CD34+ synovial fibroblasts exhibit high osteogenic potential in synovial chondromatosis

Synovial chondromatosis (SC) is a disorder of the synovium characterized by the formation of osteochondral nodules within the synovium. This study aimed to identify the abnormally differentiated progenitor cells and possible pathogenic signaling pathways. Loose bodies and synovium were obtained from patients with SC during knee arthroplasty. Single-cell RNA sequencing was used to identify cell subsets and their gene signatures in SC synovium. Cells derived from osteoarthritis (OA) synovium were used as controls. Multi-differentiation and colony-forming assays were used to identify progenitor cells. The roles of transcription factors and signaling pathways were investigated through computational analysis and experimental verification. We identified an increased proportion of CD34+ sublining fibroblasts in SC synovium. CD34+CD31- cells and CD34-CD31- cells were sorted from SC synovium. Compared with CD34- cells, CD34+ cells had larger alkaline phosphatase (ALP)-stained area and calcified area after osteogenic induction. In addition, CD34+ cells exhibited a stronger tube formation ability than CD34- cells. Our bioinformatic analysis suggested the expression of TWIST1, a negative regulator of osteogenesis, in CD34- sublining fibroblasts and was regulated by the TGF-β signaling pathway. The experiment showed that CD34+ cells acquired the TWIST1 expression during culture and the combination of TGF-β1 and harmine, an inhibitor of Twist1, could further stimulate the osteogenesis of CD34+ cells. Overall, CD34+ synovial fibroblasts in SC synovium have multiple differentiation potentials, especially osteogenic differentiation potential, and might be responsible for the pathogenesis of SC.

Mechanically stimulated osteocytes maintain tumor dormancy in bone metastasis of non-small cell lung cancer by releasing small extracellular vesicles

Although preclinical and clinical studies have shown that exercise can inhibit bone metastasis progression, the mechanism remains poorly understood. Here, we found that non-small cell lung cancer (NSCLC) cells adjacent to bone tissue had a much lower proliferative capacity than the surrounding tumor cells in patients and mice. Subsequently, it was demonstrated that osteocytes, sensing mechanical stimulation generated by exercise, inhibit NSCLC cell proliferation and sustain the dormancy thereof by releasing small extracellular vesicles with tumor suppressor micro-RNAs, such as miR-99b-3p. Furthermore, we evaluated the effects of mechanical loading and treadmill exercise on the bone metastasis progression of NSCLC in mice. As expected, mechanical loading of the tibia inhibited the bone metastasis progression of NSCLC. Notably, bone metastasis progression of NSCLC was inhibited by moderate exercise, and combinations with zoledronic acid had additive effects. Moreover, exercise preconditioning effectively suppressed bone metastasis progression. This study significantly advances the understanding of the mechanism underlying exercise-afforded protection against bone metastasis progression.

Intraosseous schwannoma of the mandible: new case series, literature update, and proposal of a classification

Intraosseous schwannoma of the mandible is rare, with diagnostic and therapeutic challenges. The aims of this study were to report new cases of intraosseous schwannoma of the mandible and to propose a clinical classification, providing suggestions for treatment methods. The cases of 13 patients treated at the authors' hospital and 86 cases reported previously in the literature were reviewed. The most common clinical feature was facial swelling (60/93). The rate of cortical thinning or expansion was 44.8% (43/96); widening of the inferior alveolar nerve canal on radiographs was observed in 15 patients.

[Efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation in the treatment of secondary acute myeloid leukemia]

