[The effect of cryopreservation on the structural and functional properties of human vascular allografts]

Abstract

Objectives: To assess the effet of cryopreservation on the structural and functional properties of venous and arterial human allografts.

Materials and methods: Segments of arteries and veins harvested from multiorgan donors were divided into 3 groups: fresh-control tested for 24 hours after harvesting, frozen directly at -80 degrees C and frozen gradually (progressive freezing technique) and preserved in liquid nitrogen at -196 degrees C degree. The 2 cryopreserved groups of segments were allowed in two different cryoprotectant solutions (M1 and M2) containing both dimethyl sulphoxide (10%), RPMI 1640 for the first and M 199 for the second. Rapid thawing was done at regular intervals over 4 months and the allografts were processed for biomechanical, ultrastructural, morphological and immunohistochemical analysis.

Results: Cell damage was less intense in the specimens conserved in M1 solution and by progressive freezing technique especially for smooth muscle cells and endothelial cells which remained preserved until 12 weeks.

Conclusion: Cryopreservation in both the solutions employed induce changes in the morphology of arterial wall. Better results were obtained with RPMI 1640 associated with progressive freezing.