Bone Morphogenetic Protein-2 in Development and Bone Homeostasis

In silico assessment of biocompatibility and toxicity: molecular docking and dynamics simulation of PMMA-based dental materials for interim prosthetic restorations

AIM

This study aimed to comprehensively assess the biocompatibility and toxicity profiles of poly(methyl methacrylate) (PMMA) and its monomeric unit, methyl methacrylate (MMA), crucial components in dental materials for interim prosthetic restorations.

METHODOLOGY

Molecular docking was employed to predict the binding affinities, energetics, and steric features of MMA and PMMA with selected receptors involved in bone metabolism and tissue development, including RANKL, Fibronectin, BMP9, NOTCH2, and other related receptors. The HADDOCK standalone version was utilized for docking calculations, employing a Lamarckian genetic algorithm to explore the conformational space of ligand-receptor interactions. Furthermore, molecular dynamics (MD) simulations over 100 nanoseconds were conducted using the GROMACS package to evaluate dynamic actions and structural stability. The LigandScout was utilized for pharmacophore modeling, which employs a shape-based screening approach to identify potential ligand binding sites on protein targets.

RESULTS

The molecular docking studies elucidated promising interactions between PMMA and MMA with key biomolecular targets relevant to dental applications. MD simulation results provided strong evidence supporting the structural stability of PMMA complexes over time. Pharmacophore modeling highlighted the significance of carbonyl and hydroxyl groups as pharmacophoric features, indicating compounds with favorable biocompatibility profiles.

CONCLUSION

This study underscores the potential of PMMA in dental applications, emphasizing its structural stability, molecular interactions, and safety considerations. These findings lay a foundation for future advancements in dental biomaterials, guiding the design and optimization of materials for enhanced biocompatibility. Future directions include experimental validation of computational findings and the development of PMMA-based dental materials with improved biocompatibility and clinical performance.

Co-delivery of rhBMP-2 and zoledronic acid using calcium sulfate/hydroxyapatite carrier as a bioactive bone substitute to enhance and accelerate spinal fusion

Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been FDA-approved for lumbar fusion, but supraphysiologic initial burst release due to suboptimal carrier and late excess bone resorption caused by osteoclast activation have limited its clinical usage. One strategy to mitigate the pro-osteoclast side effect of rhBMP-2 is to give systemic bisphosphonates, but it presents challenges with systemic side effects and low local bioavailability. The aim of this in vivo study was to analyze if posterolateral spinal fusion (PLF) could be improved by utilizing a calcium sulfate/hydroxyapatite (CaS/HA) carrier co-delivering rhBMP-2 and zoledronic acid (ZA). Six groups were allocated (CaS/HA, CaS/HA + BMP-2, CaS/HA + systemic ZA, CaS/HA + local ZA, CaS/HA + BMP-2 + systemic ZA, and CaS/HA + BMP-2 + local ZA). 10-week-old male Wistar rats, were randomly assigned to undergo L4-L5 PLF with implantation of group-dependent scaffolds. At 3 and 6 weeks, the animals were euthanized for radiography, μCT, histological staining, or biomechanical testing to evaluate spinal fusion. The results demonstrated that the CaS/HA biomaterial alone or in combination with local or systemic ZA didn't support PLF. However, the delivery of rhBMP-2 significantly promoted PLF. Combining systemic ZA with BMP-2 didn't enhance spinal fusion. Notably, the co-delivery of rhBMP-2 and ZA using the CaS/HA carrier significantly enhanced and accelerated PLF, without inhibiting systemic bone turnover, and potentially reduced the dose of rhBMP-2. Together, the treatment regimen of CaS/HA biomaterial co-delivering rhBMP-2 and ZA could potentially be a safe and cost-effective off-the-shelf bioactive bone substitute to enhance spinal fusion.

Cbfβ regulates Wnt/β-catenin, Hippo/Yap, and Tgfβ signaling pathways in articular cartilage homeostasis and protects from ACLT surgery-induced osteoarthritis

As the most common degenerative joint disease, osteoarthritis (OA) contributes significantly to pain and disability during aging. Several genes of interest involved in articular cartilage damage in OA have been identified. However, the direct causes of OA are poorly understood. Evaluating the public human RNA-seq dataset showed that CBFB (subunit of a heterodimeric Cbfβ/Runx1, Runx2, or Runx3 complex) expression is decreased in the cartilage of patients with OA. Here, we found that the chondrocyte-specific deletion of Cbfb in tamoxifen-induced Cbfbf/f;Col2a1-CreERT mice caused a spontaneous OA phenotype, worn articular cartilage, increased inflammation, and osteophytes. RNA-sequencing analysis showed that Cbfβ deficiency in articular cartilage resulted in reduced cartilage regeneration, increased canonical Wnt signaling and inflammatory response, and decreased Hippo/Yap signaling and Tgfβ signaling. Immunostaining and western blot validated these RNA-seq analysis results. ACLT surgery-induced OA decreased Cbfβ and Yap expression and increased active β-catenin expression in articular cartilage, while local AAV-mediated Cbfb overexpression promoted Yap expression and diminished active β-catenin expression in OA lesions. Remarkably, AAV-mediated Cbfb overexpression in knee joints of mice with OA showed the significant protective effect of Cbfβ on articular cartilage in the ACLT OA mouse model. Overall, this study, using loss-of-function and gain-of-function approaches, uncovered that low expression of Cbfβ may be the cause of OA. Moreover, Local admission of Cbfb may rescue and protect OA through decreasing Wnt/β-catenin signaling, and increasing Hippo/Yap signaling and Tgfβ/Smad2/3 signaling in OA articular cartilage, indicating that local Cbfb overexpression could be an effective strategy for treatment of OA.

Nonthermal biocompatible plasma in stimulating osteogenic differentiation by targeting p38/ FOXO1 and PI3K/AKT pathways in hBMSCs

Osteoporosis is manifested by decreased bone density and deterioration of bone architecture, increasing the risk of bone fractures Human bone marrow mesenchymal stem cells (hBMSCs)-based tissue engineering serves as a crucial technique for regenerating lost bone and preventing osteoporosis. Non-thermal biocompatible plasma (NBP) is a potential new therapeutic approach employed in several biomedical applications, including regenerative medicine. NBP affects bone remodeling; however, its role in the regulation of osteogenic differentiation in hBMSCs remains largely unexplored. This study aimed to explore the efficiency of NBP in promoting osteogenic differentiation, and the molecular pathways through which these responses occurred in hBMSCs. We found that NBP facilitated osteogenic differentiation through the upregulation of the bone morphogenic protein signal (BMPs) cascade, which in turn induced the expression of p38 and inhibited the forkhead box protein O1 (FOXO1). To further gain insight into the mechanism through which NBP extensively triggers the initiation of osteogenic differentiation in hBMSCs, PI3K/AKT pathway was also analyzed. Overall, these results highlight that NBP enhances osteogenic differentiation in hBMSCs by the stimulation of the p38/FOXO1 through PI3K/AKT signaling pathways. Therefore, the application of NBP in hBMSCs may offer tremendous therapeutic prospects in the treatment of bone regeneration and osteoporosis prevention.

Production and Functional Analysis of Collagen Hexapeptide Repeat Sequences in Pichia pastoris

In the development of biomaterials with specific structural domains associated with various cellular activities, the limited integrin specificity of commonly used adhesion sequences, such as the RGD tripeptide, has resulted in an inability to precisely control cellular responses. To overcome this limitation, we conducted multiple replications of the integrin α2β1-specific ligand, the collagen hexapeptide Gly-Phe-Pro-Gly-Glu-Arg (GFPGER) in Pichia pastoris. This enabled the development of recombinant collagen with high biological activity, which was subsequently expressed, isolated, and purified for structural and functional analysis. The proteins carrying the multiple replications GFPGER sequence demonstrated significant bioactivity in cells, leading to enhanced cell adhesion, osteoblast differentiation, and mineralization when compared to control groups. Importantly, these effects were mediated by integrin α2β1. The new collagen constructed in this study is expected to be a biomaterial for regulating specific cell functions and fates.

Pioneering nanomedicine in orthopedic treatment care: a review of current research and practices

A developing use of nanotechnology in medicine involves using nanoparticles to administer drugs, genes, biologicals, or other materials to targeted cell types, such as cancer cells. In healthcare, nanotechnology has brought about revolutionary changes in the treatment of various medical and surgical conditions, including in orthopedic. Its clinical applications in surgery range from developing surgical instruments and suture materials to enhancing imaging techniques, targeted drug delivery, visualization methods, and wound healing procedures. Notably, nanotechnology plays a significant role in preventing, diagnosing, and treating orthopedic disorders, which is crucial for patients' functional rehabilitation. The integration of nanotechnology improves standards of patient care, fuels research endeavors, facilitates clinical trials, and eventually improves the patient's quality of life. Looking ahead, nanotechnology holds promise for achieving sustained success in numerous surgical disciplines, including orthopedic surgery, in the years to come. This review aims to focus on the application of nanotechnology in orthopedic surgery, highlighting the recent development and future perspective to bridge the bridge for clinical translation.

