EFFECTS OF CRYOPRESERVATION ON THE PROLIFERATION AND ANTICOAGULANT ACTIVITY OF HUMAN SAPHENOUS-VEIN ENDOTHELIAL-CELLS

Human saphenous veins were cryopreserved in 4% human albumin and 10% dimethyl sulfoxide, The effect of cryopreservation on endothelial cells was studied in terms of the anticoagulant activity of thrombomodulin and in terms of cell proliferation, After storage for 2 weeks at -150 degrees C, 0.45 +/- 0.07 x 10(5) endothelial cells/cm(2) were detected in cryopreserved veins and 1.03 +/- 0.04 x 10(5) endothelial cells/cm(2) in fresh veins (p < 0.01). The thrombin-catalyzed activation of protein C decreased after cryopreservation, indicating altered thrombomodulin activity in the endothelial cells, On a cell number basis, the release of soluble thrombomodulin was three times higher from the cryopreserved endothelium than from the fresh endothelium (p < 0.05). The amount of spontaneous release of von Willebrand factor from the endothelial surface was not significantly different between fresh and cryopreserved veins, Endothelial cells were cultured from fresh veins and from their cryopreserved counterparts. On plating of endothelial cells in primary culture, the number of adhered cells was 0.9 +/- 0.09 x 10(3) cells/cm(2) from fresh veins and 0.25 +/- 0.03 x 10(3) cells/cm(2) from cryopreserved veins (p < 0.01). The positive immunohistochemical stain for von Willebrand factor indicated that the endothelial cell character was maintained after cryopreservation, The endothelial desquamation with loss of anticoagulant function and the slow proliferation of surviving cells in vitro suggest an impaired endothelial healing in vivo, The loss of anticoagulant activity complicates the problems of the exposure of thrombogenic subendothelial matrix to blood in implanted cryopreserved veins.