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Objective:To investigate the effects of Connexin-43 (Cx43) on osteoblasts proliferation and osteogenic differentiation and its regulatory mechanism.Methods:Osteoblasts were isolated and cultured in vitro. The osteogenic activity of osteoblasts was detected by alizarin red staining and alkaline phosphatase (ALP) staining after dexamethasone treatment. The expression of Cx43, Runt-related transcription factor 2 (Runx2), ALP, collagen I type (COL-I) and proliferation-related proteins PCNA and CDK4 in osteoblasts were detected by Western-blot. The expressions of osteoblast proteins were detected by immunofluorescence staining. The proliferation of osteoblasts was detected by CCK8 assay. The lentivirus-mediated Cx43 gene overexpression plasmid (Lv-Cx43) was constructed and transfected into osteoblasts. The osteogenic activity and proliferation ability of osteoblasts were further detected by the above methods. Cx43 in osteoblasts was overexpressed by pretreating PD98059. The osteogenic activity and proliferation of Cx43 in overexpressed osteoblasts was detected by CCK8 and alizarin red staining.Results:The isolated osteoblasts have osteogenic differentiation ability. Compared with the control group, 1×10 -6 mol/L dexamethasone treatment could reduce the formation of calcium nodules in osteoblasts. With the increase of dexamethasone treatment duration, the protein expression of Cx43, Runx2, ALP and COL-I in osteoblasts decreased gradually, while the expression of PCNA, CDK4 and p-ERK1/2 decreased. The OD values of normal osteoblasts at 0, 1, 2, 3 and 4 d were 0.316±0.043, 0.891±0.623, 1.683±0.154, 2.315±0.721 and 2.891±0.323, respectively. However, The OD values of osteoblasts treated with dexamethasone were 0.376±0.021, 0.657±0.121, 1.124±0.285, 1.521±0.272, 1.987±0.584, respectively. OD values of dexamethasone treated osteoblasts were lower than those of normal group at 2, 3 and 4 days ( P<0.05). The relative expression levels of Cx43 mRNA in control group, Lv-NC group and Lv-Cx43 group were 0.541±0.086, 0.598±0.018 and 1.000±0.082, respectively. The mRNA expression level of Cx43 in Lv-Cx43 group was higher than that in control group and Lv-NC group ( P<0.05). The ratio of Cx43 protein band to the gray value of GAPDH band in control group, Lv-NC group and Lv-Cx43 group were 0.816±0.737, 0.738±0.643 and 1.145±1.101, respectively. The expression level of Lv-Cx43 was higher than that in control group and Lv-NC group ( P<0.05). The expressions of Runx2, ALP, COL-I mRNA and related marker proteins in Lv-Cx43 group were higher than those in control group and Lv-NC group ( P<0.05). The number of calcium nodules in the Lv-Cx43 group was significantly higher than that in the control group and Lv-NC group. The OD value of osteoblasts and the number of calcium nodules in Lv-Cx43+PD98059 group were significantly lower than those in Lv-Cx43 group ( P<0.05). Conclusion:The proliferation and differentiation ability of osteoblasts is significantly decreased after the treatment of dexamethasone with decreased expression of Cx43. Overexpression of Cx43 can promote the proliferation and osteogenic differentiation of osteoblasts, which may be regulated through the ERK1/2 pathway.
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Osteonecrosis of the femoral head (ONFH) is caused by the blockage of the blood supply of the femoral head due to by a variety of reasons, resulting in the death of the bone in the femoral head, which is characterized by osteonecrosis occurdead bone resorption-new bone formation. And total hip arthroplasty (THA) is the final choice for the vast majority of these patients. Though treating hard, it is necessary to choose an appropriate head-preserving treatment in the early stage to delay the time of THA.Methods to treat femoral head necrosis varies, however, it is still hard to have a uniform standard until now. Thus, this paper discusses the epidemiological characteristics, related risk factors, pathology, stage, current head-preserving methods and prognostic factors of femoral head necrosis, so as to further enhance clinicians' understanding of osteonecrosis of the femoral head and provide reference to choose more appropriate head-preserving methods for those patients. As demonstrated in literatures, in China, the incidence of non-traumatic ONFH in males is significantly higher than that in females, and it is more common in northern residents and urban residents. In addition, glucocorticoid intake, hyperlipidemia, heavy smoking and alcohol abuse tend to increase the risk of ONFH; Histologically, osteonecrosis and repair of the femoral head occurred after blood supply was blocked; In terms of pathological staging, Ficat staging is the most commonly used and most directly classification method; core decompression, non-vascularized bone grafting, vascularized bone grafting and osteotomy are still the mainstream surgical methods at present. Patient's age, etiology, stage, etc are important factors affecting the prognosis of ONFH. Therefore, surgeons can choose the most appropriate treatment for the patients according to their specific conditions and prognostic factors.
