Project description:The liver is one of most important organs in our bodies. It performs many essential functions including metabolism, synthesis, secretion, detoxification, and storage. Hepatocytes are the principal cell type in the liver and are involved in multiple liver-specific functions. There have been several efforts to develop in vitro culture systems capable of maintaining hepatocyte-specific phenotype over long time periods. In hepatic tissue engineering, two commonly used culture systems are the collagen sandwich and monolayers of cells. In this study, genome-wide gene expression profiles of primary hepatocytes were measured over an 8-day period for each cell culture system using Affymetrix GeneChips and analyzed via Gene Set Enrichment Analysis (GSEA), which is a powerful method to elicit biologically meaningful information from microarray data at the level of gene sets. Results indicate that the gene expression in hepatocytes in collagen sandwich cultures gradually diverges from that in monolayer cultures. Gene sets up-regulated in collagen sandwich cultures include those associated with liver metabolic and synthetic functions. These functions are associated with lipid, amino acid, carbohydrate, and alcohol metabolism and bile acid synthesis. Nuclear receptors are up-regulated in collagen sandwiches 24 hours after seeding. Signals transmitted from these receptors may cause the up-regulation of other processes in subsequent days. Cytochrome-P450 monooxygenase expression was initially down-regulated but exhibited up-regulation after 72 hours. Our results provide a baseline for further explorations into the systems biology of engineered liver mimics as well as 2D and 3D co-cultures of primary hepatocytes and non-parenchymal cells.
Project description:The liver is one of most important organs in our bodies. It performs many essential functions including metabolism, synthesis, secretion, detoxification, and storage. Hepatocytes are the principal cell type in the liver and are involved in multiple liver-specific functions. There have been several efforts to develop in vitro culture systems capable of maintaining hepatocyte-specific phenotype over long time periods. In hepatic tissue engineering, two commonly used culture systems are the collagen sandwich and monolayers of cells.  In this study, genome-wide gene expression profiles of primary hepatocytes were measured over an 8-day period for each cell culture system using Affymetrix GeneChips and analyzed via Gene Set Enrichment Analysis (GSEA), which is a powerful method to elicit biologically meaningful information from microarray data at the level of gene sets. Results indicate that the gene expression in hepatocytes in collagen sandwich cultures gradually diverges from that in monolayer cultures. Gene sets up-regulated in collagen sandwich cultures include those associated with liver metabolic and synthetic functions.  These functions are associated with lipid, amino acid, carbohydrate, and alcohol metabolism and bile acid synthesis. Nuclear receptors are up-regulated in collagen sandwiches 24 hours after seeding. Signals transmitted from these receptors may cause the up-regulation of other processes in subsequent days. Cytochrome-P450 monooxygenase expression was initially down-regulated but exhibited up-regulation after 72 hours. Our results provide a baseline for further explorations into the systems biology of engineered liver mimics as well as 2D and 3D co-cultures of primary hepatocytes and non-parenchymal cells. To better understand differences in quality of in vitro growth of rat hepatocytes between culture on a monolayer of collagen gel and sandwiched between two layers of gel, we measured gene expression in hepatocytes in these two culture conditions in triplicate for four time points: 1 day, 2 days, 3 days, and 8 days of culturing. Overall, we obtained Affymetrix microarray data for 24 samples, divided to 12 samples from monolayer and double layer cultures each, each of which are divided into four time points with 3 sample replicates.
Project description:In this study, genome-wide gene expression profiles of primary hepatocytes and liver sinusoidal endothelial cells (LSECs) were measured at day 12 for each cell culture system using Affymetrix GeneChips and analyzed via Gene Set Enrichment Analysis (GSEA). The culture systems analyzed include the commonly used collagen sandwich and monolayers of hepatocytes, as well as 3-dimensional (3D) engineered liver models that contain hepatocytes and LSECs (3DHL) and hepatocytes, LSECs, and Kupffer cells (3DHLK). Our results highlight the up-regulation of several hepatocyte specific functions in hepatocytes and a novel interplay between Ppara signaling and bile acid biosynthesis in LSECs.
Project description:To investigate the effect of culture microenvironment in microphysiological systems on hepatocellular tissue performance in vitro, we established hepatocyte culture systems with gradually increased complexity. Gene expression profiles of culture hepatocytes were evaluated from 8 groups based on oxygen supplementation, oxygen tension, paracrine signaling from endothelial cells, and hemodynamic shear stress.
Project description:Heat exposure began each day of the stress treatment with an increasing temperature gradient from 15 °C to 45 °C over a period of 5 h, and this was then maintained at 45 °C for 6 h. During the following 5 h, the temperature was returned to 15 ºC and maintained for 8 h, thus mimicking a day-night scenario. Control plants (C) were sampled, and the following day the stress exposure began. Plant material was sampled at the end of the 6 h heat exposure on day 1 (T1), day 3 (T3), and day 5 (T5). To characterize the molecular mechanisms driving heat response, we accomplished a systems biology analysis combining two subcellular bottom-up proteomics assays.
