicate. The data were analyzed using one-way ANOVA with Graph Pad Prism version 6.01; P < 0.05 was considered as the level of significance. Results: The present data demonstrated that, similar to the positive control group, the rate of olig2+ cells in the crocin and saffron extract groups did not exceed 80% indicating that these components could significantly increase olig2 expression in NSC differentiation compared with that of the negative controls (P < 0.05). Moreover, the mean expression level of sox10 gene in the positive control, saffron and crocin groups was 1 ± 0.012, 0.72 ± 0.13, and 0.835 ± 0.015, respectively, which significantly higher than that of the negative control group (P < 0.05). Conclusions: It can be concluded that crocin and saffron are the proper alternatives for PDGF-AA in the enhancement of NSC differentiation into oligodendrocytes.