From cells to organs: progress and potential in cartilaginous organoids research.

While cartilage tissue engineering has significantly improved the speed and quality of cartilage regeneration, the underlying metabolic mechanisms are complex, making research in this area lengthy and challenging. In the past decade, organoids have evolved rapidly as valuable research tools. Methods to create these advanced human cell models range from simple tissue culture techniques to complex bioengineering approaches. Cartilaginous organoids in part mimic the microphysiology of human cartilage and fill a gap in high-fidelity cartilage disease models to a certain extent. They hold great promise to elucidate the pathogenic mechanism of a diversity of cartilage diseases and prove crucial in the development of new drugs. This review will focus on the research progress of cartilaginous organoids and propose strategies for cartilaginous organoid construction, study directions, and future perspectives.

Preliminary study of short-term outcomes and learning curves of robotic-assisted THA: comparison between closed platform robotic system and open platform robotic system.

BACKGROUND: Both closed platform and open platform robotic-assisted total hip arthroplasty (THA) have recently been recommended as a viable treatment option for achieving accurate positioning of components. Yet, limited studies paid attention to the differences between the closed platform robotic system and the open platform robotic system. Hence, this study aimed to investigate clinical outcomes, radiographic outcomes, complication rates and learning curve of two systems. MATERIALS AND METHODS: We retrospectively included 62 patients (31 closed robotic system and 31 open robotic system) who underwent THA between February 2021 and January 2023. The demographics, operating time, cup positioning, complications and hip Harris score were evaluated. Learning curves of operation time was conducted using cumulative sum (CUSUM) analysis. RESULTS: There were no differences in surgical time (76.7 ± 12.1 min vs. 72.3 ± 14.8 min), estimated blood loss (223.2 ± 13.2 ml vs. 216.9 ± 17 ml) and Harris Hip score (HHS) between closed platform robotic system and the open platform robotic system. The closed robotic system and the open robotic system were associated with a learning curve of 9 cases and 7 cases for surgical time respectively, based on the satisfying rate of Lewinnek's safe zone outliers (1/31, 96.8%) and no occurrence of complication. Both robotic systems had significant reduction in overall surgical time, the duration of acetabulum registration, and estimated blood loss between learning phase and proficiency phase. CONCLUSION: The authors suggest that the surgical outcomes and safe zone outlier rate of the open robotic-assisted THA were similar to those of the closed robotic-assisted THA. These two robotic-assisted are associated with comparable learning curves and both have the precise positioning of acetabular component. From learning phase to proficiency phase, the rate of positions within the safe zone differed only marginally (88.9-100% vs. 85.7-100%) based on a rather low number of patients. This is not a statistically significant difference. Therefore, we suggest that THA undergoing with the robotic-assisted system is the relatively useful way to achieve planned acetabular cup position so far.

Treatment of Morel-Lavallée Lesions (MLLs) with Mesh Incisions Combined with Quilting Sutures and Negative Pressure Wound Therapy (NPWT).

Purpose: The objective of this retrospective study was to evaluate the clinical effects of a novel treatment approach for Morel-Lavallée lesions (MLL) using a combination of suturing techniques and Negative Pressure Wound Therapy (NPWT) with mesh incisions. To summarize the clinical effects of a combination of suturing techniques and (Negative Pressure Wound Therapy) NPWT on the wall of Morel-Lavallée lesions (MLL) fibrotic pseudocapsules with mesh incisions in the treatment of MLLs. A retrospective analysis was performed on MLL patients from April 2017 to March 2021. Methods: This a retrospective case-control study and thirteen MLL patients were included in this retrospective analysis conducted between April 2017 and March 2021, who were treated with mesh incisions on the wall of the pseudocapsule, quilting suturing to degloved soft tissues, and NPWT. Physical examination, MRI, or ultrasound before surgery confirmed the diagnosis. Wound healing, secondary infection, recurrence, visual analog scale (VAS) scores before and after surgery, and skin and soft tissue condition were observed and evaluated. Results: The combination of mesh incisions, quilting sutures, and NPWT led to successful wound healing in 11 out of 13 cases without recurrent hematoma or secondary infection. Visual analog scale (VAS) scores significantly decreased after the operation, and the aesthetic and tactile qualities of the injured area improved. One case of skin and soft tissue necrosis infection before the operation, which healed after second-stage full-thickness skin grafting, 1 case healed after a dressing change, and the remaining 11 cases had wounds that healed by the first stage without secondary infection or recurrent hematoma formation. VAS scores decreased significantly after the operation, the appearance of the injured area was as expected, and the skin feel and elasticity recovered satisfactorily. Conclusion: The study demonstrates that the mesh incision technique, along with mattress sutures and NPWT, presents a feasible and effective approach for treating MLL with fibrotic pseudocapsules. This could shorten healing times, reduce risk of complications, and improve patient satisfaction.

