Project description:Induced pluripotent stem cell-derived human hepatocyte-like cells (iHeps) could provide a powerful tool for studying the mechanisms underlying human liver development and disease, testing the efficacy and safety of pharmaceuticals across different patients (i.e. personalized medicine), and enabling cell-based therapies in the clinic. However, current in vitro protocols that rely upon growth factors and extracellular matrices (ECM) alone yield iHeps with low levels of liver functions relative to adult primary human hepatocytes (PHHs). Moreover, these low hepatic functions in iHeps are difficult to maintain for prolonged times (weeks to months) in culture. Here, we engineered a micropatterned co-culture (iMPCC) platform in a multi-well format that, in contrast to conventional confluent cultures, significantly enhanced the functional maturation and longevity of iHeps in culture for 4 weeks in vitro when benchmarked against multiple donors of PHHs. In particular, iHeps were micropatterned onto collagen-coated domains of empirically optimized dimensions, surrounded by 3T3-J2 murine embryonic fibroblasts, and then sandwiched with a thin layer of ECM gel (Matrigel™). We assessed iHep maturity via global gene expression profiles, hepatic polarity, secretion of albumin and urea, basal CYP450 activities, phase-II conjugation, drug-mediated CYP450 induction, and drug-induced hepatotoxicity. Conclusion: Controlling both homotypic interactions between iHeps and heterotypic interactions with stromal fibroblasts significantly matures iHep functions and maintains them for several weeks in culture. In the future, iMPCCs could prove useful for drug screening, studying molecular mechanisms underlying iHep differentiation, modeling liver diseases, and integration into human-on-a-chip systems being designed to assess multi-organ responses to compounds. We used Affymetrix microarrays to profile the global gene expression of co-culture stabilized iHeps (iMPCCs) relative to freshly isolated and co-culture stabilized primary human hepatocytes (2 donors). To assess the transcriptomic stability of iHeps in iMPCCs, RNA was extracted following 9 and 21 days of culture for hybridization to Affymetrix microarrays. The hepatic maturation state of iHeps was assessed by comparing gene expression against microarrays containing data from two primary human hepatocyte donors, both following hepatocyte isolation (day 0) and after stabilization in the micropatterened co-culture platform (day 6 and day 42 MPCCs), as previously described.

Project description:Induced pluripotent stem cell-derived human hepatocyte-like cells (iHeps) could provide a powerful tool for studying the mechanisms underlying human liver development and disease, testing the efficacy and safety of pharmaceuticals across different patients (i.e. personalized medicine), and enabling cell-based therapies in the clinic. However, current in vitro protocols that rely upon growth factors and extracellular matrices (ECM) alone yield iHeps with low levels of liver functions relative to adult primary human hepatocytes (PHHs). Moreover, these low hepatic functions in iHeps are difficult to maintain for prolonged times (weeks to months) in culture. Here, we engineered a micropatterned co-culture (iMPCC) platform in a multi-well format that, in contrast to conventional confluent cultures, significantly enhanced the functional maturation and longevity of iHeps in culture for 4 weeks in vitro when benchmarked against multiple donors of PHHs. In particular, iHeps were micropatterned onto collagen-coated domains of empirically optimized dimensions, surrounded by 3T3-J2 murine embryonic fibroblasts, and then sandwiched with a thin layer of ECM gel (Matrigel™). We assessed iHep maturity via global gene expression profiles, hepatic polarity, secretion of albumin and urea, basal CYP450 activities, phase-II conjugation, drug-mediated CYP450 induction, and drug-induced hepatotoxicity. Conclusion: Controlling both homotypic interactions between iHeps and heterotypic interactions with stromal fibroblasts significantly matures iHep functions and maintains them for several weeks in culture. In the future, iMPCCs could prove useful for drug screening, studying molecular mechanisms underlying iHep differentiation, modeling liver diseases, and integration into human-on-a-chip systems being designed to assess multi-organ responses to compounds. We used Affymetrix microarrays to profile the global gene expression of co-culture stabilized iHeps (iMPCCs) relative to freshly isolated and co-culture stabilized primary human hepatocytes (2 donors).

Project description:Direct induction of induced hepatocytes (iHeps) from fibroblasts holds potential as a strategy for regenerative medicine, but until now has only been shown in culture settings. Here, we describe in vivo iHep formation using transcription factor induction and genetic fate tracing in mouse models of chronic liver disease. We show that ectopic expression of the transcription factors FOXA3, GATA4, HNF1A and HNF4A from a polycistronic lentiviral vector converts mouse myofibroblasts into cells with a hepatocyte phenotype. In vivo expression of the same set of transcription factors from a p75 neurotrophin receptor peptide (p75NTRp)-tagged adenovirus enabled the generation of hepatocyte-like cells from myofibroblasts in fibrotic mouse livers and reduced liver fibrosis. We have therefore been able to convert profibrogenic myofibroblasts in the liver into hepatocyte-like cells with positive functional benefits. This direct in vivo reprogramming approach may open new avenues for the treatment of chronic liver disease. Whole Mouse Genome Oligo Microarray v2 (4x44K) (Agilent Technologies) was used to characterize global gene expression profiles of iHeps compared to myofibroblasts and primary mouse hepatocytes. All microarrays were performed at the Research Core Unit Transcriptomics of the Hanover Medical School. Briefly, total RNA was used to prepare the aminoallyl-UTPmodified (aaUTP) cRNAs (Amino Allyl MessageAmpâ¢ II Kit; #AM1753; Life Technologies) as directed by the company. The aaUTP-cRNAs were labelled with Alexa Fluor 555 Reactive Dye (#A32756; LifeTechnologies). Prior to the reverse transcription reaction, 1Î¼l of a 1:5000 dilution of Agilentâs One-Color spike-in Kit stock solution (#5188-5282, Agilent Technologies) was added to 100ng of total RNA of each analyzed sample. The cRNA fragmentation, hybridization, and washing steps were carried out according to Agilentâs One-Color Microarray-Based Gene Expression Analysis Protocol V5.7 except that 500ng of each labelled cRNA sample were used for hybridization. Slides were scanned on the Agilent Micro Array Scanner G2565 CA (pixel resolution 5 Î¼m, bit depth 20). Data extraction was performed with the Feature Extraction Software V10.7.3.1. 12 samples were analyzed: Pr-mHSC: Primary myofibroblasts derived from hepatic stellate cells (HSCs), 2 replicates; In-vivo iHep: In-vivo myofibroblasts-derived from induced hepatocytes (iHep), 3 replicates; In-vivo eHep: In-vivo endogenous hepatocytes (eHep), 3 replicates; In-vitro iHep: In-vitro myofibroblasts-derived from induced hepatocytes (iHep), 3 replicates; PH24h: Primary hepatocytes (PH) cultured for 24 hours, 1 replicate.

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Small Molecules Screened via Conversion Kinetics Analyses Facilitate Single Factor-mediated Hepatic Transprogramming

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