Vascular Derived ECM Improves Therapeutic Index of BMP-2 and Drives Vascularized Bone Regeneration.

Vascularized osteogenesis is essential for successful bone regeneration, yet its realization during large size bone defect healing remains challenging due to the difficulty to couple multiple biological processes. Herein, harnessing the intrinsic angiogenic potential of vascular derived extracellular matrix (vECM) and its specific affinity to growth factors, a vECM/GelMA based hybrid hydrogel delivery system is constructed to achieve optimized bone morphogenetic protein-2 (BMP-2) therapeutic index and provide intrinsic angiogenic induction during bone healing. The incorporation of vECM not only effectively regulates BMP-2 kinetics to match the bone healing timeframe, but also promotes angiogenesis both in vitro and in vivo. In vivo results also show that vECM-mediated BMP-2 release remarkably enhances vascularized bone formation for critical size bone defects. In particular, blood vessel ingrowth stained with CD31 marker in the defect area is substantially encouraged over the course of healing, suggesting incorporation of vECM served roles in both angiogenesis and osteogenesis. Thus, the authors' study exemplifies that affinity of growth factor towards ECM may be a promising strategy to be leveraged to develop sophisticated delivery systems endowed with desirable properties for regenerative medicine applications.

Loss of TIMP3 expression induces inflammation, matrix degradation, and vascular ingrowth in nucleus pulposus: A new mechanism of intervertebral disc degeneration.

Low back pain (LBP) is one of the most common complains in orthopedic outpatient department and intervertebral disc degeneration (IDD) is one of the most important reasons of LBP. The mechanisms of IDD contain a complex biochemical cascade which includes inflammation, vascular ingrowth, and results in degradation of matrix. In our study, we used both in vitro and in vivo models to investigate the relation between tissue inhibitor of metalloproteinase-3 (TIMP3) expression and IDD. Loss of TIMP3 expression was found in degenerative intervertebral disc (IVD), this change of expression was closely related with the dephosphorylation of smad2/3. Overexpression of TIMP3 significantly inhibited the release of TNF-α and matrix degradation induced by Lipopolysaccharide. Vascular ingrowth was also suppressed by TIMP3 in the in vitro and in vivo models. Further, animal experiments confirmed that the degeneration of IVD was reduced after overexpression of TIMP3 in nucleus pulposus. Taken together, our results indicated TIMP-3 might play an important role in the pathogenesis of IDD and therefore be a potential therapeutic target in the future.

Epidemiologic characteristics of traumatic fractures in elderly patients during the outbreak of coronavirus disease 2019 in China.

PURPOSE: This study aimed to describe the epidemiologic characteristics of fracture in the elderly during the COVID-19. METHODS: This was a retrospective multi-centre study, which included patients who sustained fractures between 20 January and 19 February 2020. The collected data included patients' demographics (age and gender), injury-related (injury type, fracture location, injury mechanism, places where fracture occurred), and treatment modality. SPSS 23.0 was used to describe the data and perform some analysis. RESULTS: A total of 436 patients with 453 fractures were included; there were 153 males and 283 females, with an average age of 76.2 years (standard deviation, SD, 7.7 years; 65 to 105). For either males or females, 70-74 years was the most commonly involved age group. A total of 317 (72.7%) patients had their fractures occurring at home. Among 453 fractures, there were 264 (58.3%) hip fractures, accounting for 58.3%. Fall from standing height was the most common cause of fracture, making a proportion of 89.4% (405/453). Most fractures (95.8%, 434/453) were treated surgically, and 4.2% (19/453) were treated by plaster fixation or traction. Open reduction and internal fixation (ORIF) was the most used surgical method, taking a proportion of 49.2% (223/453). CONCLUSION: These findings highlighted the importance of primary prevention (home prevention) measures and could be used for references for individuals, health care providers, or health administrative department during the global pandemic of COVID-19.

Upshifting the Ipsilateral Proximal Femur May Provide Satisfactory Reconstruction of Periacetabular Pelvic Bone Defects After Tumor Resection.