YAP/miR-524-5p axis negatively regulates TXNIP expression to promote chondrosarcoma cell growth.

Chondrosarcoma (CHS) is the second most common bone malignant tumor and currently has limited treatment options. We have recently demonstrated that thioredoxin interacting protein (TXNIP) plays a crucial role in the oncogenesis of bone sarcoma, yet its implication in CHS is underdetermined. In the present study, we first found that knockdown of TXNIP promotes the proliferation of CHS cell largely through increasing their glycolytic metabolism, which is well-known as Warburg effect for providing energy. Consistent with our previous report that YAP is fundamental for CHS cell growth, herein we revealed that YAP functioned as an upstream molecule of TXNIP, and that YAP negatively regulated TXNIP mRNA and protein expression both in vitro and in vivo. Mechanistically, although knockdown of YAP upregulated both the nuclear and cytoplasmic TXNIP expression, we did not observe any obvious interaction between YAP and TXNIP; instead, miRNA-524-5p was demonstrated to be required for YAP-regulated TXNIP expression and thus controlling CHS cell growth. Together, our study reveals that TXNIP is a tumor suppressor in terms of CHS, and that the YAP/miRNA-524-5p/TXNIP signaling axis may provide a novel clue for CHS targeted therapy.

Outcomes of dual mobility articulation total hip arthroplasty in ipsilateral residual poliomyelitis.

BACKGROUND: Patients with poliomyelitis underwent total hip arthroplasty (THA) are known to be at higher risk of dislocation on account of muscular atrophy. This study aimed to investigate clinical outcomes, radiographic outcomes, complication rates, and survivorship of dual mobility THA in displaced femoral neck fractures of elderly with poliomyelitis. MATERIALS AND METHODS: We retrospectively included 17 patients (17 hips) with residual poliomyelitis who underwent THA with dual mobility articulation. Clinical outcomes were assessed with the visual analog scale (VAS) pain score, Oxford hip score, and University of California Los Angeles activity (UCLA) score. Radiographic outcomes were examined by radiographs. Complications and re-operations following THA were recorded. RESULTS: The mean follow-up period was 77.05 months. The mean VAS, Oxford hip score, and UCLA score were improved significantly. In all but one patient, no complications were occurred. Re-operation was carried out in one patient due to posterior dislocation. The Kaplan-Meier survivorship with an end point of re-operation for any reason was 94.1%. CONCLUSIONS: THA with dual mobility system is proved to be effective in strengthening stability and reducing the risk of dislocation, which is suitable for patients with neuromuscular disease. Hence, in elderly with residual poliomyelitis, dual mobility THA is a valid choice as a treatment for displaced femoral neck fractures.

The role of routine postoperative laboratory tests following hip hemiarthroplasty for an elderly femoral neck fracture.

