Multi-lineage heart-chip models drug cardiotoxicity and enhances maturation of human stem cell-derived cardiovascular cells.

Cardiovascular toxicity causes adverse drug reactions and may lead to drug removal from the pharmaceutical market. Cancer therapies can induce life-threatening cardiovascular side effects such as arrhythmias, muscle cell death, or vascular dysfunction. New technologies have enabled cardiotoxic compounds to be identified earlier in drug development. Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) and vascular endothelial cells (ECs) can screen for drug-induced alterations in cardiovascular cell function and survival. However, most existing hiPSC models for cardiovascular drug toxicity utilize two-dimensional, immature cells grown in static culture. Improved in vitro models to mechanistically interrogate cardiotoxicity would utilize more adult-like, mature hiPSC-derived cells in an integrated system whereby toxic drugs and protective agents can flow between hiPSC-ECs that represent systemic vasculature and hiPSC-CMs that represent heart muscle (myocardium). Such models would be useful for testing the multi-lineage cardiotoxicities of chemotherapeutic drugs such as VEGFR2/PDGFR-inhibiting tyrosine kinase inhibitors (VPTKIs). Here, we develop a multi-lineage, fully-integrated, cardiovascular organ-chip that can enhance hiPSC-EC and hiPSC-CM functional and genetic maturity, model endothelial barrier permeability, and demonstrate long-term functional stability. This microfluidic organ-chip harbors hiPSC-CMs and hiPSC-ECs on separate channels that can be subjected to active fluid flow and rhythmic biomechanical stretch. We demonstrate the utility of this cardiovascular organ-chip as a predictive platform for evaluating multi-lineage VPTKI toxicity. This study may lead to the development of new modalities for the evaluation and prevention of cancer therapy-induced cardiotoxicity.

Powerful, efficient QTL mapping in Drosophila melanogaster using bulked phenotyping and pooled sequencing.

Despite the value of recombinant inbred lines for the dissection of complex traits, large panels can be difficult to maintain, distribute, and phenotype. An attractive alternative to recombinant inbred lines for many traits leverages selecting phenotypically extreme individuals from a segregating population, and subjecting pools of selected and control individuals to sequencing. Under a bulked or extreme segregant analysis paradigm, genomic regions contributing to trait variation are revealed as frequency differences between pools. Here, we describe such an extreme quantitative trait locus, or extreme quantitative trait loci, mapping strategy that builds on an existing multiparental population, the Drosophila Synthetic Population Resource, and involves phenotyping and genotyping a population derived by mixing hundreds of Drosophila Synthetic Population Resource recombinant inbred lines. Simulations demonstrate that challenging, yet experimentally tractable extreme quantitative trait loci designs (≥4 replicates, ≥5,000 individuals/replicate, and selecting the 5-10% most extreme animals) yield at least the same power as traditional recombinant inbred line-based quantitative trait loci mapping and can localize variants with sub-centimorgan resolution. We empirically demonstrate the effectiveness of the approach using a 4-fold replicated extreme quantitative trait loci experiment that identifies 7 quantitative trait loci for caffeine resistance. Two mapped extreme quantitative trait loci factors replicate loci previously identified in recombinant inbred lines, 6/7 are associated with excellent candidate genes, and RNAi knock-downs support the involvement of 4 genes in the genetic control of trait variation. For many traits of interest to drosophilists, a bulked phenotyping/genotyping extreme quantitative trait loci design has considerable advantages.

Retrospective Analysis of Inflammatory Markers and Patient Characteristics in Hospitalized Covid-19 Patients: An Early Experience in Louisiana.

Background The community transmission of coronavirus disease 2019 (Covid-19) was detected in Baton Rouge, Louisiana, in March 2020. Several previous studies have reported elevations of inflammatory markers in Covid-19 positive patients and suggested a possible correlation to disease severity. Methods We identified 69 patients from Baton Rouge General (BRG) Hospital who were admitted with acute hypoxic respiratory failure and laboratory confirmed positive severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) between March 13 and April 5, 2020. Demographic and laboratory data were obtained through a review of medical records. Statistical analysis was performed on several inflammatory markers in association with clinical disease severity. Results We identified 69 patients with confirmed Covid-19 infection. The mean (±SD) age of the patients was 65±14 years, 68% were male and 32% were female. A total of 13 patients (19%) were considered to have mild disease, 25 (36%) had moderate disease, and 31 (45%) were considered to have severe disease. A total of nine patients died (13%), 25 (36%) have been discharged from the hospital, 20 (29%) remain in the ICU, and 15 (22%) remain admitted to the hospital at the time of writing. Lymphopenia was common among hospitalized patients (39%) and was found to be statistically more pronounced in patients with severe disease (p<0.05). Inflammatory marker elevations were also seen in several patients, with statistically significant elevations in C-reactive protein (CRP) and lactate dehydrogenase (LDH) (p <0.05). We found no statistically significant associations between ferritin, D-dimer, troponin I, body mass index (BMI), or creatine kinase (CK) with disease severity. Conclusions During the first three weeks of the Covid-19 outbreak in Baton Rouge, Louisiana, the most common reason for admission amongst Covid-19 positive patients was acute hypoxic respiratory failure. Previously, several studies have suggested a correlation between elevated inflammatory markers and disease severity. The presence of lymphopenia and elevations of CRP and LDH may be helpful in the risk stratification of these patients. In an effort to guide clinical decision making and provide insight into disease severity, further characterization of Covid-19 infection in hospitalized patients is urgently needed.

Human iPSC-Derived Endothelial Cells and Microengineered Organ-Chip Enhance Neuronal Development.

Human stem cell-derived models of development and neurodegenerative diseases are challenged by cellular immaturity in vitro. Microengineered organ-on-chip (or Organ-Chip) systems are designed to emulate microvolume cytoarchitecture and enable co-culture of distinct cell types. Brain microvascular endothelial cells (BMECs) share common signaling pathways with neurons early in development, but their contribution to human neuronal maturation is largely unknown. To study this interaction and influence of microculture, we derived both spinal motor neurons and BMECs from human induced pluripotent stem cells and observed increased calcium transient function and Chip-specific gene expression in Organ-Chips compared with 96-well plates. Seeding BMECs in the Organ-Chip led to vascular-neural interaction and specific gene activation that further enhanced neuronal function and in vivo-like signatures. The results show that the vascular system has specific maturation effects on spinal cord neural tissue, and the use of Organ-Chips can move stem cell models closer to an in vivo condition.