Multiphoton microscopy and fluorescence lifetime imaging of the rat and patient liver with cirrhosis ex vivo

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury that leads to portal hypertension and end stage liver disease. Conventional techniques are insufficient to precisely describe the internal structure, heterogeneous cell populations and the dynamics of biological processes of the diseased liver. Currently, multiphoton microscopy with fluorescence lifetime imaging is actively introduced to biomedical research. This technic is extremely informative and non-destructive that allows studying of a large number of processes occurring inside cells and tissues, analyzing molecular cellular composition, as well as evaluating the state of connective tissue fibers due to their ability to generate a second optical harmonic. In this study we investigated metabolic changes and collagen fibers formation in the rat liver with induced cirrhosis based on the fluorescence of the metabolic co-factors (NAD(P)H, FAD) and a second harmonic signal by multiphoton microscopy with FLIM and SHG mode. Moreover we studied ex vivo liver samples of patients with cirrhosis. We presented a separate analysis of NADH and NADPH to estimate the contribution of energy metabolism and lipogenesis in the metabolic changes. The data can be used to develop new criteria for the identification of hepatic pathology at the level of hepatocyte changes directed to personalized medicine in the future.