Macrophage-derived extracellular vesicles regulate skeletal stem/progenitor Cell lineage fate and bone deterioration in obesity.

Obesity-induced chronic inflammation exacerbates multiple types of tissue/organ deterioration and stem cell dysfunction; however, the effects on skeletal tissue and the underlying mechanisms are still unclear. Here, we show that obesity triggers changes in the microRNA profile of macrophage-secreted extracellular vesicles, leading to a switch in skeletal stem/progenitor cell (SSPC) differentiation between osteoblasts and adipocytes and bone deterioration. Bone marrow macrophage (BMM)-secreted extracellular vesicles (BMM-EVs) from obese mice induced bone deterioration (decreased bone volume, bone microstructural deterioration, and increased adipocyte numbers) when administered to lean mice. Conversely, BMM-EVs from lean mice rejuvenated bone deterioration in obese recipients. We further screened the differentially expressed microRNAs in obese BMM-EVs and found that among the candidates, miR-140 (with the function of promoting adipogenesis) and miR-378a (with the function of enhancing osteogenesis) coordinately determine SSPC fate of osteogenic and adipogenic differentiation by targeting the Pparα-Abca1 axis. BMM miR-140 conditional knockout mice showed resistance to obesity-induced bone deterioration, while miR-140 overexpression in SSPCs led to low bone mass and marrow adiposity in lean mice. BMM miR-378a conditional depletion in mice led to obesity-like bone deterioration. More importantly, we used an SSPC-specific targeting aptamer to precisely deliver miR-378a-3p-overloaded BMM-EVs to SSPCs via an aptamer-engineered extracellular vesicle delivery system, and this approach rescued bone deterioration in obese mice. Thus, our study reveals the critical role of BMMs in mediating obesity-induced bone deterioration by transporting selective extracellular-vesicle microRNAs into SSPCs and controlling SSPC fate.

Mechanosensitive protein polycystin-1 promotes periosteal stem/progenitor cells osteochondral differentiation in fracture healing.

Background: Mechanical forces are indispensable for bone healing, disruption of which is recognized as a contributing cause to nonunion or delayed union. However, the underlying mechanism of mechanical regulation of fracture healing is elusive. Methods: We used the lineage-tracing mouse model, conditional knockout depletion mouse model, hindlimb unloading model and single-cell RNA sequencing to analyze the crucial roles of mechanosensitive protein polycystin-1 (PC1, Pkd1) promotes periosteal stem/progenitor cells (PSPCs) osteochondral differentiation in fracture healing. Results: Our results showed that cathepsin (Ctsk)-positive PSPCs are fracture-responsive and mechanosensitive and can differentiate into osteoblasts and chondrocytes during fracture repair. We found that polycystin-1 declines markedly in PSPCs with mechanical unloading while increasing in response to mechanical stimulus. Mice with conditional depletion of Pkd1 in Ctsk+ PSPCs show impaired osteochondrogenesis, reduced cortical bone formation, delayed fracture healing, and diminished responsiveness to mechanical unloading. Mechanistically, PC1 facilitates nuclear translocation of transcriptional coactivator TAZ via PC1 C-terminal tail cleavage, enhancing osteochondral differentiation potential of PSPCs. Pharmacological intervention of the PC1-TAZ axis and promotion of TAZ nuclear translocation using Zinc01442821 enhances fracture healing and alleviates delayed union or nonunion induced by mechanical unloading. Conclusion: Our study reveals that Ctsk+ PSPCs within the callus can sense mechanical forces through the PC1-TAZ axis, targeting which represents great therapeutic potential for delayed fracture union or nonunion.

Age-related secretion of grancalcin by macrophages induces skeletal stem/progenitor cell senescence during fracture healing.

Skeletal stem/progenitor cell (SSPC) senescence is a major cause of decreased bone regenerative potential with aging, but the causes of SSPC senescence remain unclear. In this study, we revealed that macrophages in calluses secrete prosenescent factors, including grancalcin (GCA), during aging, which triggers SSPC senescence and impairs fracture healing. Local injection of human rGCA in young mice induced SSPC senescence and delayed fracture repair. Genetic deletion of Gca in monocytes/macrophages was sufficient to rejuvenate fracture repair in aged mice and alleviate SSPC senescence. Mechanistically, GCA binds to the plexin-B2 receptor and activates Arg2-mediated mitochondrial dysfunction, resulting in cellular senescence. Depletion of Plxnb2 in SSPCs impaired fracture healing. Administration of GCA-neutralizing antibody enhanced fracture healing in aged mice. Thus, our study revealed that senescent macrophages within calluses secrete GCA to trigger SSPC secondary senescence, and GCA neutralization represents a promising therapy for nonunion or delayed union in elderly individuals.

miR-188-3p targets skeletal endothelium coupling of angiogenesis and osteogenesis during ageing.

