TGF-β and BMP signaling in osteoblast differentiation and bone formation

Emerging Roles of Macrophage Polarization in Osteoarthritis: Mechanisms and Therapeutic Strategies

Osteoarthritis (OA) is the most common chronic degenerative joint disease in middle-aged and elderly people, characterized by joint pain and dysfunction. Macrophages are key players in OA pathology, and their activation state has been studied extensively. Various studies have suggested that macrophages might respond to stimuli in their microenvironment by changing their phenotypes to pro-inflammatory or anti-inflammatory phenotypes, which is called macrophage polarization. Macrophages accumulate and become polarized (M1 or M2) in many tissues, such as synovium, adipose tissue, bone marrow, and bone mesenchymal tissues in joints, while resident macrophages as well as other stromal cells, including fibroblasts, chondrocytes, and osteoblasts, form the joint and function as an integrated unit. In this study, we focus exclusively on synovial macrophages, adipose tissue macrophages, and osteoclasts, to investigate their roles in the development of OA. We review recent key findings related to macrophage polarization and OA, including pathogenesis, molecular pathways, and therapeutics. We summarize several signaling pathways in macrophage reprogramming related to OA, including NF-κB, MAPK, TGF-β, JAK/STAT, PI3K/Akt/mTOR, and NLRP3. Of note, despite the increasing availability of treatments for osteoarthritis, like intra-articular injections, surgery, and cellular therapy, the demand for more effective clinical therapies has remained steady. Therefore, we also describe the current prospective therapeutic methods that deem macrophage polarization to be a therapeutic target, including physical stimulus, chemical compounds, and biological molecules, to enhance cartilage repair and alleviate the progression of OA.

Suppression of BMP signaling restores mitral cell development impaired by FGF signaling deficits in mouse olfactory bulb

Fibroblast growth factors (FGFs) and bone morphogenic proteins (BMPs) play various important roles in the development of the central nervous system. However, the roles of FGF and BMP signaling in the development of the olfactory bulb (OB) are largely unknown. In this study, we first showed the expression of FGF receptors (FGFRs) and BMP receptors (BMPRs) in OB RGCs, radial glial cells (RGCs) in the developing OB, which generate the OB projection neurons, mitral and tufted cells. When the FGF signaling was inhibited by a dominant-negative form of FGFR1 (dnFGFR1), OB RGCs accelerated their state transition to mitral cell precursors without affecting their transcription cascade and fate. However, the mitral cell precursors could not radially migrate to form the mitral cell layer (MCL). In addition, FGF signaling inhibition reduced the expression of a BMP antagonist, Noggin, in the developing OB. When BMP signaling was suppressed by the ectopic expression of Noggin or a dominant-negative form of BMPR1a (dnBMPR1a) in the developing OB, the defect in MCL formation caused by the dnFGFR1 was rescued. However, the dnBMPR1a did not rescue the accelerated state transition of OB RGCs. These results demonstrate that FGF signaling is important for OB RGCs to maintain their self-renewal state and MCL formation. Moreover, the suppression of BMP signaling is required for mitral cells to form the MCL. This study sheds new light on the roles of FGFs and BMPs in OB development.

Effect of runx2b deficiency in intermuscular bones on the regulatory network of lncRNA-miRNA-mRNA

Intermuscular bones (IBs) are mineralized spicules that negatively impact the quality and value of fish products. Runx2b is a crucial modulator in promoting bone formation through regulating osteoblast differentiation. Previous studies suggested that loss of runx2b gene completely inhibited IBs formation in zebrafish. However, how the whole transcriptome, including mRNA and non-coding RNA (ncRNA), affects the IBs development in runx2b-/- zebrafish are not known. The aim of this study was to identify the regulatory networks of differentially expressed (DE) lncRNAs, miRNAs, and mRNAs in zebrafish with and without IBs (runx2b+/+ fish and runx2b-/- fish) utilizing high-throughput sequencing techniques. All together there are 1051 mRNAs, 456 lncRNAs, and 18 miRNAs differentially expressed were found between these two strains. The analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG) has highlighted significant pathways linked to the development of IBs, specifically the TGF-beta and Wnt signaling pathways, and a number of genes concentrated on these two signaling pathways related to the formation of IBs. Further, 1989 competing endogenous RNA (ceRNA) networks were created according to the correlation among mRNAs, miRNAs and lncRNAs. The ceRNA networks results revealed 52 ceRNA pairs related to the IBs formation, consisting of 52 mRNAs, 37 lncRNAs, and 6 miRNAs. Of these, we found that dre-miR-2189 was the key element of ceRNA pairs, interacting with 19 mRNAs and 11 lncRNAs, and MSTRG.13175.1 could regulate sp7 expression by interacting with dre-miR-2189 to function in osteogenic differentiation. Subsequent experiments at the cellular level also revealed the interaction mechanism. The outcomes indicated a crucial role of miRNAs and lncRNAs in the development of fish IBs, which offer new views into the functions of ncRNAs involved in IBs formation.

Biological background of colorectal polyps and carcinomas with heterotopic ossification: A national study and literature review

The biological mechanisms and potential clinical impact of heterotopic ossification (HO) in colorectal neoplasms are not fully understood. This study investigates the clinicopathological characteristics of colorectal neoplasms associated with HO and examines the potential role of the bone morphogenetic protein (BMP) pathway in development of HO. An artificial intelligence (AI) based classification of colorectal cancers (CRC) exhibiting HO and their association with consensus molecular subtypes (CMS) is performed. The study included 77 cases via the Dutch nationwide Pathology databank. Immunohistochemistry for BMP2, SMAD4, and Osterix was performed. An AI algorithm assessed the tumour-stroma ratio to approximate the CMS. A literature search yielded 96 case reports, which were analysed and compared with our cases for clinicopathological parameters. HO was more frequently observed in our cohort in traditional serrated adenomas (25%), tubulovillous adenomas (25%) and juvenile polyps (25%), while in the literature it was most often seen in juvenile polyps (38.2%) and inflammatory polyps (29.4%). In both cohorts, carcinomas were mostly conventional (>60%) followed by mucinous and serrated adenocarcinomas. Higher expression of BMP2, SMAD4, and Osterix was observed in tumour and/or stromal cells directly surrounding bone, indicating activation of the BMP pathway. The tumour-stroma analysis appointed >50% of the cases to the mesenchymal subtype (CMS4) (59%). HO has a predilection for serrated and juvenile/inflammatory polyps, mucinous and serrated adenocarcinomas. BMP signalling is activated and seems to play a role in formation of HO in colorectal neoplasms. In line with TGFβ/BMP pathway activation associated with CMS4 CRC, HO seems associated with CMS4.

GDF15 Contributes to the Regulation of the Mechanosensitive Responses of PdL Fibroblasts through the Modulation of IL-37

During orthodontic tooth movement (OTM), areas of compressive and tensile forces are generated in the periodontal ligament (PdL), a mechanoreactive connective tissue between the teeth and alveolar bone. Mechanically stimulated PdL fibroblasts (PdLFs), the main cell type of PdL, express significantly increased levels of growth differentiation factor 15 (GDF15). In compressed PdL areas, GDF15 plays a fundamental role in modulating relevant OTM processes, including inflammation and osteoclast activation. However, the specific function of this factor in tensile areas has not yet been investigated. Thus, the aim of this study was to investigate the role of GDF15 in the mechanoresponse of human PdLFs (hPdLFs) that were exposed to biaxial tensile forces in vitro. Using siRNA-mediated knockdown experiments, we demonstrated that GDF15 had no impact on the anti-inflammatory force response of elongated hPdLFs. Although the anti-inflammatory markers IL1RN and IL10, as well as the activation of immune cells remained unaffected, we demonstrated an inhibitory role of GDF15 for the IL-37 expression. By analyzing osteogenic markers, including ALPL and RUNX2, along with an assessment of alkaline phosphatase activation, we further showed that the regulation of IL-37 by GDF15 modulates the osteogenic differentiation potential of hPdLFs. Despite bone resorption in tensile areas being rather limited, GDF15 was also found to positively modulate osteoclast activation in those areas, potentially by adjusting the IL-37 levels. In light of our new findings, we hypothesize that GDF15 modulates force-induced processes in tissue and bone remodeling through its various intra- and extracellular signaling pathways as well as interaction partners. Potentially acting as a master regulator, the modulation of GDF15 levels may hold relevance for clinical implications.

Transcriptome Sequencing Identifies Abnormal lncRNAs and mRNAs and Reveals Potentially Hub Immune-Related mRNA in Osteoporosis with Vertebral Fracture

Background

Recent studies have put forward the viewpoint of "bone immunology", which holds that the immune system and immune factors play an important regulatory role in the occurrence and development of osteoporosis. This study was intended to identify genetic characteristics of differentially expressed immune-related mRNA and lncRNA in patients combined with osteoporosis and vertebral fracture.

Methods

The peripheral blood samples were obtained from 3 groups of subjects: healthy control (HC), osteoporosis patients without vertebral fracture (OWF), and osteoporosis patients combined with vertebral fracture (OVF). The data were integrated to obtain differentially expressed mRNAs (DEmRNAs) and differentially expressed lncRNAs (DElncRNAs). Subsequently, the protein-protein interaction (PPI) networks were constructed. Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analyses were performed. Cytoscape-cytoHubba plug-in was used to identify key DEmRNAs. Furthermore, lncRNA-miRNA-mRNA, mRNA-lncRNA co-expression and transcription factors (TFs) networks were constructed. In addition, real-time PCR verification was performed.