BACKGROUND: Pelvic ring reconstruction after resection of pelvic malignancies or aggressive benign tumors remains challenging, especially when the tumor invades periacetabular bone, resulting in a Type II resection as classified by Enneking and Dunham (removal of part or all of the acetabulum). Although numerous treatment approaches are in use, none is clearly superior to the others. An alternative involving use of the ipsilateral proximal femur as an autograft has not been well characterized, so we present our preliminary experience with this approach. QUESTIONS/PURPOSES: (1) What were the oncologic outcomes after using an ipsilateral proximal femur autograft for reconstruction after Type II pelvic resection in a small series of patients who underwent this reconstructive approach? (2) What were the Musculoskeletal Tumor Society (MSTS) scores after this reconstruction? (3) What complications were observed? METHODS: Between October 2006 and May 2016, we treated 67 patients with Type II malignant or aggressive benign tumors of the ilium. Of those, we used an ipsilateral proximal femur and a prosthesis as a reconstruction method for 11 patients with pelvic tumors. In general, we performed this approach in young or middle-aged patients with primary malignant or aggressive benign tumors involving pelvic area II and in whom the tumor did not invade the hip. The method used for resection of pelvic tumors included osteotomy of the femoral shaft, harvesting the proximal femur as a graft. The length of the femoral graft was determined by the extent of the pelvic defect. The proper placement was selected after a comparison of the proximal femur and the pelvic defect. A curved reconstruction plate and cancellous bone screws were used for pelvic fixation. The operative duration and total blood loss were recorded. Of the 11 patients who underwent this approach, all but one had at least 2 years of followup unless death occurred earlier, and all but one have been seen within the last year for evaluation. Functional outcomes were assessed using the MSTS scoring system. Local recurrence, metastases, and deaths were recorded as were complications including infection, bone nonunion, mechanical failure and sciatic nerve palsy. RESULTS: The followup was a mean of 37 months (range, 13-96 months). One patient was lost to followup. Three patients died of disease owing to local recurrence or lung metastasis. The other seven patients lived without evidence of tumor. The main complications included mechanical failure in two patients, nonunion in one patient, infection in two patients, and sciatic nerve palsy in one patient. The median MSTS function score was 70% (21 of 30 points; range, 11-25 points). CONCLUSIONS: Our preliminary results show that this technique of using the ipsilateral proximal femur may be an alternative method for reconstruction of pelvic bone defects after tumor resection. Even with this short followup, complications were common, but short-term function appears to be comparable to studies of other options. Longer term followup with more patients is necessary to confirm our results. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Bortezomib sensitizes human osteosarcoma cells to adriamycin-induced apoptosis through ROS-dependent activation of p-eIF2α/ATF4/CHOP axis.

Osteosarcoma is the most common bone cancer, and chemotherapy is currently indispensable for its treatment. Adriamycin has been claimed to be the most effective agent for osteosarcoma, however, the outcome of adriamycin chemotherapy remains unsatisfactory. Here, we reported a potent combination therapy that bortezomib, a proteasome inhibitor, enhances adriamycin-induced apoptosis to eliminate osteosarcoma cells and we revealed that the activation of p-eIF2α/ATF4/CHOP axis is the underlying associated mechanisms. First, we observed that bortezomib enhances adriamycin-mediated inhibition of cell proliferation and enhances the apoptosis in osteosarcoma cell lines. Moreover, this drug combination produced more potent tumor-growth inhibitory effects in human osteosarcoma cell line KHOS/NP xenografts. Our study showed that reactive oxygen species (ROS) plays an important role in apoptosis induced by adriamycin plus bortezomib, whereas ROS scavenger NAC could almost completely block the apoptosis induced by the combination treatment. Meanwhile, p-eIF2α is remarkably elevated in the combination group. As a result, ATF4 exhibits strong activation which consequently induces the activation of CHOP and leads to the cell death. Finally, 13 primary osteosarcoma cells demonstrated potent response to the combination treatment. In a human osteosarcoma patient-derived xenograft (PDX) model, our finding suggests that when combined with bortezomib, a relatively low dose of adriamycin produced more potent tumor-growth inhibitory effects without increased toxicity. Thus, our findings not only provide a promising combination strategy to overcome osteosarcoma but also shed new light on the strategy of combining increased ROS and inhibited proteasome to open up new opportunities for the clinical development of chemotherapy regimens.

Unilateral versus bilateral pedicle screw fixation in short-segment lumbar spinal fusion: a meta-analysis of randomised controlled trials.

