Presence and elimination of the xenoantigen Gal (α1, 3) Gal in tissue-engineered heart valves

Tissue engineering of heart valves promises to create functional autologous tissue with the potential for regeneration and growth without the limitations of current heart valve prostheses. The appropriate valve matrix is essential. Porcine heart valves are attractive because of their anatomical similarity. Decellularization is used for antigen reduction. The efficacy of published protocols varies, however. The absence of a specific immunological or unspecific inflammatory reaction is mandatory. The porcine cell- specific alpha- Gal epitope is known to be responsible for hyperacute rejection in xenotransplantation. In tissue engineering residual alpha- Gal epitope may induce severe inflammation in humans and may lead to graft failure. In this study porcine pulmonary conduits were decellularized with Triton X- 100, sodium deoxycholate, Igepal CA- 630, and ribonuclease treatment and were compared with specimens of the commercially available porcine decellularized SynerGraft regarding cell removal and elimination of the alpha- Gal epitope. In addition, samples of a porcine bioprosthesis were examined for the presence of the alpha- Gal epitope. In conclusion, we describe for the first time the presence of the alpha- Gal epitope in clinically used porcine bioprostheses and the first generation of a commercial tissue- engineered heart valve. In contrast, complete cell and alpha- Gal removal was achieved by a decellularization procedure developed by our group.