Results

Totally of 3378 lncRNA-mRNA pairs were obtained, and the lncRNA co-expressed mRNA was mainly enriched in immune-related pathways, especially in GO-biological process (GO-BP) analysis. A total of 8 hub immune-related DEmRNAs were obtained, including IL18R1, IL18RAP, SLC11A1, CSF2RA, CCR3, IL1R2, PGLYRP1, and IL1R1. The TFs network showed that 8 hub immune-related DEmRNAs had interacting TFs. The co-expression network showed that 7 hub immune-related DEmRNAs (IL18R1, IL18RAP, SLC11A1, CSF2RA, IL-1R2, PGLYRP1, and IL1R1) had lncRNA-mRNA co-expression relationship. In addition, the lncRNA-miRNA-mRNA network includes 32 miRNAs, 7 hub immune-related mRNAs (IL18R1, IL18RAP, CSF2RA, CCR3, IL1R2, PGLYRP1, and IL1R1), and 11 lncRNAs.

Conclusion

Our study provides a novel and in-depth identification of co-expressed mRNAs and lncRNAs in patients combined with osteoporosis and vertebral fracture at a molecular level. This may provide new candidate biomarkers for the diagnosis of patients with high-risk fractures in the future.

TGF-β1/Smad3 Signaling Is Required to Alleviate Fluoride-Induced Enamel Hypomineralization

Excessive fluoride intake during enamel development can affect enamel mineralization, leading to dental fluorosis. However, its potential mechanisms remain largely unexplored. In the present study, we aimed to investigate the impact of fluoride on the expressions of RUNX2 and ALPL during mineralization and the effect of TGF-β1 administration on fluoride treatment. A dental fluorosis model of newborn mice and an ameloblast cell line ALC were both used in the present study. The mice of the NaF group, including the mothers and newborns, were fed with water containing 150 ppm NaF after delivery to induce dental fluorosis. The mandibular incisors and molars showed significant abrasion in the NaF group. Immunostaining, qRT-PCR, and Western blotting analysis indicated that exposure to fluoride markedly down-regulated RUNX2 and ALPL in mouse ameloblasts and ALCs. Besides, fluoride treatment significantly decreased the mineralization level detected by ALP staining. Furthermore, exogenous TGF-β1 up-regulated RUNX2 and ALPL and promoted mineralization, while the addition of SIS3 could block such TGF-β1-induced up-regulation. In TGF-β1 conditional knockout mice, the immunostaining of RUNX2 and ALPL was weaker compared with wild-type mice. Exposure to fluoride inhibited the expressions of TGF-β1 and Smad3. Co-treatment of TGF-β1 and fluoride up-regulated RUNX2 and ALPL compared with the fluoride alone treatment, promoting mineralization. Collectively, our data indicated that TGF-β1/Smad3 signaling pathway was necessary for the regulatory effects of fluoride on RUNX2 and ALPL, and the fluoride-induced suppression of ameloblast mineralization was mitigated by activating TGF-β1/Smad3 signaling pathway.

Ellagic acid promotes osteoblasts differentiation via activating SMAD2/3 pathway and alleviates bone mass loss in OVX mice

Characterized by bone mass loss, osteoporosis is an orthopedic disease typically found in postmenopausal women and aging individuals. Consistent with its pathogenesis summarized as an imbalance in bone formation/resorption, current pharmacologically therapeutic strategies for osteoporosis mainly aim to promote bone formation or/and inhibit bone resorption. However, few effective drugs with mild clinical side effects have been developed, making it a well-concerned issue to seek appropriate drugs for osteoporosis. In this study, we investigated the effect of ellagic acid (EA) on osteogenesis in vitro and in vivo and searched for its molecular mechanism. Here, we showed that EA promoted osteogenic differentiation of MSCs, increased mRNA and protein expression levels of osteoblast marker genes Runt-related transcription factor2, Osterix, Alkaline phosphatase, Collagen type I alpha 1, Osteopontin and Osteocalcin. Furthermore, ovariectomized mice with orally administered EA (10 mg/kg, 50 mg/kg) had significantly higher bone mass than those in controls. And experiments such as fluorescence double-labeling and enzyme-linked immunosorbent assay also demonstrated that EA could promote osteogenesis in vivo. To probe the molecular mechanism of EA, we performed RNA sequencing analysis using EA-treated BMSCs. Significant up-regulation of SMAD2/3 transcription factors was identified by RNA-seq, and it was confirmed in vitro that EA promoted bone formation by activating the SMAD2/3 signaling pathway. Evidence from our present experiments indicates that EA may be a promising candidate for clinical treatment for osteoporosis in future.

Dehydrocostus lactone (DHC) promotes osteoblastic differentiation and mineralization through p38/RUNX-2 signaling

Dysregulation of osteoblastic differentiation is an important risk factor of osteoporosis, the therapy of which is challenging. Dehydrocostus lactone (DHC), a sesquiterpene isolated from medicinal plants, has displayed anti-inflammatory and antitumor properties. In this study, we investigated the effects of DHC on osteoblastic differentiation and mineralization of MC3T3-E1 cells. Interestingly, we found that DHC increased the expression of marker genes of osteoblastic differentiation, such as alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). Additionally, DHC increased the expressions of collagen type I alpha 1 (Col1a1) and collagen type I alpha 2 (Col1a2). We also demonstrate that DHC increased ALP activity. Importantly, the Alizarin Red S staining assay revealed that DHC enhanced osteoblastic differentiation of MC3T3-E1 cells. Mechanistically, it is shown that DHC increased the expression of Runx-2, a central regulator of osteoblastic differentiation. Treatment with DHC also increased the levels of phosphorylated p38, and its blockage using its specific inhibitor SB203580 abolished the effects of DHC on runt-related transcription factor 2 (Runx-2) expression and osteoblastic differentiation, suggesting the involvement of p38. Based on these findings, we concluded that DHC might possess a capacity for the treatment of osteoporosis by promoting osteoblastic differentiation.

Exploring the boost of steaming with wine on Ligustri Lucidi Fructus in treating postmenopausal osteoporosis based on superior "multi-component structure" and iron/bone metabolism coregulation

BACKGROUND

Clinical studies indicated that postmenopausal osteoporosis (PMOP) often accompanied by iron overload risk factor, which exacerbated bone metabolism disorders and accelerated PMOP. Previous research found that multicomponent in Ligustri Lucidi Fructus (FLL) or wine-steamed FLL (WFLL) acted on the common targets of iron overload and PMOP simultaneously, which indicated that FLL and WFLL probably regulated iron/bone metabolism dually. Additionally, WFLL had more superior effect according to the theory of Chinese medicine for thousands of years.

PURPOSE

To reveal the "superior multi-component structure (SMCS)" and its molecular mechanisms in parallelly down-regulating iron overload and rescuing bone metabolism by WFLL.

DESIGNS AND METHODS

HPLC fingerprinting was established to compare the chemical profiles of FLL and WFLL; Then, the chemical compositions and quality markers of FLL and WFLL were analyzed by UPLC-Orbitrap-MS/MS coupled with OPLS-DA; the dynamic contents of quality markers and the multi-component structure at different wine steaming times (WST) were simultaneously determined by HPLC-DAD. Meanwhile, the dynamic efficacy of FLL at different WST were hunt by systematic zebrafish model. Subsequently, potential mechanism of WFLL in treating PMOP accompanied with iron overload was obtained from network pharmacology (NP) and molecular docking (MD). Finally, zebrafish and ovariectomy rat model were carried out to validate this potential mechanism.

RESULTS

HPLC fingerprints similarity of 15 batches in FLL and WFLL were among 0.9-1.0. 126 compositions were identified, including 58 iridoids, 25 terpenes, 30 phenylethanoids, 7 flavonoids and 6 others. 20 quality markers associated with WFLL was revealed, and the ratio of phenylethanols: Iridoids: Triterpenes (P/I/T) was converted from 1: 15: 4.5 to 1: 0.8: 0.9 during steaming (0 - 24 h) calculated by the quantification of 11 quality markers; the bone mineralization and motor performance of zebrafish larvae indicated that the optimum efficacy of WFLL at 12 h (p < 0.05) in which the SMCS of P/I/T was converted to 1: 4: 1.8. NP discovered that BMP-Smad pathway is one of the potential mechanisms of FLL in anti PMOP and then regulated bone formation and iron overload simultaneously. MD revealed that 17 active ingredients and 10 core targets genes could spontaneously bind with appropriate affinity. Rats model verified that FLL and WFLL significantly reversed PMOP, based on the improvement in bone formation indexes (ALP, OPG, OGN), iron metabolism indicators (hepcidin, ferritin), bone microstructure (BMD, BV/TV, Tb. Th, Tb. N); Moreover, WFLL significant enhanced reversal effect in anti-PMOP compared to FLL (p < 0.05). FLL and WFLL increased genes and proteins expression (Hep, BMP-6, p-Smad1/5, Smad4) related to BMP-Smad pathway compared with model group, and WFLL was more superior than FLL (p< 0.05).

CONCLUSION

The SMCS of FLL was optimized by wine-steam, WFLL represented a dual effect in downregulating iron overload and promoting bone formation, and the BMP-Smad pathway is one of the potential molecular mechanisms.

The development of magnesium-based biomaterials in bone tissue engineering: A review

Bone regeneration is a vital clinical challenge in massive or complicated bone defects. Recently, bone tissue engineering has come to the fore to meet the demand for bone repair with various innovative materials. However, the reported materials usually cannot satisfy the requirements, such as ideal mechanical and osteogenic properties, as well as biocompatibility at the same time. Mg-based biomaterials have considerable potential in bone tissue engineering owing to their excellent mechanical strength and biosafety. Moreover, the biocompatibility and osteogenic activity of Mg-based biomaterials have been the research focuses in recent years. The main limitation faced in the applications of Mg-based biomaterials is rapid degradation, which can produce excessive Mg2+ and hydrogen, affecting the healing of the bone defect. In order to overcome the limitations, researchers have explored several ways to improve the properties of Mg-based biomaterials, including alloying, surface modification with coatings, and synthesizing other composite materials to control the degradation rate upon implantation. This article reviewed the osteogenic mechanism and requirement for appropriate degradation rate and focused on current progress in the biomedical use of Mg-based biomaterials to inspire more clinical applications of Mg in bone regeneration in the future.