Bone Regenerative Effect of Injectable Hypoxia Preconditioned Serum-Fibrin (HPS-F) in an Ex Vivo Bone Defect Model

Biofunctionalized hydrogels are widely used in tissue engineering for bone repair. This study examines the bone regenerative effect of the blood-derived growth factor preparation of Hypoxia Preconditioned Serum (HPS) and its fibrin-hydrogel formulation (HPS-F) on drilled defects in embryonic day 19 chick femurs. Measurements of bone-related growth factors in HPS reveal significant elevations of Osteopontin, Osteoprotegerin, and soluble-RANKL compared with normal serum (NS) but no detection of BMP-2/7 or Osteocalcin. Growth factor releases from HPS-F are measurable for at least 7 days. Culturing drilled femurs organotypically on a liquid/gas interface with HPS media supplementation for 10 days demonstrates a 34.6% increase in bone volume and a 52.02% increase in bone mineral density (BMD) within the defect area, which are significantly higher than NS and a basal-media-control, as determined by microcomputed tomography. HPS-F-injected femur defects implanted on a chorioallantoic membrane (CAM) for 7 days exhibit an increase in bone mass of 123.5% and an increase in BMD of 215.2%, which are significantly higher than normal-serum-fibrin (NS-F) and no treatment. Histology reveals calcification, proteoglycan, and collagen fiber deposition in the defect area of HPS-F-treated femurs. Therefore, HPS-F may offer a promising and accessible therapeutic approach to accelerating bone regeneration by a single injection into the bone defect site.

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

Evaluation of Cardiospermum halicacabum on Bone Morphogenetic Protein-2 (BMP2) mRNA Expression in Osteoblast Cells

Introduction Maintaining bone health is crucial for overall well-being, with osteoblasts playing a vital role in bone formation. Bone morphogenetic protein-2 (BMP2) is a key regulator, stimulating bone matrix synthesis and osteoblast differentiation. Recognizing BMP2's significance, there's growing interest in natural compounds, such as Cardiospermum halicacabum. This study explores Cardiospermum halicacabum's potential influence on BMP2 mRNA expression in osteoblast cells for insights into bone health modulation. Materials and methods  This research utilized Cardiospermum halicacabum to explore its impact on MG-63 cells, a human osteoblast cell line. Osteoblast cells were cultured in Dulbecco's modified Eagle's medium (DMEM), supplemented with 10% heat-inactivated fetal bovine serum, and maintained at 37°C in a 5% CO2 and 95% air environment. Cell viability was evaluated by seeding osteoblast cells into 96-well plates and exposing them to different concentrations of Cardiospermum halicacabum (2.0 μg/ml and 20 μg/ml). The study observed both the promotion of osteoblast cell growth in MG-63 and morphological changes in the cells under an inverted light microscope at 10x magnification. Results were presented using one-way analysis of variance (ANOVA) conducted with IBM SPSS Statistics for Windows, Version 23 (Released 2015; IBM Corp., Armonk, New York, United States). Result The reverse transcription-polymerase chain (RT-PCR) results revealed an increased expression of BMP-2 mRNA fold change in comparison to the control group. A clear positive correlation was observed between the BMP-2 mRNA fold change and the notable increase in the concentration of Cardiospermum halicacabum. This investigation revealed a direct association of BMP-2 mRNA expression with the proliferation of osteoblast cells. Specifically, the BMP-2 mRNA fold change was recorded at 2.26±1.05 in Cardiospermum halicacabum at 2.0 μg/ml and 2.0 ± 0.84 at 20 μg/ml, with corresponding significances of 0.00, respectively. Conclusion  Potential effects of Cardiospermum halicacabum on BMP-2 mRNA expression in osteoblast cells and its role in bone health modulation revealed that Cardiospermum halicacabum may upregulate BMP-2 mRNA expression, suggesting its potential as a natural compound for enhancing bone formation. The observed positive correlation between Cardiospermum halicacabum concentration and BMP-2 mRNA fold change showed the significance of this botanical agent in promoting osteoblast cell proliferation. These results highlight the importance of further research to explore the applications of Cardiospermum halicacabum in managing bone disorders and improving overall bone health.

TRIM21 silencing inhibits the apoptosis and expedites the osteogenic differentiation of dexamethasone‑induced MC3T3‑E1 cells by activating the Keap1/Nrf2 pathway

Steroid-induced osteonecrosis of the femoral head (ONFH) is a serious complication caused by long-term or excessive use of glucocorticoids. The present study aimed to ascertain the effects of tripartite motif-containing protein 21 (TRIM21) on the process of steroid-induced ONFH and its hidden action mechanism. TRIM21 expression in dexamethasone (Dex)-treated mouse MC3T3-E1 preosteoblast cells was examined using reverse transcription-quantitative PCR and western blotting. The Cell Counting Kit-8 (CCK-8) method and lactate dehydrogenase release assay were used to respectively measure cell viability and injury. Flow cytometry analysis was used to assay cell apoptosis. Caspase 3 activity was evaluated using a specific assay, while alkaline phosphatase and Alizarin red S staining were used to evaluate osteogenesis. 2,7-dichloro-dihydrofluorescein diacetate fluorescence probe was used to estimate reactive oxygen species generation. Specific assay kits were used to appraise oxidative stress levels. In addition, the expression of apoptosis-, osteogenic differentiation- and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) signaling-associated proteins was assessed using western blotting. In Nrf2 inhibitor (ML385)-pretreated MC3T3-E1 cells exposed to Dex, cell apoptosis, osteogenesis and oxidative stress were detected again as aforementioned. Results revealed that TRIM21 expression was raised in Dex-induced MC3T3-E1 cells and TRIM21 deletion improved the viability and osteogenic differentiation, whereas it hampered the oxidative stress and apoptosis in MC3T3-E1 cells with Dex induction. In addition, silencing of TRIM21 activated Keap1/Nrf2 signaling. Moreover, ML385 partially abrogated the effects of TRIM21 depletion on the oxidative stress, apoptosis and osteogenic differentiation in MC3T3-E1 cells exposed to Dex. In conclusion, TRIM21 silencing might activate Keap1/Nrf2 signaling to protect against steroid-induced ONFH.

Repair of Rat Calvarial Critical-Sized Defects Using Heparin-Conjugated Fibrin Hydrogel Containing BMP-2 and Adipose-Derived Pericytes

The repair of critical-sized calvarial defects is a challenging problem for orthopedic surgery. One of the promising strategies of bone bioengineering to enhance the efficacy of large bone defect regeneration is the combined delivery of stem cells with osteoinductive factors within polymer carriers. The purpose of the research was to study the regenerative effects of heparin-conjugated fibrin (HCF) hydrogel containing bone morphogenetic protein 2 (BMP-2) and adipose-derived pericytes (ADPs) in a rat critical-sized calvarial defect model. In vitro analysis revealed that the HCF hydrogel was able to control the BMP-2 release and induce alkaline phosphatase (ALP) activity in neonatal rat osteoblasts. In addition, it was found that eluted BMP-2 significantly induced the osteogenic differentiation of ADPs. It was characterized by the increased ALP activity, osteocalcin expression and calcium deposits in ADPs. In vivo studies have shown that both HCF hydrogel with BMP-2 and HCF hydrogel with pericytes are able to significantly increase the regeneration of critical-sized calvarial defects in comparison with the control group. Nevertheless, the greatest regenerative effect was found after the co-delivery of ADPs and BMP-2 into a critical-sized calvarial defect. Thus, our findings suggest that the combined delivery of ADPs and BMP-2 in HCF hydrogel holds promise to be applied as an alternative biopolymer for the critical-sized bone defect restoration.

A systematic scoping review of the latest data on orthobiologics in the surgical treatment of non-union

INTRODUCTION

Recent studies have shown a growing concern regarding the cost-effectiveness and the lack of supporting data for the biologic agents that are being increasingly used in the orthopedic field. Our aim was to conduct a systematic scoping review of recent publications (last five years) on the use of orthobiologics to treat fracture non-union and summarize the latest available data.

PATIENTS AND METHODS

The inclusion criteria for this review were articles published in English, from 2016 to 2022, and focusing on the use of orthobiologics for the surgical treatment of non-union. Searches were conducted in March 2023 using Pubmed/MEDLINE and Embase. Studies on spinal fusion or gene therapy were excluded. Reviews, case reports with five cases or less, conference proceedings, preliminary reports, pediatric or non-human studies were excluded as well.

RESULTS

The search found 1807 articles, 15 were eligible after PRISMA checklist and exclusions. The evidence was heterogenous and there was only one level II RCT. Recent data suggests that bone morphogenic protein (BMP-2) products could be effective for septic and aseptic tibial non-unions. However, the evidence was not conclusive regarding BMP-7, plasma rich platelets (PRP), stem cells or demineralized bone matrix (DBM).

DISCUSSION

Every non-union case is different in terms of bone defect, biology, mechanical stability, surgical technique and host factors, which contributes to the conflicting reports on the efficacy of orthobiologics in the literature. We might never see a level 1, high powered and robust study defining the efficacy, safety profile and cost-effectiveness of such products.

LEVEL OF EVIDENCE

IV.

