In Vitro Evaluation of Biomaterials for Heart Valve Prosthesis: High Hydrostatic and Enzymatic Treatments as Alternative for Bio-Derived Materials

Various biomaterials are currently used in clinical settings for heart valve repair and replacement. However, the optimal tissue preparation technique remains elusive. In this study, a non-crosslinked tissue obtained from bovine pericardium, developed by Adeka Corporation, was compared with three commercially-available tissues: two fixed tissues obtained from crosslinked bovine pericardium, CryoLife PhotoFix and LeMaitre CardioCel, and an unfixed one obtained from swine intestinal submucosa, CorMatrix CorPatch. The four biomaterials were used to produce aortic valve prostheses, and their hydrodynamic performance and durability were evaluated according to the ISO5840 standards. Resistance to calcification was evaluated by exposing the tissue to simulated body fluids, followed by SEM and Micro-CT analysis. Thrombogenicity was investigated by exposing the tissue to fresh ovine blood, followed by imaging with SEM and quantifying platelet deposition with lactate dehydrogenase assay. All constructed valves were compliant with the ISO5840 for hydrodynamic assessment. Non-crosslinked tissues, Adeka and CorPatch, showed lower durability but exhibited improved in vitro performances in the simulated biological environments compared to fixed ones. The Adeka tissue demonstrated significantly lower calcium (p < 0.05, Adeka vs. CardioCel, PhotoFix) and platelet deposition (p < 0.05, Adeka vs. CardioCel, CorPatch, PhotoFix), along with improved durability compared to the other unfixed tissue (Adeka 357,198 vs. CorPatch 0 cycles). In vitro experiments indicate that the crosslinked tissues, CardioCel and PhotoFix, provided mechanical strength adequate to withstand the operating conditions required for heart valve tissue applications. Whilst the Adeka material, a non-crosslinked tissue surrogate, provides improved properties in terms of resistance to calcification and thrombus formation.