Hemocompatibility Assays Offer a New Option for Evaluation of Decellularized Bovine Pericardium for Application in Cardiac Surgery

Objectives: Bovine pericardium is the most common material used for heart valve bioprostheses. Chemical fixation by glutaraldehyde (GA) crosslinks collagen fibers, reduces immunogenicity and makes the material sterile. Nevertheless, remaining aldehyde groups promote calcification processes leading to early loss of function of the prosthesis and need for re-operation. Therefore, the development of alternative preparation strategies is one main research focus to improve the life span of biological heart valve prostheses. One approach is the decellularization of bovine pericardium, which removes cellular and nuclear compounds, like the xenogenous α-Gal epitope. In vitro hemocompatibility assays with human whole blood offers a new option to evaluate the efficient reduction of immunogenicity by decellularization.

Methods: Bovine pericardia were decellularized with a detergent-based method. DNA content was quantified and α-Gal epitope was detected by immunohistology to test if decellularization was sufficient. The ECM compounds were quantified by hydroxyproline (Hyp) assay, glycosaminoglycan (GAG) assay and elastin assay. The mesothelial side of native, GA-fixed (0.625% in PBS) and decellularized bovine pericardium was incubated in blood chambers with fresh human whole blood (2 hours, 37°C). Subsequently, platelet and granulocyte activation as well as coagulation and complement activation were analyzed.

Result: Decellularization reduced the DNA content below 50 ng/mg. Quantitative analysis confirmed that the collagen matrix is maintained after decellularization (native: 112.1 ± 9.6 µg hyp/mg; Decell: 120.5 ±8.7 µg hyp/mg; n = 6) whereas elastin and GAG content was reduced (native: 6.2 ± 0.2 µg sGAG/mg, 37.7 ± 5.0 µg elastin/mg; Decell: 1.9 ± 0.2 µg GAG/mg, 23.6 ± 3.4 µg elastin/mg; n = 3–4). Immunohistological stainings showed that the α-Gal epitope was present in native pericardium but removed in decellularized samples. Hemocompatibility assays confirmed a reduction of immunogenicity. Decellularized pericardium showed a significant lower coagulation and complement activation than native pericardium.

Conclusion: Hemocompatibility assays offer a new application for evaluation of reduced immunogenicity of decellularized bovine pericardium. This is a requirement for the application of GA-free heart valve bioprostheses material.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
19 February 2021