Comparison Between University of Wisconsin and Celsior Solution on Morphology and Viability of Rat Aorta After Cold Storage B. Nardo, G. Cavallari, F. Catena, B. Santoni, P. Turi, E. Giordano, G. Pasquinelli, L. Badiali de Giorgi, A. Faenza, and A. Cavallari T HE EFFECT of preservation solutions with different potassium concentrations on vascular tissue is still under investigation. Some reports demonstrated that low- potassium solutions are more suitable for short-term stor- age of blood vessels, as well as for long-term preservation of arteries. 1 Moreover, solutions containing a higher potas- sium concentration, such as University of Wisconsin solu- tion (UW), can affect the homeostasis of the vascular tissue, altering the equilibrium among the several vasoactive en- dothelium-derived substances. 2,3 Endothelial cells release vasoactive substances exerting major effects on local vaso- regulation. Among them, nitric oxide (NO  ) has an impor- tant role in the powerful relaxation of vascular smooth cells and in the inhibition of platelet adhesion and aggregation. 4 We investigated the effect of long-term cold storage in high-potassium solution (UW) and low-potassium solution (CELSIOR) on functional as well as morphologic changes of the rat aorta. MATERIALS AND METHODS Male Wistar rats, weighing 220 to 250 g, maintained under standard conditions were used. All the animals were anesthetized by ether inhalation. The in-situ flushing of the thoracic aorta was performed through the abdominal aorta with 10 mL of cold UW (Viaspan) or CELSIOR (Celsior, IMTIX s.r.l.) solution. The vascular segments were then stored in UW or CELSIOR solution and kept at 4°C up to 72 hours. Circular biopsy samples of aorta segments were processed for scanning (SEM) and transmission electron microscopy (TEM). A segment of aorta was cut into a spiral strip measuring approximately 20  4 mm and used for functional analysis. Tissue functionality was evaluated during an organ bath assay in terms of contraction in response to norepi- nephrine (NE) 10 -7 mol/L, and subsequent relaxation in response to acetylcholine (Ach) 10 -5 mol/L. The administration of Ach was followed by stimulus with a saturated solution of NO  10 -6 mol/L. Statistical analysis was performed using Student’s t test for un- paired data. RESULTS The segments of aorta used as controls produced a contrac- tile response to NE 10 -7 mol/L of 429  54 mg (mean  SEM) and a percentage of relaxation to Ach 10 -5 M of 82.2  2.3%. No morphologic and functional differences were found in the aorta segments stored in both UW and CELSIOR solution after 24 and 48 hours. Better morphol- ogy and functional responses were observed after 72 hours in the aorta stored in CELSIOR as compared with UW solution (268  21 mg vs 122  34 mg to the adrenergic stimulus, P  .05; 64.3  6.8% vs 31.8  8.5% to the acetylcholinergic stimulus, P  .05. A relaxation-response to NO  10 -6 mol/L was observed in all aorta segments stored, but not in the vascular segments maintained in UW solution up to 72 hours. CONCLUSIONS The data obtained in this study show that both UW and CELSIOR solution at 4°C do not significantly alter either the morphology or the function of aortic grafts after 48 hours of preservation. On the contrary, for relatively long periods (72 hours), UW solution induced severe morpho- logic and functional modifications that were not observed in the aorta preserved in CELSIOR solution. Our results suggest that CELSIOR solution is more suitable as com- pared to UW solution for cold long-term storage of vascular allografts. REFERENCES 1. Saldanha C, Hearse DJ: J Thorac Cardiovasc Surg 288:373, 1989 2. Nardo B, Bellusci R, Badiali de Giorgi, et al: Transpl Proc 24:2077, 1992 3. Abebe W, Cavallari N, Agrawal DK, et al: Transplantation 56:808, 1993 4. Furchgott RF, Zawadski JV: Nature 98:783, 1980 From the Second Department of Surgery (B.N., G.C., F.C., P.S., B.T., A.F., A.C.), Department of Biochemistry (E.G.), Elec- tron Microscopy (G.P., L.dG.), University of Bologna, Via Mas- sarenti 9, 4138 Bologna, Italy. Address reprint requests to Dr B. Nardo, 2nd Department of Surgery, Via Massarenti 9, 40138 Bologna, Italy. © 2000 by Elsevier Science Inc. 0041-1345/00/$–see front matter 655 Avenue of the Americas, New York, NY 10010 PII S0041-1345(99)00865-9 Transplantation Proceedings, 32, 35 (2000) 35