Osteocyte-derived sclerostin impairs cognitive function during ageing and Alzheimer's disease progression.

Ageing increases susceptibility to neurodegenerative disorders, such as Alzheimer's disease (AD). Serum levels of sclerostin, an osteocyte-derived Wnt-ß-catenin signalling antagonist, increase with age and inhibit osteoblastogenesis. As Wnt-ß-catenin signalling acts as a protective mechanism for memory, we hypothesize that osteocyte-derived sclerostin can impact cognitive function under pathological conditions. Here we show that osteocyte-derived sclerostin can cross the blood-brain barrier of old mice, where it can dysregulate Wnt-ß-catenin signalling. Gain-of-function and loss-of-function experiments show that abnormally elevated osteocyte-derived sclerostin impairs synaptic plasticity and memory in old mice of both sexes. Mechanistically, sclerostin increases amyloid ß (Aß) production through ß-catenin-ß-secretase 1 (BACE1) signalling, indicating a functional role for sclerostin in AD. Accordingly, high sclerostin levels in patients with AD of both sexes are associated with severe cognitive impairment, which is in line with the acceleration of Αß production in an AD mouse model with bone-specific overexpression of sclerostin. Thus, we demonstrate osteocyte-derived sclerostin-mediated bone-brain crosstalk, which could serve as a target for developing therapeutic interventions against AD.

Preoperative Prevalence and Risk Factors For Calf Muscular Vein Thrombosis in Elderly Patients with Hip Fracture.

OBJECTIVE: Increasing evidence has shown that calf muscular vein thrombosis (CMVT) can develop into proximal deep vein thrombosis, even causing pulmonary embolism. However, opinions about the prevalence and risk factors are still controversial. This study aimed to investigate the prevalence and risk factors for CMVT in elderly patients with hip fractures to facilitate their preoperative management. METHODS: We included 419 elderly patients with hip fracture who were treated in the orthopaedic department of our hospital from June 2017 to December 2020. The patients were divided into CMVT and non-CMVT groups based on color Doppler ultrasound screening of the venous system in the lower extremities. Clinical data, such as age, sex, body mass index, time from injury to admission, and laboratory data were collected. Univariate and multivariate logistic regression analyses were performed to determine independent risk factors for CMVT. A receiver operating characteristic curve was used to analyze the predictive effectiveness of the model. Finally, the clinical utility of the model was analyzed using decision curve analysis and clinical impact curves. RESULTS: The prevalence of preoperative CMVT was 30.5% (128/419). Independent predictors of preoperative CMVT identified by univariate and multivariate logistic regression analyses were sex, time from injury to admission, American Society of Anesthesiologists (ASA) classification, C-reactive protein (CRP) level, and D-dimer level (p < 0.05). The area under curve (AUC) was 0.750 (95% CI: 0.699-0.800, p < 0.001) and the sensitivity and specificity were 0.698 and 0.711, respectively, which meant the prediction model has a good efficacy in the prediction of CMVT risk. In addition, the fitting degree of the prediction model was also good (Hosmer-Lemeshow χ2 = 8.447, p > 0.05). The clinical utility of the model was verified using decision curve analysis and clinical impact curves. CONCLUSION: Sex, time from injury to admission, ASA classification, CRP level, and D-dimer levels are independent preoperative predictors of CMVT in elderly patients with hip fractures. Measures should be taken for patients with these risk factors to prevent the occurrence and deterioration of CMVT.

Intraindividual variance of lower limb rotation in patients with bilateral knee osteoarthritis.

