Treadmill exercise promotes bone tissue recovery in rats subjected to high + Gz loads.

INTRODUCTION: High + Gz loads, the gravitational forces experienced by the body in hypergravity environments, can lead to bone loss in pilots and astronauts, posing significant health risks. MATERIALS AND METHODS: To explore the effect of treadmill exercise on bone tissue recovery, a study was conducted on 72 male Wistar rats. These rats were subjected to four weeks of varying levels of periodic high + Gz loads (1G, 8G, 20G) experiments, and were subsequently divided into the treadmill group and the control group. The treadmill group underwent a continuous two-week treadmill experiment, while the control group rested during this period. The mechanical properties, microstructure, and molecular markers of their tibial bone tissue were measured using three-point bending, micro-CT, and PCR. RESULTS: The results showed that treadmill exercise improved the elastic modulus, ultimate deflection, and ultimate load of rat bone tissue. It also increased the number, density, and volume fraction of bone trabeculae, and decreased their separation. Moreover, treadmill exercise enhanced osteogenesis and inhibited osteoclastogenesis. CONCLUSION: This study demonstrates that treadmill exercise can promote the recovery of bone tissue in rats subjected to high + Gz loads, providing a potential countermeasure for bone loss in pilots and astronauts.

Dynamically manipulating long-wave infrared polarized thermal radiation by a vanadium dioxide metasurface.

Dynamically manipulating the spectra and polarization properties of thermal radiation is the key to counter an infrared polarization imaging system (IPIS) under the different background environments. In this Letter, we propose a phase-change metasurface thermal emitter (PCMTE) composed of vanadium dioxide (VO2) dipole antenna arrays to dynamically manipulate polarized radiation spectra in the long-wave infrared (LWIR) region of 8-14 µm. During the thermally induced and reversible insulator-to-metal transition (IMT) in VO2, by simulating the LWIR images at different polarization angles for the PCMTE and background plates, the PCMTE can realize dynamically tunable LWIR camouflage; then, their degree of linear polarization (DoLP) can be calculated, which can demonstrate that the PCMTE can also achieve dynamically tunable LWIR polarization camouflage at the specific radiation angles and backgrounds. Our proposed PCMTE provides an effective scheme for adaptive IR polarization camouflage.

Research Progress on Router Devices for the OAM Optical Communication.

Vortex beams carrying orbital angular momentum (OAM) provide a new degree of freedom for light waves in addition to the traditional degrees of freedom, such as intensity, phase, frequency, time, and polarization. Due to the theoretically unlimited orthogonal states, the physical dimension of OAM is capable of addressing the problem of low information capacity. With the advancement of the OAM optical communication technology, OAM router devices (OAM-RDs) have played a key role in significantly improving the flexibility and practicability of communication systems. In this review, major breakthroughs in the OAM-RDs are summarized, and the latest technological standing is examined. Additionally, a detailed account of the recent works published on techniques related to the OAM-RDs has been categorized into five areas: channel multicasting, channel switching, channel filtering, channel hopping, and channel adding/extracting. Meanwhile, the principles, research methods, advantages, and disadvantages are discussed and summarized in depth while analyzing the future development trends and prospects of the OAM-RDs.

Mechanical properties of cracked articular cartilage under uniaxial creep and cyclic tensile loading.

Cracks may change the mechanical properties of articular cartilage, and further lead to early osteoarthritis. The study aimed to probe the mechanical properties of cracked cartilage under uniaxial tensile loading. The fracture process of cracked cartilage can be divided into two stages, namely crack-tip blunting stage and crack growth stage. The creep strain of cracked cartilage increases rapidly and then slowly with time, and it is well predicted by the nonlinear viscoelastic creep model. Compared with intact cartilage, cracked cartilage shows larger creep strain. During cyclic loading, the mean strain, degree of necking and crack-tip blunting of cracked cartilage increase with the increase of peak stress, while they decrease with the increase of loading frequency. The crack-tip morphology shows that cyclic loading has induced irreversible deformation in cartilage with a large number of collagen fibrils yielding, and further damaged the collagen fibril network of cartilage. However, no obvious crack growth is observed under the testing conditions.

