[Morphologic and apoptotic changes of cervical posterior longitudinal ligament fibroblasts in response to in vitro mechanical stretch].

Objective: To investigate the effect of mechanical stretch force on the morphologic and apoptotic changes of fibroblasts derived from the OPLL (ossification of posterior longitudinal ligaments) patients.

Methods: The third passage cells were collected and subjected to 10% elongations cyclic mechanical stretching for 6 h and 24 h with Flexercell 4000(TM) strain unit. Their morphologic changes were observed and the post-stretching apoptotic rates quantified by flow cytometer. The gene expressions of alkaline phosphatase (ALP), collagen types I (COL I) and osteocalcin (OC) were examined.

Results: The treated cells were arranged along the vertical direction of force. Stretch force led to a slight increase of apoptosis rate at 6 h and a significant increase of apoptosis rate at 24 h. No significant difference in cellular senescence was observed between control group and treated group. The mRNA expressions of ALP, COL I and OC were positively up-regulated by cyclic stretch at 24 h.

Conclusion: Stretching force can affect the cellular morphology, promote the osteogenic differentiation and enhance the cellular apoptosis.