Study On Novel Anti-calcification Technology And Property Of Bioprosthetic Artificial Heart Valves

Cardiovascular diseases have become one of the major life-threaten health problems,which have high morbidity and mortality.For end-stage valvular diseases,valve replacement surgery is the only effective therapy in clinic.There are two major types of artificial valve substitutes:mechanical heart valves and bioprosthetic heart valves.Although mechanical heart valves have a long life-span(25 years),requirement for anticoagulation treatment is needed due to the potential risks of thromboembolism,which has a negative influence on the life quality of patients.Bioprosthetic heart valves show better hemodynamic characteristics without need for anticoagulation treatment.However,due to the inevitable calcification and following dysfunction,the life-span of bioprosthetic heart valves is shorten to 10-15 years.With the development of transcatheter aortic valve replacement(TAVR),valve replacement surgery can be operated in a micro-invasive way.The ratio of bioprosthetic heart valves utilized in valve replacement surgery increses year after year and bioprosthetic heart valves are considered as the more attractive choice than mechanical heart valves.Calcification is the main factor which deteriorates the durability of bioprosthetic heart valves.For now,anti-calcification strategies can be divided into the following sorts:decellularization technology,novel crosslinking technology,endothelialization technology and inflammation regulation technology.Based on the above problems,firstly,three kinds of decellularized heart valves were fabricated to determine whether detergent concentration and treatment time have influence on the procedure of decellularization or not.By varying the concentration and treatment time of sodium deoxycholate with parameters of Triton X-100 unchanged,following by enzyme treatment and continuous shaking,three kinds of decellularized heart valves were obtained.The obtained decellularized heart valves all exhibited high decellularization efficiency without compromising the properties of decellularized heart valves,which revealed that balance between decellularization efficiency and valves’ properties can be realized effectively via optimizing the concentration and treatment time of detergent.To further optimize decellularization procedure,decellularized heart valves with worst decellularization efficiency among the above three groups were chosen.A vacuum-assisted decellularization procedure with accelerating effect was developed.Results showed that applied vacuum was benefit for shortening the time frame of decellularization and improving the decellularization efficiency.Meantime,vacuum-assisted treatment did no harm on the properties of decellularized heart valves.As a physical parameter,vacuum-assisted treatment can shorten the time frame of decellularization and decrease the time cost,which has latent financial values.To improve the poor biocompatibility of traditional detergent and inferior stability of decellularized heart valves,one kind of novel bioprosthetic heart valves was fabricated based on N-Lauroylsarcosine sodium salt(SLS,one kind of amino acid-based detergent)decellularization combined with carbodiimide crosslinking.Decellularized heart valves with better biocompatibility were obtained by optimizing SLS concentration and treatment time.After then,N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride(EDC)and NHydroxysuccinimide(NHS)were utilized to crosslink the obtained decellularized heart valves.The novel bioprosthetic heart valves exhibited excellent stability,mechanical property and biocompatibility.After subcutaneous implantation for 30 days,the above heart valves showed superior anti-calcification capacity.In addition,the results of immunohistochemical staining indicated that there might be potential connection between calcification and infiltration of immune cells.To reveal the above assumption,hydrogel coated hybrid heart valves were fabricated by combining the advantages of zwitterionic hydrogel and endothelial cell-affinity peptide(REDV).The hydrogel coated hybrid heart valves exhibited enhanced stability,mechanical property,blood compatibility and biocompatibility.In vivo experiments confirmed that hydrogel coating can reduce the infiltration of immune cells surrounding the heart valves,leading to superior anticalcification capacity.Moreover,the hydrogel coated hybrid heart valves exhibited certain endothelialization ability due to the grafting of REDV peptide.To further prove that there is direct connection between immunological response and calcification,integrated hybrid heart valves were fabricated by grafting of zwitterionic polymer and REDV peptide on the surface of glutaraldehyde crosslinked decellularized heart valves.The obtained heart valves exhibited excellent stability,mechanical property,blood compatibility and biocompatibility.In vivo experiments confirmed that there was direct connection between immunological response and calcification.The hybrid heart valves can alleviate immunological response,thus exhibited superior anti-calcification performance.In this study,three kinds of decellularization procedures were developed by optimizing related parameters.Vacuum-assisted treatment with accelerating effect was proved.Based on the above results,heart valves with superior anti-calcification property were fabricated by utilization of amino acid-based detergent and carbodiimide crosslinker.After then,heart valves were endowed with anti-calcification capacity by grafting of anti-fouling molecules on the surface of heart valves.Direct connection was proved between calcification and inflammatory reaction,which was benefit for the further development of bioprosthetic heart valves products.