OBJECTIVE: We performed this meta-analysis of randomised controlled trials to compare the efficacy and safety of unilateral with bilateral fixation in short-segment lumbar spinal fusion. METHODS: Predefined terms were used to search electronic databases to identify relevant research. Randomised controlled trials (RCTs) published in English and Chinese during 1990-2015 investigating efficacy and safety of unilateral and bilateral fixation in short-segment lumbar spinal fusion were included. Data of fusion rate, complications, visual analogue scale (VAS), Oswestry Disability Index (ODI), estimated blood loss (EBL) and length of hospital stay were extracted and analysed. Two reviewers independently searched information sources, selected eligible research, analysed data and evaluated risk of bias. RESULTS: Eleven RCTs comprising 756 participants were analysed. There was no significant difference in fusion rate, device-related complication, ODI, VAS and length of hospital stay between bilateral and unilateral groups. The unilateral group had the obvious advantage of reduced blood loss [mean difference (MD) -143.57, 95 % confidence interval (Cl) -206.61 to -80.54, P < 0.0001) and operation time (MD -52.72, 95 % Cl -73.58 to -31.87, P < 0.00001). CONCLUSION: Unilateral pedicle screw fixation is equally as effective as bilateral pedicle screw fixation in short-segment lumbar spinal fusion and may reduce operation time and blood loss.

Cartilage repair using mesenchymal stem cell (MSC) sheet and MSCs-loaded bilayer PLGA scaffold in a rabbit model.

PURPOSE: The integration of regenerated cartilage with surrounding native cartilage is a major challenge for the success of cartilage tissue-engineering strategies. The purpose of this study is to investigate whether incorporation of the power of mesenchymal stem cell (MSC) sheet to MSCs-loaded bilayer poly-(lactic-co-glycolic acid) (PLGA) scaffolds can improve the integration and repair of cartilage defects in a rabbit model. METHODS: Rabbit bone marrow-derived MSCs were cultured and formed cell sheet. Full-thickness cylindrical osteochondral defects (4 mm in diameter, 3 mm in depth) were created in the patellar groove of 18 New Zealand white rabbits and the osteochondral defects were treated with PLGA scaffold (n = 6), PLGA/MSCs (n = 6) or MSC sheet-encapsulated PLGA/MSCs (n = 6). After 6 and 12 weeks, the integration and tissue response were evaluated histologically. RESULTS: The MSC sheet-encapsulated PLGA/MCSs group showed significantly more amounts of hyaline cartilage and higher histological scores than PLGA/MSCs group and PLGA group (P < 0.05). In addition, the MSC sheet-encapsulated PLGA/MCSs group showed the best integration between the repaired cartilage and surrounding normal cartilage and subchondral bone compared to other two groups. CONCLUSIONS: The novel method of incorporation of MSC sheet to PLGA/MCSs could enhance the ability of cartilage regeneration and integration between repair cartilage and the surrounding cartilage. Transplantation of autologous MSC sheet combined with traditional strategies or cartilage debris might provide therapeutic opportunities for improving cartilage regeneration and integration in humans.

Material-based treatment strategies against intraosseous implant biofilm infection.

Implant-associated infections present a significant clinical obstacle for orthopedic practitioners, with bacterial biofilm formation serving as a pivotal factor in the initiation, progression, and management of such infections. Conventional approaches have proven inadequate in fully eradicating biofilm-related infections. Consequently, novel material-based therapeutic strategies have been developed, encompassing the utilization of antimicrobial agents, delivery vehicles, and synergistic antibacterial systems. In this review, we provide a succinct overview of recent advancements in anti-biofilm strategies, with the aim of offering insights that may aid in the treatment of intraosseous implant infections.

An omni-directional optical antenna and its beam control method based on the EC-KPA algorithm for mobile FSO.

In order to ensure the communication link stability in mobile FSO system, a new omni-directional optical antenna is designed. Being aimed at discontinuous tracking, a novel beam control method based on the error correction Kalman prediction algorithm (EC-KPA) is proposed. The comparison of EC-KPA and the conventional Kalman prediction algorithm (KPA) is given. Numerical simulations about beam control method are carried out. The results show that the prediction accuracy of EC-KPA is improved about 77% than that of KPA in Gaussian noise situation, and that the increase is up to 12.92 times in strong noise situation. Therefore, the beam control method is feasible, and this optical antenna can meet the demands of fast mobile FSO.

Valgus osteotomy in combination with dynamic hip screw fixation for fibrous dysplasia with shepherd's crook deformity.

