Cyclic stretch induced gene expression of extracellular matrix and adhesion molecules in human periodontal ligament cells.

Objective: Periodontal ligament (PDL) cells play an important role in maintaining periodontal homeostasis upon force loading caused by mastication or orthodontic force. Previous studies revealed stretch-induced realignment of human PDL cells, but the mechanism for this phenomenon still remains unclear. As extracellular matrix (ECM) and adhesion molecules play critical roles in cell migration and alignment, this study aimed to identify mechanoresponsive genes related to ECM and adhesion in human PDL cells.

Design: Human PDL cells were exposed to 10% stretch strain for 6 or 24 h, and the expression of 84 genes related to ECM and adhesion were analyzed with real-time PCR array. The protein expression of integrin α5 was examined by Western blot and flow cytometric analysis.

Results: Among the genes screened, 6 were up-regulated and 3 were down-regulated after 6 h stretch. There were 12 up-regulated and 2 down-regulated genes after 24 h stretch. These differentially expressed genes included genes encoding cell-cell adhesion molecules (CD44, ICAM1), cell-matrix adhesion molecules (ITGA5, ITGA6, ITGAL, ITGB2, SPP1), basement membrane constituents (SPARC, TNC), collagens and ECM constituents (COL5A1, COL11A1, FN1), ECM proteases (ADAMTS1, ADAMTS8, MMP8) and inhibitors (TIMP1), as well as other adhesion-related molecules (CTGF, CTNND2, TGFBI, CLEC3B). Both the cytosolic and membrane integrin α5 protein levels were up-regulated in response to stretch.

Conclusion: This study identified several force-sensitive genes related to ECM and adhesion in stretched human PDL cells and should facilitate future studies on the stretch-induced cell realignment and mechanic force related periodontal remodelling by providing potential target genes.