Zizyphus mauritiana seed extract: Paving the way for next-generation bone constructs with nano-fluorohydroxyapatite/carboxymethyl chitosan nanocomposite scaffold

This is the first study that explored the potential use of Zizyphus mauritiana seed extract (ZSE) to synthesize nano-fluorohydroxyapatite/carboxymethyl chitosan nanocomposite scaffolds at different concentrations (CFZ1, CFZ2 and CFZ3) using co-precipitation method. The proposed scaffolds showed presence of intermolecular H bonding interactions between the constituents, according to the FTIR. The mechanical studies revealed shore hardness of 72 ± 4.6 and optimal compressive modulus in case of CFZ3 [1654.48 ± 1.6 MPa], that was comparable with that of human cortical bone. The SEM, TEM and platelet adhesion images corroborated uniformly distributed needle like particles in case of CFZ3 with an average size ranging from 22 to 26 nm, linked rough morphology, and appropriate hemocompatibility. The markedly up regulation in the ALP activity and protein adsorption upon increasing ZSE concentration demonstrated that CFZ nanocomposite scaffolds were compatible with osteoblastic cells relative to CF nanocomposite. The cytotoxicity study indicated that CFZ nanocomposite do not induce toxicity over MG-63 and did not aggravate LDH leakage in contrast to CF. The histopathological investigations on albino rats confirmed significantly improved regeneration of bone in the repair of a critical-size [8 mm] calvarium defect. Therefore, CFZ3 nanocomposite scaffold represents a simple, off-the-shelf solution to the combined challenges associated with bone defects.

Differentiation of Uc-MSCs into insulin secreting islet-like clusters by trypsin through TGF-beta signaling pathway

Differentiation of human umbilical cord mesenchymal stem cells (Uc-MSCs) into islet-like clusters which are capable of synthesizing and secreting insulin can potentially serve as donors for islet transplantation in the patient deficiency in islet β cell function both in type 1 or type 2 diabetic patients. Therefore, we developed an easy and higher efficacy approach by trypsinazing the Uc-MSCs and followed culture in differentiation medium to induce of Uc-MSCs differentiation into islet-like clusters, and the potential mechanism that in the early stage of differentiation was also investigated by using RNA-sequencing and bioinformatics. Results show that induction efficacy was reached to 98% and TGF-β signaling pathway may play critical role in the early stage differentiation, it was further confirmed that the retardant effect of differentiation progress either in cell morphology or in islet specific genes expression can be observed upon blocking the activation of TGF-β signaling pathway using specific inhibitor of LY2109761 (TβRI/II kinase inhibitor). Our current study, for the first time, development a protocol for differentiation of Uc-MSCs into islet-like clusters, and revealed the importance of TGF-β signaling pathway in the early stage of differentiation of Uc-MSCs into islet-like clusters. Our study will provide alternative approach for clinical treatment of either type I or type II diabtes mellitus with dysfunctional pancreatic islets.

In Vivo Evaluation of Tissue Biocompatibility of Calcium Silicate-based and Epoxy Resin-based Sealers

Introduction

Calcium silicate-based sealers are an alternative to be used into root canal, mainly to their biological properties. However, some biological parameters need to be determined in an in vivo animal research model. So, the aim of the present study was to evaluate in vivo the tissue biocompatibility of a calcium silicate-based sealer (EndoSequence BC Sealer) and an epoxy resin-based sealer (AH-Plus).

Materials and Methods

Polyethylene tubes were filled with freshly mixed sealers and implanted in connective subcutaneous tissue of 25 rats (5/euthanasia day) (Rattus norvegicus albinus). Empty tubes were used as controls and no tubes as sham. Histopathological (hematoxylin eosin) and histochemical (Picrosirius red) examinations were conducted at 3, 7, 15, 30 and 60 days (five rats/day) after the implantation procedure (n=5/group). The type/intensity of inflammation and collagenesis was analyzed statistically with Friedman or Kruskal-Wallis/Dunn tests (P<0.05).

Results

The profile of inflammation induced by AH-Plus (Median=2, Range=2-3) was significantly greater than that by Endosequence BC Sealer (Median=1, Range=1-1) during the 15-day experimentation period (P=0.018). After 30 days, both materials produced similar tissue reaction (P>0.05). AH-Plus and Endosequence BC Sealer (Median=2, Range=1-2) induced a high level of fibrosis after 60-day than control (Median=1, Range=1-1) and sham (Median=0, Range=0-0) groups (P<0.001) of fibrosis based in type I collagen increase (P=0.025 and P=0.021, respectively). Tissue necrosis was not observed and the bioceramic sealer showed significant signs of endocytosed (Median=1, Range=1-1) material after 7 days than other groups (Median=0, Range=0-0) (P<0.05). The calcium silicate-based sealer induced tissue repair faster than the epoxy resin-based sealer tested. However, both materials showed adequate biocompatibility and tolerance by subcutaneous tissues, with few differences in inflammatory profiles, formation of granulation tissue, and collagenesis.

Conclusions

It may be concluded that calcium silicate-based sealer (EndoSequence BC Sealer) and an epoxy resin-based sealer (AH-Plus) presented suitable biocompatibility.

The Therapeutic Effect of Natural Compounds on Osteoporosis through Ferroptosis

Ferroptosis is a newly discovered non-apoptotic cell death whose key is lipid peroxidation. It has been reported that ferroptosis is involved in the occurrence and development of tumors and nervous system and musculoskeletal diseases. Cellular ferroptosis contributes to the imbalance of bone homeostasis and is involved in the development of osteoporosis; however, the detailed mechanism of which is still unclear though it may provide a new direction for anti-osteoporosis. The current drugs used in the treatment of osteoporosis, such as bisphosphonates and teriparatide, have many side effects, increasing people's search for natural compounds to treat osteoporosis. This review paper briefly summarizes the current research regarding the mechanisms of ferroptosis and natural anti-osteoporosis compounds targeting its pathway.

M2 exosomes modified by hydrogen sulfide promoted bone regeneration by moesin mediated endocytosis

Bone defects caused by trauma or tumor led to high medical costs and poor life quality for patients. The exosomes, micro vesicles of 30-150 nm in diameter, derived from macrophages manipulated bone regeneration. However, the role of hydrogen sulfide (H2S) in the biogenesis and function of exosomes and its effects on bone regeneration remains elusive. In this study, we used H2S slow releasing donor GYY4137 to stimulate macrophages and found that H2S promoted the polarization of M2 macrophages to increase bone regeneration of MSCs in vitro and in vivo. Moreover, we developed the H2S pre-treated M2 macrophage exosomes and found these exosomes displayed significantly higher capacity to promote bone regeneration in calvarial bone defects by re-establishing the local immune microenvironment. Mechanically, H2S treatment altered the protein profile of exosomes derived from M2 macrophages. One of the significantly enriched exosomal proteins stimulated by H2S, moesin protein, facilitated the exosomes endocytosis into MSCs, leading to activated the β-catenin signaling pathway to promote osteogenic differentiation of MSCs. In summary, H2S pretreated M2 exosomes promoted the bone regeneration of MSCs via facilitating exosomes uptake by MSCs and activate β-catenin signaling pathway. This study not only provides new strategies for promoting bone regeneration, but also provides new insights for the effect and mechanism of exosomes internalization.

Cross Talk Between Cells and the Current Bioceramics in Bone Regeneration: A Comprehensive Review

The conventional approach for addressing bone defects and stubborn non-unions typically involves the use of autogenous bone grafts. Nevertheless, obtaining these grafts can be challenging, and the procedure can lead to significant morbidity. Three primary treatment strategies for managing bone defects and non-unions prove resistant to conventional treatments: synthetic bone graft substitutes (BGS), a combination of BGS with bioactive molecules, and the use of BGS in conjunction with stem cells. In the realm of synthetic BGS, a multitude of biomaterials have emerged for creating scaffolds in bone tissue engineering (TE). These materials encompass biometals like titanium, iron, magnesium, and zinc, as well as bioceramics such as hydroxyapatite (HA) and tricalcium phosphate (TCP). Bone TE scaffolds serve as temporary implants, fostering tissue ingrowth and the regeneration of new bone. They are meticulously designed to enhance bone healing by optimizing geometric, mechanical, and biological properties. These scaffolds undergo continual remodeling facilitated by bone cells like osteoblasts and osteoclasts. Through various signaling pathways, stem cells and bone cells work together to regulate bone regeneration when a portion of bone is damaged or deformed. By targeting signaling pathways, bone TE can improve bone defects through effective therapies. This review provided insights into the interplay between cells and the current state of bioceramics in the context of bone regeneration.

Bioinspired synthetic peptide-based biomaterials regenerate bone through biomimicking of extracellular matrix

There have been remarkable advancements in regenerative medicine for bone regeneration, tackling the worldwide health concern of tissue loss. Tissue engineering uses the body's natural capabilities and applies biomaterials and bioactive molecules to replace damaged or lost tissues and restore their functionality. While synthetic ceramics have overcome some challenges associated with allografts and xenografts, they still need essential growth factors and biomolecules. Combining ceramics and bioactive molecules, such as peptides derived from biological motifs of vital proteins, is the most effective approach to achieve optimal bone regeneration. These bioactive peptides induce various cellular processes and modify scaffold properties by mimicking the function of natural osteogenic, angiogenic and antibacterial biomolecules. The present review aims to consolidate the latest and most pertinent information on the advancements in bioactive peptides, including angiogenic, osteogenic, antimicrobial, and self-assembling peptide nanofibers for bone tissue regeneration, elucidating their biological effects and potential clinical implications.

Differential Gene Expression and Immune Cell Infiltration in Patients with Steroid-induced Necrosis of the Femoral Head

OBJECTIVE

The study aimed to study the differential gene expression and immune cell infiltration in patients with steroid-induced necrosis of the femoral head (SANFH), identify the key genes and immune cells of SANFH, and explore the relationship between immune cells and SANFH.