Objective: To evaluate the efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with secondary acute myeloid leukemia (sAML) . Methods: In this multicenter, retrospective clinical study, adult patients aged ≥18 years who underwent allo-HSCT for sAML at four centers of the Zhejiang Hematopoietic Stem Cell Transplantation Collaborative Group from January 2014 to November 2022 were included, and the efficacy and prognostic factors of allo-HSCT were analyzed. Results: A total of 95 patients were enrolled; 66 (69.5%) had myelodysplastic syndrome-acute myeloid leukemia (MDS-AML) , 4 (4.2%) had MDS/MPN-AML, and 25 (26.3%) had therapy-related AML (tAML) . The 3-year CIR, LFS, and overall survival (OS) rates were 18.6% (95% CI 10.2%-27.0%) , 70.6% (95% CI 60.8%-80.4%) , and 73.3% (95% CI 63.9%-82.7%) , respectively. The 3-year CIRs of the M-AML group (including MDS-AML and MDS/MPN-AML) and the tAML group were 20.0% and 16.4%, respectively (P=0.430) . The 3-year LFSs were 68.3% and 75.4%, respectively (P=0.176) . The 3-year OS rates were 69.7% and 75.4%, respectively (P=0.233) . The 3-year CIRs of the groups with and without TP53 mutations were 60.0% and 13.7%, respectively (P=0.003) ; the 3-year LFSs were 20.0% and 76.5%, respectively (P=0.002) ; and the 3-year OS rates were 40.0% and 77.6%, respectively (P=0.002) . According to European LeukmiaNet 2022 (ELN2022) risk stratification, the 3-year CIRs of patients in the low-, intermediate-, and high-risk groups were 8.3%, 17.8%, and 22.6%, respectively (P=0.639) . The three-year LFSs were 91.7%, 69.5%, and 65.6%, respectively (P=0.268) . The 3-year OS rates were 91.7%, 71.4%, and 70.1%, respectively (P=0.314) . Multivariate analysis revealed that advanced disease at allo-HSCT and TP53 mutations were independent risk factors for CIR, LFS, and OS. Conclusion: There was no significant difference in the prognosis of patients who underwent allo-HSCT among the MDS-AML, MDS/MPN-AML, and tAML groups. Advanced disease at transplantation and TP53 mutations were poor prognostic factors. ELN2022 risk stratification had limited value for predicting the prognosis of patients with sAML following allo-HSCT.

Follow-up study of isolated calf muscular vein thrombosis for anticoagulant therapy after primary hip and knee arthroplasty

BACKGROUND

Although isolated calf muscular vein thrombosis (ICMVT) is commonly seen after hip and knee arthroplasty, no treatment guidelines for ICMVT after joint replacement are available. The purpose of this study was to evaluate the outcomes of patients with ICMVT for anticoagulant therapy at different time points after primary hip and knee arthroplasty.

METHODS

Patients with ICMVT after primary hip and knee arthroplasty were included in the study. Diagnosis was established with Doppler ultrasound. Patients were followed up clinically and with Doppler ultrasound at 1, 2, and 3 months. The outcomes were efficacy (complete resolution) and acceptability (hemorrhagic events). Anticoagulant therapy at curative dosage was prescribed for 1 month and was extended for 2 additional months in case of incomplete resolution at 1 month or if propagation was present. The chi-square test was used to compare the outcomes at different time points.

RESULTS

302 patients were taken hip and knee arthroplasty from January 2021 to May 2022, in which 51 patients presented with 51 ICMVTs postoperatively. The incidence of ICMVT was about 16.89%. Resolution of ICMVT was considered complete at 1, 2, and 3 months at 36.73%, 61.22%, and 91.84%, respectively, with significant differences among the time points (P < 0.05). All patients with ICMVT receiving anticoagulant therapy remained free of propagations and hemorrhagic events within 3 months.

CONCLUSION

Our findings provide new insights into the anticoagulant therapy for ICMVT after primary hip and knee arthroplasty, taking oral Rivaroxaban for 3 months is effective and safe, which contributes to provide the reference for clinical practice.

Comparative Efficacy and Safety of Measures for the Treatment of Adults with Isolated Calf Muscular Vein Thrombosis: A Systematic Review and Network Meta-analysis

BACKGROUND

Isolated calf muscular vein thrombosis (ICMVT) can result in pulmonary embolism, but the treatment of ICMVT remains controversial. Therefore, the purpose of the present study was to investigate the optimal treatment for the ICMVT by comparing the efficacy and safety of different treatments.

METHODS

A network meta-analysis was conducted to search for studies published from database inception to April 30, 2022, that compared the outcomes of 2 or more treatments for ICMVT. The primary outcomes were efficacy (resolution rate) and safety (adverse reactions). Data were extracted following predefined hierarchy and the Cochrane Collaboration risk of bias tool was used to evaluate the methodological quality of the included studies. We estimated summary odds ratios with 95% credibility intervals using Bayesian network meta-analysis with random effects.