BACKGROUND AND OBJECTIVES: The treatment of fibrous dysplasia with shepherd's crook deformity is a big challenge. The purpose of this study was to investigate the clinical effect of valgus osteotomy in combination with dynamic hip screw (DHS) fixation to treat fibrous dysplasia with shepherd's crook deformity. METHOD: Twenty-one clinical cases of femoral fibrous dysplasia with shepherd's crook deformity treated between April 2001 and May 2010 were retrospectively analyzed. The valgus osteotomy and internal fixation were performed for these patients. Six patients underwent DHS and trochanter stabilizing plate internal fixation, and the other 15 cases were stabilized by DHS fixation. RESULTS: Patients were followed for 19-128 months. The neck-shaft angle was corrected from 89° (range 65°-107°) preoperatively to 129° (range 119°-140°) postoperatively. Limb-length discrepancy was corrected from 3.0 (range 1.8-4.5) cm preoperatively to 0.7 (range 0-1.9) cm postoperatively. All osteotomies had healed at the final follow-up examination. The clinical scores, which were evaluated by the modified criteria of Guille, improved from an average of 2.9 (range 1-7) to 8.5 (range 6-10). CONCLUSION: Our results demonstrate that valgus osteotomy in combination with DHS internal fixation is an easy and effective method for the treatment of fibrous dysplasia with shepherd's crook deformity. It can restore the neck-shaft angle and re-establish the mechanical alignment of the femur to improve function.

The orthodontic implant site-switching technique: a preliminary study in dogs.

BACKGROUND: To evaluate the quantity and quality of bone in the newly formed edentulous area produced by the orthodontic implant site-switching technique. METHODS: The bilateral maxillary first premolars of five beagle dogs were extracted and bone defects were created. The right and left sides of the maxilla were randomly divided into control and experimental sides. On the experimental side, the maxillary second premolar was mesially moved into the position of the missing first premolar. On the control side, the second maxillary premolar was extracted. Six months later, the beagles were euthanized. Microcomputer tomography was used to analyze bone microstructure parameters, alveolar bone height and alveolar bone width of the regenerated bone. Histological analysis was performed by staining tissue sections with toluidine blue. RESULTS: Median BV/TV values in the experimental group (81.78%) were significantly larger than those in the control group (35.67%; p = 0.04). Median Tb.Sp values in the experimental group (0.14 mm) were significantly lower than those in the control group (0.54 mm; p = 0.04). Median Tb.Th values in the experimental group (0.48 mm) were significantly higher than those in the control group (0.21 mm; p = 0.04). Median Tb.Pf values in the experimental group (0.65/mm) were significantly lower than those in the control group (3.15/mm; p = 0.04). There was no significant difference in the trabecular number (Tb.N) between the two groups (p = 0.23). The median alveolar bone height values in the experimental group (-0.81 mm) were significantly higher than those in the control group (-2.11 mm; p = 0.04) at a distance 5 mm from the mesial CEJ of the third premolar. The median alveolar bone height values in the experimental group (0.45 mm) were significantly higher than those in the control group (-1.70 mm; p = 0.04) at a distance 6 mm from the mesial CEJ of the third premolar. There was no significant difference in alveolar bone width when compared between the two groups (p > 0.05). CONCLUSIONS: The newly formed edentulous area created by orthodontic treatment had more compact and thicker trabeculae than the extraction socket. Furthermore, the newly formed edentulous area had a greater alveolar bone height available for the placement of implants.

The m6A Reader YTHDF1 Accelerates the Osteogenesis of Bone Marrow Mesenchymal Stem Cells Partly via Activation of the Autophagy Signaling Pathway.

N6-methyladenosine (m6A) mRNA methylation has emerged as an important player in many biological processes by regulating gene expression. As a crucial reader, YTHDF1 usually improves the translation efficiency of its target mRNAs. However, its roles in bone marrow mesenchymal stem cells (BMSCs) osteogenesis remain largely unknown. Here, we reported that YTHDF1, an m6A reader, is highly expressed during osteogenic differentiation of BMSCs. Upregulation of YTHDF1 increased osteogenic differentiation and proliferation capacity of BMSCs. Accordingly, downregulation of YTHDF1 inhibited osteogenic differentiation and proliferation capacity. Possible underlying mechanisms were explored, and analysis revealed that YTHDF1 could affect autophagy levels, thus regulating osteogenesis of BMSCs. In an in vivo study, we found that upregulation of YTHDF1 accelerates fracture healing with elevated bone volume fraction and trabecular thickness. Taken together, our study revealed that m6A reader YTHDF1 accelerates osteogenic differentiation of BMSCs partly via the autophagy signaling pathway. These findings reveal a previously unrecognized mechanism involved in the regulation of BMSCs osteogenesis, providing new ideas and target sites for the treatment of fracture.