BACKGROUND: Performing postoperative laboratory tests following joint arthroplasty is a regular practice. However, the role of routine postoperative laboratory tests in primary hip arthroplasty is currently in doubt. This study aimed to assess the role of routine postoperative laboratory tests for femoral neck fractures in elderly patients who underwent hip hemiarthroplasty and to evaluate the risk factors for postoperative laboratory testing abnormalities and related interventions. METHODS: This retrospective study reviewed 735 consecutive patients with femoral neck fractures (FNFs) who underwent hip hemiarthroplasty at a single tertiary academic organization. Patient characteristic features and laboratory testing values were recorded. Logistic regression models were calculated to identify risk factors. RESULTS: A total of 321 elderly patients (> 75 years of age) were ultimately enrolled for analysis. Abnormal postoperative laboratory tests were found in 265 patients (82.6%). Only a minority of the included patients (7.5%) needed medical intervention to treat postoperative laboratory testing abnormalities. Multivariate logistic regression analysis reported that a higher Charlson comorbidity index (CCI) (P = 0.03), abnormal preoperative haemoglobin level (P < 0.01), higher intraoperative blood loss (P < 0.01) and less frequent tranexamic acid use (P = 0.05) were risk factors for abnormal postoperative laboratory tests. Furthermore, a higher CCI has been identified as a risk factor for patients needing clinical interventions related to laboratory abnormalities. CONCLUSIONS: Because 92.5% of laboratory tests did not influence postoperative management, the authors suggest that routine laboratory tests after hip hemiarthroplasty for FNFs are less instructive for the majority of elderly patients. Nevertheless, for patients with identified risk factors, postoperative laboratory tests are still required to identify the abnormalities that need to be managed.

The multiple roles of Thy-1 in cell differentiation and regeneration.

Thy-1 is a 25-37 kDa glycophosphatidylinositol (GPI)-anchored cell surface protein that was discovered more than 50 years ago. Recent findings have suggested that Thy-1 is expressed on thymocytes, mesenchymal stem cells (MSCs), cancer stem cells, hematopoietic stem cells, fibroblasts, myofibroblasts, endothelial cells, neuronal smooth muscle cells, and pan T cells. Thy-1 plays vital roles in cell migration, adhesion, differentiation, transdifferentiation, apoptosis, mechanotransduction, and cell division, which in turn are involved in tumor development, pulmonary fibrosis, neurite outgrowth, and T cell activation. Studies have increasingly indicated a significant role of Thy-1 in cell differentiation and regeneration. However, despite recent research, many questions remain regarding the roles of Thy-1 in cell differentiation and regeneration. This review aimed to summarize the roles of Thy-1 in cell differentiation and regeneration. Furthermore, since Thy-1 is an outer leaflet membrane protein anchored by GPI, we attempted to address how Thy-1 regulates intracellular pathways through cis and trans signals. Due to the complexity and mystery surrounding the issue, we also summarized the Thy-1-related pathways in different biological processes, and this might provide novel insights in the field of cell differentiation and regeneration.

HSP90 regulates osteosarcoma cell apoptosis by targeting the p53/TCF-1-mediated transcriptional network.

Osteosarcoma (OS) is the most common bone tumor that occurs predominantly in children and teenagers. Although many genes, such as p53 and Rb1, have been shown to be mutated, deregulation of the canonical Wnt/ß-catenin signaling pathway is frequently observed in OS. We recently demonstrated that heat shock protein 90 (HSP90) is involved in the regulation of runt-related transcription factor 2 via the AKT/GSK-3ß/ß-catenin signaling pathway in OS. However, the precise role of T cell factors/lymphoid enhancer-binding factor (TCFs/LEF) family members, which are the major binding complex of ß-catenin, in OS is poorly understood. In the present study, we first demonstrated that TCF-1 is overexpressed in OS compared with other bone tumors. Knockdown of TCF-1 significantly induced cell cycle arrest, severe DNA damage, and subsequent caspase-3-dependent apoptosis. Interestingly, coexpression of HSP90 and TCF-1 was observed in OS, and mechanistically, we demonstrated that TCF-1 expression is regulated by HSP90 either through a ß-catenin-dependent mechanism or a direct degradation of the proteasome. We also found that overexpression of TCF-1 partially abolishes the apoptosis induced by HSP90 inhibition. Furthermore, we provided evidence that p53, but not miR-34a, plays a crucial role in the HSP90-regulated TCF-1 expression and subsequent apoptosis. Given the diverse combination regimens of HSP90 inhibition with some other treatments, we propose that the p53 status and the expression level of TCF-1 should be taken into consideration to enhance the therapeutic efficacy of HSP90 inhibition.

