EFFECTS OF PRESERVATION TECHNIQUES ON IN-VIVO EXPRESSION OF ADHESION MOLECULES BY AORTIC-VALVE ALLOGRAFTS

Methods of sterilization and preservation of aortic valve allografts i nfluence graft longevity. The effect of storage techniques on valve du rability may be mediated by alterations in the immunologic properties of the allograft, which are reflected by expression of leukocyte adhes ion molecules. Rat aortic valve grafts were transplanted in the fresh state, after cryopreservation (-196 degrees C), or after storage at 4 degrees C for 1 to 21 days. Syngeneic and strongly allogeneic valves w ere transplanted for 4 hours to 21 days and were retrieved for immunoh istochemical staining for expression of leukocyte adhesion molecules. Unimplanted valves and transplanted syngeneic valves, regardless of st orage methods, exhibited little or no expression of leukocyte adhesion molecules. Fresh allogeneic valves expressed all molecules, indicatin g up-regulation, at all time intervals studied. Cryopreserved allogene ic valves demonstrated no leukocyte adhesion molecules at 4 hours or 2 days and weak reactivity at 10 and 21 days. Allogeneic valves stored at 4 degrees C, regardless of the duration of storage, demonstrated we ak expression of all molecules at 10 days and strong expression at 21 days. Expression of leukocyte adhesion molecules requires an allogenei c environment and may precede immune-mediated injury. Reduced expressi on of leukocyte adhesion molecules resulting from storage may predict a diminished immunologic response. Cryopreservation (-196 degrees C) c auses the greatest delay and diminution of expression of leukocyte adh esion molecules.