Effects of warm ischemia and cryopreservation on cartilage viability of tracheal allografts

Background. For clinical use of a cryopreserved tracheal allograft, it is i mportant to evaluate cartilage viability. We assessed cell viability of the cartilage in a cryopreserved tracheal allograft by measurement of (Na2SO4) -S-35 incorporation. We also investigated the effects of warm ischemic time on tracheal cartilage viability. Methods. The tracheas from Lewis rats were harvested and preserved at diffe rent warm ischemic times from cardiac death to preservation (0, 1, 2,4,6,9, and 12 hours, each group n = 8). The cartilage was labeled with 4 mu Ci/mL of (Na2SO4)-S-35. The specimen was hydrolyzed in 0.5 mol/L NaOH, and a sol ution of the extracts was then counted by liquid scintillation counter. Tra cheas were transplanted into Brown Norway rats. Results. (35)Sulfur incorporation in the cartilage decreased as warm ischem ic time increased. In addition, (35)Sulfur incorporation decreased from 76% to 67% after cryopreservation. Histologic examinations of the normal trach eal cartilage before preservation and after thawing were done in all the gr oups. After transplantation, the cartilage had severe fibrous changes, and its layer was almost nonobservable in the 9- and 12-hour groups. Conclusions. The viability of the tracheal cartilage decreased with warm is chemic time and from 76% to 67% after cryopreservation. In the rat tracheal transplantation model, a cryopreserved tracheal allotransplant could be do ne safely with a graft that was cryopreserved within 6 hours of warm ischem ic time. (Ann Thorac Surg 2000;70:1876-9) (C) 2000 by The Society of Thorac ic Surgeons.