Porcine AV cusps were cultured in a stretch bioreactor, at 10% (physiological) or 15% (pathological) stretch and 70 beats per minute for 3, 7, and 14 days, in osteogenic media supplemented with or without high phosphate (3.8 mmol/L), TGF-beta1 (1 ng/ml), as well as the BMP inhibitor noggin (1, 10, and 100 ng/ml).