Purpose: To determine the side-to-side difference in intraindividual rotation alignment of patients with bilateral varus-type knee osteoarthritis (OA) and compare it with control subjects. Methods: This retrospective study enrolled 60 patients with bilateral varus-type knee OA and 50 control subjects. All cases underwent bilateral lower limb CT angiography. Bilateral femoral and tibial rotation alignment were measured, and the overall lower limb rotation was calculated by two different methods. Method 1 was calculated by subtracting angle of the femoral torsion from the tibial torsion and method 2 was determined by relative rotation of the femoral neck angle to bimalleolar angle. The intraindividual variance and differences between the two groups were analyzed. Results: Both OA and control samples showed significant differences between right and left for all measurements. Femoral torsion for control group was 10.4 ± 5.5°, tibial torsion was -22.1 ± 6.1°, and overall leg rotation by method 1 was -15.6 ± 7.2° and method 2 was -11.7 ± 8.2°. Femoral torsion, tibial torsion, method 1, and method 2 in the patients with OA were 8.2 ± 6.3°, -18.6 ± 4.1°, -14.9 ± 7.9°, and -10.4 ± 7.6°, respectively. Patients with OA showed a more pronounced retroversion in the femur (p = 0.008) and more internal rotation in the tibia (p < 0.001). No statistical significance of both methods was found between the two groups. Patients with OA had a greater median side-to-side absolute difference in all measurements, though the differences of both two methods of overall lower limb rotation were not statistically significant. Conclusions: The discrepancy of side-to-side differences of bilateral lower limb rotation ought to be noticed with caution in diagnosing and treating rotational deformities of the lower limb, especially for patients with bilateral knee OA.

3D-printed fish gelatin scaffolds for cartilage tissue engineering.

Knee osteoarthritis is a chronic disease caused by the deterioration of the knee joint due to various factors such as aging, trauma, and obesity, and the nonrenewable nature of the injured cartilage makes the treatment of osteoarthritis challenging. Here, we present a three-dimensional (3D) printed porous multilayer scaffold based on cold-water fish skin gelatin for osteoarticular cartilage regeneration. To make the scaffold, cold-water fish skin gelatin was combined with sodium alginate to increase viscosity, printability, and mechanical strength, and the hybrid hydrogel was printed according to a pre-designed specific structure using 3D printing technology. Then, the printed scaffolds underwent a double-crosslinking process to enhance their mechanical strength even further. These scaffolds mimic the structure of the original cartilage network in a way that allows chondrocytes to adhere, proliferate, and communicate with each other, transport nutrients, and prevent further damage to the joint. More importantly, we found that cold-water fish gelatin scaffolds were nonimmunogenic, nontoxic, and biodegradable. We also implanted the scaffold into defective rat cartilage for 12 weeks and achieved satisfactory repair results in this animal model. Thus, cold-water fish skin gelatin scaffolds may have broad application potential in regenerative medicine.

Bone microenvironment regulative hydrogels with ROS scavenging and prolonged oxygen-generating for enhancing bone repair.

Large bone defects resulting from fractures and disease are a major clinical challenge, being often unable to heal spontaneously by the body's repair mechanisms. Lines of evidence have shown that hypoxia-induced overproduction of ROS in bone defect region has a major impact on delaying bone regeneration. However, replenishing excess oxygen in a short time cause high oxygen tension that affect the activity of osteoblast precursor cells. Therefore, reasonably restoring the hypoxic condition of bone microenvironment is essential for facilitating bone repair. Herein, we designed ROS scavenging and responsive prolonged oxygen-generating hydrogels (CPP-L/GelMA) as a "bone microenvironment regulative hydrogel" to reverse the hypoxic microenvironment in bone defects region. CPP-L/GelMA hydrogels comprises an antioxidant enzyme catalase (CAT) and ROS-responsive oxygen-releasing nanoparticles (PFC@PLGA/PPS) co-loaded liposome (CCP-L) and GelMA hydrogels. Under hypoxic condition, CPP-L/GelMA can release CAT for degrading hydrogen peroxide to generate oxygen and be triggered by superfluous ROS to continuously release the oxygen for more than 2 weeks. The prolonged oxygen enriched microenvironment generated by CPP-L/GelMA hydrogel significantly enhanced angiogenesis and osteogenesis while inhibited osteoclastogenesis. Finally, CPP-L/GelMA showed excellent bone regeneration effect in a mice skull defect model through the Nrf2-BMAL1-autophagy pathway. Hence, CPP-L/GelMA, as a bone microenvironment regulative hydrogel for bone tissue respiration, can effectively scavenge ROS and provide prolonged oxygen supply according to the demand in bone defect region, possessing of great clinical therapeutic potential.

BMSC exosome-enriched acellular fish scale scaffolds promote bone regeneration.

