Surface heparin treatment of the decellularized porcine heart valve: Effect on tissue calcification

Tissue calcification is a major cause of failure of bioprosthetic heart valves. Aim of this study was to examine whether surface heparin treatment of the decellularized porcine heart valve reduces tissue calcification. Fresh porcine aortic heart valves were dissected as tissue discs and divided into four groups. Group A: controls without treatment, Group B: decellularization only, Group C: decellularization and glutaraldehyde cross-linking, Group D: decellularization and glutaraldehyde cross-linking followed by surface heparin treatment. After implantation in New Zealand White rabbits for 60 days, the explanted heart valve discs from the different study groups underwent a series of histological examinations as well as determination of calcium content by the methyl thyme phenol blue colorimetric method. Results of the explanted heart valve discs for the Von Kossa staining demonstrated that in Group A the heart valve tissue was the most severely stained with black color, whereas in Group D there was hardly any area that was stained black after implantation indicating the least tissue calcification. Furthermore, the inflammatory cells identified by the Hematoxylin-eosin staining appeared to be the least in Group D. The average tissue calcium content was highest in Group A (0.197 ± 0.115 μmol mg^-1 ), modest in Group B (0.113 ± 0.041 μmol mg^-1 ), and Group C (0.089 ± 0.049 μmol mg^-1 ), and the lowest in Group D (0.019 ± 0.019 μmol mg^-1 , p < 0.05). These results suggest that surface heparin treatment tends to reduce tissue calcification of the dellellularized porcine heart valve in a rabbit intramuscular implantation model. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 400-405, 2017.