METHODS

The high-throughput gene chip dataset GSE123568 was downloaded from the GEO database, and the differential gene expression was analyzed with the R language. The STRING database and Cytoscape software were used to analyze the protein interaction network and screen key genes, and enrichment analysis was carried out on key genes. The infiltration of immune cells in SANFH patients was analyzed and verified by immunohistochemistry.

RESULTS

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 are key genes in the pathogenesis of SANFH, which mainly involve myeloid cell differentiation, cytokine-mediated signaling pathway, tumor necrosis factor-mediated signaling pathway, and cellular response to tumor necrosis factor through JAK-STAT, NOD-like receptor, toll-like receptor, and other signaling pathways, leading to the occurrence of diseases; immune infiltration and immunohistochemical results have shown the expression of memory B cells and activated dendritic cells as reduced in SANFH patients, while in the same SANFH samples, M1 macrophages have been positively correlated with monocytes, and neutrophils have been negatively correlated with monocytes expression.

CONCLUSION

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 have exhibited significant differences in SANFH (spontaneous osteonecrosis of the femoral head). Memory B cells, activated dendritic cells, M1 macrophages, monocytes, and neutrophils have shown abnormal expression in SANFH.

Exploring Omega-3's Impact on the Expression of Bone-Related Genes in Meagre (Argyrosomus regius)

Dietary supplementation with Omega-3 fatty acids seems to promote skeletal health. Therefore, their consumption at imbalanced or excessive levels has offered less beneficial or even prejudicial effects. Fish produced in aquaculture regimes are prone to develop abnormal skeletons. Although larval cultures are usually fed with diets supplemented with Omega-3 Long Chain Polyunsaturated fatty acids (LC-PUFAs), the lack of knowledge about the optimal requirements for fatty acids or about their impact on mechanisms that regulate skeletal development has impeded the design of diets that could improve bone formation during larval stages when the majority of skeletal anomalies appear. In this study, Argyrosomus regius larvae were fed different levels of Omega-3s (2.6% and 3.6% DW on diet) compared to a commercial diet. At 28 days after hatching (DAH), their transcriptomes were analyzed to study the modulation exerted in gene expression dynamics during larval development and identify impacted genes that can contribute to skeletal formation. Mainly, both levels of supplementation modulated bone-cell proliferation, the synthesis of bone components such as the extracellular matrix, and molecules involved in the interaction and signaling between bone components or in important cellular processes. The 2.6% level impacted several genes related to cartilage development, denoting a special impact on endochondral ossification, delaying this process. However, the 3.6% level seemed to accelerate this process by enhancing skeletal development. These results offered important insights into the impact of dietary Omega-3 LC-PUFAs on genes involved in the main molecular mechanism and cellular processes involved in skeletal development.

The molecular mechanisms of glycosaminoglycan biosynthesis regulating chondrogenesis and endochondral ossification

Disorders of chondrocyte differentiation and endochondral osteogenesis are major underlying factors in skeletal developmental disorders, including tibial dysplasia (TD), osteoarthritis (OA), chondrodysplasia (ACH), and multiple epiphyseal dysplasia (MED). Understanding the cellular and molecular pathogenesis of these disorders is crucial for addressing orthopedic diseases resulting from impaired glycosaminoglycan synthesis. Glycosaminoglycan is a broad term that refers to the glycan component of proteoglycan macromolecules. It is an essential component of the cartilage extracellular matrix and plays a vital role in various biological processes, including gene transcription, signal transduction, and chondrocyte differentiation. Recent studies have demonstrated that glycosaminoglycan biosynthesis plays a regulatory role in chondrocyte differentiation and endochondral osteogenesis by modulating various growth factors and signaling molecules. For instance, glycosaminoglycan is involved in mediating pathways such as Wnt, TGF-β, FGF, Ihh-PTHrP, and O-GlcNAc glycosylation, interacting with transcription factors SOX9, BMPs, TGF-β, and Runx2 to regulate chondrocyte differentiation and endochondral osteogenesis. To propose innovative approaches for addressing orthopedic diseases caused by impaired glycosaminoglycan biosynthesis, we conducted a comprehensive review of the molecular mechanisms underlying chondrocyte glycosaminoglycan biosynthesis, which regulates chondrocyte differentiation and endochondral osteogenesis. Our analysis considers the role of genes, glycoproteins, and associated signaling pathways during chondrogenesis and endochondral ossification.

Osteogenic Activities of Trifolirhizin as a Bioactive Compound for the Differentiation of Osteogenic Cells

Plant extracts are widely used as traditional medicines. Sophora flavescens Aiton-derived natural compounds exert various beneficial effects, such as anti-inflammatory, anticancer, antioxidant, and antiregenerative activities, through their bioactive compounds, including flavonoids and alkaloids. In the present study, we investigated the biological effects of an S. flavescens-derived flavonoid, trifolirhizin (trifol), on the stimulation of osteogenic processes during osteoblast differentiation. Trifol (>98% purity) was successfully isolated from the root of S. flavescens and characterized. Trifol did not exhibit cellular toxicity in osteogenic cells, but promoted alkaline phosphatase (ALP) staining and activity, with enhanced expression of the osteoblast differentiation markers, including Alp, ColI, and Bsp. Trifol induced nuclear runt-related transcription factor 2 (RUNX2) expression during the differentiation of osteogenic cells, and concomitantly stimulated the major osteogenic signaling proteins, including GSK3β, β-catenin, and Smad1/5/8. Among the mitogen-activated protein kinases (MAPKs), Trifol activated JNK, but not ERK1/2 and p38. Trifol also increased the osteoblast-mediated bone-forming phenotypes, including transmigration, F-actin polymerization, and mineral apposition, during osteoblast differentiation. Overall, trifol exhibits bioactive activities related to osteogenic processes via differentiation, migration, and mineralization. Collectively, these results suggest that trifol may serve as an effective phytomedicine for bone diseases such as osteoporosis.

Optineurin regulates osteoblast function in an age-dependent fashion in a mouse model of Paget's disease of bone

Paget's disease of bone (PDB) is a degenerative disorder affecting the skull and bones. Hyperactive osteoclasts (OCs) initiate bone degradation in the early stage, followed by increased bone formation by osteoblasts (OBs) in trabecular bones during the advanced stage. This OB-OC uncoupling results in bone deformations and irregular trabecular bone patterns. Current mouse models poorly replicate the advanced-stage characteristics of PDB. Optineurin (Gene: OPTN in humans, Optn in mice, protein: OPTN) has been implicated in PDB by genetic analyses. We identified PDB-like cortical lesions associated with OC hyperactivation in an Optn knockout (Optn-/-) mouse model. However, the effects of OPTN dysfunction on OBs and trabecular bone in advanced PDB remain unclear. In this study, we used the Optn-/- mouse model to investigate trabecular bone abnormalities and OB activity in PDB. Micro-computed tomography analysis revealed severe pagetic alterations in craniofacial bones and femurs of aged Optn-/- mice, resembling clinical manifestations of PDB. Altered OB activity was observed in aged Optn-/- mice, implicating compensatory OB response in trabecular bone anomalies. To elucidate the role of OC-OB interactions in PDB, we conducted in vitro experiments using OC conditioned media (CM) to examine the effects on OB osteogenic potential. We found OC CM restored compromised osteogenic induction of Optn-/- bone marrow stromal cells (BMSCs) from young mice, suggesting OCs maintain OB activity through secreted factors. Strikingly, OC CM from aged Optn-/- mice significantly enhanced osteogenic capability of Optn-/- BMSCs, providing evidence for increased OB activity in advanced stages of PDB. We further identified TGF-β/BMP signaling pathway in mediating the effects of OC CM on OBs. Our findings provide insights into Optn's role in trabecular bone abnormalities and OB activity in PDB. This enhances understanding of PDB pathogenesis and may contribute to potential therapeutic strategies for PDB and related skeletal disorders.

Development of artificial bone graft via in vitro endochondral ossification (ECO) strategy for bone repair

Endochondral ossification (ECO) is a form of bone formation whereby the newly deposited bone replaces the cartilage template. A decellularized artificial cartilage graft (dLhCG), which is composed of hyaline cartilage matrixes, has been developed in our previous study. Herein, the osteogenesis of bone marrow-derived MSCs in the dLhCG through chondrogenic differentiation, chondrocyte hypertrophy, and subsequent transdifferentiation induction has been investigated by simulating the physiological processes of ECO for repairing critical-sized bone defects. The MSCs were recellularized into dLhCGs and subsequently allowed to undergo a 14-day proliferation period (mrLhCG). Following this, the mrLhCG constructs were subjected to two distinct differentiation induction protocols to achieve osteogenic differentiation: chondrogenic medium followed by chondrocytes culture medium with a high concentration of fetal bovine serum (CGCC group) and canonical osteogenesis inducing medium (OI group). The formation of a newly developed artificial bone graft, ossified dLhCG (OsLhCG), as well as its capability of aiding bone defect reconstruction were characterized by in vitro and in vivo trials, such as mRNA sequencing, quantitative real-time PCR (qPCR), immunohistochemistry, the greater omentum implantation in nude mice, and repair for the critical-sized femoral defects in rats. The results reveal that the differentiation induction of MSCs in the CGCC group can realize in vitro ECO through chondrogenic differentiation, hypertrophy, and transdifferentiation, while the MSCs in the OI group, as expected, realize ossification through direct osteogenic differentiation. The angiogenesis and osteogenesis of OsLhCG were proved by being implanted into the greater omentum of nude mice. Besides, the OsLhCG exhibits the capability to achieve the repair of critical-size femoral defects.

Acyl-protein thioesterase1 alleviates senile osteoporosis by promoting osteoblast differentiation via depalmitoylation of BMPR1a

Objective

Senile osteoporosis (SOP) is an aging-related disease. The depalmitoylating enzyme Acyl-protein thiesterase1 (APT1) is involved in disease regulation. This study explored the mechanism of APT1 in SOP.

