Abstract: The aim of this study was to explore whether procyanidins (PC)-crosslinked acellular heart valves in acidic buffer solution can obtain the identical matrix compliance similar to non-crosslinked acellular ones with anti-calcification and good biocompatibility properties. Based on the different pH acidic buffer
solutions of 1 mg/mL PC, the crosslinked acellular valves were crosslinked. The compliance was determined by bending angle measurement, anti-calcification by soaking in simulated body fluid, resistance to enzymatic degradation by collagenase-Ⅱ hydrolysis. Under pH 6.0 condition, PC crosslinked valve (PC1-pH 6.0) group was as soft as its non-crosslinked counterpart. Compared with non-crosslinked group (4.64 MPa), the ultimate tensile strength of
PC1-pH 6.0 group reached up to 5.95 MPa while the elastic modulus maintained the same, showing higher tensile strength than and the same compliance as the decellularized valves. Calcification was completely inhibited after crosslinking at pH 6.0. Under this condition, the PC-crosslinked acellular valves can effectively resistant to proteolysis compatible to glutaraldehyde-crosslinked ones. Furthermore, acellular valves in PC1-pH 6.0 group provided a good substance for adhesion of heart valve interstitial cells and present anti-thrombosis potential. PC-crosslinked acellular valves in the Acidic Buffer Solution (pH 6.0) possess identical matrix compliance with non-crosslinked decellularized valves, potential of anti-calcification, resistance to enzymatic degradation,
anti-thrombosis and good cytocompatibility, which may be used for preparing bioprosthetic heart valves.

Key words: procyanidins, crosslinking, compliance, acidic condition, anti-calcification, biological compatibility