Characterization and evaluation of a femtosecond laser-induced osseointegration and an anti-inflammatory structure generated on a titanium alloy.

Cell-material interactions during early osseointegration of the bone-implant interface are critical and involve crosstalk between osteoblasts and osteoclasts. The surface properties of titanium implants also play a critical role in cell-material interactions. In this study, femtosecond laser treatment and sandblasting were used to alter the surface morphology, roughness and wettability of a titanium alloy. Osteoblasts and osteoclasts were then cultured on the resulting titanium alloy disks. Four disk groups were tested: a polished titanium alloy (pTi) control; a hydrophilic micro-dislocation titanium alloy (sandblasted Ti (STi)); a hydrophobic nano-mastoid Ti alloy (femtosecond laser-treated Ti (FTi)); and a hydrophilic hierarchical hybrid micro-/nanostructured Ti alloy [femtosecond laser-treated and sandblasted Ti (FSTi)]. The titanium surface treated by the femtosecond laser and sandblasting showed higher biomineralization activity and lower cytotoxicity in simulated body fluid and lactate dehydrogenase assays. Compared to the control surface, the multifunctional titanium surface induced a better cellular response in terms of proliferation, differentiation, mineralization and collagen secretion. Further investigation of macrophage polarization revealed that increased anti-inflammatory factor secretion and decreased proinflammatory factor secretion occurred in the early response of macrophages. Based on the above results, the synergistic effect of the surface properties produced an excellent cellular response at the bone-implant interface, which was mainly reflected by the promotion of early ossteointegration and macrophage polarization.

Microstructural and mechanical evaluations of region segmentation methods in classifications of osteonecrosis.

Measuring the location of necrotic lesions is necessary to diagnosis of osteonecrosis. Different region segmentation methods of the femoral head were proposed to quantitatively measure necrotic lesions including Japanese Investigation Committee for Avascular Necrosis (JIC) classification and China-Japan Friendship Hospital (CJFH) classification. Biomechanical methods could bring important information to evaluate the reasonability of these classifications. In this study, microstructural and mechanical properties of trabecular bone were quantitatively analyzed according to the region segmentation methods described in these classifications. Microstructural parameters of trabecular bone were analyzed based on micro-CT scanning. Mechanical properties were measured through Nanoindentation and micro-finite element analysis. It was found that microstructural and mechanical properties of trabecular bone in the middle region was more adaptive to load bearing than the medial and lateral regions according to the CJFH classification; lesions in the middle region could bring more changes to microstructure and stress distribution. According to JIC classification, differences of microstructural and mechanical properties among the three regions were not significant. Biomechanical characteristics of trabecular bones could be better distinguished with CJFH classification.

Let-7i-5p functions as a putative osteogenic differentiation promoter by targeting CKIP-1.

MicroRNA (miRNA) is an endogenous regulatory small molecule RNA. Growing evidence shows that miRNA plays an important regulatory role in gene expression. Although miRNA is a more intensive regulatory noncoding RNA in recent years, few studies have investigated the regulation of targeting genes involved in bone repair. Meanwhile, as a negative bone regulator, previous studies showed that casein kinase 2-interacting protein 1 (CKIP-1) is closely associated with bone formation and regeneration. However, the gene knockout method may not be suitable for clinical application. Therefore, it was hypothesized that miRNA molecules can inhibit the expression of CKIP-1 and ultimately promote the osteogenesis process. The present study revealed that let-7i-5p plays an important role in the process of fracture healing by inhibiting the expression of CKIP-1. Related research provides a novel gene target for fracture healing. SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s10616-020-00444-1) contains supplementary material, which is available to authorized users.

Comprehensive circRNA expression profile and function network in osteoblast-like cells under simulated microgravity.

