Bone Angiogenesis Research Articles

Combined treatment with Cinnamaldehyde and β-TCP had an additive effect on bone formation and angiogenesis in critical size calvarial defect in ovariectomized rats

Accumulating evidence suggests that improvements in osteogenesis and angiogenesis play an important role in repairing osteoporotic bone defects. Cinnamomum cassia (C. cassia), a traditional Chinese medicinal herb, is reported to show anabolic effects on osteoblasts. However, whether C. cassia could actually repair bone defects in osteoporotic conditions remains unknown. The purpose of this study was to evaluate the effect of combined treatment with Cinnamaldehyde (main oil isolated from the C. cassia) and β-tricalcium phosphate (β-TCP) on bone formation and angiogenesis in critical size calvarial defects in ovariectomized (OVX) rats. Using a previously established OVX model, 5 mm critical size calvarial defect was established in OVX rats. All OVX rats were then randomly divided into OVX group (OVX rats + empty defect), TCP group (OVX rats + β-TCP), and CTCP group (Cinnamaldehyde 75 mg/kg/day for 12 weeks + β-TCP). Twelve weeks after treatment, according to Micro-CT and HE staining, combination of Cinnamaldehyde and β-TCP had an additive effect on bone regeneration compared with other groups (p < 0.05). Based on dynamic fluorochrome-labelling analysis, Cinnamaldehyde+β-TCP continuously promoted new bone mineralization compared with other groups at each time point (p < 0.05). Microfil perfusion suggested that CTCP group showed more neovascularization compared with other groups (p < 0.05). Immunohistochemical assay supported the findings that Cinnamaldehyde+β-TCP enhanced expression of OCN, VEGF and CD31. The present study demonstrated that combined treatment with Cinnamaldehyde and β-TCP promoted bone formation and angiogenesis in osteoporotic bone defects, which provides a promising new strategy for repairing bone defects in osteoporotic conditions.

Effects of ethanol on human periodontal ligament fibroblasts subjected to static compressive force.

Consumption of toxic substances such as alcohol is widespread in the general population and thus also in patients receiving orthodontic treatment. Since human periodontal ligament (hPDL) fibroblasts play a key role in orthodontic tooth movement (OTM) by expressing cytokines and chemokines, we wanted to clarify whether ethanol modulates the physiological activity and expression pattern of hPDL fibroblasts during static compressive force application. We pre-incubated hPDL fibroblasts for 24h with different ethanol concentrations, corresponding to casual (0.041% blood alcohol concentration [BAC], % by volume) and excessive (0.179%) alcohol consumption. At each ethanol concentration, we incubated the cells for another 48h with and without an additional physiological compressive force of 2g/cm2 occurring during orthodontic tooth movement in compression areas of the periodontal ligament. Thereafter, we analyzed expression and secretion of genes and proteins involved in OTM regulation by RT-qPCR and ELISA. We also performed co-culture experiments to observe hPDL-fibroblast-mediated osteoclastogenesis. We observed no effects of ethanol on cytotoxicity or cell viability of hPDL fibroblasts in the applied concentrations. Ethanol showed an enhancing effect on angiogenesis and activity of alkaline phosphatase. Simultaneously, ethanol reduced the induction of IL-6 and increased prostaglandin E2 synthesis as well as hPDL-fibroblast-mediated osteoclastogenesis without affecting the RANK-L/OPG-system. hPDL fibroblasts thus seem to be a cell type quite resistant to ethanol, as no cytotoxic effects or influence on cell viability were detected. High ethanol concentrations, however, seem to promote bone formation and angiogenesis. Ethanol at 0.179% also enhanced hPDL-induced osteoclastogenesis, indicating increased bone resorption and thus tooth movement velocity to be expected during orthodontic therapy.

Effects of combined menaquinone-4 and PTH1-34 treatment on osetogenesis and angiogenesis in calvarial defect in osteopenic rats.

