Cryopreservation of Heart Valves: A Deceptive Illusion
Year: 2020
Type: article
Abstract: Objective: Frozen cryopreservation (FC) with storage in the vapour phase of liquid nitrogen remains the standard bio-banking technique for preservation of allogeneic heart valves. Since its introduction in 1974, FC is used for long-term storage of human heart valves. Limited understanding of cellular and extracellular matrix (ECM) architecture and less sophisticated imaging technologies resulted in an unjustified assumption of preservation of cellular and ECM integrity. Methods: Introduction of non-invasive imaging techniques such as near-infrared laser-scanning microscopy (LSM) allows non-destructive visualization of ECM components without fixation and staining. In contrast to conventional histochemistry, LSM revealed irreversible, ice-crystal induced damage of ECM following FC. Importantly, the induced damages do not undergo repair even after prolonged in vivo exposure. Results: Despite implantation without concomitant immunosuppression, the majority of the involved clinicians believe in preservation and function of valvular cells. The application of the guidelines of the American Association of Tissue Banking (AATB) for allograft heart valves includes a decontamination process using antibiotics with high cell toxicity. This mandatory treatment results in an inevitable and irreversible damage of endothelial and at least in part of the valvular interstitial cells (VICs). Without endothelium-derived relaxing factors such as nitric oxide active valve function is limited to the remaining VICs. Recent animal experiments revealed that VICs disappear already in the first week without repopulation with recipient cells. Conclusions: Hence, FC treated allografts are passively functioning heart valves without functioning cells and irreversible impaired ECM. Ice-free vitrification offers an attractive alternative to overcome the shortcoming of FC induced ECM damage. KEYWORD: e-PD-77 The authors do not declare any conflict of interest.
Source: Structural Heart
Institution: Harefield Hospital
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $2,340
OpenAlex ID: W3005756649