THE HYBRID XENOGRAFT AUTOGRAFT BIOPROSTHETIC HEART-VALVE - IN-VIVO EVALUATION OF TISSUE EXTRACTION

The major functional problem with bioprostheses is poor long-term dura bility. Bioprosthetic valves fail because of calcification and mechani cal fatigue, both of which result from the glutaraldehyde fixation pro cess. In an effort to develop a biologically active, non-cross-linked bioprosthetic valve, we devised a cellular extraction process. We test ed the mechanical integrity of the processed valves and cultured both human and porcine cells on this material. To test the potential for ca lcification, we implanted strips of fresh, extracted, and glutaraldehy de-treated porcine heart valve tissue subcutaneously into 3-week-old S prague Dawley rats for 21 days. We used atomic absorption spectroscopy to measure the extent of calcium accumulation and histopathologic ass essment to evaluate the antigenic response. We found that the cell ext raction process significantly reduced the propensity of the material t o calcify in vivo (mean +/- standard deviation, 4.12 +/- 1.02 mg/g cal cium extracted versus 10.75 +/- 3.9 mg/g calcium fresh versus 79.6 +/- 18.3 mg/g calcium glutaraldehyde fixed) but increased the antigenicit y, as evidenced by increased cellular activity and resorption. Althoug h they may reduce calcification, conventional detergent-based cell ext raction techniques do not completely remove porcine aortic valve antig ens and may in fact increase the antigenicity of the valve cusp materi al.