Viability and enzymatic activity of cryopreserved porcine heart valve

Fibroblast viability of a natural tissue valve for replacing a defective he art valve through allograft or xenograft has been suggested to affect its c linical durability. In this study, the cell viability and enzymatic activit y of porcine heart valve leaflets were examined in regard to concerning to the preservation process [variable warm ischemic time (WIT), cold ischemic time (CIT), and cryopreservation]. Porcine heart enblocs were obtained and valve dissection was performed after 2, 12, 24, or 36 hours, in respective groups A, B, C, and D, as WIT. Each group was stored for 24 hours as CIT an d cryopreserved. Leaflets were dissected from a valved conduit after each p rocess, and cell viability and enzymatic activity in the leaflet mere inves tigated using trypan blue staining and API ZYM kits. WIT extension signific antly decreased fibroblast viability (p < 0.05, 92.25 +/- 2.7%; at 2 hours, 84.9 +/- 6.7% at 12 hours, 57.0 +/- 10.2% at 24 hours, 55.9 +/- 7.9% at 36 hours), while CIT fur 24 hours was also influenced significantly (p < 0.05 ), whereas cryopreservation demonstrated no effect: on cellular viability. In enzyme activity observation, several enzymes related to lipid or nucleot ide degradation (esterase, esterase lipase, particularly phosphatase, phosp hohydrolase) were remarkably changed following the valve-fabrication proces s. After 24 hours CIT, these enzymatic activities in groups B, C and D sign ificantly increased, but the activities decreased after cryopreservation. P articularly, both the viability and enzymatic activity showed remarkable ch anges after CIT in group B (WIT = 12 hours). These results suggest that WIT is more important than CIT in maintaining viability of the valve, and that completing ail the cryopreservation process within 12 hours after acquisit ion is recommended.