[Dynamic stretching promotes osteogenic differentiation of human bone marrow mesenchymal stem cells in three-dimensional culture].

Abstract

Objective: To explore the promotion of dynamic distraction on osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMMSCs) in three-dimensional culture.

Methods: Dynamic stretching in a three-dimensional culture for hBMMSCs was achieved with proportions set at 5%, 10%, and 20%, a frequency of 0.5 Hz, and a dynamic stretching duration of 2 hours per day. Static culture was used as the control group. Deformation of hBMMSCs induced by dynamic stretching was observed through cytoplasmic fluorescence staining. After 7 days of dynamic stretching culture, the impact of dynamic stretching on the viability of hBMMSCs was observed through cell live/dead staining. The effect of dynamic stretching on the osteogenic differentiation of hBMMSCs was observed through alkaline phosphatase (ALP) staining and the expression of osteogenic related genes and proteins after 7 days of dynamic stretching culture.

Results: Dynamic stretching in a three-dimensional culture for hBMMSCs was successfully constructed, which could achieve different durations, frequencies, and ratios of dynamic stretching. Dynamic stretching led to deformation of hBMMSCs, and the greater the stretching ratio, the more pronounced the cell deformation, transitioning from a circular to a flat oval shape. After 7 days of dynamic stretching culture, hBMMSCs in the static control group and dynamic stretching groups were mostly green stained live cells, with only a few red stained dead cells. The difference in the proportion of live cells between the groups was not statistically significant (P>0.05). The ALP staining in the dynamic stretching group was deeper than that in the static control group, and the number of ALP staining positive cells observed under the microscope was higher. The expression of osteogenic related genes and proteins increased after 7 days of dynamic stretching culture, and the difference was statistically significant (P < 0.05). Among them, the dynamic stretching group with 10% had the deepest ALP staining, the highest number of positive cells, and the most significant increase in the expression of osteogenic related genes and proteins compared with the static control group.

Conclusion: Dynamic stretching caused deformation of hBMMSCs without a significant impact on cell viability, and it could effectively promote the osteogenic differentiation of hBMMSCs.