Conclusions
Based on these findings, we conclude that NELL-1 can be applied for increased osteogenic differentiation of stem cell spheroids.
Methods
Cultures of stem cell spheroids of gingiva-derived stem cells were grown in the presence of NELL-1 at concentrations of 1, 10, 100, and 500 ng/mL. Evaluations of cell morphology were performed using a microscope, and cell viability was assessed using a two-color assay and Cell Counting Kit-8. Evaluation of the activity of alkaline phosphatase and calcium deposition assays involved anthraquinone dye assay to determine the level of osteogenic differentiation of cell spheroids treated with NELL-1. Real-time quantitative polymerase chain reaction (qPCR) was used to evaluate the expressions of RUNX2, BSP, OCN, COL1A1, and β-actin mRNAs.
Results
The applied stem cells produced well-formed spheroids, and the addition of NELL-1 at tested concentrations did not show any apparent changes in spheroid shape. There were no significant changes in diameter with addition of NELL-1 at 0, 1, 10, 100, and 500 ng/mL concentrations. The quantitative cell viability results derived on Days 1, 3, and 7 did not show significant disparities among groups (p > 0.05). There was statistically higher alkaline phosphatase activity in the 10 ng/mL group compared with the unloaded control on Day 7 (p < 0.05). A significant increase in anthraquinone dye staining was observed with the addition of NELL-1, and the highest value was noted at 10 ng/mL (p < 0.05). qPCR results demonstrated that the mRNA expression levels of RUNX2 and BSP were significantly increased when NELL-1 was added to the culture. Conclusions: Based on these findings, we conclude that NELL-1 can be applied for increased osteogenic differentiation of stem cell spheroids.