A specific bone capillary subtype, namely type H vessels, with high expression of CD31 and endomucin, was shown to couple angiogenesis and osteogenesis recently. The number of type H vessels in bone tissue declines with age, and the underlying mechanism for this reduction is unclear. Here, we report that microRNA-188-3p (miR-188-3p) involves this process. miRNA-188-3p expression is upregulated in skeletal endothelium and negatively regulates the formation of type H vessels during ageing. Mice with depletion of miR-188 showed an alleviated age-related decline in type H vessels. In contrast, endothelial-specific overexpression of miR-188-3p reduced the number of type H vessels, leading to decreased bone mass and delayed bone regeneration. Mechanistically, we found that miR-188 inhibits type H vessel formation by directly targeting integrin ß3 in endothelial cells. Our findings indicate that miR-188-3p is a key regulator of type H vessel formation and may be a potential therapeutic target for preventing bone loss and accelerating bone regeneration.

Senescent immune cells release grancalcin to promote skeletal aging.

Skeletal aging is characterized by low bone turnover and marrow fat accumulation. However, the underlying mechanism for this imbalance is unclear. Here, we show that during aging in rats and mice proinflammatory and senescent subtypes of immune cells, including macrophages and neutrophils, accumulate in the bone marrow and secrete abundant grancalcin. The injection of recombinant grancalcin into young mice was sufficient to induce premature skeletal aging. In contrast, genetic deletion of Gca in neutrophils and macrophages delayed skeletal aging. Mechanistically, we found that grancalcin binds to the plexin-b2 receptor and partially inactivates its downstream signaling pathways, thus repressing osteogenesis and promoting adipogenesis of bone marrow mesenchymal stromal cells. Heterozygous genetic deletion of Plexnb2 in skeletal stem cells abrogated the improved bone phenotype of Gca-knockout mice. Finally, we developed a grancalcin-neutralizing antibody and showed that its treatment of older mice improved bone health. Together, our data suggest that grancalcin could be a potential target for the treatment of age-related osteoporosis.

Sodium Valproate Combined With Topiramate vs. Sodium Valproate Alone for Refractory Epilepsy: A Systematic Review and Meta-Analysis.

Background: Among antiepileptic drugs (AEDs), sodium valproate alone or in the combination of topiramate (TPM) for treating refractory epilepsy was controversial. This meta-analysis aimed to systematically evaluate the clinical effects of these two regimens in this population. Methods: Relevant studies up to August 2021 were identified through systematic searches of CNKI, Wanfang, PubMed, and Embase databases. We assessed the effectiveness and the frequency of absence seizures, atonic seizures, and tonic-clonic seizures. The included literature's risk of bias was evaluated using the Cochrane Collaboration's Risk of Bias tool. Sensitivity analysis was conducted to confirm the results' stability. STATA 15.0 was utilized for all pooled analyses in the included studies. Results: Totally 10 articles were determined for our meta-analysis, involving 976 patients with epilepsy in total (combined group, n = 488; monotherapy group, n = 488). The results of this meta-analysis indicated that the total effective rate of sodium valproate combined with TPM was higher than that of sodium valproate alone (random-effect model: OR = 3.52; 95% CI 1.47 to 8.47; p < 0.001; I 2 = 73.8%). The frequency of absence seizures in the combined group was lower (fixed-effect model: WMD = -6.02; 95% CI -6.50 to -5.54; I 2 = 0.0%) than that in the monotherapy group, with a statistical difference (p < 0.05). The combined group had lower frequency of atonic seizures (WMD = -4.56, 95% CI -6.02 to -3.10; I 2 = 82.6%) and lower frequency of tonic-clonic seizures (WMD = -3.32; 95% CI -4.75 to -1.89; I 2 = 96.4%). In addition, the distinct difference of adverse events was non-existent between two groups. Conclusions: Sodium valproate combined with TPM was more effective than sodium valproate alone for epilepsy therapy. This meta-analysis provides feasibility data for a larger-scale study on AED therapy of refractory epilepsy and may contribute to better therapy strategies for epilepsy clinically.

Human urinary kallindinogenase therapy for acute ischemic stroke according to Chinese ischemic stroke subclassification: Clinical efficacy and risk factors.

INTRODUCTION: To evaluate effectiveness of human urinary kallindinogenase (HUK) in patients with acute ischemic stroke (AIS) according to Chinese ischemic stroke subclassification (CISS) and analyzed risk factors of clinical efficacy. METHODS: In this retrospective study, 134 patients received conventional therapy were enrolled to control group, and 132 patients received HUK treatment were enrolled to HUK group. National Institute of Health Stroke Scale (NIHSS) score was used to evaluate the clinical efficacy. Multivariate analysis of risk factors was performed by using logistic regression. RESULTS: After treatment, NIHSS score of HUK group was significant lower than that of control group (p = .009). Effectiveness rate was 71.2% in HUK group, and 53.7% in control group, respectively (p = .003). The NIHSS of patients with large artery atherosclerosis (LAA) subtype in HUK group was significantly lower than that in control group (p = .005). The absence of HUK (OR = 2.75), homocysteine (OR = 0.15), and CS subtype (OR = 0.18) were risk factors for HUK clinical efficacy. CONCLUSIONS: Human urinary kallindinogenase is an effective therapeutic approach for treatment of patients with AIS, especially in patients with LAA subtype. The absence of HUK, elevated homocysteine, and cardiogenic stroke subtype were risk factor for clinical efficacy of HUK.