Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. The purpose of this study is to explore the regulatory mechanism of LINC01116 in osteosarcoma metastasis and its potential association with the urea cycle and chemoresistance. Transcriptomic profiling was performed, and the results were validated by qRT-PCR in 6 paired osteosarcoma and adjacent non-tumor tissues. Functional assays including in vivo xenograft models were used to verify the effect of LINC01116 on osteosarcoma cell proliferation. RNA-protein interaction studies and ChIRP-MS assays were conducted to confirm the binding between LINC01116 and CPS1.LINC01116 was significantly upregulated in metastatic osteosarcoma lesions. Silencing LINC01116 inhibited osteosarcoma cell proliferation both in vitro and in vivo. Mechanistically, LINC01116 directly binds to CPS1 -the rate-limiting enzyme of the urea cycle, which was confirmed by ChIRP-MS. Perturbing the LINC01116/CPS1 axis reduced citrulline levels, indicating impaired urea cycle function. Additionally, CPS1 silencing enhanced osteosarcoma cell sensitivity to cisplatin. This study identifies a novel LINC01116/CPS1 axis that drives osteosarcoma metastasis by regulating the urea cycle. Targeting this axis can sensitize osteosarcoma to cisplatin treatment, which highlights its potential as a therapeutic target for osteosarcoma.

Silicon, abundant in Earth’s biosphere, plays crucial roles in many organisms. However, its biological functions in animals remain inadequately characterized, primarily constrained by methodological limitations in quantifying, identifying, and visualizing biogenic silicon in tissues. Here, we refined the molybdenum blue colorimetric method (MB) for more accurate silicon quantification, developed integrated mass spectrometry techniques to delineate chemical natures of biogenic silicon, and optimized micro-X-ray fluorescence (micro-XRF) imaging for spatial mapping in animals. Employing these methodologies, we demonstrated that silicon abundance in animals substantially exceeds prior estimates—surpassing essential elements like iron. We also revealed the chemical architectures of diverse silicon compounds and visualized tissue-specific distributions in mice and humans, indicating its predominant localization within extracellular matrix (ECM) and suggesting the formation of silicified networks. These findings establish silicon as a structurally and quantitatively significant element with profound biological implications, warranting its recognition as an essential factor in human physiology and pathology. ### Competing Interest Statement The authors have declared no competing interest.

The immunosuppressive microenvironment of osteosarcoma (OS) and the inherent toxicity of current neoadjuvant chemotherapy present significant challenges in treatment, highlighting the urgent need for innovative therapeutic approaches. Photodynamic therapy (PDT) is a promising noninvasive alternative; however, its clinical application is limited by the poor stability of traditional photosensitizers (PS), insufficient reactive oxygen species (ROS) production, and a weak antitumor immune response. Given these limitations, a combination therapy that enhances PDT's therapeutic efficacy while stimulating immune activation could offer a more effective strategy. In this study, we developed a biomimetic nanomedicine (IR780@EM) by integrating the near-infrared photosensitizer IR780 with Escherichia coli-derived membrane nanovesicles (EM). This approach synergistically combines localized PDT with systemic antitumor immunity, leading to enhanced ROS generation and promoting M2-to-M1 polarization of macrophages in tumor, thereby activating the immune system and driving OS regression. Unlike conventional chemotherapy-based treatments, this strategy not only addresses the key limitations of PDT-insufficient ROS production and limited immune activation-but also helps overcome chemotherapy resistance and convert immunologically "cold" tumors into "hot" tumors, thereby improving therapeutic outcomes. This EM-based nanotherapeutic strategy holds significant translational potential for optimizing PDT efficacy and offers a multidimensional treatment approach for OS.

