Pulmonologist-scientist Veena B. Antony, MD, professor of medicine at the University of Alabama in Birmingham, grows “pulmospheres” in her lab. The tiny spheres, about 1 mL in diameter, contain cells representing all of the cell types in a lung struck with pulmonary fibrosis.
They are a three-dimensional model of idiopathic pulmonary fibrosis (IPF) that can be used to study the behavior of invasive myofibroblasts and to predict in vivo responsiveness to antifibrotic drugs;
Courtesy Lexi Coon/UAB
Dr. Veena B. Antony
“The utility is extensive, including looking at the impact of early-life exposures on mid-life lung disease. We can ask all kinds of questions and answer them much faster, and with more accuracy, than with any 2D model,” said Dr. Antony, also professor of environmental health sciences and director of UAB’s program for environmental and translational medicine.
“The future of 3D modeling of the lung will happen step by step ... but we’re right at the edge of a prime explosion of information coming from these models, in all kinds of lung diseases,” she said.
Two-dimensional model systems – mainly monolayer cell cultures where cells adhere to and grow on a plate – cannot approximate the variety of cell types and architecture found in tissue, nor can they recapitulate cell-cell communication, biochemical cues, and other factors that are key to lung development and the pathogenesis of disease.
Dr. Antony’s pulmospheres resemble what have come to be known as organoids – 3D tissue cultures emanating from induced pluripotent stem cells (iPSC) or adult stem cells, in which multiple cell types self-organize, usually while suspended in natural or synthetic extracellular matrix (with or without a scaffold of some kind).
Lung-on-a-chip
In lung-on-a-chip (LOC) models, multiple cell types are seeded into miniature chambers, or “chips,” that contain networks of microfabricated channels designed to deliver and remove fluids, chemical cues, oxygen, and biomechanical forces. LOCs and other organs-on-chips – also called tissues-on-chips – can be continuously perfused and are highly structured and precisely controlled.
It’s the organs-on-chip model – or potential fusions of the organoid and organs-on-chip models – that will likely impact drug development. Almost 9 out of 10 investigational drugs fail in clinical trials – approximately 60% because of lack of efficacy and 30% because of toxicity. More reliable and predictive preclinical investigation is key, said Danilo A. Tagle, PhD, director of the Office of Special Initiatives in the National Center for Advancing Translational Sciences, of the National Institutes of Health.
“We have so many candidate drugs that go through preclinical safety testing, and that do relatively well in animal studies of efficacy, but then fail in clinical trials,” Dr. Tagle said. “We need better preclinical models.”
In its 10 years of life, the Tissue Chip for Drug Screening Program led by the NCATS – and funded by the NIH and Defense Advanced Research Projects Agency – has shown that organs-on-chips can be used to model disease and to predict both the safety and efficacy of clinical compounds, he said.