Discovery of a novel homoisoflavonoid derivative 5g for anti-osteoclastic bone loss via targeting FGFR1

Several flavonoids have been shown to exert anti-osteoporosis activity. However, the structure-activity relationship and the mechanism of anti-osteoporosis activity of flavonoids remain unknown. In this study, we prepared a series of novel homoisoflavonoid (HIF) derivatives to evaluate their inhibitory effects on osteoclastogenesis using TRAP-activity in vitro assay. Then, the preliminary structure-activity relationship was studied. Among the evaluated novel flavonoids, derivative 5g exerted the most inhibitory bioactivity on primary osteoclast differentiation without interfering with osteogenesis. It was hence selected for further in vitro, in vivo and mechanism of action investigation. Results show that 5g likely directly binds to the fibroblast growth factor receptor 1 (FGFR1), decreasing the activation of ERK1/2 and IκBα/NF-κB signaling pathways, which in turn blocks osteoclastogenesis in vitro and osteoclastic bone loss in vivo. Our study shows that homoisoflavonoid (HIF) derivatives 5g can serve as a potential novel candidate for treating osteoporosis via inhibition of FGFR1.

Cell-permeable bone morphogenetic protein 2 facilitates bone regeneration by promoting osteogenesis

The use of the FDA-approved osteoinductive growth factor BMP2 is widespread for bone regeneration. However, its clinical application has been hindered by limitations in cell permeability and a short half-life in circulation. To address this issue, we have developed a modified version of BMP2, referred to as Cell Permeable (CP)-BMP2, which possesses improved cell permeability. CP-BMP2 incorporates an advanced macromolecular transduction domain (aMTD) to facilitate transfer across the plasma membrane, a solubilization domain, and recombinant human BMP2. Compared to traditional rhBMP2, CP-BMP2 exhibits enhanced cell permeability, solubility, and bioavailability, and activates Smad phosphorylation through binding to BMP receptor 2. The effectiveness of CP-BMP2 was evaluated in three animal studies focusing on bone regeneration. In the initial study, mice and rabbits with critical-size calvarial defects received subcutaneous (SC) injections of CP-BMP2 and rhBMP2 (7.5 mg/kg, 3 injections per week for 8 weeks).Following 8 weeks of administration, CP-BMP2 demonstrated a remarkable 65 % increase in bone formation in mice when compared to both the vehicle and rhBMP2. Moreover, rabbits exhibited faster bone formation, characterized by a filling pattern originating from the center. In a subsequent study involving injured horses, hind limb bones treated with CP-BMP2 exhibited an 85 % higher bone regeneration rate, as evidenced by Micro-CT results, in contrast to horses treated with the vehicle or rhBMP2 (administered at 150 μg/defect, subcutaneously, once a week for 8 weeks, without a scaffold). These results underscore the potential of CP-BMP2 to facilitate rapid and effective healing. No noticeable adverse effects, such as ectopic bone formation, were observed in any of the studies. Overall, our findings demonstrate that CP-BMP2 holds therapeutic potential as a novel and effective osteogenic agent.

Activation of the BMP2-SMAD1-CGRP pathway in dorsal root ganglia contributes to bone cancer pain in a rat model

Peripheral nerve remodeling and sensitization are involved in cancer-related bone pain. As a member of the transforming growth factor-β class, bone morphogenetic protein 2 (BMP2) is recognized to have a role in the development of the neurological and skeletal systems. Our previous work showed that BMP2 is critical for bone cancer pain (BCP) sensitization. However, the mechanism remains unknown. In the current study, we demonstrated a substantial increase in BMP2 expression in the dorsal root ganglia (DRG) in a rat model of BCP. Knockdown of BMP2 expression ameliorated BCP in rats. Furthermore, the DRG neurons of rats with BCP expressed higher levels of calcitonin gene-related peptide (CGRP), and BCP was successfully suppressed by intrathecal injection of a CGRP receptor blocker (CGRP8-37). Downregulation of BMP2 expression reduced the expression of CGRP in the DRG of rats with BCP and relieved pain behavior. Moreover, we revealed that upregulation of CGRP expression in the DRG may be induced by activation of the BMPR/Smad1 signaling pathway. These findings suggest that BMP2 contributes to BCP by upregulating CGRP in DRG neurons via activating BMPR/Smad1 signaling pathway and that therapeutic targeting of the BMP2-Smad1-CGRP pathway may ameliorate BCP in the context of advanced cancer.

A machine learning algorithm for peripheral artery disease prognosis using biomarker data

Peripheral artery disease (PAD) biomarkers have been studied in isolation; however, an algorithm that considers a protein panel to inform PAD prognosis may improve predictive accuracy. Biomarker-based prediction models were developed and evaluated using a model development (n = 270) and prospective validation cohort (n = 277). Plasma concentrations of 37 proteins were measured at baseline and the patients were followed for 2 years. The primary outcome was 2-year major adverse limb event (MALE; composite of vascular intervention or major amputation). Of the 37 proteins tested, 6 were differentially expressed in patients with vs. without PAD (ADAMTS13, ICAM-1, ANGPTL3, Alpha 1-microglobulin, GDF15, and endostatin). Using 10-fold cross-validation, we developed a random forest machine learning model that accurately predicts 2-year MALE in a prospective validation cohort of PAD patients using a 6-protein panel (AUROC 0.84). This algorithm can support PAD risk stratification, informing clinical decisions on further vascular evaluation and management.

Trends in bioactivity: inducing and detecting mineralization of regenerative polymeric scaffolds

Due to limitations of biological and alloplastic grafts, regenerative engineering has emerged as a promising alternative to treat bone defects. Bioactive polymeric scaffolds are an integral part of such an approach. Bioactivity importantly induces hydroxyapatite mineralization that promotes osteoinductivity and osseointegration with surrounding bone tissue. Strategies to confer bioactivity to polymeric scaffolds utilize bioceramic fillers, coatings and surface treatments, and additives. These approaches can also favorably impact mechanical and degradation properties. A variety of fabrication methods are utilized to prepare scaffolds with requisite morphological features. The bioactivity of scaffolds may be evaluated with a broad set of techniques, including in vitro (acellular and cellular) and in vivo methods. Herein, we highlight contemporary and emerging approaches to prepare and assess scaffold bioactivity, as well as existing challenges.

Interaction between immuno-stem dual lineages in jaw bone formation and injury repair

The jawbone, a unique structure in the human body, undergoes faster remodeling than other bones due to the presence of stem cells and its distinct immune microenvironment. Long-term exposure of jawbones to an oral environment rich in microbes results in a complex immune balance, as shown by the higher proportion of activated macrophage in the jaw. Stem cells derived from the jawbone have a higher propensity to differentiate into osteoblasts than those derived from other bones. The unique immune microenvironment of the jaw also promotes osteogenic differentiation of jaw stem cells. Here, we summarize the various types of stem cells and immune cells involved in jawbone reconstruction. We describe the mechanism relationship between immune cells and stem cells, including through the production of inflammatory bodies, secretion of cytokines, activation of signaling pathways, etc. In addition, we also comb out cellular interaction of immune cells and stem cells within the jaw under jaw development, homeostasis maintenance and pathological conditions. This review aims to eclucidate the uniqueness of jawbone in the context of stem cell within immune microenvironment, hopefully advancing clinical regeneration of the jawbone.

Glucocorticoids promote steroid-induced osteonecrosis of the femoral head by down-regulating serum alpha-2-macroglobulin to induce oxidative stress and facilitate SIRT2-mediated BMP2 deacetylation

Our study investigated the possible molecular mechanism of glucocorticoid in steroid-induced osteonecrosis of the femoral head (SINFH) through regulating serum alpha-2-macroglobulin and SIRT2-mediated BMP2 deacetylation. Essential genes involved in glucocorticoid-induced SINFH were screened by transcriptome sequencing and analyzed by bioinformatics, followed by identifying downstream regulatory targets. Rat bone marrow mesenchymal stem cells were isolated and treated with methylprednisolone (MP) for in vitro cell experiments. Besides, a glucocorticoid-induced rat ONFH was established using the treatment of MP and LPS. ChIP-PCR detected the enrichment of SIRT2 in the promoter region of BMP2, and the deacetylation modification of SIRT2 on BMP2 was determined. Bioinformatics analysis revealed that glucocorticoids may induce ONFH through the SIRT2/BMP2 axis. In vitro cell experiments showed that glucocorticoids up-regulated SIRT2 expression in BMSCs by inducing oxidative stress, thereby promoting cell apoptosis. The up-regulation of SIRT2 expression may be due to the decreased ability of α2 macroglobulin to inhibit oxidative stress, and the addition of NOX protein inhibitor DPI could significantly inhibit SIRT2 expression. SIRT2 could promote histone deacetylation of the BMP2 promoter and inhibit its expression. In vitro cell experiments further indicated that knocking down SIRT2 could protect BMSC from oxidative stress and cell apoptosis induced by glucocorticoids by promoting BMP2 expression. In addition, animal experiments conducted also demonstrated that the knockdown of SIRT2 could improve glucocorticoid-induced ONFH through up-regulating BMP2 expression. Glucocorticoids could induce oxidative stress by down-regulating serum α2M to promote SIRT2-mediated BMP2 deacetylation, leading to ONFH.