Elevated expression of ICAM-1 in synovium is associated with early inflammatory response for cartilage degeneration in type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) is increasingly being recognized as an independent risk factor for the onset and progression of osteoarthritis (OA). Extensive studies have focused on the contribution of obesity (excessive mechanical stress), comorbidity frequently found in T2DM, to cartilage destruction during OA development. However, a little is known about how diabetes-related inflammation may affect the local cartilage in a diabetic objective. In the present study, we were able to establish a T2DM rat model using a combination of a low dose of streptozotocin with high-fat and high-sugar diet. Although the cartilage integrity was comparable between the control and T2DM groups, the expression of matrix metalloproteinases-13 (MMP-13) was significantly upregulated in T2DM, indicating the initiation of an early cascade of cartilage degeneration. In parallel, an obvious alteration of subchondral bone remodeling (inhibition of bone formation) was observed, as evidenced by the reduction of osterix-expressing positive cells. Moreover, we demonstrated that the expression of intercellular adhesion molecule-1 (ICAM-1) in the serum and synovium of T2DM rats was elevated, accompanied by an increase of synovitis score. We also noticed that the number of F4/80-positive macrophage cells was significantly increased in the T2DM group. Mechanistically, the expression of ICAM-1 in fibroblast-like synoviocytes can be triggered by glucose and interleukin-1ß, which are the two important factors within the joint of T2DM. Given that MMP-13 expression was significantly upregulated in the T2DM cartilage, and that ICAM-1-mediated filtration of macrophage was associated with synovitis, we propose that ICAM-1 is essential for triggering a vicious cycle of inflammation within the joint, which together subsequently drivers the cartilage degradation.

Transcriptional regulation of Runx2 by HSP90 controls osteosarcoma apoptosis via the AKT/GSK-3ß/ß-catenin signaling.

Osteosarcoma (OS) is the most malignant primary bone tumor in children and adolescents with limited treatment options and poor prognosis. Recently, aberrant expression of Runx2 has been found in OS, thereby contributing to the development, and progression of OS. However, the upstream signaling molecules that regulate its expression in OS remain largely unknown. In the present study, we first confirmed that the inhibition of HSP90 with 17-AAG caused significant apoptosis of OS cells via a caspase-3-dependent mechanism, and that inhibition or knockdown of HSP90 by 17-AAG or siRNAs significantly suppressed mRNA and protein expression of Runx2. Furthermore, we provided evidence that Runx2 was transcriptionally regulated by HSP90 when using MG132 and CHX chase assay. We also demonstrated that ß-catenin was overexpressed in OS tissue, and that knockdown of ß-catenin induced pronounced apoptosis of OS cells in the presence or absence of 17-AAG. Interestingly, this phenomenon was accompanied with a significant reduction of Runx2 and Cyclin D1 expression, indicating an essential role of Runx2/Cyclin D1 in 17-AAG-induced cells apoptosis. Moreover, we demonstrated that the apoptosis of OS cells induced by 17-AAG did require the involvement of the AKT/GSK-3ß/ß-catenin signaling pathway by using pharmacological inhibitor GSK-3ß (LiCl) or siGSK-3ß. Our findings reveal a novel mechanism that Runx2 is transcriptionally regulated by HSP90 via the AKT/GSK-3ß/ß-catenin signaling pathway, and by which leads to apoptosis of OS cells.

The E3 ubiquitin ligase CHIP mediates ubiquitination and proteasomal degradation of PRMT5.