BACKGROUND: Circular RNAs (circRNAs) are a new class of non-coding RNA with a stable structure formed by special loop splicing. Research increasingly suggests that circRNAs play a vital role in the pathogenesis and progression of various diseases. However, the roles of circRNAs in osteoblast differentiation under microgravity remain largely unknown. Here, we investigated the roles and mechanobiological response of circRNAs in osteoblasts under simulated microgravity. METHODS: Differential circRNA and mRNA expression profiles of MC3T3-E1 cells during exposure to microgravity were screened by RNA transcriptome sequencing technology (RNA-seq). The selected RNAs were validated using quantitative real-time polymerase chain reaction (qRT-PCR). Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were applied for gene function analyses. RESULTS: A total of 427 circRNAs and 1912 mRNAs were differentially expressed along with osteogenic differentiation in the simulated microgravity group (SMG) compared to the control group (CON). Of these, 232 circRNAs and 991 mRNAs were upregulated, whereas 95 circRNAs and 921 mRNAs were downregulated (fold change ≥ 2, p < 0.05). The results showed that the parental genes of circRNAs and mRNAs were mainly enriched in anatomical structure morphogenesis, anchoring junction and protein binding. KEGG analysis results showed that the differentially expressed mRNAs were enriched in the regulation of the actin cytoskeleton, focal adhesion, and Ras signalling pathway. Subsequently, 9 core regulatory genes, including 6 mRNAs and 3 circRNAs, were identified based on their possible function in osteoblast differentiation. Based on this analysis, circ_014154 was selected as the target circRNA, which likely plays important roles in osteogenic differentiation processes under microgravity. The circRNA-miRNA-mRNA network showed that circRNAs might act as miRNA sponges to regulate osteoblast differentiation. CONCLUSION: By presenting a better understanding of the molecular mechanisms of genes and circRNAs in simulated microgravity, the present study will provide a novel view of circRNAs in the regulation of osteogenic differentiation and bone formation.

Two potential fields fused adaptive path planning system for autonomous vehicle under different velocities.

Path planning is a basic function for autonomous vehicle (AV). However, it is difficult to adapt to different velocities and different types of obstacles including dynamic obstacle and static obstacle (such as road boundary) for AV. To solve the problem of path planning under different velocities and different types of obstacles, a two potential fields fused adaptive path planning system (TPFF-APPS) which includes two parts, a potential field fusion controller and an adaptive weight assignment unit, is presented in this work. In the potential field fusion controller, a novel potential velocity field is built by velocity information and fused with a traditional artificial potential field for adapting various velocities. The adaptive weight assignment unit is designed to distribute adaptively the weights of two potential fields for adapting different types of obstacles at the same time, including road boundary and dynamic obstacles. The simulation is carried on the Carsim-Matlab co-simulation platform, and the simulation results indicate that the proposed TPFF-APPS has excellent performance for path planning adapting to different velocities and different types of obstacles.

Idealized conductance: A new method to evaluate stiffness of trabecular bone.

Stiffness is an important parameter to evaluate the condition of trabecular bone in biomechanical and clinical research. Microstructural parameters are commonly used to evaluate stiffness, but the accuracy needs to be improved. In this study, the electrical conductance of trabecular bone was calculated based on an idealized condition: trabeculae were electrically conductive and isotropy, other constituents in the trabecular bone were not considered in the simulation. The idealized conductance was calculated to evaluate the stiffness of trabecular bone, and the accuracy was compared with microstructural parameters. Twenty-one cubic trabecular cubes (5 × 5 × 5 mm3 ) from three femoral heads were investigated. Microstructural parameters were measured through Micro-CT scanning. Nominal elastic modulus (E) and idealized conductance (G) of trabecular cubes were measured through micro-finite element analysis. Bone volume fraction (BV/TV) is the major microstructural parameter that determine the stiffness of trabecular bone. The correlation coefficient between BV/TV and E along three directions were 0.815 (X-axis), 0.729 (Y-axis) and 0.914 (Z-axis). The correlation between G and E were stronger (X-axis: r = 0.986, Y-axis: r = 0.986, Z-axis: r = 0.991). A regression model combining different microstructural parameters was built to evaluate stiffness, but the correlation between them were not significantly improved (X-axis: r = 0.831, Y-axis: r = 0.807, Z-axis: r = 0.905). Compared with microstructural parameters, idealized conductance was a better parameter to evaluate stiffness of trabecular bone.

Rosamultin Attenuates Acute Hypobaric Hypoxia-Induced Bone Injuries by Regulation of Sclerostin and Its Downstream Signals.

