The effects of mechanical stimulation on the morphology and function of spinal ligament cells.

Background: It has been shown that mechanical signaling in the cellular microenvironment is crucial for control at the cellular and tissue levels, affecting human growth and the prevalence of disease. Ligament cells from individuals with posterior longitudinal ligament ossification (OPLL) have been found to respond to external mechanical stimulation. However, the response of mechanical stimulation to OPLL ligament cells is unclear. This study aims to comprehensively assess the effects of mechanical stimulation on the proliferation, viability, shape and function of OPLL ligament cells.

Methods: Eleven OPLL and 11 non-OPLL patient-derived Ligament cells were selected for this study. cells of test groups were exposed to 10% uniaxial cyclic stretch at frequency of 0.5 Hz for 3 h to 48 h. Calcein-AM/PI/Hoechst33342 assay was used to detect the activity of ligament cells. The CCK8 test was used to investigate the effect of stretch on cell proliferation. The level expression of pro-inflammatory factors was detected by using RT-qPCR. Cytoskeleton staining was used to evaluate changes in cytoskeleton morphology.

Results: The proportion of Live cells was not substantially different from the control group after stretch for 12 and 24 h. After 6 and 12 h of cyclic stretch, there was no discernible difference in the rate of cell proliferation; however, after 24 h and 48 h, the cell proliferation rate increased by 27% and 52%, respectively. Apart from the mRNA expression of IL-8 and GROa was 1.41 times and 1.43 times higher than that of the control group in 9-hour groups, and RANTES mRNA expression was 1.38 times higher than that of the control group in 6-hour groups, there was also no appreciable difference in the expression levels of inflammatory factors such as IL1β, TNFα and PF4. The Ligament cells became elongated and were rearranged after 12- and 24-hours' uniaxial stretch.

Conclusions: Cyclic stretch encourages OPLL ligament cell proliferation and alteration of the cytoskeleton structure, but it has no effect on the inflammatory response or cell activity, which provides a new insight into the pathophysiology of OPLL.