The aim of this study was to evaluate the effect of combining human parathyroid hormone (1-34) (PTH1-34; PTH) and menaquinone-4 (MK-4) on calvarial bone defect repair in osteopenic rats. Fourteen week olds were subject to craniotomy for the establishment of osteopenic animal models fed through a chronically low-protein diet. After that, critical calvarial defect model was established and all rats were randomly divided into four groups: sham, MK-4, PTH, and PTH + MK-4. The animals received MK-4 (30 mg/kg/day), PTH1-34 (60 μg/kg, three times a week), or PTH1-34 (60 μg/kg, three times a week) plus MK-4 (30 mg/kg/day) for 8 weeks, respectively. Serum γ-carboxylated osteocalcin (Gla-OC) levels, histological and immunofluorescent labeling were employed to evaluate the bone formation and mineralization in calvarial bone defect. In addition, Microfil perfusion, immunohistochemical, and micro-CT suggested enhanced angiogenesis and bone formation in calvarial bone healing. In this study, treatment with either PTH1-34 or MK-4 promoted bone formation and vascular formation in calvarial bone defects compared with the sham group. In addition, combined treatment of PTH1-34 plus MK-4 increased serum level of Gla-OC, improved vascular number and vascular density, and enhanced bone formation in calvarial bone defect in osteopenic conditions as compared with monotherapy. In summary, this study indicated that PTH1-34 plus MK-4 combination therapy accelerated bone formation and angiogenesis in calvarial bone defects in presence of osteopenia.

Bone Marrow-derived Endothelial Progenitor Cells Are Associated with Bone Mass and Strength.

Blood vessels of bone are thought to influence osteogenesis of bone. No clinical studies have determined whether angiogenesis is related to bone mass and gene expression of growth factors. We compared bone marrow endothelial progenitor cells (EPC), which control angiogenesis of bone in postmenopausal women incurring fragility fracture, with osteoporosis or traumatic fracture with normal bone mass (COM). Bone specimens were obtained from age-matched women with osteoporosis or COM. Mononuclear cells were isolated and EPC were detected by flow cytometry. The expression levels of specific genes were measured. Bone mineral density (BMD) was determined, and serum markers of bone turnover also were measured. Differences between OP and COM were assessed with Student t test or Mann-Whitney U test, and correlations were determined using Spearman's correlation. Compared with COM, patients with OP had significantly lower levels of serum osteocalcin, procollagen type-1 N-terminal propeptide, and 25-hydroxy vitamin D, as well as decreased BMD of total hip and femoral neck and fewer bone marrow EPC. Expression levels of vascular endothelial growth factor, angiopoietin-1 (Ang-1), angiopoietin 2 (Ang-2), and the osteoblast-specific genes runt-related transcription factor 2 (RUNX2) and osterix in bone were significantly lower in OP than in COM. We determined that mature EPC were correlated positively with BMD of the femoral neck and total hip, gene expression of Ang-1, RUNX2, and CD31, and negatively with gene expression of receptor activator of nuclear factor-κB ligand and Ang-2. Our results demonstrate correlations of bone marrow EPC with bone mass and gene expression of growth factors, which support a hypothesis of crosstalk between angiogenesis and osteogenesis in bone health.

Chondrocyte mTORC1 activation stimulates miR-483-5p via HDAC4 in osteoarthritis progression.

The hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) in chondrocytes has been shown to accelerate the severity of destabilization of the medial meniscus-induced and age-related osteoarthritis (OA) phenotypes with aberrant chondrocyte hypertrophy and angiogenesis. Meanwhile, we previously reported that miR-483-5p is essential for the initiation and development of OA by stimulating chondrocyte hypertrophy and angiogenesis. The connection between mTORC1 and miR-483-5p activation in OA progression, however, remains unclear. In this study, we elucidated their relationship and identified the underlying mechanisms. The expression of miR-483-5p in the articular cartilage ofcartilage-specific TSC1 knockout mice was assessed compared with control mice using the Agilent Mouse miRNA (8*60K) V19.0 array and real-time polymerase chain reaction (RT-PCR). The functional effects of the stimulation of miR-483-5p via histone deacetylase 4 (HDAC4) by mTORC1 in OA development, subsequently modulating its downstream targetsmatrilin 3 and tissue inhibitor of metalloproteinase 2, were examined by immunostaining, western blotting, and real-time PCR. This study revealed that miR-483-5p was responsible for mTORC1 activation-stimulated OA. Mechanistically, mTORC1 controls the HDAC4-dependent expression of miR-483-5p to stimulate chondrocyte hypertrophy, extracellular matrix degradation, and subchondral bone angiogenesis, and it consequently initiates and accelerates the development of OA. Our findings revealed a novel mTORC1-HDAC4-miR-483-5p pathway that is critical for OA development.

