Function of Cryopreserved Pig Aortas E. Rendal,* ,1 M. Rodrı ´guez,* M. V. Martı ´nez,* R. O. Ferna ´ndez,* J. Sa ´nchez,† R. Segura,‡ T. Bermu ´dez,* G. Matheu,§ P. Filgueira,§ S. Pe ´rtega,  and C. Andio ´n* *Cryobiology Unit, †Transplant Coordination Ofﬁce, ‡Department of Vascular Surgery , §Pathology Department, and Statistics Department, Complejo Hospitalario Juan Canalejo, La Corun ˜ a, Spain Submitted for publication November 19, 2003 Objectives. This paper analyzes the inﬂuence of stor- age in the gas phase or liquid phase on grafts, together with the thawing method (15°C/min or 100°C/min) on the postthawing activity of pig cryopreserved arterial grafts (aortas). Materials and methods. Obtainment of arterial grafts (aortas) was from pigs with an ischemic time not greater than 2 h. Each aorta was divided into ﬁve fragments and assigned randomly to one control group of fresh aorta and four groups of cryopreserved aortas: group 1: gas phase/slow thawing; group 2: gas phase/rapid thawing; group 3: liquid phase/slow thaw- ing; and group 4: liquid phase/rapid thawing. After the incubation in antibiotic solution, the cryopreserva- tion in RPMI medium 10% DMSO was carried out and the level of cooling used was a reduction of 1°C/min. The contraction and relaxation responses of the fresh and frozen/thawed arteries were carried out in organ baths. Results. After thawing, the sensitivity to various agonists and maximal responses to the endothelium- dependent and independent relaxant agents were de- creased. The maximal responses to the tested vasocon- strictors (KCl and noradrenaline) were, respectively, 13% and 24% of the responses obtained in unfrozen aortas. The endothelium-independent relaxant re- sponses to sodium nitroprusside (SNP) were reduced and important reductions of the endothelium- dependent relaxant responses to acetylcholine were produced. Conclusions. The cryopreservation of pig aortas un- der the conditions used in this study led to a decrease in the contractility of the pig aortas, as well as a de- crease in the endothelium-independent relaxant re- sponses. On the other hand, no apparent preservation of the endothelium-dependent relaxant responses was observed. © 2004 Elsevier Inc. All rights reserved. Key Words: functional activity; vascular segments; relaxation; contraction. INTRODUCTION In vascular surgery dealing with arterial revascular- ization or arterial reconstruction, the optimum results are obtained with autologous material, but these re- sults are not always possible [1]. Thus, arterial substi- tution is a serious problem in those patients that are not in possession of valid vessels to carry out the tech- nique of grafting or bypass and for this reason it is necessary to ﬁnd alternative solutions. The discovery of prosthetic materials has given risen to an alterna- tive but the rejection of these protheses is high [2, 3]. Vascular cryopreservation is an alternative of note in the obtainment of arterial substitutes. The use of cryo- preserved vessels from human vessel banks increases daily. Cryopreservation of tissue offers the prospect of vir- tually indeﬁnite storage. Improvements of the preser- vation techniques, such as the introduction of cryopro- tectant agents and a controlled rate of freezing, have enabled the development of human blood vessel banks [4]. It has been seen that the postthaw functional re- covery of cryopreserved isolated blood vessels is gener- ally associated with reduced contractile force and en- dothelial function [4–6]. Therefore, the aim of our study was to evaluate the inﬂuence of storage in the gas phase or liquid phase on grafts together with the thawing method (15°C/min or 100°C/min) on the post- thawing activity of pig cryopreserved arterial grafts (aortas). 1 To whom correspondence and reprint requests should be ad- dressed at Unit of Cryobiology, Carretera del Pasaje s/n, Hospital Teresa Herrera, 15006 La Corun ˜ a, Spain. E-mail: Esther_Rendal@ canalejo.org. Journal of Surgical Research 120, 304 –311 (2004) doi:10.1016/j.jss.2004.02.004 304 0022-4804/04 $30.00 © 2004 Elsevier Inc. All rights reserved.