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BACKGROUND:A large number of studies have confirmed that exosomes can promote osteogenesis and vascularization.However,simple exosome therapy has problems such as poor targeting,and the content of loaded molecules cannot reach the therapeutic concentration. OBJECTIVE:To load exosomes into injectable gluconolactone-sodium alginate β-tricalcium phosphate-polyethylene glycol hydrogel,and observe the effect of the hydrogel on peri-implant bone defect in vivo and in vitro. METHODS:Exosomes were extracted from bone marrow mesenchymal stem cells and wrapped in injectable gluconolactone-sodium alginate β-tricalcium phosphate-polyethylene glycol hydrogel.(1)In vitro experiment:The hydrogel loaded with exosomes and the hydrogel without exosomes were cocultured with endothelial progenitor cells,and exosomes uptake experiment,tubule formation experiment,cell proliferation,migration ability,and angiogenic gene detection were carried out.(2)In vivo experiment:Twelve male New Zealand white rabbits were used to prepare two standard implant cavities and corresponding bone defects in the long axis of one femur.A hydrogel loaded with exosomes was implanted in the bone defect after an implant was implanted in a cavity at the proximal end of the implant(experimental group),and an unloaded exosome hydrogel was implanted in the bone defect after an implant was implanted in a cavity at the distal end of the implant(control group).At 3,6 and 9 weeks after operation,bone defects with implants were removed and stained with hematoxylin-eosin staining and Masson staining.Simultaneously,osteogenic and angiogenic genes were detected at 9 weeks after operation. RESULTS AND CONCLUSION:(1)In vitro experiment:Exosomes could enter endothelial progenitor cells.The proliferation,migration,angiogenesis and gene(CD31,vascular endothelial growth factor and basic fibroblast growth factor)expression of endothelial progenitor cells in the hydrogel-loaded group were higher than those in the hydrogel-unloaded group(P<0.05).(2)In vivo experiment:Hematoxylin-eosin staining and Masson staining showed that at 3 weeks after operation,only a small amount of new bone was found in the two groups,and the material was partially degraded.At 6 weeks after operation,the amount of new bone in the two groups increased,and a large amount of new bone was found in the experimental group,with obvious calcium deposition.At 9 weeks after operation,compared with the control group,a large number of bone trabeculae thicker than mature were found in the experimental group,calcium salt deposition was more obvious,and a large number of osteoblasts were found around the bone trabeculae.The protein expressions of CD31,vascular endothelial growth factor,basic fibroblast growth factor,bone morphogenetic protein 2,type I collagen and osteocalcin in the experimental group were higher than those in the control group at 9 weeks after operation(P<0.05).(3)The exosome-loaded gluconolactone-sodium alginate β-tricalcium phosphate-polyethylene glycol hydrogel could promote the proliferation,migration and angiogenic differentiation of endothelial progenitor cells and promote the repair and regeneration of bone defects around implants.

Objective To investigate the expression of connective tissue growth factor (CTGF) and heat shock protein 47 (HSP47) in peritoneum fibrosis rats,and the mechanism of 1,25-dihydroxyvitamin D3 [1,25-(OH)2-VitD3] in inhibiting the peritoneum fibrosis.Methods Adult male Sprague-Dawley rats were randomly divided into 3 groups:control group (n=8),model group (n=8) and 1,25-dihydroxyvitamin D3 group (VitD3,n=8).The model of peritoneum fibrosis rats were induced by daily intraperitoneally injection of 15％ chlorhexidine gluconate (CHX) 0.2 ml/d with 0.1％ glucose for 4 weeks.Rats in VitD3 group were also treated with 1,25-(OH)2-VitD3 [i.p.6 ng· (100 g) 1 · d-1].Peritoneal transport function,renal function,peritoneum thickness and serum level of 25hydroxyvitamin D3 were detected.In vitro,primary cultured peritoneal mesothelial cells were divided into control group,high glucose group (HG,2.5％),CTGF siRNA intervention group (CTGF siRNA+HG),VitD3 intervention group (VitD3+HG) and combined intervention group (CTGF siRNA+VitD3+HG).Real-time PCR,Western blotting and immunofluorescence were applied to measure the expression of CTGF and HSP47,also ELISA was used to detect the protein level of FN in peritoneum and peritoneal mesothelial cells.Results Compared with control group,the peritoneal ultrafiltration in peritoneum fibrosis rats were significantly decreased (P ＜ 0.05),the absorbance level of peritoneal fibrosis,peritoneum thickness,the rate of dialysate urea nitrogen and blood urea nitrogen (DUN/BUN) and the expressions of CTGF and HSP47 were increased (all P＜0.05).After application of 1,25-dihydroxyvitamin D3,peritoneal fibrosis lesion was significantly improved,the peritoneum thickness,the expressions of CTGF and HSP47 were decreased (all P ＜ 0.05).In vitro,2.5％ high glucose induced-peritoneal mesothelial cells were respectively treated by CTGF siRNA,1,25-(OH)2-VitD3 and combined interventions,the expression of FN,CTGF and HSP47 was significantly lower than that in high glucose group (all P ＜ 0.05).Conclusions The expression of CTGF and HSP47 is significantly increased in peritoneal fibrosis rats.1,25-(OH)2-VitD3 may ameliorate the progression of peritoneal fibrosis via reducing the expression of CTGF,decreasing the expression of HSP47 and FN.

Cardiac senescence can change the structure and function of the heart and increase the risk of cardiovascular disease.Cardiac senescence is not only closely related to telomere damage, oxidative stress, mitochondrial dysfunction and autophagy, but also is regulated by non-coding RNA.Therefore, this article will give an overview of cardiac senescence and relative pathogenetic mechanisms, in order to provide new ideas for preventing and treating cardiac senescence and for achieving healthy and longevity.