Protein arginine methyltransferase 5 (PRMT5) is an important member of the protein arginine methyltransferase family that regulates many cellular processes through epigenetic control of target gene expression. Because of its overexpression in a number of human cancers and its essential role in cell proliferation, transformation, and cell cycle progression, PRMT5 has been recently proposed to function as an oncoprotein in cancer cells. However, how its expression is regulated in cancer cells remains largely unknown. We have previously demonstrated that the transcription of PRMT5 can be negatively regulated by the PKC/c-Fos signaling pathway through modulating the transcription factor NF-Y in prostate cancer cells. In the present study, we demonstrated that PRMT5 undergoes polyubiquitination, possibly through multiple lysine residues. We also identified carboxyl terminus of heat shock cognate 70-interacting protein (CHIP), an important chaperone-dependent E3 ubiquitin ligase that couples protein folding/refolding to protein degradation, as an interacting protein of PRMT5 via mass spectrometry. Their interaction was further verified by co-immuoprecipitation, GST pull-down, and bimolecular fluorescence complementation (BiFC) assay. In addition, we provided evidence that the CHIP/chaperone system is essential for the negative regulation of PRMT5 expression via K48-linked ubiquitin-dependent proteasomal degradation. Given that down-regulation of CHIP and overexpression of PRMT5 have been observed in several human cancers, our finding suggests that down-regulation of CHIP may be one of the mechanisms underlying PRMT5 overexpression in these cancers.

The BET Bromodomain Inhibitor JQ1 Suppresses Chondrosarcoma Cell Growth via Regulation of YAP/p21/c-Myc Signaling.

Chondrosarcoma, the second-most frequent primary bone malignancy, is generally more resistant to conventional chemotherapy and radiotherapy. Therefore, the development of an effective adjuvant therapy is necessary. Recently, targeting the epigenetic regulator such as bromodomain and extraterminal domain (BET) proteins has achieved great success. For instance, the bromodomain inhibitor JQ1 has been shown to inhibit the growth of several cancer cells both in vitro and in vivo. Herein, we demonstrated that JQ1 significantly inhibited chondrosarcoma cell growth and colony formation. JQ1 also induced marked G1-phase cell cycle arrest coincided with the up-regulation of p21WAF1/CIP1 , p27Kip1 , and Cyclin D1 expression, and the down-regulation of Cyclin E2 expression. Moreover, JQ1 induced the premature senescence of SW 1353 cells, and that prolong treatment of JQ1 caused cell apoptosis. Mechanistically, the JQ1-induced cell growth inhibition was correlated with the suppression of c-Myc and Bcl-xL, which are the prime genes for cell cycle control and anti-apoptosis. Furthermore, we demonstrated that p21 negatively regulated the expression of c-Myc and Bcl-xL upon JQ1 treatment, and that the growth inhibition of SW 1353 and Hs 819.T cells and induction of p21 were predominantly regulated by the LATS1/YAP signaling but not through a p53-dependent manner. In conclusion, we disclosed a novel mechanism that JQ1 inhibits cell proliferation, induces cell senescence and apoptosis of chondrosarcoma cells through the regulation of the YAP/p21/c-Myc/Bcl-xL signaling axis. J. Cell. Biochem. 118: 2182-2192, 2017. © 2017 Wiley Periodicals, Inc.

Andrographolide Induces Cell Cycle Arrest and Apoptosis of Chondrosarcoma by Targeting TCF-1/SOX9 Axis.

Chondrosarcoma is the second most malignant bone tumor with poor prognosis and limited treatment options. Thus, development of more effective treatments has become urgent. Recently, natural compounds derived from medicinal plants have emerged as promising therapeutic options via targeting multiple key cellular molecules. Andrographolide (Andro) is such a compound, which has previously been shown to induce cell cycle arrest and apoptosis in several human cancers. However, the molecular mechanism through which Andro exerts its anti-cancer effect on chondrosarcoma remains to be elucidated. In the present study, we showed that Andro-induced G2/M cell cycle arrest of chondrosarcoma by fine-tuning the expressions of several cell cycle regulators such as p21, p27, and Cyclins, and that prolonged treatment of cells with Andro caused pronounced cell apoptosis. Remarkably, we found that SOX9 was highly expressed in poor-differentiated chondrosarcoma, and that knockdown of SOX9 suppressed chondrosarcoma cell growth. Further, our results showed that Andro dose-dependently down-regulated SOX9 expression in chondrosarcoma cells. Concomitantly, an inhibition of T cell factor 1 (TCF-1) mRNA expression and an enhancement of TCF-1 protein degradation by Andro were observed. In contrast, the expression and subcellular localization of ß-catenin were not altered upon the treatment of Andro, suggesting that ß-catenin might not function as the primary target of Andro. Additionally, we provided evidence that there was a mutual regulation between TCF-1 and SOX9 in chondrosarcoma cells. In conclusion, these results highlight the potential therapeutic effects of Andro in treatment of chondrosarcoma via targeting the TCF-1/SOX9 axis. J. Cell. Biochem. 118: 4575-4586, 2017. © 2017 Wiley Periodicals, Inc.

