PROCOLLAGEN PRODUCTION IN FRESH AND CRYOPRESERVED AORTIC-VALVE GRAFTS

Long-term durability of aortic valve allografts may be enhanced by cel lular capacities for regeneration and repair. To evaluate aortic valve graft production of an important structural protein, rat aortic roots were implanted heterotopically into the abdominal aorta of recipient rats, Grafts were either syngeneic or strongly allogeneic, were implan ted either fresh or after cryopreservation, and were left in place 2 t o 21 days after implantation, A total of 80 aortic valve grafts and th e corresponding native aortic valves were examined, The grafts were re trieved and immunocytochemically stained for the presence of procollag en, a precursor to collagen, Regardless of histocompatibility or prese rvation, grafts exhibited consistent procollagen presence that equaled or exceeded that seen in the corresponding native valves, Positive pr ocollagen staining was predominantly in the aortic wall, The most prom inent staining was near the hinge point of the valve leaflets, with no staining in the free portion of the leaflets, Staining with alpha-act in demonstrated vascular smooth muscle in sites remote from the areas positive for procollagen, which suggests that vascular smooth muscle w as not responsible for the procollagen production, These findings indi cate that cryopreservation is compatible with persistent fibroblast vi ability and in vivo protein synthesis by both syngeneic and allogeneic aortic valve grafts.