BACKGROUND:There is no standard systemic therapy for unresectable chondrosarcoma. The purpose of this study is to explore the efficacy of combination therapy with an anti-PD-1 antibody and anlotinib in patients with advanced chondrosarcoma. METHODS:Patients with dedifferentiated or high-grade conventional chondrosarcoma were eligible. Anlotinib was administered at 12 mg orally once a day from day 1 to 14 every 3 weeks in all participants. In the combination treatment arm, patients received an additional anti-PD-1 antibody at 200 mg every 3 weeks. The primary endpoint was the 6-month progression-free survival rate (PFSR). Biomarker analyses for therapeutic effectiveness were conducted. FINDINGS:70 patients (32 with dedifferentiated and 38 with conventional chondrosarcoma) were enrolled in the study. After a medium follow-up of 15.6 months, combination treatment showed significantly improved outcomes compared to anlotinib alone in the entire population, with a higher 6-month PFSR (60.0% versus 31.4%). The PFS-event inverse probability weighting adjusted Cox model evaluation also revealed a significant benefit of combination treatment (hazard ratio = 0.14, 95% confidence interval [CI]: 0.07-0.30, p < 0.001). Patients with dedifferentiated chondrosarcoma benefited the most from the combination treatment, with improvements in objective response rate (33.3% versus 9.1%), 6-month PFSR (57.1% versus 9.1%), median PFS (7.0 months versus 3.8 months), and 1-year overall survival rate (42.9% versus 18.2%). Effector memory T cells were significantly associated with treatment response (p < 0.001). CONCLUSIONS:The combination treatment demonstrated promising efficacy in advanced chondrosarcoma, particularly for dedifferentiated cases (ClinicalTrials.gov: NCT05193188). FUNDING:This trial was supported by Chia Tai Tianqing Pharmaceutical Group Co., Ltd.

The repair and reconstruction of bone defects remain a challenge in orthopedics. Inadequate mechanical qualities, poor biocompatibility, and insufficient osteoconductivity are some of the issues facing current bone healing materials. Better materials that can replicate the composition and functionality of natural bone, promote quick and full healing, and reduce the likelihood of rejection and infection are desperately needed. Bone tissue engineering, combining biomaterial scaffolds and pro-osteogenic drugs, provides support in the repair and regeneration of bone defects. The development of an effective scaffold for bone defect repair is an urgent clinical need. The present study investigates the feasibility of using microspheres based on α-tricalcium phosphate and fibroin as an osteoconductive matrix and a carrier for controlled local delivery of the E7BMP-2 peptide, in which the E7 domain confers a calcium chelation property, while the BMP-2 mimicking peptide induces bone formation. We prepared α-tricalcium phosphate/silk fibroin (α-TCP/SF) microspheres through a high voltage electric field based on the protocol of α-TCP/SF bone cement slurry. This α-TCP/SF microspheres-based system was designed for delivery vehicles of the modified BMP-2 peptide by the E7 domain to realize sustainable and steady release of the peptide. In vitro cell tests and the experimental model of cranial bone defects in rats were used to investigate the pro-osteogenic benefits. The results demonstrated that the E7BMP-2 peptide-bound microspheres functioned as a sustained release system for the peptide and enhanced osteogenic differentiation of bone marrow mesenchymal stem cells in rat calvarial defects. Additionally, toxicity studies showed that microspheres have good biocompatibility and safety. Thus, these E7BMP-2 peptide-bound α-TCP/SF microspheres provide a promising therapeutic strategy for the treatment of bone defects.

3D bioprinting is utilized to design and construct scaffolds with scalable forms and physicochemical properties. Recently, this technology has been extensively studied in the field of biology and has achieved promising results in tissue and organ repair. However, challenges such as shape mismatch, unstable adhesion, and contamination arise during the transition from externally printed scaffolds to their internal transplantation, thereby limiting clinical applications. Compared to traditional 3D bioprinting, in situ 3D bioprinting offers enhanced tissue integration and surface construction capabilities, demonstrating greater clinical potential. Nevertheless, it places higher demands on printing technology and bio-ink. This article summarizes the methods and characteristics of in situ 3D bioprinting, and introduces research on the composition and reactivity of bio-inks. The latest progress in tissue repair using in situ bioprinting is highlighted. Further research in 3D bioprinting for tissue engineering, encompassing defect model scanning, printing platform construction, printing techniques, ink combinations, and large tissue printing, is ongoing. In situ 3D bioprinting holds promise as a novel and effective treatment method for future clinical applications.