A novel strategy for in vivo angiogenesis and osteogenesis: magnetic micro-movement in a bone scaffold

Angiogenesis and osteogenesis in tissue-engineered bone are the key factors in the clinical application of tissue-engineering technology to repair large bone defects. In vivo cells that are farther than 200 μm from capillaries cannot survive due to lack of nutrients and oxygen, and thus, the tissue-engineered bone is not suitable for repairing large bone defects. In this study, we constructed a novel artificial bone scaffold loaded with superparamagnetic plasmid gene microspheres. Magnetic micro-movement of the magnetic microspheres in the scaffold was generated by an oscillating magnetic field and a static magnetic field to promote the release of plasmid genes from microspheres for transfection of surrounding cells, resulting in protein expression of vascular endothelial growth factor, thus promoting angiogenesis and osteogenesis in the scaffold, internal vascularization of the artificial bone scaffold and repair of large bone defects.

Magnesium calcium silicate bioactive glass doped with copper ions; synthesis and in-vitro bioactivity characterization

Recent studies revealed that metallic ions have therapeutic effects on human bone metabolism and angiogenesis. Thus, in this study, a new magnesium-calcium-silicate glass powder, being doped with copper ions was synthesized through the sol-gel process; the material was termed as 60S7M2Cu. The glass was thermally treated at several temperatures up to 870 °C in order to induce crystallization, which would potentially enhance its mechanical and/or biological properties. Structural and morphological characterization, thermal analysis and in-vitro apatite forming ability evaluation were performed by X-ray diffraction-XRD, Scanning Electron Microscopy-SEM coupled with Energy Dispersion Spectrometry-EDS, Thermogravimetric Analysis, as well as Fourier Transformed Infrared-FTIR Spectrometry. Moreover, the elemental release was recorded by Inductively Coupled Plasma Atomic Emission Spectroscopy ICP-AES. Experimental results showed that a crystalline hydroxyapatite phase was developed after 3 days in the simulated body fluid (SBF) followed, after 15 days, by the growth of a carbon hydroxyapatite layer, in both untreated glass as well as treated glass-ceramics nearly at all temperatures. At lower temperatures, namely 770 and 800 °C, a whitlockite bioactive phase appeared after the immersion in SBF, while a wollastonite crystalline phase emerged when treated at 830 and 870 °C without having a negative effect on its apatite forming ability. Copper ions releasing from the glass and glass-ceramics materials was proved to be slow and stable during the whole period of soaking. In this study copper containing glass and glass-ceramics, which present apatite forming ability and according to literature possess the capability to induce the release of therapeutic ions with osteogenic and angiogenic capacity, were synthesized. Eventually, after further investigations, this glass composition could be applied in bone tissue engineering, where bioactive materials able to induce simultaneously both osteogenesis and angiogenesis constitute a constant demand.

Unfocused shockwaves for osteoinduction in bone substitutes in rat cortical bone defects.

Bone substitutes are frequently used in clinical practice but often exhibit limited osteoinductivity. We hypothesized that unfocused shockwaves enhance the osteoinductivity of bone substitutes and improve osteointegration and angiogenesis. Three different bone substitutes, namely porous tricalcium phosphate, porous hydroxyapatite and porous titanium alloy, were implanted in a critical size (i.e. 6-mm) femoral defect in rats. The femora were treated twice with 1500 shockwaves at 2 and 4 weeks after surgery and compared with non-treated controls. The net volume of de novo bone in the defect was measured by microCT-scanning during 11-weeks follow-up. Bone ingrowth and angiogenesis in the bone substitutes was examined at 5 and 11 weeks using histology. It was shown that hydroxyapatite and titanium both had an increase of bone ingrowth with more bone in the shockwave group compared to the control group, whereas resorption was seen in tricalcium phosphate bone substitutes over time and this was insensitive to shockwave treatment. In conclusion, hydroxyapatite and titanium bone substitutes favour from shockwave treatment, whereas tricalcium phosphate does not. This study shows that osteoinduction and osteointegration of bone substitutes can be influenced with unfocused shockwave therapy, but among other factors depend on the type of bone substitute, likely reflecting its mechanical and biological properties.