Wang, Xing-Min, Hui Liu, Jian-Yu Li, Jin-Xia Wei, Xia Li, Yong-Liang Zhang, Ling-Zhi Li, and Xi-Zheng Zhang. Rosamultin attenuates acute hypobaric hypoxia-induced bone injuries by regulation of sclerostin and its downstream signals. High Alt Med Biol. 21:273-286, 2020. Background: Rosamultin, one of the compounds extracted from Potentilla anserina L., exhibited significant pharmacological activity against oxidative stress and hypoxic injury in our previous study. However, the effect of rosamultin on bone damage induced by acute hypobaric hypoxia (HH) has not been thoroughly studied. Methods: In this study, we first investigated the protective effect of rosamultin against bone damage in rats following acute exposure to simulated high-altitude hypoxia. Furthermore, we explored the detailed mechanism involved in the regulation of rat bone remodeling by rosamultin in an acute HH environment through analysis of sclerostin expression and the regulation of downstream signaling pathways. Results: Pretreatment with rosamultin significantly reduced HH-induced oxidative stress and inflammation, improved bone metabolic abnormalities, and alleviated the imbalance in bone remodeling in rats exposed to acute HH. Rosamultin markedly downregulated the expression of sclerostin, activated the Wnt/ß-catenin signaling pathway, and enhanced the ratio of osteoprotegerin/receptor activator of nuclear factor kappa B ligand to maintain the balance of bone formation and resorption. Conclusions: Rosamultin attenuates acute HH-induced bone damage and improves abnormal bone remodeling in rats by inhibition of sclerostin expression and activation of the Wnt/ß-catenin signaling pathway.

Intermittent vibrations accelerate fracture healing in sheep.

PURPOSE: To investigate the effect of intermittent vibration at different intervals on bone fracture healing and optimize the vibration interval. METHODS: Ninety sheep were randomized to receive no treatment (the control group), incision only (the sham control group), internal fixation with or without metatarsal fracture (the internal fixation group), and continuous vibration in addition to internal fixation of metatarsal fracture, or intermittent vibration at 1, 2, 3, 5, 7 and 17-day interval in addition to internal fixation of metatarsal fracture (the vibration group). Vibration was done at frequency F=35 Hz, acceleration a=0.25g, 15 min each time 2 weeks after bone fracture. Bone healing was evaluated by micro-CT scan, bone microstructure and mechanical compression of finite element simulation. RESULTS: Intermittent vibration at 7-day interval significantly improved bone fracture healing grade. However, no significant changes on microstructure parameters and mechanical properties were observed among sheep receiving vibration at different intervals. CONCLUSIONS: Clinical healing effects should be the top concern. Quantitative analyses of bone microstructure and of finite element mechanics on the process of fracture healing need to be further investigated.

Mechanical property and biocompatibility of silk fibroin-collagen type II composite membrane.

Osteoarthritis is caused by injuries and cartilage degeneration. Cartilage tissue engineering provides new ideas for the treatment of osteoarthritis. Herein, the different ratios composite membranes of silk fibroin/collagen type II were constructed (SF50-50:50, SF70-70:30, SF90-90:10). The surface properties of the composite membranes and chondrocyte morphology were observed by SEM (scanning electron microscopy). Physical functionality as well as stability of composite membranes was evaluated from tensile mechanical properties, the percentage of swelling and degradation. The tensile mechanical behavior of SF70 composite membranes was also predicted based on the constitutive model established in this study, and it is found that the experimental results and predictions were in good agreement. Biocompatibility was evaluated using chondrocytes (ADTC-5) culture. Cell proliferation was analyzed and the treatment of live/dead double staining was performed to assess the viability on chondrocytes. To sum up, SF70 showed the suitable morphology, physical stability, and biological functionality to promote proliferation of chondrocytes. This indicates that the mixing ratio of SF70 shows promise in the future as a scaffold material for cartilage repair.

[Research of simulated microgravity regulate MC3T3-E1 cells differentiation through the nuclear factor-kappa B signaling pathway].

