Cyclic Strain Promotes Migration and Proliferation of Human Periodontal Ligament Cell via PI3K Signaling Pathway

Cyclic tensile forces enhance the angiogenic properties of HUVECs by promoting the activities of human periodontal ligament cells

BACKGROUND

This study aimed to investigate whether human periodontal ligament (PDL) cells secrete pro-angiogenic factors that induce the vascularization of surrounding bone tissue under tensile stress.

METHODS

Quantitative real-time PCR and Western blotting were used to analyze the mRNA and protein expression levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), Angiopoietin-I (Ang-I), connective tissue growth factor （CTGF）, and macrophage colony-stimulating factor (M-CSF) in PDL cells after tensile force treatments of different durations. Enzyme-linked immunosorbent assay was used to measure the VEGF concentration in the supernatants of cell cultures. Cell viability assay, wound healing assay, and tube formation assay were performed to evaluate the angiogenic behaviors of human umbilical vein endothelial cells (HUVECs).

RESULTS

The mRNA expression and protein expression of VEGF, bFGF, Ang-I, and M-CSF was increased in the cells that received 6 to 48 hours of tensile force treatment. And, the VEGF level in the supernatant significantly increased in the human PDL cell cultures stressed for 6 to 48 hours. The abilities of HUVECs to proliferate, migrate, and form tubes were enhanced in media conditioned with tensile-stressed human PDL cells. Hence, tensile force induced human PDL cells to express and release pro-angiogenic factors enhancing the proliferation, migration, and angiogenic capacity of HUVECs.

CONCLUSION

Tensile stress induced human PDL cells to express and release pro-angiogenic factors, including VEGF, bFGF, Ang-I, and M-CSF, thereby enhancing the proliferation, migration, and angiogenic capacity of HUVECs.