Antigenicity of Cryopreserved Arterial Allografts: Comparison with Fresh and Glutaraldehyde Treated Grafts

Abstract

The use of cryopreserved aortic allografts in cardiovascular surgery is widespread and has resulted in excellent outcomes. However, it is controversial whether cryopreservation suppresses the antigenicity of tissue. We designed experimental models to study whether the cryopreservation process alters antigenicity in comparison with that found in fresh and glutaraldehyde treated tissues. Fresh, cryopreserved, and glutaraldehyde treated thoracic aorta from Brown Norway rats were subcutaneously implanted into Lewis rats. Inflammatory cells infiltrating around the grafts were measured on days 7, 14, 28, and 56 after implantation. The glutaraldehyde treated grafts showed significantly less infiltration than the fresh or cryopreserved grafts (p < 0.005). No significant difference was detected between the fresh and cryopreserved grafts. Another study examined the effect of modifications of the aortic allograft on subsequent allogeneic skin graft antigenicity. Subcutaneous implantation of fresh, cryopreserved, and glutaraldehyde treated aortic grafts from Brown Norway into Lewis rats resulted in subsequent skin graft rejection at 4.4+/-0.7, 5.1+/-0.8, and 6.6+/-2.1 days, respectively. There was no significant difference between the fresh and cryopreserved groups; whereas skin grafts in the glutaraldehyde group survived longer than those in the cryopreserved group. These results indicate that cryopreservation had no significant influence on antigenic suppression of arterial allografts.

Effects of cryopreservation on tracheal allograft antigenicity in dogs

“…They blamed allograft failures on immune rejection possibly due to retained antigenicity after cryopreservation (8). Moriyama and colleagues also compared inflammatory infiltrates after heterotopic transplantation of fresh and cryopreserved arterial allografts to gauge any suppression of antigenicity through cryopreservation, reaching a negative conclusion (9). Using rats to assess the effects of cryopreservation on heart valve and vascular allografts, Saito et al similarly discovered that cell viability was sustained and allograft antigenicity was unaltered during cryopreservation (10).…”

“…Although some data suggest a decline in allograft antigenicity by doing so, thus raising hopes of immunosuppressant-free transplantation (and eliminating side effects, costs) (5-7), there is also evidence to the contrary (8)(9)(10)(11). Yokomise and colleagues successfully conducted tracheal allotransplantation in dogs, without use of immunosuppressants, by immersing grafts in a cryopreservative solution and deep freezing (−85 ℃) for 285±28 days (~8-10 months) (12).…”

Tracheal Replacement with Fresh and Cryopreserved Aortic Allograft in Adult Dog

“…The inflammatory response might lead to replacement by a tracheal structure with mucociliary epithelium and newly formed cartilage [10]. Both fresh and cryopreserved allograft vascular tissues induce a potent cellular and humoral immune response in recipients [17][18][19]. Also, an inflammatory response to an aortic allograft is especially profound in younger age groups [20].…”

Successful Human Vascular Reconstructions with Long-Term Refrigerated Venous Homografts

“…The degree of antigenicity of the vascular allograft plays a role in the process of biodegradation. Recent immunological studies have shown that venous allografts, cold-stored as well as cryopreserved, are antigenic and that the antigenicity is not modified by cryopreservation [19,20] . Tissue matching and immunosuppressive therapy are important issues in vascular transplantation.…”