Application of human organoids in ion transport studies

Organoid cultures won the ‘method of the year’ award from Nature Methods in 2018. These primary human stem cell-based cultures were used to develop disease models and drug development assays. Furthermore, the 3D cultures consist of individual-specific epithelial cells and can be passaged on the long-term. Our aims were to validate the intestinal organoid model for cystic fibrosis, and to develop new applications of this model to study epithelial ion transport of CFTR.

To achieve these goals, we used intestinal organoids from healthy subjects and subjects with CF to determine CFTR function (residual function and modulated function upon drug treatment) via organoid swelling. We showed that 3D intestinal organoids from subjects with CF can be used to determine efficacy of drugs that repair premature termination codons. Via a drug screening with organoids, we found that B2-adrenergic receptor agonists could enhance CFTR activity in intestinal organoids as well as subjects with CF. We generated 2D monolayers from intestinal organoids of various subjects with CF, and developed a electrophysiological assay to study ion transport in these cultures. The CFTR-dependent ion transport measurements correlated well with outcomes of donor-matched rectal biopsies and intestinal organoids. We developed a protocol to generate and culture airway organoids on the long-term, and showed that we could model CF and other diseases. To generate airway organoids, lung biopsies are needed or cells from a broncho-alveolar lavage. For CF, we could measure and discriminate CFTR activity as well as activity of the so-called alternative ion channel TMEM16A. With both intestinal and airway organoids, we showed how to identify side effects of ion transport modulators. We also used the intestinal organoid model for determining the potency of cholera toxin inhibitors.

Stem cell technologies are valuable tools to develop new culture models for better modeling of disease and drug development. These models are patient-specific and can be cultured on the long-term. We showed that ion transport capacities in intestinal and airway organoids recapitulate essential characteristics of CF and drug response. Additional applications are needed to further utilize the opportunities of these technologies.