Transcriptional activation of PRMT5 by NF-Y is required for cell growth and negatively regulated by the PKC/c-Fos signaling in prostate cancer cells.

Protein arginine methyltransferase 5 (PRMT5) symmetrically methylates arginine residues of histones and non-histone protein substrates and regulates a variety of cellular processes through epigenetic control of target gene expression or post-translational modification of signaling molecules. Recent evidence suggests that PRMT5 may function as an oncogene and its overexpression contributes to the development and progression of several human cancers. However, the mechanism underlying the regulation of PRMT5 expression in cancer cells remains largely unknown. In the present study, we have mapped the proximal promoter of PRMT5 to the -240bp region and identified nuclear transcription factor Y (NF-Y) as a critical transcription factor that binds to the two inverted CCAAT boxes and regulates PRMT5 expression in multiple cancer cell lines. Further, we present evidence that loss of PRMT5 is responsible for cell growth inhibition induced by knockdown of NF-YA, a subunit of NF-Y that forms a heterotrimeric complex with NF-YB and NF-YC for function. Significantly, we have found that activation of protein kinase C (PKC) by phorbol 12-myristate 13-acetate (PMA) in LNCaP prostate cancer cells down-regulates the expression of NF-YA and PRMT5 at the transcription level in a c-Fos-dependent manner. Given that down-regulation of several PKC isozymes is implicated in the development and progression of several human cancers, our findings suggest that the PKC-c-Fos-NF-Y signaling pathway may be responsible for PRMT5 overexpression in a subset of human cancer patients.

Trim21 Regulates the Postnatal Development and Thermogenesis of Brown Adipose Tissue.

Brown adipose tissue undergoes rapid postnatal development to mature and plays a crucial role in thermoregulation and energy expenditure, which protects against cold and obesity. Herein, it is shown that the expression of Trim21 mRNA level of interscapular brown adipose tissue elevates after birth, and peaks at P14 (postnatal day 14). Trim21 depletion severely impairs the maturation of interscapular brown adipose tissue, decreases the expression of a series of thermogenic genes, and reduces energy expenditure. Consistently, the loss of Trim21 also leads to a suppression of white adipose tissue "browning", in response to cold exposure and a ß-adrenergic agonist, CL316,243. In addition, Trim21-/- mice are more prone to high-fat diet-induced obesity compared with the control littermates. Taken together, the study for the first time reveals a critical role of Trim21 in regulating iBAT postnatal development and thermogenesis.

Apoptotic body-inspired nanotherapeutics efficiently attenuate osteoarthritis by targeting BRD4-regulated synovial macrophage polarization.

Bromodomain-containing protein 4 (BRD4) is the most well-studied BET protein that is important for the innate immune response. We recently revealed that targeting BRD4 triggers apoptosis in tumor-associated macrophages, but its role in synovial macrophages and joint inflammation is largely unknown. Herein, we demonstrated that BRD4 was highly expressed in the iNOS-positive M1 macrophages in the human and mouse osteoarthritis (OA) synovium, and conditional knockout of BRD4 in the myeloid lineage using Lyz2-cre; BRD4flox/flox mice significantly abolished anterior cruciate ligament transection (ACLT)-induced M1 macrophage accumulation and synovial inflammation. Accordingly, we successfully constructed apoptotic body-inspired phosphatidylserine-containing nanoliposomes (PSLs) loaded with the BRD4 inhibitor JQ1 to regulate inflammatory macrophages. JQ1-loaded PSLs (JQ1@PSLs) exhibited a higher cellular uptake by macrophages than fibroblast-like synoviocytes (FLSs) in vitro and in vivo, as well as the reduction in proinflammatory M1 macrophage polarization. Intra-articular injections of JQ1@PSLs showed prolonged retention within the joint, and remarkably reduced synovial inflammation and joint pain via suppressing M1 polarization accompanied by reduced TRPA1 expression by targeted inhibition of BRD4 in the macrophages, thus attenuating cartilage degradation during OA development. The results show that BRD4-inhibiting JQ1@PSLs can targeted-modulate macrophage polarization, which opens a new avenue for efficient OA therapy via a "Trojan horse".