Reversing the imbalance in bone homeostasis via sustained release of SIRT-1 agonist to promote bone healing under osteoporotic condition.

The imbalance of bone homeostasis is the root cause of osteoporosis. However current therapeutic approaches mainly focus on either anabolic or catabolic pathways, which often fail to turn the imbalanced bone metabolism around. Herein we reported that a SIRT-1 agonist mediated molecular therapeutic strategy to reverse the imbalance in bone homeostasis by simultaneously regulating osteogenesis and osteoclastogenesis via locally sustained release of SRT2104 from mineral coated acellular matrix microparticles. Immobilization of SRT2104 on mineral coating (MAM/SRT) harnessing their electrostatic interactions resulted in sustained release of SIRT-1 agonist for over 30 days. MAM/SRT not only enhanced osteogenic differentiation and mineralization, but also attenuated the formation and function of excessive osteoclasts via integrating multiple vital upstream signals (ß-catenin, FoxOs, Runx2, NFATc1, etc.) in vitro. Osteoporosis animal model also validated that it accelerated osteoporotic bone healing and improved osseointegration of the surrounding bone. Overall, our work proposes a promising strategy to treat osteoporotic bone defects by reversing the imbalance in bone homeostasis using designated small molecule drug delivery systems.

Finite element analysis of sacral-alar-iliac screw fixation for sacroiliac joint dislocation.

The percutaneous sacroiliac (SI) screw is a common fixation option for posterior ring disruption in pelvic fractures. However, SI screw placement is difficult and can injure adjacent neurovascular structures. The sacral-alar-iliac screw (SAI) is a safe, reliable free-hand sacral pelvic fixation technique. To investigate the biomechanical stability of SAI for SI joint dislocation, finite element analysis was performed in unstable Tile-Type B and C pelvic ring injuries. The displacement in S1 (fixation of a unilateral S1 segment with one SI screw), TS1 (fixation of the S1 segment with a transsacra 1 screw), TS2 (fixation of the S2 segment with a transsacra 2 screw), S1AI, and S2AI exceeded the normal SI joint mobility. Sufficient stability after SI joint dislocation was obtained with (TS1 + TS2), (TS2 + S1), (S1AI + S2AI + rod), (S1AI + S2AI), and (S1 + S2AI + S1 pedicle) fixation. The TS1 + TS2 group had the smallest displacement and lowest peak screw stress, followed by (S1 + S2AI + S1 pedicle) placement. Our findings suggest that SAI screws are a valuable option for SI joint dislocation.

The role of the Smad2/3/4 signaling pathway in osteogenic differentiation regulation by ClC-3 chloride channels in MC3T3-E1 cells.

BACKGROUND: ClC-3 chloride channels promote osteogenic differentiation. Transforming growth factor-ß1 (TGF-ß1) and its receptors are closely related to ClC-3 chloride channels, and canonical TGF-ß1 signaling is largely mediated by Smad proteins. The current study aimed to explore the role of the Smad2/3/4 signaling pathway in the mechanism by which ClC-3 chloride channels regulate osteogenic differentiation in osteoblasts. METHODS: First, real-time PCR and western blotting were used to detect the expression of Smad and mitogen-activated protein kinase (MAPK) proteins in response to ClC-3 chloride channels. Second, immunocytochemistry, coimmunoprecipitation (Co-IP) and immunofluorescence analyses were conducted to assess formation of the Smad2/3/4 complex and its translocation to the nucleus. Finally, markers of osteogenic differentiation were determined by real-time PCR, western blotting, ALP assays and Alizarin Red S staining. RESULTS: ClC-3 chloride channels knockdown led to increased expression of Smad2/3 but no significant change in p38 or Erk1/2. Furthermore, ClC-3 chloride channels knockdown resulted in increases in the formation of the Smad2/3/4 complex and its translocation to the nucleus. In contrast, the inhibition of TGF-ß1 receptors decreased the expression of Smad2, Smad3, p38, and Erk1/2 and the formation of the Smad2/3/4 complex. Finally, the expression of osteogenesis-related markers were decreased upon ClC-3 and Smad2/3/4 knockdown, but the degree to which these parameters were altered was decreased upon the knockdown of ClC-3 and Smad2/3/4 together compared to independent knockdown of ClC-3 or Smad2/3/4. CONCLUSIONS: The Smad2/3 proteins respond to changes in ClC-3 chloride channels. The Smad2/3/4 signaling pathway inhibits osteogenic differentiation regulation by ClC-3 chloride channels in MC3T3-E1 cells.

