Technical Advance
Abstract
Gut microbe–derived metabolites influence human physiology and disease. However, establishing mechanistic links between gut microbial metabolites and disease pathogenesis in animal models remains challenging. The major route of absorption for microbe-derived small molecules is venous drainage via the portal vein to the liver. In the event of presystemic hepatic metabolism, the route of metabolite administration becomes critical. To our knowledge, we describe here a novel portal vein cannulation technique using a s.c. implanted osmotic pump to achieve continuous portal vein infusion in mice. We first administered the microbial metabolite trimethylamine (TMA) over 4 weeks, during which increased peripheral plasma levels of TMA and its host liver-derived cometabolite, trimethylamine-N-oxide, were observed when compared with a vehicle control. Next, 4-hydroxyphenylacetic acid (4-HPAA), a microbial metabolite that undergoes extensive presystemic hepatic metabolism, was administered intraportally to examine effects on hepatic gene expression. As expected, hepatic levels of 4-HPAA were elevated when compared with the control group while peripheral plasma 4-HPAA levels remained the same. Moreover, significant changes in the hepatic transcriptome were revealed by an unbiased RNA-Seq approach. Collectively, to our knowledge this work describes a novel method for administering gut microbe–derived metabolites via the portal vein, mimicking their physiologic delivery in vivo.
Authors
Danny Orabi, Lucas J. Osborn, Kevin Fung, William Massey, Anthony J. Horak III, Federico Aucejo, Ibrahim Choucair, Beckey DeLucia, Zeneng Wang, Jan Claesen, J. Mark Brown
Abstract
Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) have been used extensively to model inherited heart diseases, but hiPSC-CM models of ischemic heart disease are lacking. Here our objective was to generate an hiPSC-CM model of ischemic heart disease. To this end, hiPSCs were differentiated to functional hiPSC-CMs and then purified using either a simulated ischemia media or by using magnetic antibody-based purification targeting the non-myocyte population for depletion from the cell population. Flow cytometry analysis confirmed that each purification approach generated hiPSC-CM cultures of >94% cTnT+ cells. Following purification hiPSC-CMs were re-plated as confluent syncytial monolayers for electrophysiological phenotype analysis and protein expression by Western blotting. Metabolic selected hiPSC-CM monolayers’ phenotype recapitulated many of the functional and structural hallmarks of ischemic cardiomyocytes, including: elevated diastolic calcium, diminished calcium transient amplitude, prolonged action potential duration, depolarized resting membrane potential, hypersensitivity to chemotherapy induced cardiotoxicity, depolarized mitochondrial membrane potential, depressed SERCA2a expression, reduced maximal oxygen consumption rate and abnormal response to β1-adrenergic receptor stimulation. These findings indicate that metabolic selection of hiPSC-CMs generates cell populations with phenotype like what is well known to occur in the setting of ischemic heart failure, and thus provides a novel opportunity for study of human ischemic heart disease.
Authors
Justin Davis, Ahmad Chouman, Jeffery Creech, Andre Monteiro da Rocha, Daniela Ponce-Balbuena, Eric N. Jimenez Vazquez, Ruthann Nichols, Andrey Lozhkin, Nageswara R. Madamanchi, Katherine F. Campbell, Todd J. Herron
Abstract
The recently proposed glymphatic pathway for solute transport and waste clearance from the brain has been the focus of intense debate. By exploiting an isotopically enriched MRI tracer, H217O, we directly imaged glymphatic water transport in the rat brain in vivo for the first time. Our results reveal glymphatic transport that is dramatically faster and more extensive than previously thought and unlikely to be explained by diffusion alone. Moreover, we confirm the critical role of aquaporin-4 channels in glymphatic transport.
Authors
Mohammed S. Alshuhri, Lindsay Gallagher, Lorraine M. Work, William M. Holmes
Abstract
Endothelial cells are important in the maintenance of healthy blood vessels and in the development of vascular diseases. However, the origin and dynamics of endothelial precursors and remodeling at the single-cell level have been difficult to study in vivo due to technical limitations. We aimed to develop a direct visual approach to track the fate and function of single endothelial cells over several days-weeks in the same vascular bed in vivo using multiphoton microscopy (MPM) of transgenic Cdh5-Confetti mice and the kidney glomerulus as a model. Individual cells of the vascular endothelial lineage were identified and tracked due to their unique color combination, based on the random expression of cyan/green/yellow/red fluorescent proteins. Experimental hypertension, hyperglycemia, and laser-induced endothelial cell ablation rapidly increased the number of new glomerular endothelial cells that appeared in clusters of the same color, suggesting clonal cell remodeling by local precursors at the vascular pole. Furthermore, intravital MPM allowed the detection of distinct structural and functional alterations of proliferating endothelial cells. No circulating Cdh5-Confetti+ cells were found in the renal cortex. The heart, lung, and kidneys showed more significant clonal endothelial cell expansion compared to the brain, pancreas, liver and spleen. Serial MPM of Cdh5-Confetti mice in vivo is a powerful new technical advance to study endothelial remodeling and repair in the kidney and other organs under physiological and disease conditions.