In vitro and in vivo investigation of PLA/PCL scaffold coated with metformin-loaded gelatin nanocarriers in regeneration of critical-sized bone defects

Large bone defects constitute a major challenge in bone tissue engineering and usually fail to heal due to the incomplete differentiation of recruited mesenchymal stem cells (MSCs) into osteogenic precursor cells. As previously proposed, metformin (MET) induces differentiation of MSCs into osteoblastic lineages in vitro. We fabricated a Poly (lactic acid) and Polycaprolactone (PLA/PCL) scaffold to deliver metformin loaded gelatin nanocarriers (MET/GNs) to critical-sized calvarial bone defects in a rat model. The scaffolds were evaluated regarding their morphology, porosity, contact angle, degradation rate, blood compatibility, biomechanical, cell viability and their osteogenic differentiation. In animal study, the defects were filled with autograft, scaffolds and a group was left empty. qRT-PCR analyses showed the expression level of osteogenic and angiogenic markers considerably increased in MET/GNs-PLA/PCL. The in vivo results showed that MET/GNs-PLA/PCL improved bone ingrowth, angiogenesis and defect reconstruction. Our results represent the applicability of MET/GNs-PLA/PCL for successful bone regeneration.

Angiopoietin 2 promotes angiogenesis in tissue-engineered bone and improves repair of bone defects by inducing autophagy.

Angiogenesis plays a key role in the repair of large segmental bone defects with tissue-engineered bones. However, there is no effective method of promoting angiogenesis in tissue-engineered bone. Both angiopoietin 2 (Ang2) and autophagy have been shown to be involved in angiogenesis, but their roles in angiogenesis of tissue-engineered bone remains unknown. In this in vivo study, a radius bone defect was created in New Zealand white rabbits, which were then treated by implantation of a hydroxyapatite/collagen scaffold followed by injection of different concentrations of Ang2. Expression of the autophagic modulators microtubule-associated protein 1 light chain 3 (LC3), Beclin-1, and SQSTM1/P62 were measured via western blotting, while the angiogenic modulators VEGF and CD31 were detected by western blotting and immunohistochemistry, respectively. X-ray imaging combined with general observation was used to evaluate bone defect healing. Expression of LC3 -I/LC3-II, Beclin-1, VEGF, and CD31 in the callus area increased and SQSTM1/p62 decreased in a dose-dependent manner with increasing Ang2 concentration. In the group treated with a high concentration of Ang2, the new callus grew well, accompanied by remarkable angiogenesis, leading to good repair of the bone defects. However, in the low concentration of Ang2 group, in spite of the existence of angiogenesis and new bone formation, the bone defects were not repaired. Furthermore, angiogenesis and osteogenesis were both obstructed in the control group. In conclusion, our study demonstrated that a high concentration of Ang2 promoted angiogenesis in tissue-engineered bone and improved repair of bone defects by inducing autophagy.

Enhanced angiogenesis and increased bone turnover characterize bone marrow lesions in osteoarthritis at the base of the thumb.

