Expression of Non-collagenous Bone Matrix Proteins in Osteoblasts Stimulated by Mechanical Stretching in the Cranial Suture of Neonatal Mice

Abstract

We investigated the influence of mechanical stretching on the genetic expression pattern of noncollagenous bone matrix proteins in osteoblasts. The cranial sutures of neonatal mice were subjected to ex vivo mechanical stretching. In the nonstretched control group, as osteoblast differentiation progressed, the successive genetic expression of bone sialoprotein (BSP), osteopontin (OPN), and osteocalcin (OCN) was detected using in situ hybridization, in that order. In the stretched group, the sutures were widened, and after 24 hr of cultivation, a large number of osteoblasts and abundant new osteoid were observed on the borders of the parietal bones. All new osteoblasts expressed BSP and some of them expressed OPN, but very few of them expressed OCN. After 48 hr, more extensive presence of osteoid was noted on the borders of the parietal bones, and this osteoid was partially mineralized; all osteoblasts on the osteoid surface expressed BSP, and more osteoblasts expressed OPN than those after 24 hr cultivation. Surprisingly, many of the osteoblasts that did not express OPN, expressed OCN. This suggests that when osteoblast differentiation is stimulated by mechanical stress, the genetic expression pattern of noncollagenous proteins in the newly differentiated osteoblasts is affected.

Selective Laser Melting and Electron Beam Melting of Ti6Al4V for Orthopedic Applications: A Comparative Study on the Applied Building Direction

“…During the initial proliferative phase, cells go through a massive DNA synthesis and cell division, resulting in a rapid increase in cell number until confluence. Then, proliferation is arrested, and there is an increase in the sequential expression of mature osteoblastic characteristics including alkaline phosphatase (ALP) expression, conversion of procollagen to collagen, and the deposition of extracellular matrix containing calcium and additive proteins such as bone sialoprotein (BSP), osteopontin (OPN), matrix extracellular phosphoglycoprotein (MEPE), and, as a late-stage marker, osteocalcin (OCN) on the substrate, which is subsequently mineralized [64].…”

Osteopontin as a Link between Inflammation and Cancer: The Thorax in the Spotlight

“…The OPN protein is produced in a wide range of tissues all over the body in physiologic and disease conditions (Figure 2). However, only a few cell types can express OPN, such as osteoblasts of osseous tissue [24,25,26,27], fibroblasts and activated macrophages of healing wounds [9,28,29], and dendritic, lymphoid, and mononuclear cells of the immune system [30,31,32,33]. Secretory OPN (sOPN) is present in biologic fluids like human serum (average level of 159 ng/mL) [34], bovine milk (average levels 18-138 mg/L) [35], and human urine (average level of 4 µg/mL) [36].…”

Hydroxyapatite Nanoparticles Facilitate Osteoblast Differentiation and Bone Formation Within Sagittal Suture During Expansion in Rats

“…13,24,25 Thus, current strategies use pharmaceuticals, exosomes or cytokines to induce SuSCs to osteoblast differentiation and enhance bone regeneration during the expansion process. [26][27][28][29] However, the success of these reconstructions remains highly challenging owing to a number of limitations. 7 In the present study, we hypothesized that applying nHAP could prevent the expanded suture occlusion via inducing SuSCs to osteoblast differentiation and enhance local mechanical strength in certain sutures.…”