Authors
Dorinne Desposito, Ina Maria Schiessl, Georgina Gyarmati, Anne Riquier-Brison, Audrey Izuhara, Hiroyuki Kadoya, Balint Der, Urvi Nikhil Shroff, Young-Kwon Hong, Janos Peti-Peterdi
Abstract
Human pluripotent stem cells (PSCs), which are composed of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), provide an opportunity to advance cardiac cell therapy–based clinical trials. However, an important hurdle that must be overcome is the risk of teratoma formation after cell transplantation due to the proliferative capacity of residual undifferentiated PSCs in differentiation batches. To tackle this problem, we propose the use of a minimal noncardiotoxic doxorubicin dose as a purifying agent to selectively target rapidly proliferating stem cells for cell death, which will provide a purer population of terminally differentiated cardiomyocytes before cell transplantation. In this study, we determined an appropriate in vitro doxorubicin dose that (a) eliminates residual undifferentiated stem cells before cell injection to prevent teratoma formation after cell transplantation and (b) does not cause cardiotoxicity in ESC-derived cardiomyocytes (CMs) as demonstrated through contractility analysis, electrophysiology, topoisomerase activity assay, and quantification of reactive oxygen species generation. This study establishes a potentially novel method for tumorigenic-free cell therapy studies aimed at clinical applications of cardiac cell transplantation.
Authors
Tony Chour, Lei Tian, Edward Lau, Dilip Thomas, Ilanit Itzhaki, Olfat Malak, Joe Z. Zhang, Xulei Qin, Mirwais Wardak, Yonggang Liu, Mark Chandy, Katelyn E. Black, Maggie P.Y. Lam, Evgenios Neofytou, Joseph C. Wu
Abstract
The retinal pigment epithelium (RPE) provides vital metabolic support for retinal photoreceptor cells and also is an important player in numerous retinal diseases. Gene manipulation in mice using the Cre-LoxP system is an invaluable tool for studying the genetic basis of these retinal diseases. However, existing RPE-targeted Cre mouse lines have critical limitations that restrict their reliability for studies of disease pathogenesis and treatment, including mosaic Cre expression, inducer-independent activity, off-target Cre expression, and intrinsic toxicity. Here, we report the generation and characterization of a knock-in mouse line in which a P2A-CreERT2 coding sequence is fused with the native RPE-specific 65 kDa protein (Rpe65) gene for co-translational expression of CreERT2. Cre+/- mice were able to recombine a stringent Cre reporter allele with >99% efficiency and absolute RPE specificity upon tamoxifen induction at both post-natal days (PD) 21 and 50. Tamoxifen-independent Cre activity was negligible at PD64. Moreover, tamoxifen-treated Cre+/- mice displayed no signs of structural or functional retinal pathology up to 4 months of age. Despite weak RPE65 expression from the knock-in allele, visual cycle function was normal in Cre+/- mice. These data indicate that Rpe65CreERT2 mice are well-suited for studies of gene function and pathophysiology in the RPE.
Authors
Elliot H. Choi, Susie Suh, David E. Einstein, Henri Leinonen, Zhiqian Dong, Sriganesh Ramachandra Rao, Steven J. Fliesler, Seth Blackshaw, Minzhong Yu, Neal S. Peachey, Krzysztof Palczewski, Philip D. Kiser
Abstract
Morphologic examination of tissue biopsies is essential for histopathological diagnosis. However, accurate and scalable cellular quantification in human samples remains challenging. Here, we present a deep learning-based approach for antigen-specific cellular morphometrics in human kidney biopsies, which combines indirect immunofluorescence imaging with U-Net-based architectures for image-to-image translation and dual segmentation tasks, achieving human-level accuracy. In the kidney, podocyte loss represents a hallmark of glomerular injury and can be estimated in diagnostic biopsies. Thus, we profiled over 27,000 podocytes from 110 human samples, including patients with anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN), an immune-mediated disease with aggressive glomerular damage and irreversible loss of kidney function. We identified previously unknown morphometric signatures of podocyte depletion in patients with ANCA-GN, which allowed patient classification and, in combination with routine clinical tools, showed potential for risk stratification. Our approach enables robust and scalable molecular morphometric analysis of human tissues, yielding deeper biological insights into the human kidney pathophysiology.