Parkin Inhibits RANKL-Induced Osteoclastogenesis and Ovariectomy-Induced Bone Loss.

Osteoporosis and osteoporotic fractures comprise a substantial health and socioeconomic burden. The leading cause of osteoporosis is an imbalance in bone formation and bone resorption caused by hyperactive osteoclasts. Therefore, a new strategy to suppress osteoclastogenesis is needed. Parkin is likely closely associated with bone metabolism, although its role in osteoclastogenesis is unclear. In this study, the Parkin protein inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation, osteoclast-specific gene expression, F-actin ring formation, and bone resorption pit formation in vitro. Moreover, depletion of Parkin enhanced RANKL-induced osteoclast formation, osteoclast-specific gene expression, F-actin ring formation, and bone resorption pit formation. Reactive oxygen species (ROS) activity was suppressed, while autophagy was upregulated with the presence of the Parkin protein. ROS activity was upregulated and autophagy was decreased due to Parkin knockdown. In addition, intravenous administration of Parkin rescued ovariectomy-induced bone loss and reduced osteoclastogenesis in vivo. Collectively, Parkin has therapeutic potential for diseases associated with overactive osteoclasts.

[Resection pseudoarthrosis for pelvic malignant tumors around acetabular].

OBJECTIVE: To discuss the resection pseudoarthrosis for pelvic malignant tumors around acetabular. METHODS: From May 1997 to June 2005, 25 patients with malignant tumors around acetabular were treated surgically with resection pseudoarthrosis. The series comprised 15 males and 10 females with an average age of 42 years old (range from 16 to 75 years old). There were 4 osteosarcomas, 12 chondrosarcomas, 1 Ewing's sarcoma, 1 neuroectodermal tumor, 1 myeloma, 1 malignant fibrohistiocytoma, 2 synovial sarcomas, and 3 metastases. Pseudoarthrosis was performed after resection of pelvic malignant tumors around acetabular. The affected side was protected postoperatively by skin traction with 2 - 3 kg weight for 6 to 8 weeks. After then, the patients walked gradually with a cane. RESULTS: Among 25 patients, 6 had complications (24%). At a follow-up ranging from 3 to 10 years, 11 patients died of lung metastases, 2 relapsed, 12 remained alive free of disease. There was an average crispation of 5 cm (range from 2.5 to 7.5 cm). The patients were functionally evaluated according to Enneking's MSTS criteria in 1993. The average MSTS functional score was 17 points (12 to 19 points). After 3 months postoperative, the patients could sit normally, walk with a cane, and even walk limpingly without cane. CONCLUSIONS: Resection pseudoarthrosis for pelvic malignant tumors around acetabular results in good clinical results at the time of mid-term and long-term follow-up. And pseudoarthrosis is advisable especially for patients with malignant highly tumors around acetabular, poor soft tissue reconstruction condition, high risk for infection, poor economy.

The Role of Forkhead Box Family in Bone Metabolism and Diseases.

Forkhead box (Fox) family, an evolutionarily conserved family of transcription factors carrying the "Forkhead" motif, plays an indispensable role in human health and disease. Fox family genes are involved in cell differentiation, proliferation and apoptosis, embryonic development, aging, glucose and lipid metabolism, and immune regulation. The regulatory role of the Fox family in the context of bone metabolism and orthopedic diseases is an emerging research hotspot. In this review, we highlight the major molecular mechanisms underlying the regulatory role of Fox factors in bone metabolism, bone development, bone homeostasis, and bone diseases associated with inhibition or upregulation of Fox factors. In addition, we discuss the emerging evidence in the realm of Fox factor-based therapeutics.

a-PET and Weakened Triplet-Triplet Annihilation Self-Quenching Effects in Benzo-21-Crown-7-Functionalized Diiodo-BODIPY.

