The bio‐response of osteocytes and its regulation on osteoblasts under vibration

Abstract

Vibration, especially at low magnitude and high frequency (LMHF), was demonstrated to be anabolic for bone, but how the LMHF vibration signal is perceived by osteocytes is not fully studied. On the other hand, the mechanotransduction of osteocytes under shear stress has been scientists' primary focus for years. Due to the small strain caused by low-magnitude vibration, whether the previous explanation for shear stress will still work for LMHF vibration is unknown. In this study, a finite element method (FEM) model based on the real geometrical shape of an osteocyte was built to compare the mechanical behaviors of osteocytes under LMHF vibration and shear stress. The bio-response of osteocytes to vibration under different frequencies, including the secretion of soluble factors and the concentration of intracellular calcium, were studied. The regulating effect of the conditioned medium (CM) from vibrated osteocytes on osteoblasts was also studied. The FEM analysis result showed the cell membrane deformation under LMHF vibration was very small (with a peak value of 1.09%) as compared to the deformation caused by shear stress (with a peak value of 6.65%). The F-actin stress fibers of osteocytes were reorganized, especially on the nucleus periphery after LMHF vibration. The vibration at 30 Hz has a promoting effect on osteocytes and the osteogenesis of osteoblasts, whereas vibration at 90 Hz was suppressive. These results lead to a conclusion that the bio-response of osteocytes to LMHF vibration is frequency-dependent and is more related to the cytoskeleton on nuclear periphery rather than the membrane deformation.

Vibratory stimulation enhances thyroid epithelial cell function

“…Although these shear stresses are quite small in the TRB, it is still possible that they also are a source of mechanical stimulation in vivo when movement is less confined. For example, similar to our study, computational simulations on the effect of LMS on osteocytes in vitro conclude that membrane deformations from fluid shear stresses are too low to be stimulatory [55] . However, simulations of LMS on trabecular bone in vivo estimate median shear stresses between 0.3 and 1.1 Pa that are considered high enough to produce an anabolic effect [56] .…”

The effect of local application of low-magnitude high-frequency vibration on the bone healing of rabbit calvarial defects—a pilot study

“…The impact of low-magnitude high-frequency vibration (LMHFV), in particular, has been the subject of many experiments which have pointed out effects on multiple levels, starting from the molecular level, to the cell cultures, and extending to the experiments in animals and humans. Consistently across studies, the application of vibrations showed anabolic and/or anti-catabolic effects in bone [9–12]. Lau et al confirmed that osteocytes are actually mechanosensors able to detect LMHFV stimulus at the transcriptional level and produce soluble factors that inhibit osteoclast formation [13].…”

Mandible and iliac osteoblasts exhibit different Wnt signaling responses to LMHF vibration

“…These findings are consistent with a previous study that found culture in conditioned medium from vibrated osteocyte-like MLO-Y4 cells increased ALP activity in MC3T3-E1 mouse calvarial cells. 27 Additionally, human long bone osteoblasts subjected to 60 Hz vibration for 4 days had higher ALP activity. 21 This study also indicates that the effects of vibration on osteoblastlike cells are mediated, at least in part, through induction of extracellular signaling molecules.…”