Impact of the incubation medium on the endothelium of autologous vein grafts: damage scoring by scanning electron microscopy.

The aim of this study was to examine the influence of different incubation media on the morphology of the endothelium of great saphenous vein grafts and establish a suitable scoring system for the evaluation of damage caused by these media. Fifty specimens of saphenous veins from ten patients during elective aorto-coronary bypass surgery were used. Ten specimens served as controls; the others were assigned to test groups and exposed to heparinized whole blood, Bretschneider's HTK, human albumin or Ringer's solution. Specimens exposed to heparinized blood showed only slight morphological alterations, whereas the other three mediums caused severe damage. Thus, heparinized blood seems to be most suitable as a rinsing and incubation medium. A widely accepted scoring system for the quantification of endothelial damage caused by the incubation media did not adequately reflect the morphology alterations in the cytoskeleton and membrane topology. The proposed scoring system, which is based on endothelial cell separation, endothelial cell loss, amount of deposits, endothelial cell surface homogeneity, in addition to the frequency of spikes and blebs, seems to be suitable for characterizing differences in endothelial morphology.