RESULTS

A total of 16 studies were enrolled in the study. In terms of efficacy and safety, urokinase thrombolysis combined with low-molecular-weight heparin (LMWH) was most effective but had the lowest safety, while physical therapy was safest but had the lowest efficacy. More important, direct oral factor Xa inhibitors were most likely to be second most effective and safe compared with other treatments. For the duration of treatment, anticoagulant therapy for at least 3 months could effectively increase the resolution rate of ICMVT.

CONCLUSIONS

Considering both efficacy and safety, taking direct oral factor Xa inhibitors for at least 3 months was the optimal treatment compared to LMWH, urokinase thrombolysis combined LMWH, physical therapy and warfarin for patients with ICMVT.

A prediction nomogram for deep venous thrombosis risk in patients undergoing primary total hip and knee arthroplasty: a retrospective study

INTRODUCTION

Deep venous thrombosis (DVT) prediction after total hip and knee arthroplasty remains challenging. Early diagnosis and treatment of DVT are crucial. This research aimed to develop a nomogram for early DVT prediction.

METHODS

A total of 317 patients undergoing primary total hip and knee arthroplasty in Sun Yat-sen Memorial Hospital were enrolled between May 2020 and September 2022. Data from May 2020 to February 2022 were used as the development datasets to build the nomogram model (n = 238). Using multivariate logistic regression, independent variables and a nomogram for predicting the occurrence of DVT were identified. Datasets used to validate the model for internal validation ranged from March 2022 to September 2022 (n = 79). The nomogram's capacity for prediction was also compared with the Caprini score.

RESULTS

For both the development and validation datasets, DVT was found in a total of 38 (15.97%) and 9 patients (11.39%) on post-operative day 7 (pod7), respectively. 59.6% patients were symptomatic DVT (leg swelling). The multivariate analysis revealed that surgical site (Knee vs. Hip), leg swelling and thrombin-antithrombin complex (TAT) were associated with DVT. The previously indicated variables were used to build the nomogram, and for the development and validation datasets, respectively. In development and validation datasets, the area under the receiver operating characteristic curve was 0.836 and 0.957, respectively. In both datasets, the predictive value of the Nomogram is greater than the Caprini score.

CONCLUSIONS

A proposed nomogram incorporating surgical site (Knee vs. Hip), leg swelling, and thrombin antithrombin complex (TAT) may facilitate the identification of patients who are more prone to develop DVT on pod7.

Invited review: Good practices in genome-wide association studies to identify candidate sequence variants in dairy cattle

Genotype data from dairy cattle selection programs have greatly facilitated GWAS to identify variants related to economic traits. Results can enhance the accuracy of genomic prediction, analyze more complex models that go beyond additive effects, elucidate the genetic architecture of a trait, and finally, decipher the underlying biology of traits. The entire process, comprising data generation, quality control, statistical analyses, interpretation of association results, and linking results to biology should be designed and executed to minimize the generation of false-positive and false-negative associations and misleading links to biological processes. This review aims to provide general guidelines for data analysis that address data quality control, association tests, adjustment for population stratification, and significance evaluation to improve the reliability of conclusions. We also provide guidance on post-GWAS strategy and the interpretation of results. These guidelines are tailored to dairy cattle, which are characterized by long-range linkage disequilibrium, large half-sib families, and routinely collected phenotypes, requiring different approaches than those applied in human GWAS. We discuss common limitations and challenges that have been overlooked in the analysis and interpretation of GWAS to identify candidate sequence variants in dairy cattle.

[Bioinformatics analysis in metagenomic next-generation sequencing of pathogenic microorganisms: current status and challenges]

The clinical application of metagenomic next-generation sequencing (mNGS) in the diagnosis of unknown pathogenic infections and critical infections has become increasingly valuable. Due to the huge volume of mNGS data and the complexity of clinical diagnosis and treatment, mNGS has difficulties in data analysis and interpretation in practical application. Therefore, in the process of clinical practice, it is crucial to grasp the key points of bioinformatics analysis and establish a standardized bioinformatics analysis process, which is an important step in the transformation of mNGS from laboratory to clinic. At present, bioinformatics analysis of mNGS has made great progress, but with the high requirements of clinical standardization of bioinformatics analysis and the development of computer technology, bioinformatics analysis of mNGS is also facing new challenges. This article mainly elaborates on quality control, and identification and visualization of pathogenic bacteria.