Goat mammary epithelial cells provide a better expression system for production of recombinant human bone morphogenetic protein 2 compared to Chinese hamster ovarian cells

Bone Morphogenetic Protein 2 (BMP2), a member of the Transforming Growth Factor-β (TGF-β) super family of proteins and is instrumental in the repair of fractures. The synthesis of BMP2 involves extensive post-translational processing and several studies have demonstrated the abysmally low production of rhBMP2 in eukaryotic systems, which may be due to the short half-life of the bioactive protein. Consequently, production costs of rhBMP2 are quite high, limiting its availability to the general populace. Therefore, there is an urgent need to identify better in-vitro systems for large scale production of rhBMP2. In the present study, we have carried out a comparative analysis of rhBMP2 production by the conventionally used Chinese Hamster ovarian cells (CHO) and goat mammary epithelial cells (GMEC), upon transfection with appropriate construct. Udder gland cells are highly secretory, and we reasoned that such cells may serve as a better in-vitro model for large scale production of rhBMP2. Our results indicated that the synthesis and secretion of bioactive rhBMP2 by goat mammary epithelial cells was significantly higher as compared to that by CHO-K1 cells. Our results provide strong evidence that GMECs may serve as a better alternative to other mammalian cells used for therapeutic protein production.

Osteogenically committed hUCMSCs-derived exosomes promote the recovery of critical-sized bone defects with enhanced osteogenic properties

Low viability of seed cells and the concern about biosafety restrict the application of cell-based tissue-engineered bone (TEB). Exosomes that bear similar bioactivities to donor cells display strong stability and low immunogenicity. Human umbilical cord mesenchymal stem cells-derived exosomes (hUCMSCs-Exos) show therapeutic efficacy in various diseases. However, little is known whether hUCMSCs-Exos can be used to construct TEB to repair bone defects. Herein, PM-Exos and OM-Exos were separately harvested from hUCMSCs which were cultured in proliferation medium (PM) or osteogenic induction medium (OM). A series of in-vitro studies were performed to evaluate the bioactivities of human bone marrow mesenchymal stem cells (hBMSCs) when co-cultured with PM-Exos or OM-Exos. Differential microRNAs (miRNAs) between PM-Exos and OM-Exos were sequenced and analyzed. Furthermore, PM-Exos and OM-Exos were incorporated in 3D printed tricalcium phosphate scaffolds to build TEBs for the repair of critical-sized calvarial bone defects in rats. Results showed that PM-Exos and OM-Exos bore similar morphology and size. They expressed representative surface markers of exosomes and could be internalized by hBMSCs to promote cellular migration and proliferation. OM-Exos outweighed PM-Exos in accelerating the osteogenic differentiation of hBMSCs, which might be attributed to the differentially expressed miRNAs. Furthermore, OM-Exos sustainably released from the scaffolds, and the resultant TEB showed a better reparative outcome than that of the PM-Exos group. Our study found that exosomes isolated from osteogenically committed hUCMSCs prominently facilitated the osteogenic differentiation of hBMSCs. TEB grafts functionalized by OM-Exos bear a promising application potential for the repair of large bone defects.

Morphogenesis of fungiform papillae in developing miniature pigs

Objective

Fungiform papillae contain taste buds and play a critical role in mastication and the gustatory system. In this study, we report a series of sequential observations of organogenesis of fungiform papillae in miniature pigs, as well as changes in the expression of BMP2, BMP4, Wnt5a, Sox2, and Notch1 signaling pathway components.

Design

In this study, we investigated the spatiotemporal expression patterns of BMP, Wnt, Sox2 and Notch in the fungiform papillae of miniature pigs at the bud stage (E40), cap stage (E50) and bell stage (E60). Pregnant miniature pigs were obtained, and the samples were processed for histological staining. Immunohistochemistry and real-time PCR were used to detect the mRNA and protein expression levels of BMP2, BMP4, Wnt5a, Sox2, and Notch1.

Results

At E40, fungiform papillae were present on the anterior two-thirds of the tongue in a specific array and pattern. The fungiform papillae were enlarged and basically developed at E50 and were largest at the earlier stage (E60). Most of the BMP2 was concentrated in the epithelial layer and the connective tissue core of the fungal papilloma and gradually accumulated from E40-E60. BMP-4 was weakly expressed in the fungiform papillae epithelia, but BMP-4-positive cells were also observed in the developing tongue muscle at E50 and E60. Wnt5a-positive cells were observed in the fungiform papillae epithelia and developing tongue muscle at all three time points. Sox2-positive cells were observed only in fungiform papillae epithelial cells, and Notch1-positive cells could not be detected.

Conclusions

This study provides primary data regarding the morphogenesis and expression of developmental signals in the fungiform papillae of miniature pigs, establishing a foundation for further research in both this model and humans.

High-yield BMP2 expression in rice cells via CRISPR and endogenous αAmy3 promoter

Plant cells serve as versatile platforms for the production of high-value recombinant proteins. This study explored the efficacy of utilizing an endogenous αAmy3 promoter for the expression of a bioactive pharmaceutical protein, specifically the mature region of human bone morphogenetic protein 2 (hBMP2m). Utilizing a refined CRISPR/Cas9-mediated intron-targeting insertion technique, which incorporates an artificial 3' splicing site upstream of the target gene, we achieved a transformation efficiency of 13.5% in rice calli that carried the rice-codon optimized mature region of hBMP2 cDNA (rhBMP2m) in the αAmy3 intron 1. Both homozygous and heterozygous rhBMP2m knock-in rice suspension cell lines were generated. These lines demonstrated the endogenous αAmy3 promoter regulated rhBMP2m mRNA and rhBMP2m recombinant protein expression, with strongly upregulation in respond to sugar depletion. The homozygous rhBMP2m knock-in cell line yielded an impressive 21.5 μg/mL of rhBMP2m recombinant protein, accounting for 1.03% of the total soluble protein. The high-yield expression was stably maintained across two generations, indicating the genetic stability of rhBMP2m gene knock-in at the αAmy3 intron 1 locus. Additionally, the rice cell-derived rhBMP2m proteins were found to be glycosylated, capable of dimer formation, and bioactive. Our results indicate that the endogenous rice αAmy3 promoter-signal peptide-based expression system is an effective strategy for producing bioactive pharmaceutical proteins. KEY POINTS: • The endogenous αAmy3 promoter-based expression system enhanced the yield of BMP2 • The increased yield of BMP2 accounted for 1.03% of the total rice-soluble proteins • The rice-produced BMP2 showed glycosylation modifications, dimer formation, and bioactivity.

Stiffness and BMP-2 Mimetic Peptide Jointly Regulate the Osteogenic Differentiation of Rat Bone Marrow Stromal Cells in a Gelatin Cryogel

Both biochemical and mechanical cues could regulate the function of stem cells, but the interaction mechanism of their signaling pathway remains unclear, especially in the three-dimensional (3D) culture mode. Higher matrix stiffness promotes osteogenic differentiation of stem cells, and bone morphogenic protein-2 (BMP-2) has been clinically applied to promote bone regeneration. Here, the crosstalk of extracellular mechanical signals on BMP-2 signaling was investigated in rat bone marrow stromal cells (rMSCs) cultured inside cryogels with interconnective pores. Stiff cryogel independently promoted osteogenic differentiation and enhanced the autocrine secretion of BMP-2, thus stimulating increased phosphorylation levels of the Smad1/5/8 complex. BMP-2 mimetic peptide (BMMP) and high cryogel stiffness jointly guided the osteogenic differentiation of rMSCs. Inhibition of rho-associated kinase (ROCK) by Y-27632 or inhibition of nonmuscle myosin II (NM II) by blebbistatin showed that osteogenesis induction by BMP-2 signaling, as well as autocrine secretion of BMP-2 and phosphorylation of the Smad complex, requires the involvement of cytoskeletal tension and ROCK pathway signaling. An interconnective microporous cryogel scaffold promoted rMSC osteogenic differentiation by combining matrix stiffness and BMMP, and it accelerated critical cranial defect repair in the rat model.

A comparative analysis of the cytocompatibility, protein adsorption, osteogenic and angiogenic properties of the 45S5- and S53P4-bioactive glass compositions

Despite their long history of application in orthopedics, the osteogenic and angiogenic properties as well as the cytocompatibility and protein adsorption of the 45S5- (in wt%: 45.0 SiO2, 24.5 Na2O, 24.5 CaO, 6.0 P2O5) and S53P4- (in wt%: 53.0 SiO2, 23.0 Na2O, 20.0 CaO, 4.0 P2O5) bioactive glass (BG) compositions have not yet been directly compared in one and the same experimental setting. In this study, the influence of morphologically equal granules of both BGs on proliferation, viability, osteogenic differentiation and angiogenic response of human bone-marrow-derived mesenchymal stromal cells (BMSCs) was assessed. Furthermore, their impact on vascular tube formation and adsorption of relevant proteins was evaluated. Both BGs showed excellent cytocompatibility and stimulated osteogenic differentiation of BMSCs. The 45S5-BG showed enhanced stimulation of bone morphogenic protein 2 (BMP2) gene expression and protein production compared to S53P4-BG. While gene expression and protein production of vascular endothelial growth factor (VEGF) were stimulated, both BGs had only limited influence on tubular network formation. 45S5-BG adsorbed a higher portion of proteins, namely BMP2 and VEGF, on its surface. In conclusion, both BGs show favorable properties with slight advantages for 45S5-BG. Since protein adsorption on BG surfaces is important for their biological performance, the composition of the proteome formed by osteogenic cells cultured on BGs should be analyzed in order to gain a deeper understanding of the mechanisms that are responsible for BG-mediated stimulation of osteogenic differentiation.

