Preparation And Characterization Of Biomimetic Artificial Heart Valves

Heart valves diseases are prevalent worldwide,with the number of patients requiring heart valve replacement exceeding 290000 and keeping 5%～12%growth.Current valve replacements show advantages and disvantages.Therefore,novel heart valve scaffolds are fabricated using biocompatiable polyethylene(PEG)and structural collagen fibers from eggshell memberances(ESM).Polyethylene-eggshell membrance(PEG-ESM)composites have been mainly characterized by mechanical characterization and biological tests.In addition,the performance of PEG-ESM heart valves has been investigated using a vivitro pulse duplicator.Our results show that the fiber structures and the compostion of ESM are similar with human heart valves.The specific stress-strain curve and the self-repair ability with water also makes ESM be a perfect material for biomimetic heart valves.The elastic modulous and elongation rate of GA-ESM are in the range of those from native heart valves.PEG-ESM composites(400 μm thickness with four layers ESM)show the elastic moduli about 3.73±0.34 MPa and elongation rates approximate 43.11±11.36%,close to those from native heart valves.The dynamic mechanical analyses and stress relaxation tests indicate the viscoelastic properites of PEG-ESM composites.Moreover,there was no significant difference of the elastic modulous and elongation of PEG-ESM composites before and after fatigue tests,suggesting they have great potential as artificial heart valve substitutes.In addition,there was no siginificant difference in mechanical properties of PEG-ESM composites after type I collagenase and pepsin treatment for 2 weeks or 4 weeks,showing preventation of enzyme degradation by PEG hydrogels in the composites.No evidence of calcification was observed on the surface of PEG-ESM composites,while obvious calcification were found in all samples from the ESM,GA-ESM,and bioprosthetic heart valve groups,indicating the improved anti-calcification function of these novel PEG-ESM composites.Furthermore,ESM,GA-ESM and PEG-ESM samples all show good biocompatibility without immulogical rejection after subcutaneous implantation on the back of sprague dawley(SD)rats up to 4 weeks.The PEG-ESM artificial heart valves were able to pulsatily open and close,with an effective orifice area～1.32±0.02 cm~2,qualifying for the ISO 5840 standand.However,significant regurgitation and much lower pressure were found for these PEG-ESM valves during pulsatile tests,which should be optimized in future work.