In this study, we aim to investigat the effect of microgravity on osteoblast differentiation in osteoblast-like cells (MC3T3-E1). In addition, we explored the response mechanism of nuclear factor-kappa B (NF-κB) signaling pathway to "zero- g" in MC3T3-E1 cells under the simulated microgravity conditions. MC3T3-E1 were cultured in conventional (CON) and simulated microgravity (SMG), respectively. Then, the expression of the related osteoblastic genes and the specific molecules in NF-κB signaling pathway were measured. The results showed that the mRNA and protein levels of alkaline phosphatase (ALP), osteocalcin (OCN) and type Ⅰ collagen (CoL-Ⅰ) were dramatically decreased under the simulated microgravity. Meanwhile, the NF-κB inhibitor α (IκB-α) protein level was decreased and the expressions of phosphorylation of IκB-α (p-IκB-α), p65 and phosphorylation of p65 (p-p65) were significantly up-regulated in SMG group. In addition, the IL-6 content in SMG group was increased compared to CON. These results indicated that simulated microgravity could activate the NF-κB pathway to regulate MC3T3-E1 cells differentiation.

Intermittent vibrations accelerate fracture healing in sheep

Abstract Purpose: To investigate the effect of intermittent vibration at different intervals on bone fracture healing and optimize the vibration interval. Methods: Ninety sheep were randomized to receive no treatment (the control group), incision only (the sham control group), internal fixation with or without metatarsal fracture (the internal fixation group), and continuous vibration in addition to internal fixation of metatarsal fracture, or intermittent vibration at 1, 2, 3, 5, 7 and 17-day interval in addition to internal fixation of metatarsal fracture (the vibration group). Vibration was done at frequency F=35 Hz, acceleration a=0.25g, 15 min each time 2 weeks after bone fracture. Bone healing was evaluated by micro-CT scan, bone microstructure and mechanical compression of finite element simulation. Results: Intermittent vibration at 7-day interval significantly improved bone fracture healing grade. However, no significant changes on microstructure parameters and mechanical properties were observed among sheep receiving vibration at different intervals. Conclusions: Clinical healing effects should be the top concern. Quantitative analyses of bone microstructure and of finite element mechanics on the process of fracture healing need to be further investigated.

Novel Zinc Finger Transcription Factor ZFP580 Facilitates All-Trans Retinoic Acid -Induced Vascular Smooth Muscle Cells Differentiation by Rarα-Mediated PI3K/Akt and ERK Signaling.

BACKGROUND/AIMS: Phenotypic switching of vascular smooth muscle cells (VSMC) plays a vital role in the development of vascular diseases. All-trans retinoic acid (ATRA) is known to regulate VSMC phenotypes. However, the underlying mechanisms remain completely unknown. Here, we have investigated the probable roles and underlying mechanisms of the novel C2H2 zinc finger transcription factor ZFP580 on ATRA-induced VSMC differentiation. METHODS: VSMCs were isolated, cultured, and identified. VSMCs were infected with an adenovirus encoding ZFP580 or Ad-siRNA to silence ZFP580. The expression levels of ZFP580, SMα-actin, SM22α, SMemb, RARα, RARß, and RARγ were assayed by Q-PCR and western blot. A rat carotid artery injury model and morphometric analysis of intimal thickening were also used in this study. RESULTS: ATRA caused a significant reduction of VSMC proliferation and migration in a doseand time-dependent manner. Moreover, it promoted VSMC differentiation by enhancing expression of differentiation markers and reducing expression of dedifferentiation markers. This ATRA activity was accompanied by up-regulation of ZFP580, with concomitant increases in RARα expression. In contrast, silencing of the RARα gene or inhibiting RARα with its antagonist Ro41-5253 abrogated the ATRA-induced ZFP580 expression. Furthermore, ATRA binding to RARα induced ZFP580 expression via the PI3K/Akt and ERK pathways. Adenovirusmediated overexpression of ZFP580 promoted VSMC differentiation by enhancing expression of SM22α and SMα-actin and reducing expression of SMemb. In contrast, silencing ZFP580 dramatically reduced the expression of differentiation markers and increased expression of dedifferentiation markers. The classic rat carotid artery balloon injury model demonstrated that ZFP580 inhibited proliferation and intimal hyperplasia in vivo. CONCLUSION: The novel zinc finger transcription factor ZFP580 facilitates ATRA-induced VSMC differentiation by the RARα-mediated PI3K/Akt and ERK signaling pathways. This might represent a novel mechanism of regulation of ZFP580 by ATRA and RARα, which is critical for understanding the biological functions of retinoids during VSMC phenotypic modulation.