Tissue engineering scaffolds are essential for repairing bone defects. The use of biomimetic scaffolds for bone tissue engineering has been investigated for decades. To date, the trend in this area has been moved toward the construction of biomimetic acellular scaffolds with effective modification to enhance the osteogenic differentiation efficiency of bone marrow mesenchymal stem cells (BMSCs). The exosomes derived from BMSCs have been shown as a potential therapeutic tool for repairing bone defects. In this study, we demonstrated the pro-osteogenic effects of exosomes derived form osteogenic differentiated BMSCs (OBMSC) and presented a novel exosmes-functionalized decellularized fish scale (DE-FS) scaffold for promoting bone regeneration in vivo. The DE-FS scaffolds were obtained through decellularization and decalcification processes, which exhibited high biocompatibility and low immunological rejection. The intrinsic anisotropic structures of DE-FS could enhance the adhesion and proliferation ability of BMSCs in vitro. In addition, we demonstrated that the porous structure of DE-FS endowed them with the capacity to load and release exosomes to BMSCs, resulting in the enhanced osteogenic differentiation of BMSCs. Concerning these pro-osteogenic effects, it was further proved that OBMSC exosome-modified DE-FS scaffolds could effectively promote bone regeneration in the mouse calvarial defect models. In conclusion, our work provided a new insight to design exosome-riched biomimetic scaffolds for bone tissue engineering and clinical applications.

Polydopamine-Coated Poly(l-lactide) Nanofibers with Controlled Release of VEGF and BMP-2 as a Regenerative Periosteum.

The periosteum plays an important role in vascularization and ossification during bone repair. However, in most studies, an artificial periosteum cannot restore both functions of the periosteum concurrently. In this study, a novel nanofiber that can sustain the release of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) was fabricated to enhance the durability of angiogenesis and osteogenesis during bone regeneration. A cell-free tissue engineered periosteum based on an electrospinning poly-l-lactic acid (PLLA) nanofiber was fabricated, on which VEGF and BMP-2 were immobilized through a polydopamine (PDA) coating conveniently and safely (BVP@PLLA membrane). The results indicated a significantly improved loading rate as well as a slow and sustained release of VEGF and BMP-2 with the help of the PDA coating. BMP-2 immobilized on nanofibers successfully induced the osteogenic differentiation of human bone marrow mesenchymal stem cells (BMSCs) in vitro with high expression of runt-related transcription factor 2 (Runx2), osteopontin (OPN), and alkaline phosphatase (ALP). Similarly, angiogenic differentiation of BMSCs with the expression of fetal liver kinase-1 (Flk-1) and vascular endothelial cadherin (VE-cadherin) was observed under the environment of VEGF sustained release. Moreover, an in vivo study revealed that the BVP@PLLA membrane could enhance vascular formation and new bone formation, which accelerates bone regeneration in rat femoral defects along with a massive periosteum defect. Therefore, our study suggests that the novel artificial periosteum with dual growth factor controlled release is a promising system to improve bone regeneration in bone defects along with a massive periosteum defect.

Decreased Serum Exosomal miR-152-3p Contributes to the Progression of Acute Ischemic Stroke.

BACKGROUND: The current study aims to investigate the expression and potential role of exosome-derived miR-152-3p in acute ischemic stroke (AIS) patients. METHODS: Exosomes were isolated from AIS patients and healthy controls. The level of exosome miR-152-3p was examined using RT-PCR. Receiver operating characteristic (ROC) curves were used to assess exosome miR-152-3p as a biomarker, and the area under the curve (AUC) was reported. RESULTS: Our data showed that the expression of serum exosome miR-152-3p in patients with AIS was significantly lower than in healthy controls. In contrast to those with NIHSS score < 7, the level of exosome miR-152-3p was significantly reduced in AIS patients with NIHSS score ≥ 7, indicating that the decrease of exosome miR-152-3p level is significantly related to the severity of endothelial injury. Moreover, the lowest level of exosome miR-152-3p was found in large-artery atherosclerosis (LAA) patients compared to that in small-vessel occlusion (SAA), cardioembolism (CE) and stroke of undetermined etiology (SUE) group. In addition, exosome miR-152-3p level was significantly lower in acute phase than in chronic phase. ROC curve showed that the AUC of exosome miR-152-3p level was 0.935, which indicated that exosome miR-152-3p level could distinguish AIS patients from non-healthy controls. CONCLUSIONS: In summary, exosome miR-152-3p is a risk factor of cerebral infarction. Enhancing the expression of exosome miR-152-3p in the circulating system may be a promising strategy for the prevention and treatment of AIS.