Cryopreservation of veins as an alternative to autografts in coronary by-pass grafting.
Cryopreserved venous segments could be used as allografts in coronary by-pass surgery in patients with limited availability of venous or arterial conduits for autologous grafting. After primarily disappointing clinical results it was the aim of these experiments to improve freezing procedure and incubation media in order to maintain most of the functional integrity of the biological material after cryopreservation, and thus to contribute to the essential prerequisites for a successful implantation. Freshly prepared segments of human saphenous vein were cryopreserved: 1) using various computer-assisted freezing programs with definite cooling rates and seeding temperatures; 2) after incubation in media consisting of RPMI 1640 and cryoprotective agents in different combinations and concentrations. The veins were stored at -196 degrees C, thawed quickly and analyzed in an in vitro perfusion system. The degree of vitality of the vein segments was assessed by measuring vasoconstriction after application of Norepinephrine and Serotonine and vasodilatation following release of endothelium-derived relaxing factor (EDRF) after perfusion with Acetylcholine. Our results show that the preservation of vascular smooth muscle can be maintained only by: 1) equilibrating the vein in RPMI 1640 with 2.2 M Glycerol and 1.6 M Ethylene-Glycol and 2) preventing an increase of temperature during the crystallization in the cooling process. The results clearly demonstrate the maintainance of vitality in vein segments after an appropriate freezing and equilibration process with specific cryoprotective agents. The data obtained in the study could serve as the basis for a better longterm prognosis of transplanted cryopreserved venous allografts.
Korb
H
H
Clinic for Heart Surgery, University of Cologne, Germany.
Borowski
A
A
Esbati
A
A
Schlesinger
U
U
Dhein
S
S
D000109:Acetylcholine / Q000494:pharmacology; D001026:Coronary Artery Bypass; D015925:Cryopreservation / Q000379:methods; D003451:Cryoprotective Agents / Q000494:pharmacology; D003460:Crystallization; D019855:Ethylene Glycol; D005026:Ethylene Glycols / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000032:analysis; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D012501:Saphenous Vein / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology; D014661:Vasoconstriction; D014664:Vasodilation
D003451:Cryoprotective Agents; D005026:Ethylene Glycols; D009569:Nitric Oxide; D012701:Serotonin; D019855:Ethylene Glycol; D000109:Acetylcholine; D005990:Glycerol; D009638:Norepinephrine