Study On Cellular Response Mechanism Of Bioactive Glass In Myocardial Regeneration And Repair

Myocardial infarction(MI)and heart failure(HF)are the two most common cardiovascular diseases(CVD),MI is the main cause of HF.MI is often accompanied by the large-scale death of cardiomyocytes with limited regeneration and repair capacity of mature myocardium,which cannot make up for the lost cardiomyocytes and seriously harms heart function.Meanwhile,the effect of clinical drugs and surgical treatments to promote cardiomyocyte regeneration and recover heart function is inadequate.Cell therapy and myocardial tissue engineering provide a new idea for promoting myocardial regeneration and repair.At present,cells from various sources have been used to treat MI and scaffolds in myocardial tissue engineering provide a microenvironment for cells,which makes up for the inefficiency of cell therapy.Bioactive glasses(BGs)are widely used in tissue engineering and regenerative medicine due to their good biocompatibility and bioactivity.In addition to be used as replacement materials to repair hard tissues such as bone or teeth,BGs also play a promising role in promoting angiogenesis,wound healing,regeneration and repair of soft tissues such as myocardium.Most of existing researches on the application of BGs in myocardial repair and regeneration have focused on incorporating BGs into polymer matrix to improve the biocompatibility and mechanical properties of the scaffolds,ignoring the investigation about the interaction between BGs and the cells involved in myocardial regeneration and repair.As an inorganic material with bioactivity,the ionic products of BGs have special impacts on cell behaviors,trigger a variety of biological responses to enhance the bioactivity of the scaffolds in tissue regeneration and repair.Therefore,exploring the regulation and relevant mechanism of ionic products released form BGs on cells in cardiac tissue or myocardial tissue engineering will be helpful to understand the functions of BGs in myocardial regeneration and repair,and explore the application potential of BGs.The main research contents and conclusions of this study are showed as follows:(1)Using dodecylamine(DDA)as the catalyst and template,BG microspheres with regular morphology,uniform particle size and good dispersibility were successfully prepared by sol-gel method.BG extracts with different concentrations were prepared and the results of ion concentration test showed that the BG extracts were Si-enriched.(2)The expressions of angiogenic factor and related signaling pathway in cardiomyocytes were detected after cultured with BG extracts.The migration and in vitro tube formation of endothelia cells stimulated with cardiomyocyte-derived condition medium were detected.The results showed that BG could up-regulate PI3K/Akt/HIF-1?signaling pathway to promote the synthesis and secretion of vascular endothelial growth factor(VEGF)in cardiomyocytes to regulate the behavior of endothelial cells.(3)Sodium dithionite(Na₂S₂O₄)was used to induce Hypoxia/Reoxygenation(H/R)injury in cardiomyocytes after cultured with BG extracts.The regulatory effect of BG on cardiomyocytes with H/R injury and its related mechanism were investigated.The results showed that BG effectively inhibited H/R injury in cardiomyocytes by regulating mitochondrial behavior,oxidative stress and apoptotic pathways to exert its cardioprotective effect.(4)Bone marrow mesenchymal stem cells(BMMSCs)were induced to differentiate into cardiomyocytes.After cultured with BG extracts,the proliferation behavior and expressions of cardiomyocyte-specific molecules together with related signaling pathways were detected.The results showed that BG regulated the differentiation of BMMSCs via Wnt/?-catenin and TGF-?/Smad signaling pathways to enhance the proliferation ability and differentiation ratio of differentiated cells.(5)Transwell was used to establish the co-culture model of cardiomyocytes and BMMSCs and the regulatory effect of BG on cellular communication was investigated.The results showed that BG could not only promote the production of anti-apoptotic factors from BMMSCs to inhibit H/R injury of cardiomyocytes,but also promote cardiomyocytes to secrete cytokines to create a cardiac microenvironment to induce the cardiomyocyte differentiation of BMMSCs.(6)Lipopolysaccharide(LPS)was used to induce cardiomyocytes after cultured with BG extracts and the expressions of fibrotic factors and related signaling pathway were detected.The results showed that BG inhibited the excessive expressions of fibrotic factors and extracellular matrix(ECM)proteins induced by LPS in cardiomyocytes by inhibiting TGF-?/Smad signaling pathway.In summary,the ionic dissolution products of BG can not only regulate the apoptosis and differentiation,but also promote the expression of functional proteins and active agents to strengthen cellular crosstalk of cells in cardiac tissue or relevant to myocardial tissue engineering.By exploring cellular responses and mechanisms of BG in myocardial regeneration and repair,it provides a new prospective and theoretical basis for the subsequent research of BGs in myocardial tissue engineering.