The technique bottleneck of repairing large bone defects with tissue engineered bone is the vascularization of tissue engineered grafts. Although some studies have shown that extracellular vesicles (EVs) derived from bone marrow mesenchymal stem cells (BMSCs) promote bone healing and repair by accelerating angiogenesis, the effector molecules and the mechanism remain unclear, which fail to provide ideas for the future research and development of cell-free interventions. Here, we found that Nidogen1-enriched EV (EV-NID1) derived from BMSCs interferes with the formation and assembly of focal adhesions (FAs) by targeting myosin-10, thereby reducing the adhesion strength of rat arterial endothelial cells (RAECs) to the extracellular matrix (ECM), and enhancing the migration and angiogenesis potential of RAECs. Moreover, by delivery with composite hydrogel, EV-NID1 is demonstrated to promote angiogenesis and bone regeneration in rat femoral defects. This study identifies the intracellular binding target of EV-NID1 and further elucidates a novel approach and mechanism, thereby providing a cell-free construction strategy with precise targets for the development of vascularized tissue engineering products.
Abstract BackgroundThe pathological characteristics of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are pulmonary edema resulting from pulmonary permeability increasing. The main cause is uncontrolled inflammatory response leading to the damage of pulmonary vascular endothelial and alveolar epithelial barriers. However, there has not been effective drugs against ALI. In this study, we investigated the function of Isopropyl 3-(3, 4-dihydroxypheny l)-2-hydroxypropanoate (IDHP), a novel metabolite of Danshen dripping pill having anti-inflammatory effect, in lipopolysaccharide (LPS) induced ALI in mice, and its underlying mechanisms.MethodsPretreatment of IDHP in LPS-induced acute lung injury in mice were observed on survival rate, pulmonary morphologic changes, total protein content in bronchoalveolar lavage fluid (BALF), and inflammatory cytokines in lung tissue and BALF. To further explore its mechanism on ALI, THP-1 macrophages was studied to analyse pyroptosis related proteins and co-culture with epithelial or endothelial cells to assess protection function of IDHP in vitro.ResultsAs revealed by survival study, pretreatment with high dose of IDHP reduced the mortality of mice from ALI. IDHP pretreatment significantly improved LPS-induced lung pathological changes, reduced protein leakage and lung myeloperoxidase activity. IDHP also inhibited the release of inflammatory mediators TNFα, IL-1β, IL-6 and IL-18 in BALF and lung tissue. Meanwhile, IDHP decreased the expression of active-caspase1 (in canonical pyroptosis pathway), caspase4/5 (non-canonical pyroptosis pathway), Nrlp3, mature IL-1β, mature IL-18, Asc speck formation, and cleaved Gsdmd, all these are required for pyroptosis, in LPS stimulated THP-1 macrophages. Moreover, IDHP also decreased ROS production in LPS-stimulated THP-1 macrophages, inhibited the expression of tight junction proteins (Occludin, Zo-1) in endothelial cells, and decreased lactate dehydrogenase activity in supernatants of epithelial or endothelial cells, co-cultured with LPS-stimulated THP-1 macrophages. ConclusionsPretreatment of IDHP improves survival rate and ameliorates LPS-induced ALI in mice possibly via inhibiting canonical and non-canonical pyroptosis pathways.