ObjectivesLittle is known about tissue changes underlying bone marrow lesions (BMLs) in non-weight-bearing joints with osteoarthritis (OA). Our aim was to characterize BMLs in OA of the hand using dynamic histomorphometry. We therefore quantified bone turnover and angiogenesis in subchondral bone at the base of the thumb, and compared the findings with control bone from hip OA.MethodsPatients with OA at the base of the thumb, or the hip, underwent preoperative MRI to assess BMLs, and tetracycline labelling to determine bone turnover. Three groups were compared: trapezium bones removed by trapeziectomy from patients with thumb base OA (n = 20); femoral heads with (n = 24); and those without (n = 9) BMLs obtained from patients with hip OA who underwent total hip arthroplasty.ResultsAll trapezium bones demonstrated MRI-defined BMLs. Compared with femoral heads without BMLs, the trapezia demonstrated significantly higher bone turnover (mean sd 0.2 (0.1) versus 0.01 (0.01) µm3/µm2/day), mineralizing surface (18.5% (13.1) versus 1.4% (1.3)) and vascularity (5.2% (1.1) versus 1.2% (0.6)). Femoral heads with BMLs exhibited higher bone turnover (0.3 (0.2) versus 0.2 (0.1) µm3/µm2/day), a higher mineralization rate (26.6% (10.6) versus 18.6% (11.9)) and greater trabecular thickness (301.3 µm (108) versus 163.6 µm (24.8)) than the trapezia.ConclusionBone turnover and angiogenesis were enhanced in BMLs of both the thumb base and hip OA, of which the latter exhibited the highest bone turnover. Thus, the increase in bone turnover in weight-bearing joints like the hip may be more pronounced than less mechanically loaded osteoarthritic joints demonstrating BMLs. The histological changes observed may explain the water signal from BMLs on MRI.Cite this article: M. Shabestari, N. J. Kise, M. A. Landin, S. Sesseng, J. C. Hellund, J. E. Reseland, E. F. Eriksen, I. K. Haugen. Enhanced angiogenesis and increased bone turnover characterize bone marrow lesions in osteoarthritis at the base of the thumb. Bone Joint Res 2018;7:406–413. DOI: 10.1302/2046-3758.76.BJR-2017-0083.R3.

The Effect of Laser Irradiation on Reparative Osteogenesis

Introduction: The use of non-medicinal facilities for correcting processes in various pathological conditions is one of the most urgent problems of modern medicine. Purpose of the Work: To study the effect of low-intensity infrared laser radiation on reparative bone formation and angiogenesis in bone regeneration which is formed in treatment of fractures under conditions of transosseous osteosynthesis. Material and Methods: A tibia fracture was modeled experimentally in rats in the control and experimental groups. Reposition and fixation of fragments were performed. The fracture zone in the experimental group animals was exposed to the impact of pulsed infrared laser irradiation of low intensity. Animals from the control group underwent the impact simulation. The operated bones were investigated using the methods of X-ray, light and electron microscopy, X-ray electron probe microanalysis. Results: It was established that laser radiation exposure sessions activated fibrillogenesis and angiogenesis, accelerated compacting of newly formed bone tissue and increased its maturity while primary fracture healing occurred. Prolonged capillary dilatation and endothelium-dependent vasodilation, intensive capillarogenesis were noted after sessions of laser therapy in bone regeneration. Endothelial outgrowth was formed in the lumen of the vessels forming capillary buds that propagate along the “mother” vessels (endovascular capillarogenesis). Conclusion: The data obtained revealed a possible mechanism of laser radiation exposure at the level of a whole organism and proved the effectiveness of its application in clinical practice at the early stages of patient rehabilitation under conditions of transosseous osteosynthesis.

Novel multifunctional strontium-copper co-substituted mesoporous bioactive particles

Sr-Cu co-substituted mesoporous bioactive glasses were synthesized by two different sol-gel approaches: an ultrasound-assisted base-catalyzed sol-gel procedure and an aerosol-assisted spray-drying method. The produced spherical shaped particles showed high specific surface area values and tunable pore size. The two different routes allowed obtaining samples with different morphology and size, characterized by the ability to induce hydroxyapatite deposition, to incorporate a specific amount of therapeutic ions (strontium with the aim to improve bone formation and copper for its antibacterial and pro-angiogenic properties) and to release them. The obtained multifunctional biomaterials synergistically combine the ability to promote bone formation and angiogenesis and to impart an antibacterial effect.