Trim21 depletion alleviates bone loss in osteoporosis via activation of YAP1/ß-catenin signaling.

Despite the diverse roles of tripartite motif (Trim)-containing proteins in the regulation of autophagy, the innate immune response, and cell differentiation, their roles in skeletal diseases are largely unknown. We recently demonstrated that Trim21 plays a crucial role in regulating osteoblast (OB) differentiation in osteosarcoma. However, how Trim21 contributes to skeletal degenerative disorders, including osteoporosis, remains unknown. First, human and mouse bone specimens were evaluated, and the results showed that Trim21 expression was significantly elevated in bone tissues obtained from osteoporosis patients. Next, we found that global knockout of the Trim21 gene (KO, Trim21-/-) resulted in higher bone mass compared to that of the control littermates. We further demonstrated that loss of Trim21 promoted bone formation by enhancing the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and elevating the activity of OBs; moreover, Trim21 depletion suppressed osteoclast (OC) formation of RAW264.7 cells. In addition, the differentiation of OCs from bone marrow-derived macrophages (BMMs) isolated from Trim21-/- and Ctsk-cre; Trim21f/f mice was largely compromised compared to that of the littermate control mice. Mechanistically, YAP1/ß-catenin signaling was identified and demonstrated to be required for the Trim21-mediated osteogenic differentiation of BMSCs. More importantly, the loss of Trim21 prevented ovariectomy (OVX)- and lipopolysaccharide (LPS)-induced bone loss in vivo by orchestrating the coupling of OBs and OCs through YAP1 signaling. Our current study demonstrated that Trim21 is crucial for regulating OB-mediated bone formation and OC-mediated bone resorption, thereby providing a basis for exploring Trim21 as a novel dual-targeting approach for treating osteoporosis and pathological bone loss.

Effect of Diabetes Mellitus on Implant Osseointegration of Titanium Screws: An Animal Experimental Study.

OBJECTIVE: To explore the effect of diabetes mellitus (DM) on implant osseointegration of titanium screws. METHODS: Sixty rats were randomly divided into a DM group and a control group (each group, n = 30). DM group rats were injected with 1% Streptozotocin solution at 65 mg/kg to establish a DM model. Titanium screws were implanted into the rats' distal femurs in both groups. The rats were sacrificed for micro-CT scanning, micro-indentation, biomechanical detection, confocal Raman microspectroscopy, and histological and histomorphometric analysis at 4, 8, and 12 weeks post-implantation, respectively. Messenger RNA (mRNA) expression and protein expression of the related growth factors around the implant were analyzed using real-time polymerase chain reaction and Western blots. RESULTS: At 4, 8 and 12 weeks, micro-CT scanning, hematoxylin-eosin (HE) staining, Gieson's acid-magenta staining, and fluorescent labeled staining showed disorder in the bone tissue arrangement, a lack of new bone tissue, poor maturity and continuity, and poor trabecular bone parameters around the implant in the DM group. At 4, 8, and 12 weeks, the interfacial bone binding rate in the DM group was significantly lower (16.2% ± 4.8%, 25.7% ± 5.7%, 42.5% ± 5.8%, respectively) than that in the control group (23.6% ± 5.2%, 40.8% ± 6.3%, 64.2% ± 7.3%, respectively; P < 0.05). At 8 and 12 weeks, the elastic modulus (17.0 ± 1.8 and 15.1 ± 1.5 GPa, respectively) and trabecular bone hardness (571 ± 39 and 401 ± 37 MPa, respectively) in the DM group were significantly lower than the elastic modulus (23.4 ± 2.3 and 23.8 ± 1.8 GPa, respectively) and trabecular bone hardness (711 ± 45 and 719 ± 46 MPa, respectively) in the control group (P < 0.05). The maximum load required for the prosthesis pull-out experiment in the DM group at 4, 8, and 12 weeks (55.14 ± 6.74 N, 73.34 ± 8.43 N, and 83.45 ± 8.32 N, respectively) was significantly lower than that in the control group (77.45 ± 7.48 N, 93.28 ± 8.29 N, and 123.62 ± 9.43 N, respectively, P < 0.05). At 8 and 12 weeks, the mineral-to-collagen ratio in the DM group (6.56 % ± 1.35% and 4.45%± 1.25%, respectively) was significantly higher than that in the control group (5.31% ± 1.42% and 3.62% ± 1.33%, respectively, P < 0.05). At 12 weeks, mRNA and protein expression levels of bone morphogenetic protein 2, transforming growth factor-ß1, vascular endothelial growth factor, osteopontin, osteocalcin, and runt-related transcription factor 2 in the DM group were significantly lower than that in the control group. CONCLUSIONS: DM can negatively affect bone osseointegration, manifesting as disorder in bone tissue arrangement around the implant, a lack of new bone tissue, poor maturity and continuity, poor trabecular bone parameters and lower expression of the related growth factors.

