In vivo real-time imaging of the liver with confocal endomicroscopy permits visualization of the temporospatial patterns of hepatocyte apoptosis.
ABSTRACT Apoptosis is a dynamic process of programmed cell death and is involved in multiple diseases. However, its mechanisms and sequence of events are still incompletely understood, partly because of the inability to visualize single cells continuously in vivo. The aim of the present study was to monitor hepatocyte apoptosis with confocal endomicroscopy in living rodents. In 73 anaesthetized mice, apoptotic liver injury was induced by injection of the CD95-agonistic antibody Jo2. Individual hepatocytes were followed for up to 240 min with a handheld confocal probe (FIVE1; Optiscan) providing 0.7 μm resolution (1,000-fold magnification). Different fluorescence staining protocols were used for cellular staining, vascular and cellular barrier function imaging, and caspase activation visualization. The time course of apoptosis could be visualized in vivo while liver perfusion and tissue integrity were maintained. In contrast to most ex vivo studies, initial cell swelling was observed that coincided with early defects in barrier function of sinusoids and hepatocytes. Cytoplasmic vesicle formation, nuclear condensation, cellular disintegration, and macrophage infiltration were captured sequentially. Labeling of caspases allowed molecular imaging. Our study allowed for the first time to continuously follow distinct morphological, functional, and molecular features of apoptosis in a solid organ in vivo and at high resolution. Intravital confocal microscopy may be a valuable tool to study the effects of therapeutic intervention on apoptosis in animal models and humans.
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ABSTRACT: Confocal laser endomicroscopy (CLE) is a novel imaging modality providing in vivo histology and allowing capture of very high-resolution images of human and animal liver. The manuscript from Goetz and colleagues in this issue of American Journal of Physiology GI and Liver, used CLE to continuously follow distinct morphological, functional and molecular features of apoptosis in intact liver in vivo and at high resolution. This new technology allowed the authors to make several important observations whilst highlighting the enormous promise of this technology for future in vivo studies of hepatic apoptosis and its pharmacological manipulation in animals and humans.AJP Gastrointestinal and Liver Physiology 08/2011; 301(5):G762-3. DOI:10.1152/ajpgi.00310.2011 · 3.74 Impact Factor
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ABSTRACT: Time-lapse fluorescence microscopy is one of the main tools used to image subcellular structures in living cells. Yet for decades it has been applied primarily to in vitro model systems. Thanks to the most recent advancements in intravital microscopy, this approach has finally been extended to live rodents. This represents a major breakthrough that will provide unprecedented new opportunities to study mammalian cell biology in vivo and has already provided new insight in the fields of neurobiology, immunology, and cancer biology.The Journal of Cell Biology 06/2013; 201(7):969-979. DOI:10.1083/jcb.201212130 · 9.69 Impact Factor
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ABSTRACT: Performing real-time microscopy has been a vision of endoscopists since the very early phases of gastrointestinal endoscopy. Confocal endomicroscopy, an adaption of confocal laser scanning microscopy, and endocytoscopy, an adaption of white-light microscopy, have been introduced into the endoscopic armamentarium in the past decade. Both techniques yield on-site histological information. Multiple trials have demonstrated the ability of gastroenterologists to obtain and interpret microscopic images from the upper and lower gastrointestinal tract, and also the hepatobiliary-pancreatic system, during endoscopy. Such microscopic information has been successfully used in expert hands to minimize sampling error by 'smart', microscopically targeted biopsies and to guide endoscopic interventions. However, endomicroscopy is also unique in its ability to dynamically visualize cellular processes in their native environment free of artefacts. This ability enables fundamental insights into mechanisms of human diseases in clinical and translational science.Nature Reviews Gastroenterology & Hepatology 07/2013; 11(1). DOI:10.1038/nrgastro.2013.134 · 10.81 Impact Factor