A Single-Cell RNA-Sequencing Analysis of Distinct Subsets of Synovial Macrophages in Rheumatoid Arthritis

The polarization states and molecular signatures of macrophages in the synovium of patients with rheumatoid arthritis (RA) are not well understood. We aimed to identify specific subpopulations of macrophages and their features in RA synovium thereby providing a theoretical basis for treatment of RA. Single-cell RNA sequencing (scRNA-seq) was used to identify cell subsets and their gene signatures in synovial cells of patients with RA and osteoarthritis (OA). Spatial distribution of macrophages was visualized by deconvolving spatial transcriptomic data with scRNA-seq data. Flow cytometry and immunofluorescence were applied to investigate the expression of macrophage polarization indicators CD86 and CD206. Trajectory analysis was used to determine differentiation relationships. Transcription factor (TF) analysis was performed to find specific TFs. scRNA-seq identified three cell clusters of macrophages: M0-like MARCO⁺ Mϕ1, M2-like CSF1R⁺ Mϕ2, and M1-like PLAUR⁺ Mϕ3. Mϕ1 distributed widely in the synovium, whereas Mϕ2 and Mϕ3 distributed sparsely. CD86 and CD206 were both upregulated in macrophages of RA synovium, especially in lining layer. Trajectory analysis showed that Mϕ1 existed at the start of the differentiation trajectory. HOXB6, STAT1, and NFKB2 were TFs specific to Mϕ1, Mϕ2, and Mϕ3 under RA condition, respectively. Compared with in OA condition, three macrophage clusters upregulated CXCL2, CXCL1, IL1B, TNFAIP3, ICAM1, CXCL3, PLAU, CCL4L2, CCL4, and TNF in NF-kappa B signaling pathway. The identification of macrophage subsets with different polarized states and their molecular signatures provided a more precise understanding of macrophages, which may contribute to the development of novel therapeutic strategy for RA.

Reliability and validity of the functional combined anteversion measurement method using standing lateral radiography after total hip arthroplasty

Background

The functional safe zone of combined anteversion (CA) shows a superior predictive value for dislocation after total hip arthroplasty (THA) compared to that of the Lewinnek safe zone. Thus, it is necessary to establish a feasible and accurate method for assessing CA for the evaluation of dislocation risk. We aimed to evaluate the reliability and validity of using standing lateral (SL) radiographs for determining CA.

Methods

Sixty-seven patients who underwent SL radiography and computed tomography (CT) scans after THA were included. Radiographic CA values were obtained via the calculation of the sum of the acetabular cup and femoral stem anteversion (FSA) measurements as obtained from the SL radiographs. Acetabular cup anteversion (AA) was measured based on the tangential line to the face of the cup, whereas FSA was calculated using the developed formula based on the neck-shaft angle. The intra-observer and inter-observer reliabilities for each measurement were examined. Radiological CA values were compared with the CT scan measurements to evaluate their validity.

Results

The intra-observer and inter-observer agreements of the SL radiography were excellent [intraclass correlation coefficient (ICC) ≥0.90]. The radiographic measurements correlated well with the CT scan measurements (r=0.869, P<0.001). The mean difference between the radiographic and CT scan measurements was -0.55°±4.68° and ranged from 0.3° to 2.2° in terms of the 95% confidence interval (CI).

Conclusions

SL radiography is a reliable and valid imaging tool for the assessment of functional CA.

Avascular necrosis under different treatment in children with developmental dysplasia of the hip: a network meta-analysis

The objective of this study was to evaluate the incidence of avascular necrosis (AVN) of the femoral head in children less than 3 years of age with developmental dysplasia of the hip (DDH) treated with closed reduction, open reduction alone and open reduction combined with osteotomy. We reviewed clinical trials from the PubMed, EMBASE and Cochrane Library databases (up to November 2020) that were related to closed reduction, open reduction alone and open reduction combined with osteotomy for the treatment of children under 3 years of age with DDH. The screening and quality evaluation of the literature were performed independently by two researchers. In case of disagreement, a third researcher resolved the discourse. Finally, the data were extracted, and the R software and GeMTC program package were used to conduct a network meta-analysis (NMA). The evaluation index was the incidence of AVN. Fourteen articles were included. The NMA showed that in terms of the incidence of AVN, cases treated with open reduction alone were higher than those with closed reduction, and the difference was statistically significant. Open reduction alone had the highest probability (94.4%) of having the highest incidence of AVN, followed by open reduction combined with osteotomy (5.5%) and closed reduction (0.1%). In the treatment of children with DDH who are younger than 3 years old, open reduction alone is most likely to be the treatment with the highest incidence of AVN, followed by open reduction combined with osteotomy. The closed reduction had the smallest probability of AVN.

