This ongoing project is examining the potential for isolating LSECs from young and old livers in order to provide purified cells for experiments to investigate mechanisms related to defenestration. Previously, we found that depleting isolated LSECs of ATP caused rapid defenestration. Consequently, we compared the ATP status of young and old isolated LSECs. Although we found no significant difference between the ATP levels of these two groups of cells, we did find that within 24 hours of isolation LSECs lose the ability to retain their fenestrae and their viability declines markedly. The poor survival of these cells outside of the liver currently limits their usefulness for defenestration studies.