Effect of storage at 4 degrees C in a nutrient medium on antigenic properties of rat aortic valve allografts.

The effects of prolonged storage at 4 degrees C in nutrient medium on the antigenic properties of aortic valve allografts are unknown. Lewis rats received heterotopic aortic valve allografts from Brown Norway donors. Valves were transplanted immediately after harvest (fresh), or after antibiotic sterilization and storage in a nutrient medium at 4 degrees C for 3, 7, 14, or 21 days. Additional rats underwent sham laparotomy (sham). All recipient rats received Brown Norway skin grafts 3 weeks after valve transplant or sham procedure. Time to skin graft rejection for all groups was as follows: fresh (n = 10), 4.5 +/- 0.9 days; sham (n = 10), 7.1 +/- 0.3 days; 3-day (n = 10), 4.9 +/- 0.3 days; 7-day (n = 10), 5.2 +/- 0.4 days; 14-day (n = 10), 6.1 +/- 0.7 days; and 21-day (n = 10), 6.0 +/- 0.6 days. Significant differences existed between the sham group and each of the transplanted groups. No significant differences existed between the fresh group and either the 3-day or 7-day groups. The difference between the fresh group and the 14-day group approached significance (0.05 less than p less than 0.10), and the difference between the fresh and 21-day groups was significant (p less than 0.05). Additional valves not used for transplantation were studied with scanning electron microscopy. The valves preserved in nutrient medium exhibited a progressive loss of endothelium as compared with fresh valves. Storage of aortic valve allografts in a nutrient medium at 4 degrees C is associated with a progressive attenuation of antigenic response.(ABSTRACT TRUNCATED AT 250 WORDS)