Potential biomarkers in the fibrosis progression of nonalcoholic steatohepatitis (NASH)

PURPOSE

Fibrosis is the only histological feature reflecting the severity and prognosis of nonalcoholic steatohepatitis (NASH). We aim to explore novel genes associated with fibrosis progression in NASH.

METHODS

Two human RNA-seq datasets were downloaded from the public database. Weighted gene co-expression network analysis (WGCNA) was used to identify their co-expressed modules and further bioinformatics analysis was performed to identify hub genes within the modules. Finally, based on two single-cell RNA-seq datasets from mice and one microarray dataset from human, we further observed the expression of hub genes in different cell clusters and liver tissues.

RESULTS

7 hub genes (SPP1, PROM1, SOX9, EPCAM, THY1, CD34 and MCAM) associated with fibrosis progression were identified. Single-cell RNA-seq analysis revealed that those hub genes were expressed by different cell clusters such as cholangiocytes, natural killer (NK) cells, and hepatic stellate cells (HSCs). We also found that SPP1 and CD34 serve as markers of different HSCs clusters, which are associated with inflammatory response and fibrogenesis, respectively. Further study suggested that SPP1, SOX9, MCAM and THY1 might be related to NASH-associated hepatocellular carcinoma (HCC). Receiver operating characteristic (ROC) analysis showed that the high expression of these genes could well predict the occurrence of HCC. At the same time, there were significant differences in metabolism-related pathway changes between different HCC subtypes, and SOX9 may be involved in these changes.

CONCLUSIONS

The present study identified novel genes associated with NASH fibrosis and explored their effects on fibrosis from a single-cell perspective that might provide new ideas for the early diagnosis, monitoring, evaluation, and prediction of fibrosis progression in NASH.

Reliability and Validity of Standing Lateral Radiograph Method for Measuring Acetabular Component Version: A Modified Cross-table Lateral Radiograph Method

OBJECTIVES

To investigate the effect of the X-ray incidence angle on cup version measurements and the reliability and validity of standing lateral (SL) radiography for measuring cup versions.

METHODS

Cup versions under different X-ray incidence angles were investigated by the 3D simulation analysis. Ninety-three patients, who underwent primary total hip arthroplasty (THA) with postoperative SL radiographs and CT scans between April 2020 and December 2021, were retrospectively analyzed. SL radiography was taken under naturally standing position, correcting for the measurement error of pelvic tilt in cross-table lateral (CL) radiography. Cup versions were measured on SL radiographs and CT images by two qualified orthopedic physicians. The intra- and inter-observer reliabilities were assessed by intra-class correlation coefficient. The consistency between radiographic and CT measurements was evaluated using Pearson correlation coefficient.

RESULTS

No significant differences in cup version measurements were observed between groups of different X-ray incidence angles (P = 0.663) in the 3D simulation analysis. All measurements had excellent intra- and inter-observer reliabilities, with an intraclass correlation coefficient of >0.95. Mean cup version measurements from SL radiographs correlated well with those from CT scans (r = 0.853, P < 0.001). The mean difference between radiographic and CT measurements was -0.49° (range -12.62° to 10.37°, SD 3.95°), and the majority of differences were within the 95% limits of agreement.

CONCLUSION

The cup versions measured with SL radiography were close to the CT measurements. SL radiograph method is reliable and valid for measuring acetabular component version after THA.

Thrombin antithrombin complex concentration as an early predictor of deep vein thrombosis after total hip arthroplasty and total knee arthroplasty

Aim

Early predictive markers of venous thromboembolism (VTE) after total hip arthroplasty (THA)/total knee arthroplasty (TKA) remain unclear. Our study identified early predictive markers for VTE after THA/TKA.

Methods

A single-institution retrospective review study was conducted between May 2020 and April 2022 (n = 256). All patients underwent Doppler ultrasounds exam in preoperation and seventh day after surgery. Deep vein thrombosis (DVT) was defined by Doppler ultrasound of the lower extremities, which revealed thrombosis. Thrombin-antithrombin complex (TAT), thrombomodulin (TM), and plasmin-antiplasmin complex (PIC) concentration were tested from each patient’s preoperative and postoperative days 1, 4, 7, 14. These values were then accessed via receiver operating characteristic (ROC) curve analysis and further quantified the level of this risk by concentration.