Effects of constrained dynamic loading, CKIP­1 gene knockout and combination stimulations on bone loss caused by mechanical unloading.

Mechanical stimulation plays an important role in maintaining the growth and normal function of the skeletal system. Mechanical unloading occurs, for example, in astronauts spending long periods of time in space or in patients on prolonged bed rest, and causes a rapid loss of bone mass. Casein kinase 2­interacting protein­1 (CKIP­1) is a novel negative bone regulation factor that has been demonstrated to reduce bone loss and enhance bone formation. The aim of this study was to investigate the effect of constrained dynamic loading (Loading) in combination with CKIP­1 gene knockout (KO) on unloading­induced bone loss in tail­suspension mice. The blood serum metabolism index [alkaline phosphatase (ALP) activity and osteocalcin (OCN) levels], tibia mechanical behavior (including bone trabecular microstructure parameters and tibia biomechanical properties), osteoblast­related gene expression [ALP, OCN, collagen I and bone morphogenetic protein­2 and osteoprotegerin (OPG)] and osteoclast­related gene expression [receptor activators of NF­kB ligand (RANKL)] were measured. The results demonstrated that mice experienced a loss of bone mass after four weeks of tail suspension compared with a wild type group. The mechanical properties, microarchitecture and mRNA expression were significantly increased in mice after Loading + KO treatment (P<0.05). Furthermore, compared with loading or KO alone, the ratio of OPG/RANKL was increased in the combined treatment group. The combined effect of Loading + KO was greater than that observed with loading or KO alone (P<0.05). The present study demonstrates that Loading + KO can counter unloading­induced bone loss, and combining the two treatments has an additive effect. These results indicate that combined therapy could be a novel strategy for the clinical treatment of disuse osteoporosis associated with space travel or bed rest.

[Osteogenesis effect of dynamic mechanical loading on MC3T3-E1 cells in three-dimensional printing biomimetic composite scaffolds].

Objective: To observe the effect of dynamic mechanical loading on the proliferation, differentiation, and specific gene expression of MC3T3-E1 cells that on three-dimensional (3D) biomimetic composite scaffolds prepared by low temperature 3D printing technology combined with freeze-drying. Methods: The silk fibroin, collagen type Ⅰ, and nano-hydroxyapatite (HA) were mixed at a mass ratio of 3∶9∶2 and were used to prepare the 3D biomimetic composite scaffolds via low temperature 3D printing technology combined with freeze-drying. General morphology of 3D biomimetic composite scaffold was observed. Micro-CT was used to observe the pore size and porosity of the scaffolds, and the water swelling rate, stress, strain, and elastic modulus were measured. Then, the MC3T3-E1 cells were seeded on the 3D biomimetic composite scaffolds and the cell-scaffold composites were randomly divided into 2 groups. The experimental group was subjected to dynamic mechanical loading (3 500 µÎµ, 1 Hz, 15 minutes per day); the control group was not subjected to loading treatment. After 7 days and 14 days, the cell-scaffold composites of 2 groups were harvested to observe the growth of cells on the scaffolds by HE staining and scanning electron microscope. And the gene and protein expressions of collagen type Ⅰ, BMP-2, and osteocalcin (OCN) were measured by real-time fluorescent quantitative PCR and Western blot. Results: The 3D biomimetic composite scaffold was a white cubic grid. Micro-CT detection showed the pore network structure in the scaffold material with good pore connectivity. The diameters of large pore and micro-aperture were (506.37±18.63) µm and (62.14±17.35) µm, respectively. The porosity was 97.70%±1.37%, and the water absorption swelling rate was 1 341.97%±64.41%. Mechanical tests showed that the compression displacement of the scaffold was (0.376±0.004) mm, the compressive stress was (0.016±0.002) MPa, and the elastic modulus was (162.418±18.754) kPa when the scaffold was compressed to 10%. At 7 days and 14 days, HE staining and scanning electron microscope observation showed that the cells grew inside the scaffold, mainly distributed around the scaffold pore wall. The cells in experimental group were more than control group, and the cells morphology changed from shuttle to flat. There was no significant difference in the cell counting between 2 groups at 14 days after 200-fold microscopy ( t=-2.024， P=0.080), but significant differences were found between 2 groups at different time points under different magnifications ( P<0.05). Real-time fluorescent quantitative PCR showed that the mRNA relative expressions of collagen type Ⅰ and OCN in experimental group were significantly higher than those in control group at 7 and 14 days ( P<0.05). However, the mRNA relative expression of BMP-2 showing no significant difference between 2 groups ( P>0.05). The protein relative expressions of collagen type Ⅰ, BMP-2, and OCN in experimental group were significantly higher than those in control group at 7 and 14 days ( P<0.05). Conclusion: After dynamic mechanical loading, the expressions of BMP-2, collagen type Ⅰ, and OCN in MC3T3-E1 cells inoculated into 3D biomimetic composite scaffolds are significantly up-regulated, indicating that appropriate mechanical loads favor osteoblast differentiation of MC3T3-E1 cells.