Methods

Eight-week-old SAMP6 mice were selected as SOP models and SAMR1 mice were controls, while osteoblasts were isolated from the femoral surface-soft tissues of SOP and control mice as in vitro models. Mouse femur morphological, bone mineral density (BMD), femur maximum elastic stress and maximum load, and APT1 expression were detected by HE staining, X-ray bone densitometer, material testing machine, and RT-qPCR and Western blot (WB). Osteoprotegrin (OPG)-labeled osteoblasts and APT1 localization in bone tissues were detected by immunohistochemical staining. APT1 expression was promoted in SOP mice by tail vein injection of APT1 lentivirus or promoted/silenced in osteoblasts by transfection of pcDNA3.1-APT1 overexpression or si-APT1 plasmids. SOP mouse osteoblast differentiation (OD), OD-related protein levels, osteoblast proliferation, BMPR1a palmitoylation level, and BMP/Smad pathway were detected by alizarin red staining, ALP activity detection, WB, CCK-8, and IP-ABE method. The effects of the pathway inhibitor LDN-193189 on OD were detected.

Results

APT1 was under-expressed in osteoblasts of bone tissue in SOP mice and mainly localized in osteoblasts. SOP mice manifested increased bone marrow cavity and bone trabecular space, thinned trabecular bone, decreased BMD, maximum elastic stress, maximum load, and reduced OPG-positive osteoblasts in bone tissues, which were averted by APT1 overexpression, thus alleviating SOP. APT1 overexpression increased osteoblast calcium nodules, ALP activity, OD-related protein levels, and cell proliferation. In mechanism, APT1 overexpression inhibited BMPR1a palmitoylation in SOP mouse osteoblasts and activated the BMP/Smad pathway, thus promoting OD.

Conclusion

APT1 activated the BMP/Smad pathway and promoted OD by regulating BMPR1a depalmitoylation, thus alleviating mouse SOP.

Targeting transforming growth factor beta signaling in metastatic osteosarcoma

Osteosarcoma is a rare type of bone cancer, and half of the cases affect children and adolescents younger than 20 years of age. Despite intensive efforts to improve both chemotherapeutics and surgical management, the clinical outcome for metastatic osteosarcoma remains poor. Transforming growth factor β (TGF-β) is one of the most abundant growth factors in bones. The TGF-β signaling pathway has complex and contradictory roles in the pathogenesis of human cancers. TGF-β is primarily a tumor suppressor that inhibits proliferation and induces apoptosis of premalignant epithelial cells. In the later stages of cancer progression, however, TGF-β functions as a metastasis promoter by promoting tumor growth, inducing epithelial-mesenchymal transition (EMT), blocking antitumor immune responses, increasing tumor-associated fibrosis, and enhancing angiogenesis. In contrast with the dual effects of TGF-β on carcinoma (epithelial origin) progression, TGF-β seems to mainly have a pro-tumoral effect on sarcomas including osteosarcoma (mesenchymal origin). Many drugs that target TGF-β signaling have been developed: neutralizing antibodies that prevent TGF-β binding to receptor complexes; ligand trap employing recombinant Fc-fusion proteins containing the soluble ectodomain of either type II (TβRII) or the type III receptor ((TβRIII), preventing TGF-β from binding to its receptors; antisense nucleotides that reduce TGF-β expression at the transcriptional/translational level; small molecule inhibitors of serine/threonine kinases of the type I receptor (TβRI) preventing downstream signaling; and vaccines that contain cell lines transfected with TβRII antisense genes, or target furin convertase, resulting in reduced TGF-β signaling. TGF-β antagonists have been shown to have effects on osteosarcoma in vitro and in vivo. One of the small molecule TβRI inhibitors, Vactosertib, is currently undergoing a phase 1/2 clinical trial to evaluate its effect on osteosarcoma. Several phase 1/2/3 clinical trials have shown TGF-β antagonists are safe and well tolerated. For instance, Luspatercept, a TGF-β ligand trap, has been approved by the FDA for the treatment of anemia associated with myeloid dysplastic syndrome (MDS) with ring sideroblasts/mutated SF3B1 with acceptable safety. Clinical trials evaluating the long-term safety of Luspatercept are in process.

Biological Evaluation of the Osteoinductive Potential of Dry Teeth after Chemical Demineralization Treatment Using the Tooth Transformer Device

Several studies have already demonstrated the biocompatibility of a tooth as a grafting material in the regeneration of bone tissue, showing its osteoconductive potential, while no studies have verified whether the osteoinductive potential of a tooth remains constant or is altered after its treatment with the Tooth Transformer (TT) device. The aim of the study was to demonstrate that the treatment with the TT device did not alter the osteoinductivity of an extracted tooth that was stored dry. Twelve extracted human teeth were collected from real patients. Caries, tartar and filling materials were removed from each tooth; each tooth was coarsely cut and stored at room temperature (RT) until use. Each sample was shredded, demineralized and disinfected, using the TT device. Protein extraction was carried out for each sample, and Western Blot analysis was performed to test the presence of mineralization protein LIM-1 and transforming growth factor-β. The presence of the human Bone Morphogenetic Protein 2 (BMP-2) and human collagen Type I (COL-I) was found in dry tooth samples processed with the TT device and subjected to Enzyme-Linked Immunosorbent Assay (ELISA) testing. The treatment of chemical demineralization using the TT device does not alter the osteoinductive potential of a dry tooth.

Effect of Stand-Alone Oblique Lateral Interbody Fusion (OLIF) in Treating Lumbar Spine Lesions

BACKGROUND The aim of this study was to investigate the safety and early clinical results of stand-alone oblique lateral interbody fusion (OLIF) in the fusion of lumbar spine lesions and to explore the indications for surgery. MATERIAL AND METHODS A total of 92 cases of lumbar spine lesions treated with stand-alone OLIF in 2 medical centers from October 2014 to December 2018 were retrospectively analyzed. We included 30 males and 62 females, ages 32-83 years. RESULTS Our results showed that the operation time was 60.92±27.40 min (average 36.6 min) and the intraoperative blood loss was 68.22±141.6 ml (average 23.8 ml). The height of the intervertebral space was restored - before the operation (9.23±1.94 mm) and (12.68±2.01 mm) after the operation - and it was 10.18±2.14 mm at the last follow-up. There was a significant difference between the postoperative and preoperative values (t=9.27, P<0.0001), and there was also a significant difference between the final follow-up and postoperative comparison value (t=8.43, P<0.0001). CONCLUSIONS The use of stand-alone OLIF in treating fusion of lumbar spine lesions showed excellent clinical efficacy and achieved the expected clinical improvements.

Osteogenic Potential of Human Dental Pulp Stem Cells (hDPSCs) Growing on Poly L-Lactide-Co-Caprolactone and Hyaluronic Acid (HYAFF-11TM) Scaffolds

Bone tissue engineering using different scaffolds is a new therapeutic approach in regenerative medicine. This study explored the osteogenic potential of human dental pulp stem cells (hDPSCs) grown on a hydrolytically modified poly(L-lactide-co-caprolactone) (PLCL) electrospun scaffold and a non-woven hyaluronic acid (HYAFF-11™) mesh. The adhesion, immunophenotype, and osteogenic differentiation of hDPSCs seeded on PLCL and HYAFF-11™ scaffolds were analyzed. The results showed that PLCL and HYAFF-11™ scaffolds significantly supported hDPSCs adhesion; however, hDPSCs' adhesion rate was significantly higher on PLCL than on HYAFF-11™. SEM analysis confirmed good adhesion of hDPSCs on both scaffolds before and after osteogenesis. Alizarin red S staining showed mineral deposits on both scaffolds after hDPSCs osteogenesis. The mRNA levels of runt-related transcription factor 2 (Runx2), collagen type I (Coll-I), osterix (Osx), osteocalcin (Ocn), osteopontin (Opn), bone sialoprotein (Bsp), and dentin sialophosphoprotein (Dspp) gene expression and their proteins were higher in hDPSCs after osteogenic differentiation on both scaffolds compared to undifferentiated hDPSCs on PLCL and HYAFF-11™. These results showed that PLCL scaffolds provide a better environment that supports hDPSCs attachment and osteogenic differentiation than HYAFF-11™. The high mRNA of early osteogenic gene expression and mineral deposits observed after hDPSCs osteogenesis on a PLCL mat indicated its better impact on hDPSCs' osteogenic potential than that of HYAFF-11™, and hDPSC/PLCL constructs might be considered in the future as an innovative approach to bone defect repair.

Consequences of Aging on Bone

With the aging of the global population, the incidence of musculoskeletal diseases has been increasing, seriously affecting people's health. As people age, the microenvironment within skeleton favors bone resorption and inhibits bone formation, accompanied by bone marrow fat accumulation and multiple cellular senescence. Specifically, skeletal stem/stromal cells (SSCs) during aging tend to undergo adipogenesis rather than osteogenesis. Meanwhile, osteoblasts, as well as osteocytes, showed increased apoptosis, decreased quantity, and multiple functional limitations including impaired mechanical sensing, intercellular modulation, and exosome secretion. Also, the bone resorption function of macrophage-lineage cells (including osteoclasts and preosteoclasts) was significantly enhanced, as well as impaired vascularization and innervation. In this study, we systematically reviewed the effect of aging on bone and the within microenvironment (including skeletal cells as well as their intracellular structure variations, vascular structures, innervation, marrow fat distribution, and lymphatic system) caused by aging, and mechanisms of osteoimmune regulation of the bone environment in the aging state, and the causal relationship with multiple musculoskeletal diseases in addition with their potential therapeutic strategy.

