Assembly of biliary lipids in native hepatic bile after orthotopic liver transplantation: A biochemical and ultra-structural study in humans

Abstract

In gallbladder bile, lipids aggregate as micelles and vesicles, yet the presence of lamellae remains controversial. Little is known on lipid assembly in dilute hepatic bile. Liver transplantation represents a condition in which bile is diluted immediately after transplant and tends to normalize thereafter. To study biliary lipidic carriers after liver transplantation in relation to the increasing bile lipid concentration. Three bile samples were harvested from six patients (3M/3F) with normal post-transplant outcome: sample 1 at days 2-3, sample 2 at 1 week, and sample 3 at 2 weeks after transplant. Samples were analyzed by biochemical, morphological and quasi-elastic light scattering methodology. Lipid concentration increased from 0.6g/dl at day 2-3 to 3.6g/dl at week 2. Electron microscopy showed the presence of unilamellar vesicles in all samples. Large amorphous particles interpreted as proteic aggregates were also present at day 2-3, while lamellae coexisted with vesicles later. Quasi-elastic light scattering data were consistent with electron microscopic findings. Liquid crystals were observed at polarizing microscopy with increasing bile lipid concentration. Normalization of biliary lipid secretion after liver transplantation is associated with: (i) increased proportion of vesicles and reduction of their size; (ii) presence of lamellae.