Effects of continuous or intermittent low-magnitude high-frequency vibration on fracture healing in sheep.

PURPOSE: Vibration therapy has been shown to improve fracture healing. In this study, we investigated the effects of continuous or different intermittent vibration regimens on fracture healing in sheep models on the basis of radiographs, mechanical, and biochemical testing. METHODS: The 63 right-hind metatarsals from 63 sheep (12-month-old) were osteotomized; followed by surgical fixation with a steel plate. Two weeks after the surgery, the sheep with right-hind metatarsal fractures were randomly divided into seven groups (n=9/group): control (no vibration treated), continuous vibration (CV), one, three, five, seven and 14-day intermittent vibration (named IV-1, -3, -5, -7, and -14, respectively) groups, which represented a cycle of the successive n-day vibration and successive n-day break. Vibration stimulation (F=35 Hz, a=0.25 g) lasted 15 minutes each treatment. After eight weeks with/without vibration treatment, the sheep were euthanized with intravenous anesthetic. The callus formation, mechanical properties, and biochemical compositions of fracture metatarsals were analyzed. RESULTS: In CV and IV-7 groups, X-ray images showed an increased callus volume around the fracture area. The bone elastic modulus and the concentrations of Ca, P, and Ca/P ratio of the area at 15 and 25 mm away from the fracture centerline were higher in CV and IV-7 groups compared with the other groups. CONCLUSIONS: Our results demonstrate that both CV and IV-7 vibration patterns showed better improvement of fracture healing.

The Combination of icariin and constrained dynamic loading stimulation attenuates bone loss in ovariectomy-induced osteoporotic mice.

Osteoporosis is a disease characterized by low bone mass and progressive destruction of bone microstructure, resulting in increasing the risk of fracture. Icariin (ICA) as a phytoestrogen shows osteogenic effects, and the mechanical stimulation has been demonstrated the improving effect on osteoporosis. The objective of this study was to investigate the effect of ICA in combination with constrained dynamic loading (CDL) stimulation on osteoporosis in ovariectomized (OVX) mice. The serum hormone levels, bone turnover markers, trabecular architecture, ulnar biomechanical properties, and the expression of osteoblast-related gene (alkaline phosphatase, ALP; osteocalcin, OCN; bone morphogenetic protein-2, BMP-2; Collagen I (α1), COL1; osteoprotegerin, OPG) and osteoclast-related genes (receptor activators of NF-κB ligand, RANKL; tartrate-resistant acid phosphatase, TRAP) were analyzed. The results showed that ICA + CDL treatment could increase the osteocalcin (20.85%), estradiol levels (20.61%) and decrease the TRAP activity (26.27%) significantly than CDL treatment. The combined treatment attenuated bone loss and biomechanical decrease more than single use of CDL treatment. ICA + CDL treatment significantly up-regulated the level of osteoblast-related gene expression and down-regulated the osteoclast-related genes expression; moreover, the combined treatment increased the ratio of OPG/RANKL significantly compared to ICA (72.83%) or CDL (65.63%) treatment alone. The present study demonstrates that icariin in combination with constrained dynamic loading treatment may have a therapeutic advantage over constrained dynamic loading treatment alone for the treatment of osteoporosis, which would provide new evidence for the clinical treatment of osteoporosis. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1415-1424, 2018.