Intraocular liver spheroids for non-invasive high-resolution in vivo monitoring of liver cell function

Longitudinal monitoring of liver function in vivo is hindered by the lack of high-resolution non-invasive imaging techniques. Using the anterior chamber of the mouse eye as a transplantation site, we have established a platform for longitudinal in vivo imaging of liver spheroids at cellular resolution. Transplanted liver spheroids engraft on the iris, become vascularized and innervated, retain hepatocyte-specific and liver-like features and can be studied by in vivo confocal microscopy. Employing fluorescent probes administered intravenously or spheroids formed from reporter mice, we showcase potential use of this platform exemplified by monitoring hepatocyte cell cycle activity, bile secretion and lipoprotein uptake. Moreover, we show that hepatic lipid accumulation during diet-induced hepatosteatosis is mirrored in intraocular grafts in vivo. The here described technology will provide a crucial tool to study liver physiology and disease progression in both pre-clinical and basic research as well as a drug screening platform in the pharma industry. To understand the suitability of this in vivo imaging platform to monitor different hepatocyte functions, we analyzed the transcriptome of the explanted liver spheroids at 2 months post-tx by RNA-seq.