Psychological approaches to the study of saving / 7

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Proteomic and Functional Analysis of In Vitro Systems for Studies of Drug Disposition in the Human Small Intestine and Liver

To reach the bloodstream, an orally administered drug must be absorbed through the small intestine and avoid extensive clearance in the liver. Estimating these parameters in vitro is therefore important in drug discovery and development. This can be achieved with cellular models that simulate human organ function, such as Caco-2 cells and primary hepatocytes. No model fits every scenario, however, and this thesis aimed at using proteomic and functional analysis to better understand and increase the applicability of in vitro models based on Caco-2 cells and human hepatocytes. First, the proteome of filter-grown Caco-2 cells was analyzed. This included near-complete coverage of enterocyte-related proteins, and over 300 ADME proteins. Further, by scaling uptake transport kinetics from Caco-2 cells to human jejunum, the importance of considering in vitro­-in vivo expression differences to correctly interpret in vitro transport studies was demonstrated. Focus was then turned to hepatocytes, where proteomics was used as a basis for the successful development of an apoptosis inhibition protocol for restoration of attachment properties and functionality in suboptimal batches of cryopreserved human hepatocytes. As a spin-off project, image-based quantification of cell debris was developed into a novel apoptosis detection method. Next, the in vivo heterogeneity of human hepatocytes was explored in an in vitro setting, where it was observed that human hepatocyte batches contain a wide range of cell sizes. By separating the cells into different size fractions, it was found that hepatocyte size corresponds to the microarchitectural zone of origin in the liver. Size separation can thus be used to study zonated liver functions in vitro. Finally, the proteomes of the major types of non-parenchymal liver cells were analyzed, i.e. liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. The different cell types all had distinctly different proteomes, and the expression of certain important ADME proteins indicated that non-parenchymal cells participate in drug disposition. In conclusion, this thesis has improved the phenotypic understanding and extended the applicability of Caco-2 cells and primary human hepatocytes, two of the most important in vitro models for studies of small intestinal and hepatic drug disposition

Proteomic and Functional Analysis of In Vitro Systems for Studies of Drug Disposition in the Human Small Intestine and Liver

To reach the bloodstream, an orally administered drug must be absorbed through the small intestine and avoid extensive clearance in the liver. Estimating these parameters in vitro is therefore important in drug discovery and development. This can be achieved with cellular models that simulate human organ function, such as Caco-2 cells and primary hepatocytes. No model fits every scenario, however, and this thesis aimed at using proteomic and functional analysis to better understand and increase the applicability of in vitro models based on Caco-2 cells and human hepatocytes. First, the proteome of filter-grown Caco-2 cells was analyzed. This included near-complete coverage of enterocyte-related proteins, and over 300 ADME proteins. Further, by scaling uptake transport kinetics from Caco-2 cells to human jejunum, the importance of considering in vitro­-in vivo expression differences to correctly interpret in vitro transport studies was demonstrated. Focus was then turned to hepatocytes, where proteomics was used as a basis for the successful development of an apoptosis inhibition protocol for restoration of attachment properties and functionality in suboptimal batches of cryopreserved human hepatocytes. As a spin-off project, image-based quantification of cell debris was developed into a novel apoptosis detection method. Next, the in vivo heterogeneity of human hepatocytes was explored in an in vitro setting, where it was observed that human hepatocyte batches contain a wide range of cell sizes. By separating the cells into different size fractions, it was found that hepatocyte size corresponds to the microarchitectural zone of origin in the liver. Size separation can thus be used to study zonated liver functions in vitro. Finally, the proteomes of the major types of non-parenchymal liver cells were analyzed, i.e. liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. The different cell types all had distinctly different proteomes, and the expression of certain important ADME proteins indicated that non-parenchymal cells participate in drug disposition. In conclusion, this thesis has improved the phenotypic understanding and extended the applicability of Caco-2 cells and primary human hepatocytes, two of the most important in vitro models for studies of small intestinal and hepatic drug disposition

Cell-type-resolved proteomic analysis of the human liver

Background & Aims The human liver functions through a complex interplay between parenchymal and non-parenchymal cells. Mass spectrometry-based proteomic analysis of intact tissue has provided an in-depth view of the human liver proteome. However, the predominance of parenchymal cells (hepatocytes) means that the total tissue proteome mainly reflects hepatocyte expression. Here we therefore set out to analyse the proteomes of the major parenchymal and non-parenchymal cell types in the human liver. Methods We applied quantitative label-free proteomic analysis on the major cell types of the human liver: hepatocytes, liver endothelial cells, Kupffer cells and hepatic stellate cells. Results We identified 9791 proteins, revealing distinct protein expression profiles across cell types, whose in vivo relevance was shown by the presence of cell-type-specific proteins. Analysis of proteins related to the immune system indicated that mechanisms of immune-mediated liver injury include the involvement of several cell types. Furthermore, in-depth investigation of proteins related to the absorption, distribution, metabolism, excretion and toxicity (ADMET) of xenobiotics showed that ADMET-related tasks are not exclusively confined to hepatocytes, and that non-parenchymal cells may contribute to drug transport and metabolism. Conclusions Overall, the data we provide constitute a unique resource for exploring the proteomes of the major types of human liver cells, which will facilitate an improved understanding of the human liver in health and disease