Versatile Nano-PROTAC-Induced Epigenetic Reader Degradation for Efficient Lung Cancer Therapy.

Recent evidence has indicated that overexpression of the epigenetic reader bromodomain-containing protein 4 (BRD4) contributes to a poor prognosis of lung cancers, and the suppression of its expression promotes cell apoptosis and leads to tumor shrinkage. Proteolysis targeting chimera (PROTAC) has recently emerged as a promising therapeutic strategy with the capability to precisely degrade targeted proteins. Herein, a novel style of versatile nano-PROTAC (CREATE (CRV-LLC membrane/DS-PLGA/dBET6)) is developed, which is constructed by using a pH/GSH (glutathione)-responsive polymer (disulfide bond-linked poly(lactic-co-glycolic acid), DS-PLGA) to load BRD4-targeted PROTAC (dBET6), followed by the camouflage with engineered lung cancer cell membranes with dual targeting capability. Notably, CREATE remarkably confers simultaneous targeting ability to lung cancer cells and tumor-associated macrophages (TAMs). The pH/GSH-responsive design improves the release of dBET6 payload from nanoparticles to induce pronounced apoptosis of both cells, which synergistically inhibits tumor growth in both subcutaneous and orthotopic tumor-bearing mouse model. Furthermore, the efficient tumor inhibition is due to the direct elimination of lung cancer cells and TAMs, which remodels the tumor microenvironment. Taken together, the results elucidate the construction of a versatile nano-PROTAC enables to eliminate both lung cancer cells and TAMs, which opens a new avenue for efficient lung cancer therapy via PROTAC.

Single-Cell RNA Sequencing Reveals Transcriptional Changes in the Cartilage of Subchondral Insufficiency Fracture of the Knee.

Purpose: Subchondral insufficiency fracture of the knee (SIFK) is a common cause of knee joint pain that mainly afflicts the elderly. Until now, how a sudden insufficiency fracture of subchondral bone affects the transcriptomic profiles of cartilage in SIFK and OA patients are largely unknown. Methods: Single-cell RNA sequencing (scRNA-seq) was used to identify various cell subsets and evaluate transcriptomic differences in cartilage of SIFK and OA patients. In addition, the above findings were confirmed by histological evaluation and immunohistochemical (IHC) staining. Results: We found that the transcriptomic profiles of cartilage in the SIFK patient was completely different from those of normal and OA patients. Accordingly, several novel cell clusters with activation of hypoxia and endochondral ossification signaling were identified in the SIFK cartilage. Chondrocyte trajectories analysis and IHC staining revealed that transcription factors including TCF4 were found to be highly up-regulated during the occurrence of SIFK, which might drive the reactive formation of cartilage and fibrous tissue and the activation of endochondral ossification. Conclusion: This is the first report to elucidate the transcriptomic alterations and distinct cell type subpopulations in the cartilage of SIFK and OA by the use of scRNA-seq, which provides a new insight in the understanding of the initiation and progression of SIFK.