title: Human cryopreserved homografts: electron microscopic analysis of cellular injury.
abstract: Twenty-five human cryopreserved valves with harvest-related warm ischemic times (WITs) ranging from 0 to 20 hours were studied using transmission electron microscopy to characterize the effects of harvesting and preservation on leaflet matrix cells. The valves were divided into seven groups on the basis of WIT and processed using standard transmission electron microscopic methods. Each cell (528 micrographs) was graded for reversible and irreversible cellular injury and subjected to a Cochran-Mantel-Haenszel trend analysis. Our results demonstrated a progression in cellular injury with increasing WIT. During the first 12 hours of warm ischemia, reversible cellular injury predominated (0.0%, 30.0%, 51.2%, 31.3%, 35.1%, 45.1%, and 40.0% at WITs of 0, 1, 2, 8, 12, 16, and 20 hours, respectively). A positive correlation (p < 0.0001) between increasing WIT and reversible cellular injury through the first 12 hours was observed. Minimal morphologic evidence of irreversible injury was noted in valves harvested with less than 12 hours of warm ischemia; however, after 12 hours there was a marked increase (0.0%, 0.0%, 4.7%, 2.4%, 2.7%, 31.4%, and 40.0% at WITs of 0, 1, 2, 8, 12, 16, and 20 hours, respectively) in irreversible cellular injury (p < 0.001 between 12 and 20 hours WIT). These data demonstrate a progression in cellular injury with increasing WIT. There was virtually no morphologic injury in valves with harvest-related WITs less than 2 hours and minimal irreversible cellular injury observed in valves exposed to 12 hours or less of warm ischemia. If cellular viability is critical to homograft durability then harvest-related warm ischemia may need to be restricted to 12 hours.
authors.affiliation: Georgetown University School of Medicine, Washington, DC.
authors.forename: D G
authors.initials: DG
authors.lastname: Crescenzo
authors.forename: S L
authors.initials: SL
authors.lastname: Hilbert
authors.forename: R H
authors.initials: RH
authors.lastname: Messier
authors.forename: P W
authors.initials: PW
authors.lastname: Domkowski
authors.forename: M K
authors.initials: MK
authors.lastname: Barrick
authors.forename: P L
authors.initials: PL
authors.lastname: Lange
authors.forename: V J
authors.initials: VJ
authors.lastname: Ferrans
authors.forename: R B
authors.initials: RB
authors.lastname: Wallace
authors.forename: R A
authors.initials: RA
authors.lastname: Hopkins
mesh_terms: D001021:Aortic Valve / Q000473:pathology / Q000637:transplantation*; D001705:Bioprosthesis; D002470:Cell Survival / Q000502:physiology; D015925:Cryopreservation; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005347:Fibroblasts / Q000473:pathology; D006085:Graft Survival / Q000502:physiology*; D006350:Heart Valve Prosthesis; D006801:Humans; D008854:Microscopy, Electron; D011664:Pulmonary Valve / Q000473:pathology / Q000637:transplantation*; D014021:Tissue Preservation