Joint multi-ancestry and admixed GWAS reveals the complex genetics behind human cranial vault shape

The cranial vault in humans is highly variable, clinically relevant, and heritable, yet its genetic architecture remains poorly understood. Here, we conduct a joint multi-ancestry and admixed multivariate genome-wide association study on 3D cranial vault shape extracted from magnetic resonance images of 6772 children from the ABCD study cohort yielding 30 genome-wide significant loci. Follow-up analyses indicate that these loci overlap with genomic risk loci for sagittal craniosynostosis, show elevated activity cranial neural crest cells, are enriched for processes related to skeletal development, and are shared with the face and brain. We present supporting evidence of regional localization for several of the identified genes based on expression patterns in the cranial vault bones of E15.5 mice. Overall, our study provides a comprehensive overview of the genetics underlying normal-range cranial vault shape and its relevance for understanding modern human craniofacial diversity and the etiology of congenital malformations.

Bone regeneration property of tooth-derived bone substitute prepared chairside for periodontal bone defects: an experimental study

BACKGROUND

Periodontitis often leads to progressive destruction and loss of alveolar bone, the reconstruction of which remains difficult in periodontal therapy. As a novel bone graft material, tooth-derived bone substitute (TDBS) processed from extracted teeth has been previously reported about its osteoconductivity and promising results in bone regeneration. This study was to investigate the biological effects and bone regeneration properties of TDBS in vitro and in vivo using rat periodontal bone defect model.

METHODS

Three groups of materials were used in the experiments: TDBS, TDBS treated with ethylene diamine tetraacetic acid (EDTA) (TDBS-E), and allogeneic bone materials. Calcium (Ca) and phosphate (P) ion dissolutions were quantified by spectrophotometer for seven days. The releases of bone morphogenetic protein-2 (BMP-2) and transforming growth factor-β1 (TGF-β1) were identified by enzyme-linked immunosorbent assay (ELISA). Human osteoblast proliferation, migration, and differentiation were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell counting, alkaline phosphatase activity (ALP), and alizarin red staining (ARS), respectively. Furthermore, the osteogenic effects of TDBS on periodontal furcation bone defects were evaluated at eight weeks postoperatively using micro-computed tomography (Micro-CT) and histological analysis.

RESULTS

The dissolution of both Ca and P ions in TDBS increased over time. The BMP-2 released from TDBS was significantly higher than that from TDBS-E and allografts, while the TGF-β1 release from TDBS and TDBS-E groups was higher than that in the allografts. The TDBS-E group could induce the highest level of osteoblast proliferation compared to other groups. Cell migration with allografts co-culture was significantly induced compared to the blank control. However, all groups demonstrated similar positive effects on osteoblast differentiation. Furthermore, in the periodontal model, all materials could effectively enhance bone regeneration in the furcation defect.

CONCLUSIONS

The TDBS prepared chairside as an autogenous bone graft, demonstrating osteoinductivity, which enhances the osteogenic biological characteristics. Therefore, TDBS is suggested as an economical and biocompatible material for periodontal bone regeneration.

Canonical Wnt and TGF-β/BMP signaling enhance melanocyte regeneration but suppress invasiveness, migration, and proliferation of melanoma cells

Melanoma is the deadliest form of skin cancer and develops from the melanocytes that are responsible for the pigmentation of the skin. The skin is also a highly regenerative organ, harboring a pool of undifferentiated melanocyte stem cells that proliferate and differentiate into mature melanocytes during regenerative processes in the adult. Melanoma and melanocyte regeneration share remarkable cellular features, including activation of cell proliferation and migration. Yet, melanoma considerably differs from the regenerating melanocytes with respect to abnormal proliferation, invasive growth, and metastasis. Thus, it is likely that at the cellular level, melanoma resembles early stages of melanocyte regeneration with increased proliferation but separates from the later melanocyte regeneration stages due to reduced proliferation and enhanced differentiation. Here, by exploiting the zebrafish melanocytes that can efficiently regenerate and be induced to undergo malignant melanoma, we unravel the transcriptome profiles of the regenerating melanocytes during early and late regeneration and the melanocytic nevi and malignant melanoma. Our global comparison of the gene expression profiles of melanocyte regeneration and nevi/melanoma uncovers the opposite regulation of a substantial number of genes related to Wnt signaling and transforming growth factor beta (TGF-β)/(bone morphogenetic protein) BMP signaling pathways between regeneration and cancer. Functional activation of canonical Wnt or TGF-β/BMP pathways during melanocyte regeneration promoted melanocyte regeneration but potently suppressed the invasiveness, migration, and proliferation of human melanoma cells in vitro and in vivo. Therefore, the opposite regulation of signaling mechanisms between melanocyte regeneration and melanoma can be exploited to stop tumor growth and develop new anti-cancer therapies.

Significance of Premature Vertebral Mineralization in Zebrafish Models in Mechanistic and Pharmaceutical Research on Hereditary Multisystem Diseases

Zebrafish are increasingly becoming an important model organism for studying the pathophysiological mechanisms of human diseases and investigating how these mechanisms can be effectively targeted using compounds that may open avenues to novel treatments for patients. The zebrafish skeleton has been particularly instrumental in modeling bone diseases as-contrary to other model organisms-the lower load on the skeleton of an aquatic animal enables mutants to survive to early adulthood. In this respect, the axial skeletons of zebrafish have been a good read-out for congenital spinal deformities such as scoliosis and degenerative disorders such as osteoporosis and osteoarthritis, in which aberrant mineralization in humans is reflected in the respective zebrafish models. Interestingly, there have been several reports of hereditary multisystemic diseases that do not affect the vertebral column in human patients, while the corresponding zebrafish models systematically show anomalies in mineralization and morphology of the spine as their leading or, in some cases, only phenotype. In this review, we describe such examples, highlighting the underlying mechanisms, the already-used or potential power of these models to help us understand and amend the mineralization process, and the outstanding questions on how and why this specific axial type of aberrant mineralization occurs in these disease models.

Differentiation of osteoblasts: the links between essential transcription factors

Osteoblasts, cells derived from mesenchymal stem cells (MSCs) in the bone marrow, are cells responsible for bone formation and remodeling. The differentiation of osteoblasts from MSCs is triggered by the expression of specific genes, which are subsequently controlled by pro-osteogenic pathways. Mature osteoblasts then differentiate into osteocytes and are embedded in the bone matrix. Dysregulation of osteoblast function can cause inadequate bone formation, which leads to the development of bone disease. Various key molecules are involved in the regulation of osteoblastogenesis, which are transcription factors. Previous studies have heavily examined the role of factors that control gene expression during osteoblastogenesis, both in vitro and in vivo. However, the systematic relationship of these transcription factors remains unknown. The involvement of ncRNAs in this mechanism, particularly miRNAs, lncRNAs, and circRNAs, has been shown to influence transcriptional factor activity in the regulation of osteoblast differentiation. Here, we discuss nine essential transcription factors involved in osteoblast differentiation, including Runx2, Osx, Dlx5, β-catenin, ATF4, Ihh, Satb2, and Shn3. In addition, we summarize the role of ncRNAs and their relationship to these essential transcription factors in order to improve our understanding of the transcriptional regulation of osteoblast differentiation. Adequate exploration and understanding of the molecular mechanisms of osteoblastogenesis can be a critical strategy in the development of therapies for bone-related diseases.Communicated by Ramaswamy H. Sarma.

Berberine and aspirin prevent traumatic heterotopic ossification by inhibition of BMP signalling pathway and osteogenic differentiation

Heterotopic ossification (HO) is a pathological process that often occurs in soft tissues following severe trauma. There is no effective therapy for HO. The BMP signalling pathway plays an essential role in the pathogenesis of HO. Our previous study showed that AMPK negatively regulates the BMP signalling pathway and osteogenic differentiation. The present study aims to study the effect of two AMPK activators berberine and aspirin on osteogenic differentiation and HO induced by traumatic injury. The effects of two AMPK activators, berberine and aspirin, on BMP signalling and osteogenic differentiation were measured by western blot, ALP and Alizarin red S staining in C3H10T1/2 cells. A mouse model with Achilles tenotomy was employed to assess the effects of berberine and aspirin on HO using μCT and histological analysis. First, our study showed that berberine and aspirin inhibited phosphorylation of Smad1/5 induced by BMP6 and the inhibition was attributed to the down-regulation of ALK2 expression. Second, the combination of berberine and aspirin yielded more potent effects on BMP signalling. Third, we further found that there was an additive effect of berberine and aspirin combination on osteogenic differentiation. Finally, we found that berberine and aspirin blocked trauma-induced ectopic bone formation in mice, which may be through suppression of phosphorylation of Smad1/5 in injured tissues. Collectively, these findings indicate that berberine and aspirin inhibit osteogenic differentiation in C3H10T1/2 cells and traumatic HO in mice, possibly through the down-regulation of the BMP signalling pathway. Our study sheds a light on prevention and treatment of traumatic HO using AMPK pharmacological activators berberine and aspirin.

PRMT1-mediated arginine methylation promotes postnatal calvaria bone formation through BMP-Smad signaling

PRMT1 deficiency leads to severely compromised craniofacial development in neural crest cells and profound abnormalities of the craniofacial tissues. Here, we show PRMT1 controls several key processes in calvarial development, including frontal and parietal bone growth rate and the boundary between sutural and osteogenic cells. Pharmacologic PRMT1 inhibition suppresses MC3T3-E1 cell viability and proliferation and impairs osteogenic differentiation. In this text, we investigate the cellular events behind the morphological changes and uncover an essential role of PRMT1 in simulating postnatal bone formation. Inhibition of PRMT1 alleviated BMP signaling through Smads phosphorylation and reduced the deposition of the H4R3me2a mark. Our study demonstrates a regulatory mechanism whereby PRMT1 regulates BMP signaling and the overall properties of the calvaria bone through Smads methylation, which may facilitate the development of an effective therapeutic strategy for craniosynostosis.