Relapsed or refractory osteosarcoma carries a poor prognosis after standard chemotherapy. We conducted a multicenter, randomized, phase II trial (NCT05277480) to compare apatinib plus ifosfamide/etoposide (IE) with IE alone in patients who had progressed following at least one prior line of chemotherapy. Patients were randomized 2:1 to receive apatinib (500 mg orally once daily) plus IE (ifosfamide 1.8 g/m²/day and etoposide 100 mg/m²/day, days 1-3 every 3 weeks) or IE alone (same doses, days 1-5 every 3 weeks). The primary endpoint was progression-free survival (PFS). Between April 14, 2022, and August 22, 2023, 81 patients were enrolled (53 in apatinib plus IE group and 28 in IE group). After a median follow-up of 19.9 months, the median PFS was 5.5 months (95% confidence interval [CI]: 3.9, 6.4) with apatinib plus IE compared with 3.4 months (95% CI: 1.4, 4.6) with IE (hazard ratio, 0.60; 95% CI: 0.37, 0.98; P = 0.0402). The trial met its pre-specified primary endpoint. These results suggest that apatinib plus IE may improve PFS in relapsed or refractory osteosarcoma, but as a randomized phase II study, the findings are exploratory and require confirmation in phase III trials.

Circular RNAs (circRNAs) are non-coding RNAs that exist naturally in various eukaryotic organisms. The majority of circRNAs are produced through the splicing of exons, although there are a limited number that are generated through the circularization of introns. Studies have shown that circRNAs play an irreplaceable role in the pathogenesis, disease progression, diagnosis, and targeted therapy of motor system tumors (osteosarcoma), metabolic diseases (osteoporosis), and degenerative diseases (osteonecrosis of the femoral head, osteoarthritis, intervertebral disc degeneration). This review summarizes the advancements in circRNA detection techniques and the research progress of circRNAs in orthopedic diseases.

Bionic bioelectronics has promising applications in bone defect repair, with current research primarily focusing on the development of electroactive biomaterials and self-powered systems, which can mimic the electrophysiological microenvironment of natural bone tissue, accelerating bone healing by promoting osteoblast proliferation and differentiation through electrical stimulation. However, the biological mechanisms of bionic electrical stimulation in bone defect repair remain incompletely understood. Here, the study developed a self-sustained biomimetic bioelectronic system comprising a triboelectric/piezoelectric hybrid nanogenerator (TP-hNG) and a multifunctional gold-coated polymer internal fixation plate (GP-IFP), which utilizes the natural biomechanical properties of rat heartbeat and respiratory movements to generate bionic electric signals (Bio-SIG) that are closely related to physiological neurofeedback signals. The Bio-SIG can disrupt the glucose metabolic homeostasis in osteoblasts, enhancing the osteoblasts' dependence on aerobic glycolysis while attenuating dependence on oxidative phosphorylation (OXPHOS). This metabolic shift triggers critical steps in osteogenic differentiation, bone formation and mineralization, effectively facilitating the repair of bone defects. This work reveals the key role of glucose metabolic reprogramming in osteogenesis mediated by bionic electrical stimulation, elucidates the complex regulatory mechanisms of bionics in bone regenerative medicine and deepens the understanding of how biofeedback electrical stimulation precisely regulates the bone regeneration process, which provides a solid theoretical basis for clinical personalized treatment.