Authors
Marina Zimmermann, Martin Klaus, Milagros N. Wong, Ann-Katrin Thebille, Lukas Gernhold, Christoph Kuppe, Maurice Halder, Jennifer Kranz, Nicola Wanner, Fabian Braun, Sonia Wulf, Thorsten Wiech, Ulf Panzer, Christian F. Krebs, Elion Hoxha, Rafael Kramann, Tobias B. Huber, Stefan Bonn, Victor G. Puelles
Abstract
With the advent of cancer immunology, mass cytometry has been increasingly employed to characterize the responses to cancer therapies and the tumor microenvironment (TME). One of its most notable applications is efficient multiplexing of samples into batches by dedicating a number of metal isotope channels to barcodes, enabling robust data acquisition and analysis. Barcoding is most effective when markers are present in all cells of interest. While CD45 has been shown to be a reliable marker for barcoding all immune cells in a given sample, a strategy to reliably barcode mouse cancer cells has not been demonstrated. To this end, we identified CD29 and CD98 as markers widely expressed by commonly used mouse cancer cell lines. We conjugated anti-CD29 and anti-CD98 antibodies to cadmium or indium metals and validated their utility in 10-plex barcoding of live cells. Finally, we established a novel barcoding system incorporating the combination of CD29, CD98, and CD45 to multiplex ten tumors from subcutaneous MC38 and KPC tumor models, while successfully recapitulating the known contrast in the PD1-PDL1 axis between the two models. The ability to barcode tumor cells along with immune cells empowers the interrogation of the tumor-immune interactions in mouse TME studies.
Authors
Soren Charmsaz, Nicole Gross, Elizabeth Jaffee, Won Jin Ho
Abstract
Complexity of lung microenvironment and changes in cellular composition during disease make it exceptionally hard to understand molecular mechanisms driving development of chronic lung diseases. Although recent advances in cell-type resolved approaches hold great promise for studying complex diseases, their implementation relies on local access to fresh tissue, as traditional tissue storage methods do not allow viable cell isolation. To overcome these hurdles, we developed a versatile workflow that allows storage of lung tissue with high viability, permits thorough sample quality check before cell isolation, and befits sequencing-based profiling. We demonstrate that cryopreservation enables isolation of multiple cell types from both healthy and diseased lungs. Basal cells from cryopreserved airways retain their differentiation ability, indicating that cellular identity is not altered by cryopreservation. Importantly, using RNA sequencing and EPIC Array, we show that gene expression and DNA methylation signatures are preserved upon cryopreservation, emphasizing the suitability of our workflow for -omics profiling of lung cells. Moreover, we obtained high-quality single-cell RNA sequencing data of cells from cryopreserved human lung, demonstrating that cryopreservation empowers single-cell approaches. Overall, thanks to its simplicity, our workflow is well-suited for prospective tissue collection by academic collaborators and biobanks, opening worldwide access to viable human tissue.
Authors
Maria Llamazares Prada, Elisa Espinet, Vedrana Mijošek, Uwe Schwartz, Pavlo Lutsik, Raluca Tamas, Mandy Richter, Annika Behrendt, Stephanie T. Pohl, Naja P. Benz, Thomas Muley, Arne Warth, Claus Peter Heußel, Hauke Winter, Jonathan J. M. Landry, Felix J.F. Herth, Tinne C.J. Mertens, Harry Karmouty-Quintana, Ina Koch, Vladimir Benes, Jan O. Korbel, Sebastian M. Waszak, Andreas Trumpp, David M. Wyatt, Heiko F. Stahl, Christoph Plass, Renata Z. Jurkowska
Abstract
To unequivocally address their unresolved intimate structures in blood, we scrutinized the size distribution of circulating cell-free DNA (cfDNA) using whole genome sequencing (WGS) from both double- and single-strand DNA library preparations (DSP and SSP), as well as using Q-PCR. The size profile in healthy individuals was remarkably homogenous when using either DSP sequencing (DSP-S) or SSP sequencing (SSP-S). Our findings also confirmed that cfDNA size profile shows a characteristic nucleosome fragmentation pattern. Overall, our data indicate that the proportion of cfDNA inserted in mono-nucleosomes, di-nucleosomes and chromatin of higher molecular size (>1,000bp) can be estimated as 67.5-80%, 9.4-11.5% and 8.5-21.0%, respectively. Thus, our data on WGS (N=7) and Q-PCR (N=116 taken together suggests that only a minor proportion of cfDNA is bigger than that existing in mono-nucleosome or transcription factor complexes circulating in blood. Although DNA on single chromatosomes or mono-nucleosomes is detectable, our data revealed that cfDNA is highly nicked (97-98%) on those structures, which appear to be subjected to continuous nuclease activity in the bloodstream. Fragments analysis allows the distinction of cfDNA of different origins: first, cfDNA size profile analysis may be useful in cfDNA extract quality control; second, subtle but reliable differences between healthy metastatic colorectal cancer (mCRC) patients and healthy individuals vary with the proportion of malignant cell-derived cfDNA in plasma extracts, pointing to a higher degree of cfDNA fragmentation and nuclease activity in samples with high malignant cell cfDNA content. Size profile analysis, or ‘fragmentomics’, has shown significant potential to improve diagnostics and cancer screening.
Authors
Cynthia Sanchez, Benoit Roch, Thilbault Mazard, Philippe Blache, Zahra Al Amir Dache, Brice Pastor, Ekaterina Pisareva, Rita Tanos, Alain R. Thierry
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