Osteoimmunity-regulating nanosilicate-reinforced hydrogels for enhancing osseointegration

Following the introduction of osteo-immunomodulation as a new and important strategy to enhance material osseointegration, achieving an appropriate immune response after biomaterial implantation has become a significant challenge for efficient bone repair. In this study, a nanosilicate-reinforced sodium alginate (SA) hydrogel was fabricated by introducing montmorillonite (MMT) nanoparticles. Meanwhile, an immunogenically bioactive agent, harmine (HM), was loaded and released to induce macrophage differentiation into the M2 type. The fabricated SA/MMT/HM (SMH) hydrogel exhibited improved mechanical stiffness and stability, which also efficiently promoted macrophage anti-inflammatory M2 phenotype polarization and enhanced the secretion of pro-tissue healing cytokines for inducing a favorable immunomodulatory microenvironment for the osteogenic differentiation of bone marrow stromal cells (BMSCs). Furthermore, a rat air-pouch model and a critical-size bone defect model were used and the results showed that the SMH hydrogel increased the proportion of M2 macrophages and markedly reduced local inflammation, while enhancing desirable new bone formation. Transcriptomic analysis revealed that the SMH hydrogel accelerated the M1-to-M2 transition of macrophages by inhibiting relevant inflammatory signaling pathways and activating the PI3K-AKT1 signaling pathway. Taken together, this high-intensity immunomodulatory hydrogel may be a promising biomaterial for bone regeneration and provide a valuable base and positive enlightenment for massive bone defect repair.

Analysis of Cellular Crosstalk and Molecular Signal between Periosteum-Derived Precursor Cells and Peripheral Cells During Bone Healing Process Using a Paper-Based Osteogenesis-On-A-Chip Platform

Periosteum-derived progenitor cells (PDPCs) are highly promising cell sources that are indispensable in the bone healing process. Adipose-derived stem cells (ADSCs) are physiologically close to periosteum tissue and release multiple growth factors to promote the bone healing process. Co-culturing PDPCs and ADSCs can construct periosteum-bone tissue microenvironments for the study of cellular crosstalk and molecular signal in the bone healing process. In the current work, a paper-based osteogenesis-on-a-chip platform was successfully developed to provide an in vitro three-dimensional coculture model. The platform was a paper substrate sandwiched between PDPC-hydrogel and ADSC-hydrogel suspensions. Cell secretion could be transferred through the paper substrate from one side to another side. Growth factors including BMP2, TGF-β, POSTN, Wnt proteins, PDGFA, and VEGFA were directly analyzed by a paper-based immunoassay. Cellular crosstalk was studied by protein expression on the paper substrate. Moreover, osteogenesis of PDPCs was investigated by examining the mRNA expressions of PDPCs after culture. Neutralizing and competitive assays were conducted to understand the correlation between growth factors secreted from ADSCs and the osteogenesis of PDPCs. In vitro periosteum-bone tissue microenvironment was established by the paper-based osteogenesis-on-a-chip platform. The proposed approach provides a promising assay of cellular crosstalk and molecular signal in 3D coculture microenvironment that may potentially lead to the development of effective bone regeneration therapy.

Deubiquitinase USP17 Regulates Osteoblast Differentiation by Increasing Osterix Protein Stability

Deubiquitinases (DUBs) are essential for bone remodeling by regulating the differentiation of osteoblast and osteoclast. USP17 encodes for a deubiquitinating enzyme, specifically known as ubiquitin-specific protease 17, which plays a critical role in regulating protein stability and cellular signaling pathways. However, the role of USP17 during osteoblast differentiation has not been elusive. In this study, we initially investigated whether USP17 could regulate the differentiation of osteoblasts. Moreover, USP17 overexpression experiments were conducted to assess the impact on osteoblast differentiation induced by bone morphogenetic protein 4 (BMP4). The positive effect was confirmed through alkaline phosphatase (ALP) expression and activity studies since ALP is a representative marker of osteoblast differentiation. To confirm this effect, Usp17 knockdown was performed, and its impact on BMP4-induced osteoblast differentiation was examined. As expected, knockdown of Usp17 led to the suppression of both ALP expression and activity. Mechanistically, it was observed that USP17 interacted with Osterix (Osx), which is a key transcription factor involved in osteoblast differentiation. Furthermore, overexpression of USP17 led to an increase in Osx protein levels. Thus, to investigate whether this effect was due to the intrinsic function of USP17 in deubiquitination, protein stabilization experiments and ubiquitination analysis were conducted. An increase in Osx protein levels was attributed to an enhancement in protein stabilization via USP17-mediated deubiquitination. In conclusion, USP17 participates in the deubiquitination of Osx, contributing to its protein stabilization, and ultimately promoting the differentiation of osteoblasts.

BMP-9 Improves the Osteogenic Differentiation Ability over BMP-2 through p53 Signaling In Vitro in Human Periosteum-Derived Cells

Bone morphogenetic proteins (BMPs) have tremendous therapeutic potential regarding the treatment of bone and musculoskeletal disorders due to their osteo-inductive ability. More than twenty BMPs have been identified in the human body with various functions, such as embryonic development, skeleton genesis, hematopoiesis, and neurogenesis. BMPs can induce the differentiation of MSCs into the osteoblast lineage and promote the proliferation of osteoblasts and chondrocytes. BMP signaling is also involved in tissue remodeling and regeneration processes to maintain homeostasis in adults. In particular, growth factors, such as BMP-2 and BMP-7, have already been approved and are being used as treatments, but it is unclear as to whether they are the most potent BMPs that induce bone formation. According to recent studies, BMP-9 is known to be the most potent inducer of the osteogenic differentiation of mesenchymal stem cells, both in vitro and in vivo. However, its exact role in the skeletal system is still unclear. In addition, research results suggest that the molecular mechanism of BMP-9-mediated bone formation is also different from the previously known BMP family, suggesting that research on signaling pathways related to BMP-9-mediated bone formation is actively being conducted. In this study, we performed a phosphorylation array to investigate the signaling mechanism of BMP-9 compared with BMP-2, another influential bone-forming growth factor, and we compared the downstream signaling system. We present a mechanism for the signal transduction of BMP-9, focusing on the previously known pathway and the p53 factor, which is relatively upregulated compared with BMP-2.

Alkaline shear-thinning micro-nanocomposite hydrogels initiate endogenous TGFβ signaling for in situ bone regeneration

Recruiting endogenous stem cells to bone defects without stem cell transplantation and exogenous factor delivery represents a promising strategy for bone regeneration. Herein, we develop an alkaline shear-thinning micro-nanocomposite hydrogel (10-MmN), aiming to alkaline-activate endogenous TGFβ1 and achieve in situ bone regeneration. It contains polyethyleneimine (PEI)-modified gelatin, laponite nanoplatelets (LAP), a bicarbonate buffer with a pH of 10, and gelatin microspheres (MSs). PEI-modified gelatin plays a pivotal role in hydrogel fabrication. It endows the system with sufficient positive charges, and forms a shear-thinning nanocomposite matrix in the pH 10 buffer (10-mN) with negatively charged LAP via electrostatic gelation. For biological functions, the pH 10 buffer dominates alkaline activation of endogenous serum TGFβ1 to recruit rat bone marrow stem cells through the Smad pathway, followed by improved osteogenic differentiation. In addition, MSs are incorporated into 10-mN to form 10-MmN, and function as substrates to provide good attachment sites for the recruited stem cells and facilitate further their osteogenic differentiation. In a rat critical-sized calvarial defect model, 10-MmN exhibits excellent biocompatibility, biodegradability, hydrogel infusion and retention in bone defects with flexible shapes and active bleeding. Importantly, it repairs ~95% of the defect areas in 3 months by recruiting TGFβR2+ and CD90+CD146+ stem cells, and promoting cell proliferation, osteogenic differentiation and bone formation. The present study provides a biomaterial-based strategy to regulate alkalinity in bone defects for the initiation of endogenous TGFβ signaling, which can be extended to treat other diseases.

Platelet-rich fibrin improves the osteoneogenesis in non-critical defects in calvaria: a histological and histometric study

PURPOSE

The aim of this study was to evaluate the effect of platelet-rich fibrin (PRF) and autograft on non-critical bone repair.

METHODS

Four bone defects (8.3 × 2 mm) were produced on the calvarium of 15 rabbits. The surgical defects were treated with either autograft, autograft associated to PRF, PRF alone, and sham. Animals were euthanized on the second, fourth or sixth posteoperative week. Histological analyses for presence of bone development on deffect was evaluated comparing the groups treated with autograft and without the autograft separately within the same period. Mann-Whitney's tests were used to compare the percentage of bone repair in each post-operative period for autograft × autograft + PRF groups and also for control × PRF groups (α = 5%).

RESULTS

No differences were observed between the groups that received autograft and autograft associated to PRF on the second and fourth postoperative week, but areas treated with PRF demonstrated significant osteogenesis when compared to sham group on the fourth and sixth weeks. The groups that received PRF (with autograft or alone) demonstrated an enlarged bone deposition when compared to their control group.

CONCLUSIONS

The use of PRF may influence bone repair and improve the bone deposition in late period of repair demonstrating osteoconductive and osteogenic properties.