Abstract Background: The pathological characteristics of acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are pulmonary edema resulting from pulmonary permeability increasing. The main cause is uncontrolled inflammatory response leading to the damage of pulmonary vascular endothelial and alveolar epithelial barriers. However, there has not been effective drugs against ALI. In this study, we investigated the function of Isopropyl 3-(3, 4-dihydroxypheny l)-2-hydroxypropanoate (IDHP), a novel metabolite of Danshen dripping pill having anti-inflammatory effect, in lipopolysaccharide (LPS) induced ALI in mice, and its underlying mechanisms. Methods: Pretreatment of IDHP in LPS-induced acute lung injury in mice were observed on survival rate, pulmonary morphologic changes, total protein content in bronchoalveolar lavage fluid (BALF), and inflammatory cytokines in lung tissue and BALF. To further explore its mechanism on ALI, THP-1 macrophages was studied to analyse propotosis related proteins and co-culture with epithelial or endothelial cells to assess protection function of IDHP in vitro. Results: As revealed by survival study, pretreatment with high dose of IDHP reduced the mortality of mice from ALI. IDHP pretreatment significantly improved LPS-induced lung pathological changes, reduced protein leakage and lung myeloperoxidase activity. IDHP also inhibited the release of inflammatory mediators TNFα, IL-1β, IL-6 and IL-18 in BALF and lung tissue. Meanwhile, IDHP decreased the expression of active-caspase1 (in canonical pyroptosis pathway), caspase4/5 (non-canonical pyroptosis pathway), Nrlp3, mature IL-1β, mature IL-18, Asc speck formation, and cleaved Gsdmd, all these are required for pyroptosis, in LPS stimulated THP-1 macrophages. Moreover, IDHP also decreased ROS production in LPS-stimulated THP-1 macrophages, inhibited the expression of tight junction proteins (Occludin, Zo-1) in endothelial cells, and decreased lactate dehydrogenase activity in supernatants of epithelial or endothelial cells, co-cultured with LPS-stimulated THP-1 macrophages. Conclusions: Pretreatment of IDHP improves survival rate and ameliorates LPS-induced ALI in mice possibly via inhibiting canonical and non-canonical pyroptosis pathways.
Microcystin-leucine arginine (MC-LR), a potentially carcinogenic toxin, is produced by Cyanobacteria such as Microcystis and Ananabacteria during water bloom. Increasing evidence demonstrated that MC-LR induces male reproductive toxicity, mainly by inducing germ cell apoptosis, destroying cell cytoskeleton, interfering with DNA damage repair pathway, and damaging blood-testicular barrier (BTB), which eventually lead to male sterility. Testicular Sertoli cells are the somatic cells that directly contact with spermatogenic cells in seminiferous tubules. They not only regulate immune response to maintain testicular immune homeostasis by secreting a variety of cytokines and immunosuppressive factors, but also provide the protective effects of spermatogenic cells by forming BTB. MC-LR induces inflammation and apoptosis of Sertoli cells, and destroys the integrity of the BTB, and then causes spermatogenesis dysfunction.
Introduction: Developmental engineering based on endochondral ossification has been proposed as a potential strategy for repairing of critical bone defects. Bone development is driven by growth plate-mediated endochondral ossification. Under physiological conditions, growth plate chondrocytes undergo compressive forces characterized by micro-mechanics, but the regulatory effect of micro-mechanical loading on endochondral bone formation has not been investigated. Methods: In this study, a periodic static compression (PSC) model characterized by micro-strain (with 0.5% strain) was designed to clarify the effects of biochemical/mechanical cues on endochondral bone formation. Hydrogel scaffolds loaded with bone marrow mesenchymal stem cells (BMSCs) were incubated in proliferation medium or chondrogenic medium, and PSC was performed continuously for 14 or 28 days. Subsequently, the scaffold pretreated for 28 days was implanted into rat femoral muscle pouches and femoral condylar defect sites. The chondrogenesis and bone defect repair were evaluated 4 or 10 weeks post-operation. Results: The results showed that PSC stimulation for 14 days significantly increased the number of COL II positive cells in proliferation medium. However, the chondrogenic efficiency of BMSCs was significantly improved in chondrogenic medium, with or without PSC application. The induced chondrocytes (ichondrocytes) spontaneously underwent hypertrophy and maturation, but long-term mechanical stimulation (loading for 28 days) significantly inhibited hypertrophy and mineralization in ichondrocytes. In the heterotopic ossification model, no chondrocytes were found and no significant difference in terms of mineral deposition in each group; However, 4 weeks after implantation into the femoral defect site, all scaffolds that were subjected to biochemical/mechanical cues, either solely or synergistically, showed typical chondrocytes and endochondral bone formation. In addition, simultaneous biochemical induction/mechanical loading significantly accelerated the bone regeneration. Discussion: Our findings suggest that microstrain mechanics, biochemical cues, and in vivo microenvironment synergistically regulate the differentiation fate of BMSCs. Meanwhile, this study shows the potential of micro-strain mechanics in the treatment of critical bone defects.
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