Effects of depolarizing or non-depolarizing preservation solutions on human endothelial cells during cold hypoxia

1. Hypothermic storage of whole organs flushed with a preservation solution is common practice in clinical transplantation. This procedure leaves vascular endothelial cells in direct contact with the preservation solution during the length of the cold ischaemic period. 2. Aiming to study the effects of organ preservation on vascular endothelium, we subjected cultures of human umbilical vein endothelial cells to hypoxic and hypothermic storage conditions in vitro for 3 or 16 h. Four preservation solutions with different levels of sodium and potassium were tested. Morphometric analysis and 51Cr leakage index were used to assess monolayer continuity, cell viability and membrane integrity. 3. Hypothermic storage resulted in severe changes in endothelial cell morphology with formation of intercellular gaps that destroyed monolayer continuity after only 3h. Cellular blebbing was a common feature in seriously damaged cells. 4. Morphometric analysis and 51Cr leakage results correlated well. No significant differences between the solutions tested were found after 3h of hypothermic hypoxic storage. After 16h, viability and monolayer continuity were significantly better preserved (Mann-Whitney, P < 0.01) in cells stored in lactobionate-based solutions than in hypertonic citrate solutions. No significant differences were found between endothelial cells stored in extracellular versus intracellular types of solutions for the lactobionate-based solutions. 5. The results of the present experiment showed that after a period of hypothermic hypoxic storage, vascular endothelial cells appeared morphologically deformed and poorly attached in vitro. Lactobionate-based preservation solutions were more effective in preserving viability and continuity. Protection of vascular endothelium under cold hypoxic conditions could be a critical factor in successfully preserving organs for transplantation.