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Objective:To investigate the expression of connexin-43 (Cx43) in steroid-induced osteonecrosis of femoral head and osteoblasts in rats and its regulation mechanism.Methods:The model of steroid-induced osteonecrosis of femoral head (SIONFH) of rat was established. Micro-CT and HE staining were used to observe the degree of bone trabecular destruction and the incidence of empty lacunae. The expression levels of Cx43 and PI3K/Akt signaling pathway related molecules and osteoblast-related proteins in model group and control group were detected by RT-PCT and Western blot. The osteoblast (OB) of rats was further isolated and cultured in vitro. Under treatment of dexamethasone (Dex), Cx43 expression in OB cells was detected by Western blot and immunofluorescence. Western blot was used to detect the effect of glucocorticoid (GC) on the expression of related molecules of PI3K/Akt/β-catenin signaling pathway. Akt activator (SC79) and PI3K inhibitor (LY294002) were used to study the molecular mechanism of Dex regulation on Cx43 expression in OB cells. The regulatory relationship between β-catenin and Cx43 was investigated by immunoprecipitation and small interfere RNA (siRNA) technology.Results:The model of SIONFH in rats was successfully established, which proved that Cx43 expression level in the SIONFH model group was significantly lower than that in the control group, and the expression level of Cx43 was positively correlated with the expression of PI3K/Akt signaling pathway related molecules and osteoblast-related proteins Runx2, ALP and Collagen I Type (COL). In addition, in vitro culture of isolated rat OB cells, the expression of Cx43, p-PI3K, P-Akt and β-catenin in OB cells decreased gradually as the Dex action time went on. Moreover, SC79 pretreatment could significantly reverse the inhibitory effect of GCs on Cx43 expression, while LY294002 could significantly enhance the inhibitory effect of GCs on Cx43. In addition, the immunoprecipitation results showed that β-catenin expression was closely related to Cx43 expression, and further studies showed that β-catenin-siRNA could significantly down-regulate the expression of Cx43.Conclusion:Under the action of GC, the expression level of Cx43 in bone tissue and OB cells decreased significantly, and the possible mechanism was that GCs inhibited the expression of Cx43 by inhibiting the PI3K/Akt/β-catenin signaling pathway, which laid a new theoretical foundation for the further study of the role of Cx43 in the pathogenesis of steroid-induced femoral head necrosis.
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<p><b>OBJECTIVE</b>To evaluate the structural characteristics and biocompatibility of a novel nano-Ta-Ti alloy rod for its potential application in internal fixation.</p><p><b>METHODS</b>Ta coating of a Ti alloy rod with nano-Ta (tantalum) powder was performed using laser melting with symmetrical grooves repleted with nano-Ta powder along the whole length. The microstructure of the cross section of Ta-Ti alloy rod, pore diameter and components of the coating were analyzed using scanning electron microscopy. The influence of this nano-Ta-Ti alloy on proliferation and differentiation of MC3T3-E1 cells was evaluated by MTT cytotoxicity test and ALP activity test.</p><p><b>RESULTS</b>Under scanning electron microscope, the Ta-coating surface presented with a gross porous (200-300 µm) structure with dense fusion between Ta particles, and no new element was produced after laser melting. Biocompatibility evaluation showed that Ti alloys with and without Ta coating both promoted the proliferation of MC3T3-E1 cells, but the coated alloy showed better performance and obviously promoted the differentiation of the osteoblasts.</p><p><b>CONCLUSION</b>Alloying between Ta and Ti can be accomplished successfully by laser melting technique, and the alloy obtained has ideal surface structure and good biocompatibility.</p>
Subject(s)
Animals , Mice , 3T3 Cells , Alloys , Biocompatible Materials , Cell Differentiation , Cell Proliferation , Materials Testing , Microscopy, Electron, Scanning , Osteoblasts , Cell Biology , Porosity , Tantalum , TitaniumABSTRACT
Endothelial progenitor cells play a significant role in neovascularization of ischemic tissues and in reendothelialization of damaged blood vessels. Cytokines, an important components of micro-environment of angiogenesis,play an important role in regulation of endothelial progenitor cells. The effective application of cytokines can significantly argument the number, enhance the biological function and improve the therapeutic effect of endothelial progenitor cells, which play a positive role in regulation of endothelial progenitor cells.This article briefly reviewed the regulating mechanisms of the vascular endothelial growth factor and other cytokines in a total of 7 endothelial progenitor cells.