Mitigation of BMP-induced inflammation in craniofacial bone regeneration and improvement of bone parameters by dietary hesperidin

Based on anti-inflammatory and osteogenic properties of hesperidin (HE), we hypothesized its systemic administration could be a cost-effective method of improving BMP-induced bone regeneration. Sprague-Dawley rats were allocated into 4 groups (n = 10/group): a 5-mm critical-sized mandible defect + collagen scaffold or, scaffold + 1 µg of BMP2 with and without dietary HE at 100 mg/kg. HE was administered by oral gavage 4 weeks prior to surgeries until euthanasia at day 7 or 14 post-surgery. The healing tissue within the defect collected at day 7 was subjected to gene expression analysis. Mandibles harvested at day 14 were subjected to microcomputed tomography and histology. HE + BMP2-treated rats had a statistically significant decrease in expression of inflammatory genes compared to BMP2 alone. The high-dose BMP2 alone caused cystic-like regeneration with incomplete defect closure. HE + BMP2 showed virtually complete bone fusion. Collagen fibril birefringence pattern (red color) under polarized light indicated high organization in BMP2-induced newly formed bone (NFB) in HE-supplemented group (p < 0.05). Clear changes in osteocyte lacunae as well as a statistically significant increase in osteoclasts were found around NFB in HE-treated rats. A significant increase in trabecular volume and thickness, and trabecular and cortical density was found in femurs of HE-supplemented rats (p < 0.05). Our findings show, for the first time, that dietary HE has a remarkable modulatory role in the function of locally delivered high-dose BMP2 in bone regeneration possibly via control of inflammation, osteogenesis, changes in osteocyte and osteoclast function and collagen maturation in regenerated and native bone. In conclusion, HE had a significant skeletal bone sparing effect and the ability to provide a more effective BMP-induced craniofacial regeneration.

Explorating the mechanism of Epimedii folium-Rhizoma drynariae herbal pair promoted bone defects healing through network pharmacology and experimental studies

ETHNOPHARMACOLOGICAL RELEVANCE

Bone defects are difficult to treat and have a high incidence of nonunion. The Epimedii folium-Rhizoma drynariae herbal pair (EDP) is a traditional Chinese medicine (TCM) used for treating bone diseases. However, the mechanisms by which EDP promotes osteogenesis or bone formation remain largely unclear.

AIM OF THE STUDY

This study aimed to investigate the mechanism of EDP promoted bone formation in bone defects using network pharmacology and experiments.

MATERIALS AND METHODS

The chemical components of EDP were analyzed by UHPLC-MS. The hub target and pathway enrichment analysis was conducted using molecular docking or network pharmacology. The pharmacological actions of EDP were determined by μCT and histopathology examination using a bone defect rat model. The effects of EDP on the mRNA expression of Bmp2, Smad2/5, Runx2, and Alp genes were measured by RT-PCR, while changes in the protein expressions of BMP2, COL1A1, SPP1, ALP, and RUNX2in the tibia tissues of the rats in response to EDP were analyzed by immunohistochemical staining or Western blot. We also performed cell viability assays, Alizarin Red and ALP staining assays, and RT-PCR to better understand how EDP affected osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).

RESULTS

Identified 14 key compounds and 47 hub targets of EDP that may be involved in promoting osteogenesis to repair bone defects. And the BMP/Smad/Runx2 pathway was likely the key pathway through which EDP promoted bone defects repairing. The results of in vivo rat experiments indicated that EDP effectively promoted tibia repair in the model rats and activated the BMP/Smad/Runx2 pathway in the tibia tissue, with upregulating Bmp2, Bmpr1α, Smad2/5, Runx2, and Alp genes, and increased the protein expression of BMP2, COL1A1, RUNX2, and ALP. In vitro, EDP was found to increase the proliferation, differentiation, and mineralization in BMSCs- and also up-regulated the expression of key genes in the BMP/Smad/Runx2 pathway.

CONCLUSION

This study highlighted the ability of EDP to promote the osteogenic differentiation to enable bone repair by activating the BMP/Smad/Runx2 pathway.

Cbfβ regulates Wnt/β-catenin, Hippo/Yap, and TGFβ signaling pathways in articular cartilage homeostasis and protects from ACLT surgery-induced osteoarthritis

As the most common degenerative joint disease, osteoarthritis (OA) contributes significantly to pain and disability during aging. Several genes of interest involved in articular cartilage damage in OA have been identified. However, the direct causes of OA are poorly understood. Evaluating the public human RNA-seq dataset showed that Cbfβ, (subunit of a heterodimeric Cbfβ/Runx1,Runx2, or Runx3 complex) expression is decreased in the cartilage of patients with OA. Here, we found that the chondrocyte-specific deletion of Cbfβ in tamoxifen-induced Cbfβf/fCol2α1-CreERT mice caused a spontaneous OA phenotype, worn articular cartilage, increased inflammation, and osteophytes. RNA-sequencing analysis showed that Cbfβ deficiency in articular cartilage resulted in reduced cartilage regeneration, increased canonical Wnt signaling and inflammatory response, and decreased Hippo/YAP signaling and TGF-β signaling. Immunostaining and western blot validated these RNA-seq analysis results. ACLT surgery-induced OA decreased Cbfβ and Yap expression and increased active β-catenin expression in articular cartilage, while local AAV-mediated Cbfβ overexpression promoted Yap expression and diminished active β-catenin expression in OA lesions. Remarkably, AAV-mediated Cbfβ overexpression in knee joints of mice with OA showed the significant protective effect of Cbfβ on articular cartilage in the ACLT OA mouse model. Overall, this study, using loss-of-function and gain-of-function approaches, uncovered that low expression of Cbfβ may be the cause of OA. Moreover, Local admission of Cbfβ may rescue and protect OA through decreasing Wnt/β-catenin signaling, and increasing Hippo/Yap signaling and TGFβ/Smad2/3 signaling in OA articular cartilage, indicating that local Cbfβ overexpression could be an effective strategy for treatment of OA.

Functionalization of Osteoplastic Material with Human Placental Growth Factor and Assessment of Biocompatibility of the Resulting Material In Vitro

This article provides the results of a study of the interaction of placental growth factor with adipose-derived stem cells (ASCs) of various origins, as well as the possibility of generating osteoplastic material based on xenogeneic matrix functionalization with human placental growth factor (PLGF). It is demonstrated that the greatest release of this factor from the functionalized material into the medium occurs during the first 3 h of contact with the model medium, but then the levels of the factor being released fall sharply, although release did continue throughout the 7 days of observation. The modified material was not cytotoxic, and its surface provided good cell adhesion. During 3 days of cultivation, the ASCs proliferated and migrated more actively on the surfaces of the modified material than on the surfaces of the control material. This study can serve as the basis for the development of original methods to functionalize such osteoplastic material by increasing PLGF immobilization by creating stronger bonds in order to regulate both factor dosage and the dynamics of the factor release into the environment. Further studies in experimental animals should facilitate assessment of the effectiveness of the functionalized materials. Such studies will be useful in the development of osteoplastic materials with new properties resulting from the inclusion of growth factors and in research on their biological activity.

Chemical substances and their activities in sea cucumber Apostichopus japonicus: A review

Apostichopus japonicus, also known as Stichopus japonicus, with medicinal and food homologous figures, is a globally recognized precious ingredient with extremely high nutritional value. There is no relevant review available through literature search, so this article selects the research articles through the keywords "sea cucumber" and "Apostichopus japonicus (Stichopus japonicus)" in six professional databases, such as Wiley, PubMed, ScienceDirect, ACS, Springer, and Web of Science, from 2000 to the present, summarizing the extraction, isolation, and purification methods for the four major categories (polysaccharides, proteins and peptides, saponins, and other components) of the A. japonicus chemical substances and 10 effective biological activities of A. japonicus. Included are anticoagulation, anticancer/antitumor activities, hematopoiesis, regulation of gut microbiota, and immune regulatory activities that correspond to traditional efficacy. Literature support is provided for the development of medicines and functional foods and related aspects that play a leading role in future directions.

The functional and molecular impact of triamcinolone acetonide on primary human bone marrow mesenchymal stem cells

Traumatic or degenerative joint pain is abundant in the population. Symptom relief by intra- and periarticular glucocorticoid administration is frequently used, however may have potentially devastating effects, changing the normal healing process of the joint. Mesenchymal stem cells (MSCs) are important for wound-healing processes due to their multipotency in regenerating osteoblasts, chondrocytes and adipocytes but also have immunomodulatory properties. The aim of this study was to investigate the impact of triamcinolone acetonide (TA) a common glucocorticoid administrated intra- and periarticularly, on human bone marrow derived MSC viability, functionality, multi-lineage differentiation and transcriptomic output. We found that TA treatment induced apoptosis and promoted adipogenesis while impairing chondrogenesis of MSCs. RNA sequencing indicated that TA modulated the inflammatory response of MSCs, which may have an impact on the immunologic environment where the inflammatory phase is a physiological part of the natural healing process. These data indicate that triamcinolone acetonide should be used with consideration bearing the patient's outcome in mind, with the intention to optimize joint recovery and homeostasis.