Mesenchymal Stem/Stromal Cells: Immunomodulatory and Bone Regeneration Potential after Tumor Excision in Osteosarcoma Patients

Osteosarcoma (OS) is a type of bone cancer that is derived from primitive mesenchymal cells typically affecting children and young adults. The current standard of treatment is a combination of neoadjuvant chemotherapy and surgical resection of the cancerous bone. Post-resection challenges in bone regeneration arise. To determine the appropriate amount of bone to be removed, preoperative imaging techniques such as bone and CT scans are employed. To prevent local recurrence, the current standard of care suggests maintaining bony and soft tissue margins from 3 to 7 cm beyond the tumor. The amount of bone removed in an OS patient leaves too large of a deficit for bone to form on its own and requires reconstruction with metal implants or allografts. Both methods require the bone to heal, either to the implant or across the allograft junction, often in the setting of marrow-killing chemotherapy. Therefore, the issue of bone regeneration within the surgically resected margins remains an important challenge for the patient, family, and treating providers. Mesenchymal stem/stromal cells (MSCs) are potential agents for enhancing bone regeneration post tumor resection. MSCs, used with scaffolds and growth factors, show promise in fostering bone regeneration in OS cases. We spotlight two MSC types-bone marrow-derived (BM-MSCs) and adipose tissue-derived (ASCs)-highlighting their bone regrowth facilitation and immunomodulatory effects on immune cells like macrophages and T cells, enhancing therapeutic outcomes. The objective of this review is two-fold: review work demonstrating any ability of MSCs to target the deranged immune system in the OS microenvironment, and synthesize the available literature on the use of MSCs as a therapeutic option for stimulating bone regrowth in OS patients post bone resection. When it comes to repairing bone defects, both MB-MSCs and ASCs hold great potential for stimulating bone regeneration. Research has showcased their effectiveness in reconstructing bone defects while maintaining a non-tumorigenic role following wide resection of bone tumors, underscoring their capability to enhance bone healing and regeneration following tumor excisions.

The Effects of Platelet-Rich Fibrin in the Behavior of Mineralizing Cells Related to Bone Tissue Regeneration-A Scoping Review of In Vitro Evidence

Platelet-rich fibrin (PRF) is a second-generation blood concentrate that serves as an autologous approach for both soft and hard tissue regeneration. It provides a scaffold for cell interaction and promotes the local release of growth factors. PRF has been investigated as an alternative to bone tissue therapy, with the potential to expedite wound healing and bone regeneration, though the mechanisms involved are not yet fully understood. This review aims to explore the in vitro evidence of PRF's effects on the behavior of mineralizing cells related to bone tissue regeneration. A systematic electronic search was conducted up to August 2023, utilizing three databases: PubMed, Web of Science, and Scopus. A total of 76 studies were selected, which presented in vitro evidence of PRF's usefulness, either alone or in conjunction with other biomaterials, for bone tissue treatment. PRF membranes' influence on the proliferation, differentiation, and mineralization of bone cells is linked to the constant release of growth factors, resulting in changes in crucial markers of bone cell metabolism and behavior. This further reinforces their therapeutic potential in wound healing and bone regeneration. While there are some notable differences among the studies, the overall results suggest a positive effect of PRF on cell proliferation, differentiation, mineralization, and a reduction in inflammation. This points to its therapeutic potential in the field of regenerative medicine. Collectively, these findings may help enhance our understanding of how PRF impacts basic physiological processes in bone and mineralized tissue.

Guided Bone Regeneration Using Barrier Membrane in Dental Applications

Guided bone regeneration (GBR) is a widely used technique in preclinical and clinical studies due to its predictability. Its main purpose is to prevent the migration of soft tissue into the osseous wound space, while allowing osseous cells to migrate to the site. GBR is classified into two main categories: resorbable and non-resorbable membranes. Resorbable membranes do not require a second surgery but tend to have a short resorption period. Conversely, non-resorbable membranes maintain their mechanical strength and prevent collapse. However, they require removal and are susceptible to membrane exposure. GBR is often used with bone substitute graft materials to fill the defect space and protect the bone graft. The membrane can also undergo various modifications, such as surface modification and biological factor loading, to improve barrier functions and bone regeneration. In addition, bone regeneration is largely related to osteoimmunology, a new field that focuses on the interactions between bone and the immune system. Understanding these interactions can help in developing new treatments for bone diseases and injuries. Overall, GBR has the potential to be a powerful tool in promoting bone regeneration. Further research in this area could lead to advancements in the field of bone healing. This review will highlight resorbable and non-resorbable membranes with cellular responses during bone regeneration, provide insights into immunological response during bone remodeling, and discuss antibacterial features.

Bone Involvement in Rheumatoid Arthritis and Spondyloartritis: An Updated Review

Several rheumatologic diseases are primarily distinguished by their involvement of bone tissue, which not only serves as a mere target of the condition but often plays a pivotal role in its pathogenesis. This scenario is particularly prominent in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Given the immunological and systemic nature of these diseases, in this review, we report an overview of the pathogenic mechanisms underlying specific bone involvement, focusing on the complex interactions that occur between bone tissue's own cells and the molecular and cellular actors of the immune system, a recent and fascinating field of interest defined as osteoimmunology. Specifically, we comprehensively elaborate on the distinct pathogenic mechanisms of bone erosion seen in both rheumatoid arthritis and spondyloarthritis, as well as the characteristic process of aberrant bone formation observed in spondyloarthritis. Lastly, chronic inflammatory arthritis leads to systemic bone involvement, resulting in systemic bone loss and consequent osteoporosis, along with increased skeletal fragility.

17β-Trenbolone activates androgen receptor, upregulates transforming growth factor beta/bone morphogenetic protein and Wnt signaling pathways, and induces masculinization of caudal and anal fins in female guppies (Poecilia reticulata)

Sexually mature female guppies (Poecilia reticulata) were exposed to environmentally relevant concentrations (20, 200, and 2000 ng/L) of 17β-trenbolone for four weeks. As evidenced by the increased caudal fin index and anal fins developing into gonopodium-like structures, exposed females displayed masculinized secondary sexual characteristics. Differential gene expression and subsequent pathway analysis of mRNA sequencing data revealed that the transcription of transforming growth factor beta/bone morphogenetic protein signaling pathway and Wnt signaling pathway were upregulated following 17β-trenbolone exposure. Enzyme-linked immunosorbent assays showed that the bone morphogenetic protein 7 protein content was elevated after 17β-trenbolone exposure. Finally, real-time PCR revealed that 17β-trenbolone treatment significantly increased androgen receptor mRNA levels, and molecular docking showed potent interaction between 17β-trenbolone and guppy androgen receptor. Furthermore, 17β-trenbolone-induced masculinization of caudal and anal fins in female guppies, concomitant to the upregulated expression of differentially expressed genes involved in the above-mentioned two signaling pathways, was significantly inhibited by flutamide (androgen receptor antagonist). These findings demonstrated that 17β-trenbolone masculinized fins of female guppies by activating the androgen receptor. This study revealed that 17β-trenbolone could upregulate signaling pathways related to fin growth and differentiation, and eventually cause caudal and anal fin masculinization in female guppies.

The role of E3 ubiquitin ligases in bone homeostasis and related diseases

The ubiquitin-proteasome system (UPS) dedicates to degrade intracellular proteins to modulate demic homeostasis and functions of organisms. These enzymatic cascades mark and modifies target proteins diversly through covalently binding ubiquitin molecules. In the UPS, E3 ubiquitin ligases are the crucial constituents by the advantage of recognizing and presenting proteins to proteasomes for proteolysis. As the major regulators of protein homeostasis, E3 ligases are indispensable to proper cell manners in diverse systems, and they are well described in physiological bone growth and bone metabolism. Pathologically, classic bone-related diseases such as metabolic bone diseases, arthritis, bone neoplasms and bone metastasis of the tumor, etc., were also depicted in a UPS-dependent manner. Therefore, skeletal system is versatilely regulated by UPS and it is worthy to summarize the underlying mechanism. Furthermore, based on the current status of treatment, normal or pathological osteogenesis and tumorigenesis elaborated in this review highlight the clinical significance of UPS research. As a strategy possibly remedies the limitations of UPS treatment, emerging PROTAC was described comprehensively to illustrate its potential in clinical application. Altogether, the purpose of this review aims to provide more evidence for exploiting novel therapeutic strategies based on UPS for bone associated diseases.

Cytomodulin-10 modified GelMA hydrogel with kartogenin for in-situ osteochondral regeneration

The incidence of osteochondral defect is increasing year by year, but there is still no widely accepted method for repairing the defect. Hydrogels loaded with bioactive molecules have provided promising alternatives for in-situ osteochondral regeneration. Kartogenin (KGN) is an effective and steady small molecule with the function of cartilage regeneration and protection which can be further boosted by TGF-β. However, the high cost, instability, and immunogenicity of TGF-β would limit its combined effect with KGN in clinical application. In this study, a composite hydrogel CM-KGN@GelMA, which contained TGF-β1 analog short peptide cytomodulin-10 (CM-10) and KGN, was fabricated. The results indicated that CM-10 modified on GelMA hydrogels exerted an equivalent role in enhancing chondrogenesis as TGF-β1, and this effect was also boosted when combined with KGN. Moreover, it was revealed that CM-10 and KGN had a synergistic effect on promoting the chondrogenesis of BMSCs by up-regulating the expression of RUNX1 and SOX9 at both mRNA and protein levels in vitro. Finally, the composite hydrogel exhibited a satisfactory osteochondral defect repair effect in vivo, showing similar structures close to the native tissue. Taken together, this study has revealed that CM-10 may serve as an alternative for TGF-β1 and can collaborate with KGN to accelerate chondrogenesis, which suggests that the fabricated CM-KGN@GelMA composite hydrogel can be acted as a potential scaffold for osteochondral defect regeneration. STATEMENT OF SIGNIFICANCE: Kartogenin and TGF-β have shown great value in promoting osteochondral defect regeneration, and their combined application can enhance the effect and show great potential for clinical application. Herein, a functional CM-KGN@GelMA hydrogel was fabricated, which was composed of TGF-β1 mimicking peptide CM-10 and KGN. CM-10 in hydrogel retained an activity like TGF-β1 to facilitate BMSC chondrogenesis and exhibited boosting chondrogenesis by up-regulating RUNX1 and SOX9 when being co-applied with KGN. In vivo, the hydrogel promoted cartilage regeneration and subchondral bone reconstruction, showing similar structures as the native tissue, which might be vital in recovering the bio-function of cartilage. Thus, this study developed an effective scaffold and provided a promising way for osteochondral defect repair.