Halofuginone Attenuates Osteoarthritis by Rescuing Bone Remodeling in Subchondral Bone Through Oral Gavage

Osteoarthritis (OA) is a common debilitating joint disorder worldwide without effective medical therapy. Articular cartilage and subchondral bone act in concert as a functional unit with the onset of OA. Halofuginone is an analog of the alkaloid febrifugine extracted from the plant Dichroa febrifuga, which has been demonstrated to exert inhibition of SMAD 2/3 phosphorylation downstream of the TGF-β signaling pathway and osteoclastogenesis. To investigate whether halofuginone (HF) alleviates OA after administration by oral gavage, 3-month-old male mice were allocated to the Sham group, vehicle-treated anterior cruciate ligament transection (ACLT) group, and HF-treated ACLT group. The immunostaining analysis indicated that HF reduced the number of matrix metalloproteinase 13 (MMP-13) and collagen X (Col X) positive cells in the articular cartilage. Moreover, HF lowered histologic OA score and prevented articular cartilage degeneration. The micro-computed tomography (μCT) scan showed that HF maintained the subchondral bone microarchitecture, demonstrated by the restoration of bone volume fraction (BV/TV), subchondral bone plate thickness (SBP.Th.), and trabecular pattern factor (Tb.Pf) to a level comparable to that of the Sham group. Immunostaining for CD31 and μCT based angiography showed that the number and volume of vessels in subchondral bone was restored by HF. HF administered by oral gavage recoupled bone remodeling and inhibited aberrant angiogenesis in the subchondral bone, further slowed the progression of OA. Therefore, HF administered by oral gavage could be a potential therapy for OA.

Bone morphogenetic protein-2 exhibits therapeutic benefits for osteonecrosis of the femoral head through induction of cartilage and bone cells.

Osteonecrosis of the femoral head is an orthopedic disease caused by femoral head damage or insufficient blood supply, which leads to the death of bone cells and bone marrow. Osteonecrosis of the femoral head leads to changes in the structure of the femoral head, femoral head collapse and joint dysfunction. Bone morphogenetic protein-2 (BMP-2) exhibits beneficial effects on bone formation, repair and angiogenesis at the femoral head. In the present study, the therapeutic effects of recombinant human BMP-2 containing an Fc fragment (rBMP-2/Fc) were investigated on a steroid induced mouse model of osteonecrosis of the femoral head. Bone cell viability was used to determine the in vitro effects of rBMP-2/Fc. The therapeutic efficacies of rBMP-2/Fc on mice with osteonecrosis of the femoral head were evaluated using clinical arthritis scores. The expression levels of inflammatory factors in the mice were analyzed by reverse transcription-quantitative polymerase chain reaction. Histological analysis was used to evaluate the effects of rBMP-2/Fc on the femoral head. The results revealed that rBMP-2/Fc treatment significantly increased the IL-6, IL-10, vascular endothelial growth factor and macrophage colony-stimulating factor expression levels in synovial cells compared with the control group (P<0.01). Furthermore, it was observed that rBMP-2/Fc significantly improved the viability and growth of synovial cells (P<0.01) through the nuclear factor (NF)-κB signaling pathway. Treatment with rBMP-2/Fc significantly decreased receptor activator of NF-κB ligand expression levels. Furthermore, in vivo experiments demonstrated that rBMP-2/Fc treatment markedly relieved the arthralgia and damage caused by osteonecrosis of the femoral head. In conclusion, rBMP-2/Fc treatment may be beneficial for articular cartilage repair by the upregulation of angiogenesis factors through the down regulation of the NF-κB signaling pathway in mice with osteonecrosis of the femoral head. This preclinical data suggests that rBMP-2/Fc may be a promising novel agent for treatment of osteonecrosis of the femoral head.

Erythropoietin Enhances Bone Repair Effects via the Hypoxia-Inducible Factor Signal Pathway in Glucocorticoid-Induced Osteonecrosis of the Femoral Head