Transforming growth factor-beta superfamily regulates mesenchymal stem cell osteogenic differentiation: A microRNA linking

The ability to differentiate into cells of different lineages, such as bone cells, is the principal value of adult mesenchymal stem cells (MSCs), which can be used with the final aim of regenerating damaged tissue. Due to its potential use and importance in regenerative medicine and tissue engineering, several questions have been raised regarding the molecular mechanisms of MSC differentiation. As one of the crucial mediators in organism development, the transforming growth factor-beta (TGF-β) superfamily directs MSCs' commitment to selecting differentiation pathways. This review aims to give an overview of the current knowledge on the mechanisms of the TGF-β superfamily in MSCs bone differentiation, with additional insight into the mutual regulation of microRNAs and TGF-β in osteogenesis.

Carnosine, Zinc and Copper: A Menage a Trois in Bone and Cartilage Protection

Dysregulated metal homeostasis is associated with many pathological conditions, including arthritic diseases. Osteoarthritis and rheumatoid arthritis are the two most prevalent disorders that damage the joints and lead to cartilage and bone destruction. Recent studies show that the levels of zinc (Zn) and copper (Cu) are generally altered in the serum of arthritis patients. Therefore, metal dyshomeostasis may reflect the contribution of these trace elements to the disease's pathogenesis and manifestations, suggesting their potential for prognosis and treatment. Carnosine (Car) also emerged as a biomarker in arthritis and exerts protective and osteogenic effects in arthritic joints. Notably, its zinc(II) complex, polaprezinc, has been recently proposed as a drug-repurposing candidate for bone fracture healing. On these bases, this review article aims to provide an overview of the beneficial roles of Cu and Zn in bone and cartilage health and their potential application in tissue engineering. The effects of Car and polaprezinc in promoting cartilage and bone regeneration are also discussed. We hypothesize that polaprezinc could exchange Zn for Cu, present in the culture media, due to its higher sequestering ability towards Cu. However, future studies should unveil the potential contribution of Cu in the beneficial effects of polaprezinc.

The Critical Role of The Piezo1/β-catenin/ATF4 Axis on The Stemness of Gli1+ BMSCs During Simulated Microgravity-Induced Bone Loss

Disuse osteoporosis is characterized by decreased bone mass caused by abnormal mechanical stimulation of bone. Piezo1 is a major mechanosensitive ion channel in bone homeostasis. However, whether intervening in the action of Piezo1 can rescue disuse osteoporosis remains unresolved. In this study, a commonly-used hindlimb-unloading model is employed to simulate microgravity. By single-cell RNA sequencing, bone marrow-derived mesenchymal stem cells (BMSCs) are the most downregulated cell cluster, and coincidentally, Piezo1 expression is mostly enriched in those cells, and is substantially downregulated by unloading. Importantly, activation of Piezo1 by systemically-introducing yoda1 mimics the effects of mechanical stimulation and thus ameliorates bone loss under simulated microgravity. Mechanistically, Piezo1 activation promotes the proliferation and osteogenic differentiation of Gli1+ BMSCs by activating the β-catenin and its target gene activating transcription factor 4 (ATF4). Inhibiting β-catenin expression substantially attenuates the effect of yoda1 on bone loss, possibly due to inhibited proliferation and osteogenic differentiation capability of Gli1+ BMSCs mediated by ATF4. Lastly, Piezo1 activation also slightly alleviates the osteoporosis of OVX and aged mice. In conclusion, impaired function of Piezo1 in BMSCs leads to insufficient bone formation especially caused by abnormal mechanical stimuli, and is thus a potential therapeutic target for osteoporosis.

Microenvironment-targeted strategy steers advanced bone regeneration

Treatment of large bone defects represents a great challenge in orthopedic and craniomaxillofacial surgery. Traditional strategies in bone tissue engineering have focused primarily on mimicking the extracellular matrix (ECM) of bone in terms of structure and composition. However, the synergistic effects of other cues from the microenvironment during bone regeneration are often neglected. The bone microenvironment is a sophisticated system that includes physiological (e.g., neighboring cells such as macrophages), chemical (e.g., oxygen, pH), and physical factors (e.g., mechanics, acoustics) that dynamically interact with each other. Microenvironment-targeted strategies are increasingly recognized as crucial for successful bone regeneration and offer promising solutions for advancing bone tissue engineering. This review provides a comprehensive overview of current microenvironment-targeted strategies and challenges for bone regeneration and further outlines prospective directions of the approaches in construction of bone organoids.

Application of Escherichia coli-Derived Recombinant Human Bone Morphogenic Protein-2 to Unstable Spinal Fractures

(1) Background: Recently, Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E. coli-derived rhBMP-2) has been increasingly applied to different types of spinal surgeries and reported to achieve successful fusion. This pilot study aimed to evaluate the clinical efficacy and safety of rhBMP-2 in patients undergoing posterior instrumented fusions for unstable spinal fractures. (2) Methods: This study included ten consecutive patients undergoing spinal surgery using E. coli-derived rhBMP-2 with more than one year of follow-up. Radiologic outcomes were compared, including the average fracture healing period, local kyphosis correction, and clinical outcomes between preoperative and the last follow-up. (3) Results: The average time of radiographic union was 99.9 ± 45.4 (62-192) days, with an average use of 5.2 ± 3.9 months of anabolic agents. Radiologic parameters such as anterior vertebral height and vertebral wedge angle were significantly corrected postoperatively and at the last follow-up. Clinical outcomes other than leg pain were significantly improved after the surgery. In addition, four patients with preoperative neurologic deficits showed improved neurologic status. (4) Conclusions: Combined with the anabolic agents, applying E. coli-derived rhBMP-2 to the fractured vertebral body could be an effective surgical treatment for unstable spinal fractures. Further trials are needed to validate this result.

Enhanced Osteogenic Activity and Bone Repair Ability of PLGA/MBG Scaffolds Doped with ZIF-8 Nanoparticles Loaded with BMP-2

Background

Tissue engineering scaffolds are porous and can be loaded with growth factors to promote osteogenesis and bone repair, which can solve the problem of clinical bone defects. The direct loading of growth factors on scaffolds is hindered by the disadvantages of low loading capacities, and uncontrollable burst release. Zeolitic imidazolate framework-8 (ZIF-8) has osteoinductive activity and drug-loading potential and can be loaded with growth factors to achieve sustained release. In this study, we aimed to establish a sustained release system of composite scaffolds loaded with growth factors to achieve the goal of slow controlled release and effective bone repair.

Methods

ZIF‑8 nanoparticles loaded with bone morphogenetic protein-2 (BMP-2) were incorporated into poly-(lactide-co-glycolide)/mesoporous bioactive glass (PLGA/MBG) porous scaffolds by a 3D-printing method. The surface morphology, chemical properties and BMP-2 release of the prepared scaffold were investigated. The osteoblast adhesion, proliferation, spreading, and osteogenic differentiation in vitro and the bone repair ability in vivo of the PLGA/MBG/ZIF-8/BMP-2 (PMZB) scaffold were evaluated, and compared with those of PLGA/MBG (PM) and PLGA/MBG/ZIF-8 (PMZ) scaffolds.

Results

The results showed that the PMZB scaffold exhibited a slow and continuous BMP-2 release pattern, enhanced osteoblast adhesion, proliferation, spreading and osteogenic differentiation in vitro, and promoted new bone formation and bone repair in vivo.

Conclusion

The PLGA/MBG/ZIF-8/BMP-2 porous scaffold could continuously and slowly release BMP-2, enhance osteogenic activity, and promote new bone formation and bone repair at bone defects. The PMZB scaffold can be used as a bone graft material to repair bone defect at non-weight-bearing sites.

Biofabrication of functional bone tissue: defining tissue-engineered scaffolds from nature

Damage to bone leads to pain and loss of movement in the musculoskeletal system. Although bone can regenerate, sometimes it is damaged beyond its innate capacity. Research interest is increasingly turning to tissue engineering (TE) processes to provide a clinical solution for bone defects. Despite the increasing biomimicry of tissue-engineered scaffolds, significant gaps remain in creating the complex bone substitutes, which include the biochemical and physical conditions required to recapitulate bone cells' natural growth, differentiation and maturation. Combining advanced biomaterials with new additive manufacturing technologies allows the development of 3D tissue, capable of forming cell aggregates and organoids based on natural and stimulated cues. Here, we provide an overview of the structure and mechanical properties of natural bone, the role of bone cells, the remodelling process, cytokines and signalling pathways, causes of bone defects and typical treatments and new TE strategies. We highlight processes of selecting biomaterials, cells and growth factors. Finally, we discuss innovative tissue-engineered models that have physiological and anatomical relevance for cancer treatments, injectable stimuli gels, and other therapeutic drug delivery systems. We also review current challenges and prospects of bone TE. Overall, this review serves as guide to understand and develop better tissue-engineered bone designs.