Background: Retrospective analysis have indicated potential benefits of combining apatinib, a multi-targeted tyrosine kinase inhibitor, with ifosfamide and etoposide (IE) for advanced osteosarcoma. This study aims to compare the efficacy of apatinib plus IE versus IE alone in patients with relapsed or refractory osteosarcoma. Methods: This multicenter, randomized controlled trial (NCT05277480) involved patients with relapsed or refractory osteosarcoma, who had progressed on first-line chemotherapy, typically comprising high-dose methotrexate, doxorubicin, cisplatin with or without ifosfamide (MAP/I). Participants were randomized in a 2:1 ratio to receive either apatinib plus IE or IE alone. The apatinib plus IE group received 500 mg of oral apatinib daily, along with ifosfamide (1.8 g/m²/day) and etoposide (100 mg/m²/day) d1-3 q3w. The IE group received the same daily regimen d1-5 q3w. The primary endpoint was median progression-free survival (mPFS). Results: From April 2022 to August 2023, 81 patients were enrolled, with 53 receiving apatinib plus IE and 28 receiving IE alone. With median follow-up of 19.9 months, the mPFS was 5.5 months (95% confidence interval [CI], 3.9 to 6.4) for the apatinib+IE, compared to 3.4 months (95% CI, 1.4 to 4.6) for single IE (hazard ratio, 0.60; 95% CI, 0.37 to 0.98; P=0.0402). The median OS was 18.2 months (95% confidence interval [CI], 13.7 to 25.2) for apatinib+IE, compared to 22.9 months (95% CI, 19.3 to NE) for single IE (hazard ratio, 1.48; 95% CI, 0.76 to 2.89; P=0.2493). The incidence of neutropenia and thrombocytopenia was similar between two groups. Quality of life assessments revealed significant improvements in global health status in apatinib+IE. Conclusion: Combining apatinib with IE significantly enhances PFS in patients with relapsed or refractory osteosarcoma post MAP/I chemotherapy, maintaining an acceptable safety profile.

11527 Background: Retrospective studies have suggested the potential of apatinib, an anti-angiogenesis tyrosine kinase inhibitor, plus ifosfamide and etoposide (IE) over IE in advanced osteosarcoma. This trial aimed to further compared apatinib plus IE versus IE alone in patients with advanced osteosarcomas post first-line chemotherapy failure. Methods: In this multicenter, randomized controlled trial, patients with histologically confirmed osteosarcoma, progressing after at least one prior line of chemotherapy, were randomized (2:1) to either apatinib plus IE or IE alone. The apatinib plus IE group received oral apatinib 500mg daily plus ifosfamide (1.8 g/m 2 /d) and etoposide (100 mg/m 2 /d) on days 1-3, every 3 weeks. The IE group received IE on days 1-5, every 3 weeks. Apatinib was continued until disease progression or for a maximum of one year, and IE was administered for up to 10 cycles. The primary endpoint was progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors 1.1. Results: A total of 81 patients were enrolled, with 53 receiving apatinib and IE, while 28 using IE alone. The median follow-up period was 9.5 (interquartile range, 7.1 to 13.0) months. The apatinib plus IE group showed a median PFS of 5.5 months (95% confidence interval [CI], 3.9 to 6.7), compared to 3.4 months (95% CI, 1.4 to 4.6) in the IE group, yielding a hazard ratio of 0.41 (95% CI, 0.24 to 0.71), P=0.0010. Objective response rates were 32.1% (95% CI, 19.9 to 46.3) for the apatinib plus IE group and 25.0% (95% CI, 10.7 to 44.9) for the IE group. Disease control rates were numerically higher in the apatinib plus IE group at 90.6% (95% CI, 79.3 to 96.9), compared to 60.7% (95% CI, 40.6 to 78.5) in the IE group. The median time to response was 1.4 months (95% CI, 1.2 to 2.6) for the apatinib plus IE group and 1.5 months (95% CI, 1.3 to 2.0) for the IE group. Duration of response also favored the apatinib plus IE group, with a median of 6.1 months (95% CI, 1.9 to 8.0) compared to 4.1 months (95% CI, 1.7 to not estimated [NE]) in the IE group. The median overall survival has not yet been reached in either group. Grade 3-4 treatment-related adverse events occurred in 69.8% of patients in the apatinib plus IE group and 64.3% in the IE group, with the most common events being white blood cell count decreased and neutrophil count decreased. Conclusions: Apatinib plus IE demonstrated a significant improvement in PFS in patients with advanced osteosarcomas, with an acceptable safety. Clinical trial information: NCT05277480 . [Table: see text]