BackgroundThis study aimed to determine whether erythropoietin could repair glucocorticoid-induced osteonecrosis of the femoral head after the systemic or local administration of recombinant human erythropoietin. Materials and MethodsGelatin microspheres were used to load recombinant human erythropoietin for local delivery. Forty-eight Wistar rats were included in the glucocorticoid-induced osteonecrosis of the femoral head model and randomly divided into the placebo, systemic erythropoietin and local erythropoietin groups. Eight weeks later, all rats were killed and their tissues were subjected to radiographic, histological, histometric, quantitative polymerase chain reaction and western blot analyses. ResultsOur results show that the use of recombinant human erythropoietin increased bone volume, trabecular number, trabecular thickness and trabecular separation compared with the placebo. Erythropoietin administration significantly improved the expression of runt-related transcription factor 2, alkaline phosphates, hypoxia-inducible factor-1α and vascular endothelial growth factor in the femoral head. We also found that the local injection of erythropoietin could better mediate hypoxia-inducible factor-1α–controlled osteogenic and angiogenic factor expression and better repair the glucocorticoid-induced osteonecrosis of the femoral head. ConclusionsThe use of recombinant human erythropoietin exerted effects on improving the bone structures in glucocorticoid-induced osteonecrosis of the femoral head and up-regulated the expression of runt-related transcription factor 2, alkaline phosphates, hypoxia-inducible factor-1α and vascular endothelial growth factor. It provided a novel idea that erythropoietin administration could repair glucocorticoid-induced osteonecrosis of the femoral head by improving bone formation and angiogenesis and may be associated with the hypoxia-inducible factor-1α pathway. The sequential delivery of erythropoietin from gelatin microspheres seems worth recommending.

Hepatocyte growth factor improves bone regeneration via the bone morphogenetic protein‑2‑mediated NF‑κB signaling pathway.

Bone regeneration is an important process associated with the treatment of osteonecrosis, which is caused by various factors. Hepatocyte growth factor (HGF) is an active biological factor that has multifunctional roles in cell biology, life sciences and clinical medicine. It has previously been suggested that bone morphogenetic protein (BMP)‑2 exerts beneficial roles in bone formation, repair and angiogenesis in the femoral head. The present study aimed to investigate the benefits and molecular mechanisms of HGF in bone regeneration. The viability of osteoblasts and osteoclasts were studied invitro. In addition, the expression levels of tumor necrosis factor (TNF)‑α, monocyte chemotactic protein (MCP)‑1, interleukin (IL)‑1 and IL‑6 were detected in a mouse fracture model following treatment with HGF. The expression and activity of nuclear factor (NF)‑κB were also analyzed in osteocytes post‑treatment with HGF. Histological analysis was used to determine the therapeutic effects of HGF on mice with fractures. The migration and differentiation of osteoblasts and osteoclasts were investigated in HGF‑incubated cells. Furthermore, angiogenesis and BMP‑2 expression were analyzed in the mouse fracture model post‑treatment with HGF. The results indicated that HGF regulates the cell viability of osteoblasts and osteoclasts, and also balanced the ratio between osteoblasts and osteoclasts. In addition, HGF decreased the serum expression levels of TNF‑α, MCP‑1, IL‑1 and IL‑6 in experimental mice. The results of a mechanistic analysis demonstrated that HGF upregulated p65, IκB kinase‑β and IκBα expression in osteoblasts from experimental mice. In addition, the expression levels of vascular endothelial growth factor, BMP‑2 receptor, receptor activator of NF‑κB ligand and macrophage colony‑stimulating factor were upregulated by HGF, which may effectively promote blood vessel regeneration, and contribute to the formation and revascularization of tissue‑engineered bone. Furthermore, HGF promoted BMP‑2 expression and enhanced angiogenesis at the fracture location. These results suggested that HGF treatment may significantly promote bone regeneration in a mouse fracture model. In conclusion, these results indicated that HGFis involved in bone regeneration, angiogenesis and the balance between osteoblasts and osteoclasts, thus suggesting that HGF may be considered a potential agent for the treatment of fractures via the promotion of bone regeneration through regulation of the BMP‑2‑mediated NF‑κB signaling pathway.