Osteogenic stimulation of osteoprogenitors by putamen ovi peptides and hyaluronic acid

Eggshell peptides (EP) majorly contribute to rapid bone building in chicks, wherefore this paper investigated their potential for stimulating osteogenesis in vitro. In this study, the effects of EP, also called putamen ovi peptides and a combination of hyaluronic acid with EP in cell culture medium were tested towards proliferation, differentiation, gene expression and mineralization of bovine osteoprogenitors and primary human osteoblasts. The influence of EP at concentrations of 0.005 g/L, 0.5 g/L and 0.5 g/L with 0.25% hyaluronic acid was analyzed using immunocytochemical staining of bone-specific matrix proteins, namely collagen type I, osteonectin, osteopontin and osteocalcin, to prove osteoblastic differentiation. Additionally, Richardson-staining was performed. All tests revealed a superior osteoblastic differentiation with EP at 0.5 g/L after 5 days of cultivation. Hyaluronic acid alone showed controversial results and partially constrained osteoblastic differentiation in combination with EP to a level as low as for pure EP at 0.005 g/L. Of particular interest is the osteoblast-typical mineralization, as an important indicator of bone formation, which was measured indirectly via the calcium concentration after cultivation over 4 weeks. The mineralization showed an increase by a factor of 286 during the cultivation of primary human osteoblasts with hyaluronic acid and EP. Meanwhile, cell cultures treated with EP (0.5 g/L) only showed an 80-fold increase in calcium concentration.The influence of EP (0.5 g/L) on primary human osteoblasts was investigated by gene expression after 2 weeks of cultivation. Microarray and qRT-PCR analysis showed a strongly increased expression of main important genes in bone formation, bone regeneration and the physiological bone remodelling processes. Namely, BMP 2, osteopontin and the matrix metalloproteinases 1 and 9, were present during in vitro osteoprogenitor culture with EP. By explicitly underlining the potential of eggshell peptides for stimulating osteogenesis, as well as emphasizing complex and controversial interaction with hyaluronan, this manuscript is relevant for developing new functionalized biomaterials for bone regeneration.

Recent Advances in Bioengineering Bone Revascularization Based on Composite Materials Comprising Hydroxyapatite

The natural healing process of bone is impaired in the presence of tumors, trauma, or inflammation, necessitating external assistance for bone regeneration. The limitations of autologous/allogeneic bone grafting are still being discovered as research progresses. Bone tissue engineering (BTE) is now a crucial component of treating bone injuries and actively works to promote vascularization, a crucial stage in bone repair. A biomaterial with hydroxyapatite (HA), which resembles the mineral makeup of invertebrate bones and teeth, has demonstrated high osteoconductivity, bioactivity, and biocompatibility. However, due to its brittleness and porosity, which restrict its application, scientists have been prompted to explore ways to improve its properties by mixing it with other materials, modifying its structural composition, improving fabrication techniques and growth factor loading, and co-cultivating bone regrowth cells to stimulate vascularization. This review scrutinizes the latest five-year research on HA composite studies aimed at amplifying vascularization in bone regeneration.

Bone Morphogenic Protein and Mesenchymal Stem Cells to Regenerate Bone in Calvarial Defects: A Systematic Review

BACKGROUND

The use of bone morphogenic protein and mesenchymal stem cells has shown promise in promoting bone regeneration in calvarial defects. However, a systematic review of the available literature is needed to evaluate the efficacy of this approach.

METHODS

We comprehensively searched electronic databases using MeSH terms related to skull defects, bone marrow mesenchymal stem cells, and bone morphogenic proteins. Eligible studies included animal studies that used BMP therapy and mesenchymal stem cells to promote bone regeneration in calvarial defects. Reviews, conference articles, book chapters, and non-English language studies were excluded. Two independent investigators conducted the search and data extraction.

RESULTS

Twenty-three studies published between 2010 and 2022 met our inclusion criteria after a full-text review of the forty-five records found in the search. Eight of the 23 studies used mice as models, while 15 used rats. The most common mesenchymal stem cell was bone marrow-derived, followed by adipose-derived. BMP-2 was the most popular. Stem cells were embedded in Scaffold (13), Transduction (7), and Transfection (3), and they were delivered BMP to cells. Each treatment used 2 × 10⁴-1 × 10⁷ mesenchymal stem cells, averaging 2.26 × 10⁶. Most BMP-transduced MSC studies used lentivirus.

CONCLUSIONS

This systematic review examined BMP and MSC synergy in biomaterial scaffolds or alone. BMP therapy and mesenchymal stem cells in calvarial defects, alone, or with a scaffold regenerated bone. This method treats skull defects in clinical trials. The best scaffold material, therapeutic dosage, administration method, and long-term side effects need further study.

Efficient autocrine and paracrine signaling explain the osteogenic superiority of transgenic BMP-2 over rhBMP-2

Bone morphogenetic protein-2 (BMP-2) is an osteogenic protein used clinically to enhance bone healing. However, it must be applied in very high doses, causing adverse side effects and increasing costs while providing only incremental benefit. Preclinical models of bone healing using gene transfer to deliver BMP-2 suggest that transgenic BMP-2 is much more osteogenic than rhBMP-2. Using a reporter mesenchymal cell line, we found transgenic human BMP-2 cDNA to be at least 100-fold more effective than rhBMP-2 in signaling. Moreover, a substantial portion of the BMP-2 produced by the transduced cells remained cell associated. Signaling by transgenic BMP-2 occurred via binding to the type I receptor, activating the associated kinase and generating phospho-smads. Signaling was partially resistant to noggin, an important extracellular inhibitor of BMP-2, possibly because nascent BMP-2 binds to its cell surface receptor during secretion and thus signals in a protected peri-cellular environment. Although the amounts of BMP-2 secreted by the transduced cells were too low to affect distant cells, transduced cells were able to induce signaling in a paracrine fashion that required close proximity of the cells, possibly cell-to-cell contact. The greater osteogenic potency of transgenic BMP-2 was confirmed with human bone marrow stromal cells.

Application of rhBMP in spinal fusion surgery: any correlation of cancer incidence? A systematic review and meta-analysis

PURPOSE

Safety concerns regarding the application of bone morphogenetic proteins (BMPs) have been highlighted in recent years. It is noted that both BMP and their receptors being identified as a trigger for cancer growth. Here, we aimed to determine the safety and efficacy of BMP for spinal fusion surgery.

METHODS

We conducted this systematic review on topics of spinal fusion surgery with rhBMP application from three database (PubMed, EuropePMC, and Clinicaltrials.gov) with MeSH phrases such as "rh-BMP," "rhBMP," "spine surgery," "spinal arthrodesis," and "spinal fusion" were searched (using the Boolean operators "and" and "or"). Our research includes all articles, as long as published in English language. In the face of disagreement between the two reviewers, we discussed it together until all authors reached a consensus. The primary key outcome of our study is the incidence of cancer following rhBMP implantation.

RESULTS

Our study included a total of 8 unique studies (n = 37,682). The mean follow-up varies among all studies, with the longest follow-up is 66 months. Our meta-analysis showed that exposure to rhBMP in spinal surgery did increase the risk of cancers (RR 1.85, 95%CI [1.05, 3.24], p = 0.03).

CONCLUSIONS

Our study found that rhBMP was not associated with the increased risk of cancer incidence within the rhBMP cohort. Still, we did face several limitations, in which further studies are needed to confirm the result of our meta-analysis.

Revisiting Resveratrol as an Osteoprotective Agent: Molecular Evidence from In Vivo and In Vitro Studies

Resveratrol (RSV) (3,5,4'-trihydroxystilbene) is a stilbene found in abundance in berry fruits, peanuts, and some medicinal plants. It has a diverse range of pharmacological activities, underlining the significance of illness prevention and health promotion. The purpose of this review was to delve deeper into RSV's bone-protective properties as well as its molecular mechanisms. Several in vivo studies have found the bone-protective effects of RSV in postmenopausal, senile, and disuse osteoporosis rat models. RSV has been shown to inhibit NF-κB and RANKL-mediated osteoclastogenesis, oxidative stress, and inflammation while increasing osteogenesis and boosting differentiation of mesenchymal stem cells to osteoblasts. Wnt/β-catenin, MAPKs/JNK/ERK, PI3K/AKT, FoxOs, microRNAs, and BMP2 are among the possible kinases and proteins involved in the underlying mechanisms. RSV has also been shown to be the most potent SIRT1 activator to cause stimulatory effects on osteoblasts and inhibitory effects on osteoclasts. RSV may, thus, represent a novel therapeutic strategy for increasing bone growth and reducing bone loss in the elderly and postmenopausal population.

