Impact of current cryopreservation procedures on mechanical and functionalproperties of human aortic homografts

We evaluated the impact of standard cryopreservation on mechanical and func tional properties of human aortic homografts. From 14 human heart-valve don ors, the thoracic descending aorta was obtained. Effects of cryopreservatio n on mechanical (elastic properties and breaking stress) and smooth muscle cell (SMC) and endothelium function were tested. Cryopreservation (cryo) di d not significantly affect Young's modulus of elastin (fresh: 3.1 +/- 1.0, cryo: 2.7 +/- 0.9 x 10(5) Nm(-2)), collagen recruitment pressure (fresh: 1. 1 +/- 0.3, cryo: 1.1 +/- 0.4 x 10(4) Nm(-2)), distensibility (fresh: 3.8 +/ - 1.8, cryo: 3.6 +/- 1.6 x 10(5) N(-1)m(2)), or breaking stress (fresh: 2.4 +/- 1.0, cryo: 2.2 +/- 1.0 x 10(6) Nm(-2)). Following explantation, no end othelium-dependent relaxation was found. SMC function and endothelium-indep endent relaxation were mainly intact after explantation but significantly d ecreased after cryopreservation. Aortic mechanical properties are not influ enced by cryopreservation. Following explanation, almost no endothelial cel l function is present, and SMC contractility is strongly affected after cry opreservation.