Circular RNAs (circRNAs) are a class of non-coding RNAs which take part in the regulation of the initiation and development of different types of cancer. Numerous studies have demonstrated that circRNAs are involved in the progression of osteosarcoma (OS) as well. Thus, we put our emphasis on the exploration of crucial circRNAs in the process of OS initiation and progression. Using RNA sequencing, we found that circSATB2 was highly expressed in OS tissues compared with adjacent normal tissues. Then, we confirmed the high expression of circSATB2 in OS cell lines and OS tissues and its high expression was related to poor prognosis of OS patients. Functional experiments exhibited that circSATB2 promoted OS proliferation and migration in vitro, primary OS model and OS lung metastasis model showed that circSATB2 aggravated OS progression in vivo. Mechanistically, circSATB2 was found to promote OS progression through sponging miR-661 and FUS regulating the mRNA of ZNFX1. Therefore, circSATB2 could act as a prognostic marker and a therapeutic target for osteosarcoma in the future.

Objective To explore the imaging features,clinical outcome,and prognosis of indeterminate pulmonary nodules(IPN)in patients with high-grade soft tissue sarcoma.Methods A retrospective study of 82 patients with high-grade soft tissue sarcoma who have IPNs.The clinical characteristics,imaging features of IPN,and survival of patients were analyzed with statistical software.Results The IPN size of 82 patients was 6.453±0.864 mm.IPN diameter,shape,density,and nodule discovery interval may be CT imaging features related to malignancy tendency.Age(HR=1.047,95%CI:1.007-1.088)and interval between each nodule discovery(HR=3.194,95%CI:1.052-9.694)are independent factors that affect the survival of patients with malignant IPN.Conclusion The imaging features of chest CT may provide important guidance for determining the nature and survival prognosis of benign and malignant nodules.

FRS2 has demonstrated oncogenic roles in various malignancies, including liposarcoma and giant cell tumor of bone. However, its role in osteosarcoma remains less understood, and the upstream regulatory molecules influencing FRS2 remain unclear. This study aims to explore the clinical implications and biological function of FRS2 in osteosarcoma, and the potential regulatory microRNAs (miRNAs) governing its expression. Our study indicated significant upregulation of FRS2 in osteosarcoma cells and tissues by Western blotting and immunohistochemical staining. Elevated FRS2 expression correlated positively with increased angiogenesis and poor prognosis, possibly serving as an independent prognostic indicator for osteosarcoma patients. Functional assays revealed that attenuating FRS2 in osteosarcoma cells could mitigate proliferation, migration, and angiogenesis of vascular endothelial cells. Further investigations revealed that miR-429 and miR-206 directly targeted FRS2, exerting a negative regulation on its expression. Furthermore, FRS2 played a role in repressing osteosarcoma advancement influenced by miR-429 or miR-206. In summary, FRS2, influenced by miR-429 and miR-206, emerges as a promising therapeutic candidate for antiangiogenic osteosarcoma treatments.