Results

On postoperative day 1 (pod-1), all patients’ TAT and PIC concentrations were significantly higher than those preoperatively (p < 0.05). The levels of TAT and PIC in patients in the DVT group on pod-1 were significantly higher than those in the non-DVT group (p < 0.05). At pod-1, the TAT concentration for DVT patients was 49.47 ng/mL compared to 20.70 ng/mL for non-DVT patients, PIC was 3.72μg/mL compared to 1.65μg/mL. ROC curve analysis demonstrated that a TAT concentration of 24.3 ng/mL had a sensitivity of 87.9% and a specificity of 69.1%.

Conclusion

TAT levels on pod-1 may predict DVT early after THA/TKA, which makes it possible for early intervention to decrease the incidence of DVT.

[Heparin-binding hemagglutinin as a composition antigen of tuberculosis vaccine exerts protective immune effects by inducing IL-17]

To explore the protective immune effect induced by mucosal delivery heparin-binding hemagglutinin (HBHA)-a candidate vaccine antigen of Mycobacterium tuberculosis. Female C57BL/6 mice were between 6 and 8 weeks of age before experimental use. Thirty mice received different immunization strategies and were randomly divided into the control group, the early secreting antigen target-6 (ESAT-6) intranasal immunization group, the HBHA intranasal immunization group, the BCG priming PBS control group, or BCG priming HBHA boost group, 6 mice in each group. In order to analyzed the immune effect, the concentrations of plasma Interleukin-17A (IL-17A) and other cytokines were measured by ELISA. Quantitative real-time PCR analyses were performed to detect the relative quantity (RQ) mRNA of IL-17A in the lung. The lung tissue sections were stained to detect the formation of the tertiary lymphoid structures. The chemokines contributed to formation of the tertiary lymphoid structures were also measured. Flow cytometry was used to detect the frequency of Th1 and Th17 cells in the system. Sixty mice in the BCG priming PBS control group and the BCG priming HBHA boost group were sacrificed at different time points after infection to count the lung bacterial burden. The concentrations of plasma IL-17A and relative quantity of lung IL-17A mRNA were highest in the BCG priming HBHA boost group [(14.76±4.73) pg/mL,RQ (12.27±6.71)], which was significantly higher than the control group [(5.57±2.95) pg/mL,RQ (1.30±0.97)] (t=4.213, P<0.001; t=5.984, P<0.001), and also significantly higher than the BCG priming PBS control group [(6.81±2.18) pg/mL,RQ (1.44±1.16)] (t=3.646 P=0.001; t=6.185 P<0.001). Compared with the BCG priming PBS control group (0.38±0.38)% the frequency of spleen Th17 cells were also significantly increased (t=-0.280, P=0.048) in the BCG-primary HBHA boost group (1.02±0.34)%. In addition, HBHA boosting could promote better formation of the tertiary lymphoid structures in the lung, and decrease the bacterial load on the early stage after BCG challenge. Collectively, mucosal delivery of HBHA can effectively enhance the protective effect after BCG vaccination, and it is a potential candidate vaccine component.

Damaged brain accelerates bone healing by releasing small extracellular vesicles that target osteoprogenitors

Clinical evidence has established that concomitant traumatic brain injury (TBI) accelerates bone healing, but the underlying mechanism is unclear. This study shows that after TBI, injured neurons, mainly those in the hippocampus, release osteogenic microRNA (miRNA)-enriched small extracellular vesicles (sEVs), which targeted osteoprogenitors in bone to stimulate bone formation. We show that miR-328a-3p and miR-150-5p, enriched in the sEVs after TBI, promote osteogenesis by directly targeting the 3'UTR of FOXO4 or CBL, respectively, and hydrogel carrying miR-328a-3p-containing sEVs efficiently repaires bone defects in rats. Importantly, increased fibronectin expression on sEVs surface contributes to targeting of osteoprogenitors in bone by TBI sEVs, thereby implying that modification of the sEVs surface fibronectin could be used in bone-targeted drug delivery. Together, our work unveils a role of central regulation in bone formation and a clear link between injured neurons and osteogenitors, both in animals and clinical settings.