Image-based quantification of cell debris as a measure of apoptosis

Apoptosis is a controlled form of cell death that can be induced by various diseases and exogenous toxicants. Common apoptosis detection methods rely on fluorescent markers, which necessitates the use of costly reagents and time-consuming labeling procedures. Label-free methods avoid these problems, but often require specialized instruments instead. Here, we utilize apoptotic cell disintegration to develop a novel label-free detection method based on the quantification of subcellular debris particles in bright-field microscopy images. Debris counts show strong correlations with fluorescence-based annexin V staining, and can be used to study concentration-dependent and temporal apoptosis activation. The method is rapid, low-cost, and easy to apply, as the only experimental step comprises bright-field imaging of culture media samples, followed by automated image processing. The late-stage nature of the debris measurement means that the method can complement other, established apoptosis assays, and its accessibility will allow a wider community of researchers to study apoptotic cell death

A simple approach for restoration of differentiation and function in cryopreserved human hepatocytes

Primary human hepatocytes are used in all facets of liver research, from in vitro studies of xenobiotic disposition and toxicity to the clinical management of liver failure. Unfortunately, cellular stress during isolation and cryopreservation causes a highly unpredictable loss of the ability to attach and form cell-matrix and cell-cell interactions. Reasoning that this problem could be mitigated at the post-thawing stage, we applied label-free quantitative global proteomics to analyze differences between attached and non-attached fractions of cryopreserved human hepatocyte batches. Hepatocytes that were unable to attach to a collagen matrix showed many signs of cellular stress, including a glycolytic phenotype and activation of the heat shock response, ultimately leading to apoptosis activation. Further analysis of the activated stress pathways revealed an increase in early apoptosis immediately post-thawing, which suggested the possibility of stress reversal. Therefore, we transiently treated the cells with compounds aimed at decreasing cellular stress via different mechanisms. Brief exposure to the pan-caspase apoptosis inhibitor Z-VAD-FMK restored attachment ability and promoted a differentiated morphology, as well as formation of 3D spheroids. Further, Z-VAD-FMK treatment restored metabolic and transport functions, with maintained sensitivity to hepatotoxic insults. Altogether, this study shows that differentiation and function of suboptimal human hepatocytes can be restored after cryopreservation, thus markedly increasing the availability of these precious cells

Newly developed dual topoisomerase inhibitor P8-D6 is highly active in ovarian cancer

Background: Ovarian cancer (OvCa) constitutes a rare and highly aggressive malignancy and is one of the most lethal of all gynaecologic neoplasms. Due to chemotherapy resistance and treatment limitations because of side effects, OvCa is still not sufficiently treatable. Hence, new drugs for OvCa therapy such as P8-D6 with promising antitumour properties have a high clinical need. The benzo[c]phenanthridine P8-D6 is an effective inductor of apoptosis by acting as a dual topoisomerase I/II inhibitor. Methods: In the present study, the effectiveness of P8-D6 on OvCa was investigated in vitro. In various OvCa cell lines and ex vivo primary cells, the apoptosis induction compared with standard therapeutic agents was determined in two-dimensional monolayers. Expanded by three-dimensional and co-culture, the P8-D6 treated cells were examined for changes in cytotoxicity, apoptosis rate and membrane integrity via scanning electron microscopy (SEM). Likewise, the effects of P8-D6 on non-cancer human ovarian surface epithelial cells and primary human hepatocytes were determined. Results: This study shows a significant P8-D6-induced increase in apoptosis and cytotoxicity in OvCa cells which surpasses the efficacy of well-established drugs like cisplatin or the topoisomerase inhibitors etoposide and topotecan. Non-cancer cells were affected only slightly by P8-D6. Moreover, no hepatotoxic effect in in vitro studies was detected. Conclusion: P8-D6 is a strong and rapid inductor of apoptosis and might be a novel treatment option for OvCa therapy

Conditions for maintenance of hepatocyte differentiation and function in 3D cultures

Spheroid cultures of primary human hepatocytes (PHH) are used in studies of hepatic drug metabolism and toxicity. The cultures are maintained under different cone-lions, with possible confounding results. We performed an in-depth analysis of the influence of various culture conditions to find the optimal conditions for the maintenance of an in vivo like phenotype. The formation, protein expression, and function of PHH spheroids were followed for three weeks in a high-throughput 384-well format. Medium composition affected spheroid histology, global proteome profile, drug metabolism and drug-induced toxicity. No epithelial-mesenchymel transition was observed. Media with fasting glucose and insulin levels gave spheroids with phenotypes closest to normal PHH. The most expensive medium resulted in PHH features most divergent from that of native PHH. Our results provide a protocol for culture of healthy PHH with maintained function a prerequisite for studies of hepatocyte homeostasis and more reproducible hepatocyte research

Proteome deconvolution of liver biopsies reveals hepatic cell composition as an important marker of fibrosis

Human liver tissue is composed of heterogeneous mixtures of different cell types and their cellular stoichiometry can provide information on hepatic physiology and disease progression. Deconvolution algorithms for the identification of cell types and their proportions have recently been developed for transcriptomic data. However, no method for the deconvolution of bulk proteomics data has been presented to date. Here, we show that proteomes, which usually contain less data than transcriptomes, can provide useful information for cell type deconvolution using different algorithms. We demonstrate that proteomes from defined mixtures of cell lines, isolated primary liver cells, and human liver biopsies can be deconvoluted with high accuracy. In contrast to transcriptome-based deconvolution, liver tissue proteomes also provided information about extracellular compartments. Using deconvolution of proteomics data from liver biopsies of 56 patients undergoing Roux-en-Y gastric bypass surgery we show that proportions of immune and stellate cells correlate with inflammatory markers and altered composition of extracellular matrix proteins characteristic of early-stage fibrosis. Our results thus demonstrate that proteome deconvolution can be used as a molecular microscope for investigations of the composition of cell types, extracellular compartments, and for exploring cell-type specific pathological events. We anticipate that these findings will allow the refinement of retrospective analyses of the growing number of proteome datasets from various liver disease states and pave the way for AI-supported clinical and preclinical diagnostics