Long-term storage of Ice-free preserved vascular allografts

Objective: Arterial allografts are routinely employed for reconstruction of infected prosthetic grafts. The existing conventional frozen cryopreservation (CFC) demand complex and expensive infrastructure. Ice-free cryopreservation (IFC) might offer an attractive alternative resulting in a facilitated and cost-effective processing, storage and shipping method. Objective of this study was to determine structural integrity and haemocompatibility of long-term preserved IFC vascular allografts.

Methods: Fresh porcine arteries (each n = 6) were processed by either CFC or IFC and stored for 2 years at either -80 ° or in vapour phase of liquid nitrogen. Untreated fresh arteries served as controls (C). Tissues underwent morphological (light, scanning electron and laser scanning microscopy), viability and hemocompatibility testing.

Results: CFC and IFC resulted in tissue shrinkage and loss of endothelial coverage compared to fresh controls. There were no quantitative differences for either elastin autofluorescence or collagen second harmonic generation measured by laser scanning microscopy or rhaman spectroscopy. Haemocompatibility testing revealed no differences in between the three groups. Cell viability in IFC arteries was significantly reduced compared to CFC and controls.

Conclusions: The obtained results demonstrate no statistically significant structural or hemocompatibility differences between IFC and CFC even after years storage. The observed reduced cell viability diminishes graft immunogenicity and might improved long-term in vivo performance. IFC is a safe facilitated, and cost-effective technique for cryopreservation of blood vessel allograft.