Synergistic Effect of QNZ, an Inhibitor of NF-κB Signaling, and Bone Morphogenetic Protein 2 on Osteogenic Differentiation in Mesenchymal Stem Cells through Fibroblast-Induced Yes-Associated Protein Activation

Biomaterials carrying recombinant human bone morphogenetic protein 2 (BMP2) have been developed to enhance bone regeneration in the treatment of bone defects. However, various reports have shown that in the bone repair microenvironment, fibroblasts can inhibit BMP2-induced osteogenic differentiation in mesenchymal stem cells (MSCs). Thus, factors that can target fibroblasts and improve BMP2-mediated osteogenesis should be explored. In this project, we focused on whether or not an inhibitor of the NF-κB signaling pathway, QNZ (EVP4593), could play a synergistic role with BMP2 in osteogenesis by regulating the activity of fibroblasts. The roles of QNZ in regulating the proliferation and migration of fibroblasts were examined. In addition, the effect of QNZ combined with BMP2 on the osteogenic differentiation of MSCs was evaluated both in vitro and in vivo. Furthermore, the detailed mechanisms by which QNZ improved BMP2-mediated osteogenesis through the modulation of fibroblasts were analyzed and revealed. Interestingly, we found that QNZ inhibited the proliferation and migration of fibroblasts. Thus, QNZ could relieve the inhibitory effects of fibroblasts on the homing and osteogenic differentiation of mesenchymal stem cells. Furthermore, biomaterials carrying both QNZ and BMP2 showed better osteoinductivity than did those carrying BMP2 alone both in vitro and in vivo. It was found that the mechanism of QNZ involved reactivating YAP activity in mesenchymal stem cells, which was inhibited by fibroblasts. Taken together, our results suggest that QNZ may be a candidate factor for assisting BMP2 in inducing osteogenesis. The combined application of QNZ and BMP2 in biomaterials may be promising for the treatment of bone defects in the future.

Drug-Delivery Nanoplatform with Synergistic Regulation of Angiogenesis-Osteogenesis Coupling for Promoting Vascularized Bone Regeneration

It has been confirmed that substantial vascularization is an effective strategy to heal large-scale bone defects in the field of bone tissue engineering. The local application of deferoxamine (DFO) is among the most common and effective methods for promoting the formation of blood vessels, although its short half-life in plasma, rapid clearance, and poor biocompatibility limit its therapeutic suitability. Herein, zeolitic imidazolate framework-8 (ZIF-8) was selected as a vehicle to extend the half-life of DFO. In the present study, a nano DFO-loaded ZIF-8 (DFO@ZIF-8) drug delivery system was established to promote angiogenesis-osteogenesis coupling. The nanoparticles were characterized, and their drug loading efficiency was examined to confirm the successful synthesis of nano DFO@ZIF-8. Additionally, due to the sustained release of DFO and Zn²⁺, DFO@ZIF-8 NPs were able to promote angiogenesis in human umbilical vein endothelial cells (HUVECs) culture and osteogenesis in bone marrow stem cells (BMSCs) in vitro. Furthermore, the DFO@ZIF-8 NPs promoted vascularization by enhancing the expression of type H vessels and a vascular network. The DFO@ZIF-8 NPs promoted bone regeneration in vivo by increasing the expression of OCN and BMP-2. RNA sequencing analysis revealed that the PI3K-AKT-MMP-2/9 and HIF-1α pathways were upregulated by DFO@ZIF-8 NPs in HUVECs, ultimately leading to the formation of new blood vessels. In addition, the mechanism by which DFO@ZIF-8 NPs promoted bone regeneration was potentially related to the synergistic effect of angiogenesis-osteogenesis coupling and Zn²⁺-mediation of the MAPK pathway. Taken together, DFO@ZIF-8 NPs, which were demonstrated to have low cytotoxicity and excellent coupling of angiogenesis and osteogenesis, represent a promising strategy for the reconstruction of critical-sized bone defects.

Isolation, characterization, proteome, miRNAome, and the embryotrophic effects of chicken egg yolk nanovesicles (vitellovesicles)

Egg yolk constitutes about a third of the structure of the chicken egg however, the molecular structure and physiological effects of egg yolk-derived lipid membranous vesicles are not clearly understood. In this study, for the first record, the egg yolk nanovesicles (vitellovesicles, VVs) were isolated, characterized, and used as a supplement for porcine embryo culture. Yolks of ten freshly oviposited eggs were filtered and ultracentrifuged at 100,000 × g for 3 h to obtain a pellet. Cryogenic transmission electron microscopy and nanoparticle tracking analysis of the pellet revealed bilipid membranous vesicles. Protein contents of the pellet were analyzed using tandem mass spectrometry and the miRNA content was also profiled through BGISEQ-500 sequencer. VVs were supplemented with the in vitro culture medium of day-7 hatched parthenogenetic blastocysts. After 2 days of blastocyst culture, the embryonic cell count was increased in VVs supplemented embryos in comparison to the non-supplemented embryos. TUNEL assay showed that apoptotic cells were increased in control groups when compared with the VVs supplemented group. Reduced glutathione was increased by 2.5 folds in the VVs supplemented group while reactive oxygen species were increased by 5.3 folds in control groups. Quantitative PCR analysis showed that VVs significantly increased the expression of lipid metabolism-associated genes (monoglyceride lipase and lipase E), anti-apoptotic gene (BCL2), and superoxide dismutase, while significantly reducing apoptotic gene (BAX). Culturing embryos on Matrigel basement membrane matrix indicated that VVs significantly enhanced embryo attachment and embryonic stem cell outgrowths compared to the non-supplemented group. This considers the first report to characterize the molecular bioactive cargo contents of egg yolk nanovesicles to show their embryotrophic effect on mammalian embryos. This effect might be attributed to the protein and miRNA cargo contents of VVs. VVs can be used for the formulation of in vitro culture medium for mammalian embryos including humans.

Progress of Wnt Signaling Pathway in Osteoporosis

Osteoporosis, one of the serious health diseases, involves bone mass loss, bone density diminishing, and degeneration of bone microstructure, which is accompanied by a tendency toward bone fragility and a predisposition to fracture. More than 200 million people worldwide suffer from osteoporosis, and the cost of treating osteoporotic fractures is expected to reach at least $25 billion by 2025. The generation and development of osteoporosis are regulated by genetic factors and regulatory factors such as TGF-β, BMP, and FGF through multiple pathways, including the Wnt signaling pathway, the Notch signaling pathway, and the MAPK signaling pathway. Among them, the Wnt signaling pathway is one of the most important pathways. It is not only involved in bone development and metabolism but also in the differentiation and proliferation of chondrocytes, mesenchymal stem cells, osteoclasts, and osteoblasts. Dkk-1 and SOST are Wnt inhibitory proteins that can inhibit the activation of the canonical Wnt signaling pathway and block the proliferation and differentiation of osteoblasts. Therefore, they may serve as potential targets for the treatment of osteoporosis. In this review, we analyzed the mechanisms of Wnt proteins, β-catenin, and signaling molecules in the process of signal transduction and summarized the relationship between the Wnt signaling pathway and bone-related cells. We hope to attract attention to the role of the Wnt signaling pathway in osteoporosis and offer new perspectives and approaches to making a diagnosis and giving treatment for osteoporosis.

Vertebral Primary Bone Lesions: Review of Management Options

The assessment and treatment of vertebral primary bone lesions continue to pose a unique yet significant challenge. Indeed, there exists little in the literature in the way of compiling and overviewing the various types of vertebral lesions, which can often have complicated intervention strategies. Given the severe consequences of mismanaged vertebral bone tumors-including the extreme loss of motor function-it is clear that such an overview of spinal lesion care is needed. Thus, in the following paper, we aim to address the assessment of various vertebral primary bone lesions, outlining the relevant nonsurgical and surgical interventional methods. We describe examples of primary benign and malignant tumors, comparing and contrasting their differences. We also highlight emerging treatments and approaches for these tumors, like cryoablation and stereotactic body radiation therapy. Ultimately, we aim to emphasize the need for further guidelines in regard to correlating lesion type with proper therapy, underscoring the innate diversity of vertebral primary bone lesions in the literature.

A Mixture of Cervus elaphus sibiricus and Glycine max (L.) Merrill Inhibits Ovariectomy-Induced Bone Loss Via Regulation of Osteogenic Molecules in a Mouse Model

Osteoporosis is a metabolic skeletal disease characterized by lowered bone mineral density and quality, which lead to an increased risk of fracture. The aim of this study was to evaluate the anti-osteoporosis effects of a mixture (called BPX) of Cervus elaphus sibiricus and Glycine max (L.) Merrill and its underlying mechanisms using an ovariectomized (OVX) mouse model. BALB/c female mice (7 weeks old) were ovariectomized. From 12 weeks of ovariectomy, mice were administered BPX (600 mg/kg) mixed in a chow diet for 20 weeks. Changes in bone mineral density (BMD) and bone volume (BV), histological findings, osteogenic markers in serum, and bone formation-related molecules were analyzed. Ovariectomy notably decreased the BMD and BV scores, while these were significantly attenuated by BPX treatment in the whole body, femur, and tibia. These anti-osteoporosis effects of BPX were supported by the histological findings for bone microstructure from H&E staining, increased activity of alkaline phosphatase (ALP), but a lowered activity of tartrate-resistant acid phosphatase (TRAP) in the femur, along with other parameters in the serum, including TRAP, calcium (Ca), osteocalcin (OC), and ALP. These pharmacological actions of BPX were explained by the regulation of key molecules in the bone morphogenetic protein (BMP) and mitogen-activated protein kinase (MAPK) pathways. The present results provide experimental evidence for the clinical relevance and pharmaceutical potential of BPX as a candidate for anti-osteoporosis treatment, especially under postmenopausal conditions.