3D hepatic organoid production from human pluripotent stem cells

Hepatic organoids might provide a golden opportunity for realizing precision medicine in various hepatic diseases. Previously described hepatic organoid protocols from pluripotent stem cells rely on complicated multiple differentiation steps consisting of both 2D and 3D differentiation procedures. Therefore, the spontaneous formation of hepatic organoids from 2D monolayer culture is associated with a low-throughput production, which might hinder the standardization of hepatic organoid production and hamper the translation of this technology to the clinical or industrial setting. Here we describe the stepwise and fully 3D production of hepatic organoids from human pluripotent stem cells. We optimized every differentiation step by screening for optimal concentrations and timing of differentiation signals in each differentiation step. Hepatic organoids are stably expandable without losing their hepatic functionality. Moreover, upon treatment of drugs with known hepatotoxicity, we found hepatic organoids are more sensitive to drug-induced hepatotoxicity compared with 2D hepatocytes differentiated from PSCs, making them highly suitable for in vitro toxicity screening of drug candidates. The standardized fully 3D protocol described in the current study for producing functional hepatic organoids might serve as a novel platform for the industrial and clinical translation of hepatic organoid technology.

A Protocol for In Vitro High-Throughput Chemical Susceptibility Screening in Differentiating NT2 Stem Cells

The incidence of neurological diseases including learning and developmental disorders has increased in recent years. Concurrently, the number and volume of worldwide registered and traded chemicals have also increased. There is a broad consensus that the developing brain is particularly sensitive to damage by chemicals and that evaluation of chemicals for developmental toxicity or neurotoxicity is critical to human health. Human pluripotent embryonal carcinoma (NTERA-2 or NT2) cells are increasingly considered as a suitable model for in vitro developmental toxicity and neurotoxicity (DT/DNT) studies as they undergo neuronal differentiation upon stimulation with retinoic acid (RA) and allow toxicity assessment at different stages of maturation. Here we describe a protocol for cell fitness screening in differentiating NT2 cells based on the analysis of intracellular ATP levels allowing for the identification of chemicals which are potentially harmful to the developing brain. The described method is suitable to be adapted to low-, medium-, and high-throughput screening and allows multiplexing with other cell fitness indicators. While the presented protocol focuses on cell fitness screening in human pluripotent stem cells it may also be applied to other in vitro models.

A Protocol for a High-Throughput Multiplex Cell Viability Assay

High-throughput cell viability assays are broadly used in RNAi and small molecule screening experiments to identify compounds that selectively kill cancer cells or as counter screens to exclude the compounds that have a generic effect on cell growth. While there are several assaying techniques available, cellular fitness is often assessed on the basis of one single and often rather indirect physiological indicator. This can lead to inconsistencies and poor correspondence between cell viability screening experiments, conducted under comparable conditions but with different viability indicators. Multiplexing, i.e., the combination of different individual assaying techniques in one experiment and subsequent comparative analysis of multiparametric data can decrease inter-assay variability and increase dataset concordance. Here, we describe a protocol for a multiplexing approach for high-throughput cell viability screening to address the issues encountered in the classical strategy using a single fitness indicator described above. The method combines a biochemical, luminescence-based approach and two fluorescence-based assay types. The biochemical method assesses cellular fitness by quantifying intracellular ATP concentration. Calcein labeling reflects cell fitness through membrane integrity and indirect measurement of ATP-dependent enzymatic esterase activity. Hoechst DNA stain correlates cell fitness with cellular DNA content. The presented multiplexing approach is suitable for low, medium and high-throughput screening and has the potential to decrease inter-assay variability and increase dataset concordance as well as reproducibility of experimental results.