Background/Objective Brain metastasis in osteosarcoma (BMO) is rare and its clinical characteristics are often buried among studies on brain metastasis of bone and soft tissue sarcomas. The aim of the present study was to summarize the incidence, clinical characteristics, treatment and outcomes of patients with BMO.Methods This retrospective study included 7 patients with BMO who received treatment in our center between 2005 and 2019. The clinical medical records of the 7 patients, together with data of 70 BMO patients published in 33 articles and retrieved by means of PubMed and Medline, were analyzed, retrospectively.Results Data analysis of the 97 BMO patients showed a high correlation between the interval from the primary diagnosis to BMO occurrence and the interval from the primary diagnosis to prior metastases. Multivariate analysis showed that chemotherapy, radiotherapy and surgery were three main factors affecting the overall survival of BMO patients (HR = 0.427; HR = 0.372; HR = 0.296). Surgery combined with chemotherapy or radiotherapy offered a better overall survival than surgery alone.Conclusion Patients with BMO may obtain survival benefits from regular neuroimaging and early aggressive multi-disciplinary interventions including surgical resection, postoperative radiotherapy and chemotherapy.Synopsis This is a retrospective study describing the characteristics of metastasic intervals, locations, clinical features and prognosis in 97 patients with brain metastasis of osteosarcoma (BMO). Multivariate analysis showed that chemotherapy was effective as surgery and radiotherapy for the treatment of BMO. Our findings emphasize the importance of regular neuroimaging and early aggressive multi-disciplinary interventions including surgical resection, postoperative radiotherapy and chemotherapy.

Extremity soft tissue sarcoma (ESTS) is a rare malignant nonepithelial disease, calling for combined modality treatments with surgery to further improve local control rates and long-term survival, especially in patients with multiple local recurrences with or without risk of amputation. In this double-arm, open-label, Phase II clinical trial, we will enroll 30 patients with pathologically confirmed ESTS without nodal involvement or distant metastases. Patients are randomly assigned to the combination treatment group or the radiation monotherapy group. Additionally, tumor and biological samples will be obtained directly before and after neoadjuvant therapy, allowing for studies of immune response and primary drug resistance mechanisms.

Objective:To compare outcomes between standardized and misdiagnosis and mistreatment of osteosarcoma.Methods:A retrospective analysis of patients with high-grade osteosarcoma who received appropriate surgical treatment and chemotherapy (299 cases, control group) and those who were misdiagnosed (benign or infective) and received mistreatment (23 cases, study group) between January 2009 and December 2021. Gender, age, first operation mode, recurrence time, recurrence interval, metastasis time, metastasis interval, total survival time (months), survival status in the two group and tumor site reoperation mode in the study group were statistically analyzed. Further, chi-square test was performed for comparison of the clinical between two groups. The survival analysis was performed using Kaplan-Meier test and Log-rank test.Results:All the 322 patients were followed up. In the control group, the average follow-up time was 42 months (1-137 months), the average age was 24 years (3-80 years), male 184 cases, female 115 cases, and limb salvage rate was 85.3% (255/299). Seven patients underwent amputation, and the amputation rate was 17.7% (44/299). The recurrence rate was 8.4% (25/299), the average recurrence interval was 22.8 months (7-36 months), and the metastasis rate was 28.1% (85/299), the average metastasis time was 32.7 months (0-58 months). In the study group, the average of follow-up time was 30 months (9-117 months), the average age was 36 years (5-67 years), 17 males and 6 females. Among them, eleven patients were treated with limb salvage in the second stage, and the limb salvage rate was 47.8% (11/23). Seven patients underwent amputation, and the amputation rate was 30.4% (7/23). The recurrence rate was 26.1% (6/23), the average recurrence interval was 11 months (1-42 months), and the metastasis rate was 43.4% (10/23), the average metastasis time was 20.3 months (1-44 months). The 5-year survival rate was 50.7% in the study group and 56.1% in the control group. There was no significant difference between the two groups (χ 2=0.09, P=0.760). Conclusion:The overall prognosis of patients with high-grade osteosarcoma who receive active treatment after mistreatment is similar to that of patients with standardized treatment, but the recurrence and metastasis rate is higher, the recurrence time is earlier, and the amputation rate is higher.