Project description:Human germ cells perpetuate human genetic and epigenetic information. However, the underlying mechanism remains elusive, due to a lack of appropriate experimental systems. Here, we show that human primordial germ cell‐like cells (hPGCLCs) derived from human‐induced pluripotent stem cells (hiPSCs) can be propagated to at least ~10^6‐fold over a period of 4 months under a defined condition in vitro. During expansion, hPGCLCs maintain an early hPGC‐like transcriptome and preserve their genome‐wide DNA methylation profiles, most likely due to retention of maintenance DNA methyltransferase activity. These characteristics contrast starkly with those of mouse PGCLCs, which, under an analogous condition, show a limited propagation (up to ~50‐fold) and persist only around 1 week, yet undergo cell‐autonomous genome‐wide DNA demethylation. Importantly, upon aggregation culture with mouse embryonic ovarian somatic cells in xenogeneic‐reconstituted ovaries, expanded hPGCLCs initiate genome‐wide DNA demethylation and differentiate into oogonia/gonocyte‐like cells, demonstrating their germline potential. By creating a paradigm for hPGCLC expansion, our study uncovers critical divergences in expansion potential and the mechanism for epigenetic reprogramming between the human and mouse germ cell lineage.
Project description:Human germ cells perpetuate human genetic and epigenetic information. However, the underlying mechanism remains elusive, due to a lack of appropriate experimental systems. Here, we show that human primordial germ cell‐like cells (hPGCLCs) derived from human‐induced pluripotent stem cells (hiPSCs) can be propagated to at least ~10^6‐fold over a period of 4 months under a defined condition in vitro. During expansion, hPGCLCs maintain an early hPGC‐like transcriptome and preserve their genome‐wide DNA methylation profiles, most likely due to retention of maintenance DNA methyltransferase activity. These characteristics contrast starkly with those of mouse PGCLCs, which, under an analogous condition, show a limited propagation (up to ~50‐fold) and persist only around 1 week, yet undergo cell‐autonomous genome‐wide DNA demethylation. Importantly, upon aggregation culture with mouse embryonic ovarian somatic cells in xenogeneic‐reconstituted ovaries, expanded hPGCLCs initiate genome‐wide DNA demethylation and differentiate into oogonia/gonocyte‐like cells, demonstrating their germline potential. By creating a paradigm for hPGCLC expansion, our study uncovers critical divergences in expansion potential and the mechanism for epigenetic reprogramming between the human and mouse germ cell lineage.
Project description:Human germ cells perpetuate human genetic and epigenetic information. However, the underlying mechanism remains elusive, due to a lack of appropriate experimental systems. Here, we show that human primordial germ cell‐like cells (hPGCLCs) derived from human‐induced pluripotent stem cells (hiPSCs) can be propagated to at least ~10^6‐fold over a period of 4 months under a defined condition in vitro. During expansion, hPGCLCs maintain an early hPGC‐like transcriptome and preserve their genome‐wide DNA methylation profiles, most likely due to retention of maintenance DNA methyltransferase activity. These characteristics contrast starkly with those of mouse PGCLCs, which, under an analogous condition, show a limited propagation (up to ~50‐fold) and persist only around 1 week, yet undergo cell‐autonomous genome‐wide DNA demethylation. Importantly, upon aggregation culture with mouse embryonic ovarian somatic cells in xenogeneic‐reconstituted ovaries, expanded hPGCLCs initiate genome‐wide DNA demethylation and differentiate into oogonia/gonocyte‐like cells, demonstrating their germline potential. By creating a paradigm for hPGCLC expansion, our study uncovers critical divergences in expansion potential and the mechanism for epigenetic reprogramming between the human and mouse germ cell lineage.
Project description:The transcriptional response to interferon alpha is cell type specific. To data, majority of investigations of interferon alpha induced gene expression have been made using immortalized or transformed cell lines underlining interferon's importance for treatment of cancer but omitting physiological relevance. Here in we have determined gene expression change in primary culture of hepatocytes after interferon alpha treatment. We used Affymetrix Rat Genome 230 2 microarrays to determine gene expression profiles in primary rat hepatocytes after interferon alpha treatment and untreated cells. Primary hepatocytes were chosen because they are most relevant to physiological state in intact liver. Hepatocytes was isolated from rat liver using collagenase treatment procedure and purified on percoll gradient. Next day after isolation primary hepatocytes culture was cultivated with (or without) 250u/ml rat interferon alpha for 3 and 6 hours. Experiment was performed in 3 biological replicates. cRNA preparation was performed according manufacturer's recommendation from 5ug of total RNA and gene expression profiles were determined.
Project description:Small hepatocyte progenitor cells (SHPCs) can be derived from primary adult human hepatocytes on mouse embryonic fibroblasts (MEFs). SHPCs derived and cultured on MEFs retain their differentiated morphology and gene expression profiles over several passages. SHPCs in MEF co-culture metabolize acetaminophen to all of its major metabolites at rates equal to mature adult primary human hepatocytes.