Isoliquiritigenin blunts osteoarthritis by inhibition of bone resorption and angiogenesis in subchondral bone

Isoliquiritigenin (ISL), a natural flavonoid extracted from licorice, has been demonstrated to exert attenuation of osteoclastogenesis and anti-angiogenesis activity in a wide variety of cells. Here, we first evaluated the effects of ISL on pathogenesis of osteoarthritis in a mouse model of OA. The data showed that ISL blunted progression of OA and lowered the Osteoarthritis Research Society International (OARSI)-Modified Making Score and protected the articular cartilage. The thickness of calcified cartilage zone was significantly decreased in ISL-treated ACLT mice compared with vehicle group. ISL increased expression level of lubricin and decreased collagen X (Col X), matrix metalloproteinase-13 (MMP-13). Moreover, ISL reduced aberrant active subchondral bone remodelling, including lowered trabecular pattern factor (Tb.pf) and increased bone volume/tissue volume (BV/TV, %) and thickness of subchondral bone plate (SBP) compared with vehicle-treated group. The results of immunostaining further revealed that ISL directly reduced RANKL-RANK-TRAF6 singling pathway induced osteoclastogenesis, prevented abnormal bone formation through indirect inhibition of TGF-β release. Additionally, ISL exerts anti-angiogenesis effects in subchondral bone through direct suppression of MMP-2. These results indicated that ISL attenuates progression of OA by inhibition of bone resorption and angiogenesis in subchondral bone, indicating that this may be a potential preventive therapy for OA.

Positive-Feedback Regulation of Subchondral H-Type Vessel Formation by Chondrocyte Promotes Osteoarthritis Development in Mice.

Vascular-invasion-mediated interactions between activated articular chondrocytes and subchondral bone are essential for osteoarthritis (OA) development. Here, we determined the role of nutrient sensing mechanistic target of rapamycin complex 1 (mTORC1) signaling in the crosstalk across the bone cartilage interface and its regulatory mechanisms. Then mice with chondrocyte-specific mTORC1 activation (Tsc1 CKO and Tsc1 CKOER ) or inhibition (Raptor CKOER ) and their littermate controls were subjected to OA induced by destabilization of the medial meniscus (DMM) or not. DMM or Tsc1 CKO mice were treated with bevacizumab, a vascular endothelial growth factor (VEGF)-A antibody that blocks angiogenesis. Articular cartilage degeneration was evaluated using the Osteoarthritis Research Society International score. Immunostaining and Western blotting were conducted to detect H-type vessels and protein levels in mice. Primary chondrocytes from mutant mice and ADTC5 cells were treated with interleukin-1β to investigate the role of chondrocyte mTORC1 in VEGF-A secretion and in vitro vascular formation. Clearly, H-type vessels were increased in subchondral bone in DMM-induced OA and aged mice. Cartilage mTORC1 activation stimulated VEGF-A production in articular chondrocyte and H-type vessel formation in subchondral bone. Chondrocyte mTORC1 promoted OA partially through formation of VEGF-A-stimulated subchondral H-type vessels. In particular, vascular-derived nutrients activated chondrocyte mTORC1, and stimulated chondrocyte activation and production of VEGF, resulting in further angiogenesis in subchondral bone. Thus a positive-feedback regulation of H-type vessel formation in subchondral bone by articular chondrocyte nutrient-sensing mTORC1 signaling is essential for the pathogenesis and progression of OA. © 2018 American Society for Bone and Mineral Research.

A Novel Secretome Biotherapeutic Influences Regeneration in Critical Size Bone Defects.

Severe traumatic injuries often result in critical size bone defects, which are unable to heal without treatment. Autologous grafting is the standard of care but requires additional surgeries for graft procurement. Amnion-derived multipotent progenitor cells release a secretome of biomolecules identified as integral to the process of bone regeneration and angiogenesis. This secretome is currently under development as a biotherapeutic. The efficacy of this secretome biotherapeutic was evaluated in vitro on the proliferation and migration of mesenchymal stem cells and osteoprogenitor cells as well as in vivo using a critical size rat calvarial defect model. The secretome biotherapeutic was loaded onto a collagen scaffold and placed into the defect, which was allowed to heal for 4 and 12 weeks. The secretome biotherapeutic enhanced the proliferation and migration of mesenchymal stem cells and proliferation of osteoprogenitor cells. Further, the secretome biotherapeutic improved new bone volume and connectivity by 12 weeks and significantly improved angiogenesis at 4 weeks and bone density at 4 and 12 weeks with no deleterious effects. The improvement in new bone volume, connectivity, and angiogenesis suggests that the secretome biotherapeutic has beneficial effects for bone healing and a higher dose of the secretome biotherapeutic may further improve regeneration.