Strain-related collagen gene expression in human osteoblast-like cells

Abstract

The gene expression of cells in the musculoskeletal system, such as in bone, cartilage, ligament and tendon, is profoundly affected by mechanical loading. Previous studies have demonstrated that the expression of many genes, including collagen types I and III, are affected by mechanical strain in diverse cell types, such as human osteoblast-like SaOs-2 cells. However, whether the effect of mechanical loading on collagen gene expression is strain-related remains unclear. The goal of this study was to determine the relationship between mechanical strain and the gene expression of collagen types I and III in SaOs-2 cells. A Flexercell cellular mechanical loading system was used to subject SaOs-2 cells to equibiaxial cyclic tensile stress at a rate of 0.5 Hz with various strains of 5%, 7.5%, 10%, and 12.5% for 24 h. The relative amount of mRNA of both collagen I and collagen III increased at 5% strain compared with that of the control. As the strain increased, the relative amount of mRNA of collagen I remained stable at strain levels up to 12.5%. However, the mRNA for collagen III began to drop when the strain was greater than 5%, until a 10% strain was reached. From the application of a 10% strain through the maximum loading of a 12.5% strain, the relative amount of collagen III mRNA remained stable at amounts lower than that of the control. Thus, the gene expression of collagen types I and III responds differentially to mechanical strain at various magnitudes.

Response of a Preosteoblastic Cell Line to Cyclic Tensile Stress Conditioning and Growth Factors for Bone Tissue Engineering

“…In previous literature, type I collagen was shown to be induced by TGF-b1 in MC3T3-E1 cells, 37 whereas cyclic tensile stress (5%-12.5%, 0.5 Hz, 24 h) only slightly promoted type 1 collagen mRNA compared with static-cultivated SaOs-2 cells. 11 However, we observed that type I collagen mRNA induction by GFs was FIG. 8.…”

“…3,6,7 This bioreactor has applied 5%-10% elongation with 0.2-1 Hz frequency to 3D scaffolds including polyurethane nanofibrous scaffolds, 8 and fibrin, 9 and collagen gels. 10 Tensile stress of 3%-20% magnitude modulated expression of bone-related molecules such as collagen, 7,11 osteocalcin (OCN), 1,7 osteopontin (OPN), 1,7 matrix metalloproteinase-13 (MMP-13), 12 osteoprotegerin (OPG), 6 prostaglandin E 2 (PGE 2 ), 13 cyclooxygenase-2 (COX-2), 14 vascular endothelial growth factor (VEGF), 1,15 and transforming growth factor-b1 (TGF-b1). 16 Other external stimulating factors for bone regeneration are osteoinductive growth factors (GFs) such as TGF, bone morphogenetic protein (BMP), and platelet-derived GF.…”

Periprosthetic strain magnitude-dependent upregulation of type I collagen synthesis in human osteoblasts through an ERK1/2 pathway

“…Most investigations demonstrated that tensile force increased the mRNA level of type I collagen in bone marrow stromal cells [17], anterior cruciate ligament cells [14] and human osteoblast-like cells [22]. Unfortunately, the corresponding increase of type I collagen protein synthesis was not indicated in these studies.…”

“…Type I collagen accounts for 90% of the bone matrix proteins [9]. Most investigations indicated that tensile strain regulated the expression of type I collagen in cells [14,17,22], and some of these responses may be related to the strain magnitude. The carboxyterminal propeptide of type I procollagen (PICP) is cleaved from the biochemical precursor of type I collagen and used as a new marker of the bone turnover after THA.…”

Quantification and significance of fluid shear stress field in biaxial cell stretching device

“…Osteoblasts, producing mineralised matrix, have an essential role in fracture healing and are known to be mechanosensitive (Einhorn 1998); they have shown a differential response to stimuli magnitude in the synthesis of several factors important for bone healing (Chen et al 2005;Liu et al 2005;Tang et al 2006;Bhatt et al 2007).…”