Histological and Structural Evaluation of Canine Pulmonary Valves Following Cryopreservation

Abstract

The objective of this study was to establish a cryopreservation protocol for canine pulmonary valves and assess the preservation quality of the tissue for transplantation. Pulmonary valves were harvested from six beagle dogs, with portions analyzed after antibiotic treatment, while the remaining sections were cryopreserved for six months. Following the thawing process, the cryopreserved valves were evaluated using histological and cellular analyses. The results indicated no significant structural damage in cryopreserved valves when compared to fresh valves. The trilaminar structure, consisting of the fibrosa, spongiosa, and ventricularis layers, was well-preserved, with the extracellular matrix (ECM) largely intact. The fibrosa layer, rich in collagen, exhibited minor disorganization in cryopreserved samples, which was statistically significant. The spongiosa layer, which contains proteoglycans, showed good preservation of its loose and hydrated matrix. Similarly, the ventricularis layer retained its elastic fiber network with minimal alterations. Cell density analysis revealed a mild decrease in cellularity within the fibrosa layer of cryopreserved tissues, but the overall difference in cell count between fresh and cryopreserved tissues was not statistically significant. Cellular viability was maintained, confirming the effectiveness of the cryopreservation protocol in preserving tissue quality. These findings suggest that long-term cryopreservation of canine pulmonary valves could be used for transplantation. This study provides important data for developing tissue banks in veterinary medicine and supports the potential use of cryopreserved valves in canine heart valve transplantation.