Weakening the triplet-triplet annihilation (TTA) self-quenching effect induced by sensitizers remains a tremendous challenge due to the very few investigations carried out on them. Herein, benzo-21-crown-7 (B21C7)-functionalized 2,6-diiodo-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene (DIBDP) was synthesized to investigate the influences of huge bulks and electron-rich cavities of B21C7 moieties on the fluorescence emission and triplet-state lifetimes of DIBDP moieties. Density functional theory (DFT)/time-dependent DFT (TDDFT) computable results preliminarily predicted that B21C7 moieties had influences on the fluorescence emissions of DIBDP moieties but not on their localization of triplet states of B21C7-functionalized DIBDP (B21C7-DIBDP). The UV-vis absorption spectra, fluorescence emission spectra, and cyclic voltammograms verified that there was an electron-transfer process from the B21C7 moiety to the DIBDP moiety in B21C7-DIBDP. However, the calculated results of ΔG CS and E CS values and nanosecond time-resolved transient absorption spectra demonstrated that the electron-transfer process from the B21C7 moiety to the DIBDP moiety in B21C7-DIBDP had direct influences on the fluorescence emission of DIBDP moieties but not on the triplet states of DIBDP moieties. The experimental values of triplet-state lifetimes of B21C7-DIBDP were obviously longer than those of DIBDP at a high concentration (1.0 × 10-5 M); however, the fitted values of intrinsic triplet-state lifetimes of B21C7-DIBDP were slightly greater than those of DIBDP in the same solvent. These results demonstrated that the steric hindrance of B21C7 moieties could weaken the TTA self-quenching effect of DIBDP moieties at a high concentration and the a-PET effect induced a proportion of the produced singlet states of DIBDP moieties and could not emit fluorescence in the form of radiation transition but they could be transformed into triplet states through intersystem crossing (ISC) processes due to the iodine atoms in the DIBDP moiety. The stronger a-PET effects in polar solvents induced smaller fluorescence quantum yields so that more singlet states of DIBDP moieties were transformed into triplet states to weaken the TTA self-quenching effects.

Low-dose IL-34 has no effect on osteoclastogenesis but promotes osteogenesis of hBMSCs partly via activation of the PI3K/AKT and ERK signaling pathways.

BACKGROUND: Inflammatory microenvironment is significant to the differentiation and function of mesenchymal stem cells (MSCs). It evidentially influences the osteoblastogenesis of MSCs. IL-34, a newly discovered cytokine, playing a key role in metabolism. However, the research on its functional role in the osteogenesis of MSCs was rarely reported. Here, we described the regulatory effects of low-dose IL-34 on both osteoblastogenesis and osteoclastogenesis. METHODS: We performed the osteogenic effects of hBMSCs by exogenous and overexpressed IL-34 in vitro, so were the osteoclastogenesis effects of mBMMs by extracellular IL-34. CCK-8 was used to assess the effect of IL-34 on the viability of hBMSCs and mBMMs. ALP, ARS, and TRAP staining was used to evaluate ALP activity, mineral deposition, and osteoclastogenesis, respectively. qRT-PCR and Western blotting analysis were performed to detect the expression of target genes and proteins. ELISA was used to evaluate the concentrations of IL-34. In vivo, a rat tibial osteotomy model and an OVX model were established. Radiographic analysis and histological evaluation were performed to confirm the therapeutic effects of IL-34 in fracture healing and osteoporosis. Statistical differences were evaluated by two-tailed Student's t test, one-way ANOVA with Bonferroni's post hoc test, and two-way ANOVA with Bonferroni multiple comparisons post hoc test in the comparison of 2 groups, more than 2 groups, and different time points of treated groups, respectively. RESULTS: Promoted osteoblastogenesis of hBMSCs was observed after treated by exogenous or overexpressed IL-34 in vitro, confirmed by increased mineral deposits and ALP activity. Furthermore, exogenous or overexpressed IL-34 enhanced the expression of p-AKT and p-ERK. The specific AKT and ERK signaling pathway inhibitors suppressed the enhancement of osteoblastogenesis induced by IL-34. In a rat tibial osteotomy model, imaging and histological analyses testified the local injection of exogenous IL-34 improved bone healing. However, the additional IL-34 has no influence on both osteoclastogenesis of mBMMs in vitro and osteoporosis of OVX model of rat in vivo. CONCLUSIONS: Collectively, our study demonstrate that low-dose IL-34 regulates osteogenesis of hBMSCs partly via the PIK/AKT and ERK signaling pathway and enhances fracture healing, with neither promoting nor preventing osteoclastogenesis in vitro and osteoporosis in vivo.