Hydrophilic bile salts protect bile duct epithelium during cold preservation: a scanning electron microscopy study

Prolonged graft preservation is associated with postoperative bile duct strictures after liver transplantation. We previously showed that hydrophilic bile salts mitigate bile duct preservation injury in a pig model. Because this injury occurs at the epithelial level, scanning electron microscopy was performed to further characterize this effect in vitro. Swine livers were harvested after the intravenous infusion of 1 of 3 solutions: saline (n = 7), tauroursodeoxycholate ([TUDC] hydrophilic; n = 4), or taurodeoxycholate ([TDC] hydrophobic; n = 4). Livers were perfused with University of Wisconsin solution. The bile ducts were flushed retrograde, and the liver was stored at 0 degrees C to 1 degrees C for 20 hours. Bile duct samples were obtained at the time of harvest and 8, 12, 16, and 20 hours thereafter. In saline-infused controls at time 0, the epithelium was intact and composed of uniform cuboidal cells covered with fine regular microvilli. There were no spaces between individual cells. After 8 to 12 hours of preservation, cells were more irregular in shape, with loss of cell-cell contact. The cell surfaces showed fewer microvilli. Surface erosions suggested loss of cell-wall integrity. TUDC was protective, evidenced by normal-appearing cells with uniform microvilli after 16 hours. In contrast, TDC accelerated the injury process, causing cell-surface erosions, blebs, and loss of microvilli as early as time 0. Scanning electron microscopy is an excellent tool to study injury to bile duct epithelium. This study supports the hypothesis that hydrophilic bile salts protect bile ducts during preservation. To determine whether treatment with hydrophilic bile salts can prevent postoperative stricture, in vivo transplantation studies are needed.