FUNCTIONAL RECOVERY OF HUMAN MESENTERIC AND CORONARY-ARTERIES AFTER CRYOPRESERVATION AT - 196-DEGREES-C IN A SERUM-FREE MEDIUM

Purpose: Long-term patency of cryopreserved vascular grafts is determi ned by maintained cellular and tissue viability, which implies preserv ation of various biochemical, smooth muscle, and endothelial functions . Therefore, it was investigated whether the presence of fetal calf se rum (FCS) in the cryomedium improves the postthaw contractile and endo thelial function of human arteries. Methods: Rings from human mesenter ic (HMA) and left circumflex coronary arteries (HCA) obtained from org an donors were randomized into three groups and studied either unfroze n or after storage for 3 to 6 weeks at -196 degrees C while suspended in Krebs-Henseleit solution without or with 20% FCS as the vehicles an d 1.8 mol/L dimethyl sulfoxide and 0.1 mol/L sucrose as cryoprotecting agents. The samples were slowly frozen to -70 degrees C and then stor ed in liquid nitrogen. Before use, the tissues were thawed within 3 mi nutes in a 40 degrees C water bath. Results: After thawing the sensiti vity to various agonists and maximal responses to the endothelium-inde pendent relaxing agent sodium nitroprusside were unchanged. However, a fter cryopreservation of HMA was performed without and with FCS, maxim al contractile responses to noradrenaline were significantly reduced t o 10.1 +/- 0.7 gm and 9.9 +/- 0.9 gm compared with 13.3 +/- 0.6 gm in unfrozen HMA (mean +/- SEM, n = 15). After cryopreservation of HCA was performed without and with FCS, maximal contractile responses to pros taglandin F-2 alpha (6.9 +/- 0.4 gm in unfrozen HCA) were significantl y reduced to 4.3 +/- 0.3 gm and 3.8 +/- 0.2 gm (mean +/- SEM, n = 6). In both types of arteries cryopreservation also attenuated significant ly the endothelium-dependent relaxant responses to bradykinin during U 46619 (10 nmol/L)-induced tone. In HMA the maximal bradykinin-induced relaxation (85% +/- 4%) was significantly diminished to 29% +/- 7% and 38% +/- 9% after cryopreservation without and with FCS (mean a SEM, n = 6). In HCA maximal bradykinin-induced relaxation (88% +/- 4%) was s ignificantly diminished to 26% +/- 10% and 36% +/- 11% after cryoprese rvation without and with FCS (mean +/- SEM, n = 6). This result was re flected by a marked endothelial denudation in all groups of cryopreser ved arteries. Neither functional nor morphologic preservation of the e ndothelial cell lining was significantly improved by FCS supplementati on of the cryomedium. Conclusions: Cryopreservation diminished contrac tile and endothelium-dependent relaxant responses of human arteries. T he presence of FCS in the cryomedium did not modify these changes.