Technical validation and feasibility of video particle tracking for low-volume measurement of biliary micro-viscosity after liver transplantation

Abstract

Reliable quantification of the biophysical properties of human bile requires analytically validated methods and standardized pre-analytical conditions. We hypothesized that biliary micro-viscosity can be quantified in human bile after liver transplantation (LTx) with predefined analytical performance (accuracy \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 15\%$$\end{document} deviation from reference, reproducibility CV \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<10\%$$\end{document}). In this method-development and technical-validation study, we established a method to quantify micro-viscosity in human bile after LTx. Validation using sucrose standards demonstrated high accuracy (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 15\%$$\end{document} deviation from reference), strong linear correlation (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\textrm{R}^2 = 0.996$$\end{document}), and good reproducibility (CV \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$<10\%$$\end{document}). The method was applied to 21 bile samples from nine patients collected longitudinally after LTx. Mean micro-viscosity was \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.58 \pm 0.54~\text {mPa s}$$\end{document} (postoperative day 1), \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.94 \pm 0.63~\text {mPa s}$$\end{document} (day 7), and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$1.44 \pm 0.16~\text {mPa s}$$\end{document} (day 14). Pre-analytical freezing and cooling introduced measurement variability, supporting analysis shortly after collection. These findings demonstrate the analytical performance and practical feasibility of video particle-tracking-based biliary micro-viscosity measurements after LTx. Larger studies combining standardized fresh-sample workflows, biochemical bile characterization, and longitudinal clinical outcome data are required to determine the biological relevance of biliary micro-viscosity and its potential value for future graft modeling.