Efficient generation of hepatocyte-like cells from human induced pluripotent stem cells

High-throughput screening in embryonic stem cell-derived neurons identifies potentiators of alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate-type glutamate receptors

Stem cell biology offers advantages to investigators seeking to identify new therapeutic molecules. Specifically, stem cells are genetically stable, scalable for molecular screening, and function in cellular assays for drug efficacy and safety. A key hurdle for drug discoverers of central nervous system disease is a lack of high quality neuronal cells. In the central nervous system, alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate (AMPA) subtype glutamate receptors mediate the vast majority of excitatory neurotransmissions. Embryonic stem (ES) cell protocols were developed to differentiate into neuronal subtypes that express AMPA receptors and were pharmacologically responsive to standard compounds for AMPA potentiation. Therefore, we hypothesized that stem cell-derived neurons should be predictive in high-throughput screens (HTSs). Here, we describe a murine ES cell-based HTS of a 2.4 x 10(6) compound library, the identification of novel chemical "hits" for AMPA potentiation, structure function relationship of compounds and receptors, and validation of chemical leads in secondary assays using human ES cell-derived neurons. This reporting of murine ES cell derivatives being formatted to deliver HTS of greater than 10(6) compounds for a specific drug target conclusively demonstrates a new application for stem cells in drug discovery. In the future new molecular entities may be screened directly in human ES or induced pluripotent stem cell derivatives.

Roadblocks en route to the clinical application of induced pluripotent stem cells

Since the first studies of human embryonic stem cells (hESCs) and, more recently, human induced pluripotent stem cells (hiPSCs), the stem-cell field has been abuzz with the promise that these pluripotent populations will one day be a powerful therapeutic tool. Although it has been proposed that hiPSCs will supersede hESCs with respect to their research and/or clinical potential because of the ease of their derivation and the ability to create immunologically matched iPSCs for each individual patient, recent evidence suggests that iPSCs in fact have several underappreciated characteristics that might mean they are less suitable for clinical application. Continuing research is revealing the similarities, differences and deficiencies of various pluripotent stem-cell populations, and suggests that many years will pass before the clinical utility of hESCs and hiPSCs is realized. There are a plethora of ethical, logistical and technical roadblocks on the route to the clinical application of pluripotent stem cells, particularly of iPSCs. In this Essay, we discuss what we believe are important issues that should be considered when attempting to bring hiPSC-based technology to the clinic.

[Infection of Schwann cells along corneal stromal nerve fiber in experimental herpes simplex keratitis]

Malaria eradication is a major goal in public health but is challenged by relapsing malaria species, expanding drug resistance, and the influence of host genetics on antimalarial drug efficacy. To overcome these hurdles, it is imperative to establish in vitro assays of liver-stage malaria for drug testing. Induced pluripotent stem cells (iPSC) potentially allow the assessment of donor-specific drug responses, and iPSC-derived hepatocyte-like cells (iHLCs) can facilitate the study of host genetics on host-pathogen interactions and the discovery of novel targets for antimalarial drug development. We establish in vitro liver-stage malaria infections in iHLCs using P. berghei, P. yoelii, P. falciparum, and P. vivax and show that differentiating cells acquire permissiveness to malaria infection at the hepatoblast stage. We also characterize antimalarial drug metabolism capabilities of iHLCs using prototypical antimalarial drugs and demonstrate that chemical maturation of iHLCs can improve their potential for antimalarial drug testing applications.

•

iPSC-derived hepatocyte-like cells (iHLCs) can host liver-stage malaria in vitro

•

iHLCs become permissive to Plasmodium infection at the hepatoblast stage

•

Plasmodium-infected iHLCs are sensitive to atovaquone but not primaquine

•

Small molecule-mediated maturation of iHLCs confers primaquine sensitivity