LOC models
One of the first LOC models – and a galvanizing event for organs-on-chips more broadly – was a 1- to 2-cm–long model of the alveolar-capillary interface developed at the Wyss Institute for Biologically Inspired Engineering at Harvard Medical School, Boston.
Microchannels ran alongside a porous membrane coated with extracellular matrix, with alveolar cells seeded on one side and lung endothelial cells on the other side. When a vacuum was applied rhythmically to the channels, the cell-lined membrane stretched and relaxed, mimicking breathing movements.
Lead investigator Dongeun (Dan) Huh, PhD, then a postdoctoral student working with Donald E. Ingber, MD, PhD, founding director of the institute, ran tests showing that the model could reproduce organ-level responses to bacteria and inflammatory cytokines, as well as to silica nanoparticles. The widely cited paper was published in 2010 (Science. 2010;328[5986]:1662-8), and was followed by another study published in 2012 (Sci Transl Med. 2012;4[159]:159ra147) that used the LOC device to reproduce drug toxicity–induced pulmonary edema. “Here we were demonstrating for the first time that we could use the lung-on-chip to model human lung disease,” said Dr. Huh, who started his own lab at the University of Pennsylvania, Philadelphia, in 2013.
Since then, “as a field we’ve come a long way in modeling the complexity of human lung tissues ... with more advanced devices that can be used to mimic different parts of the lung and different processes, like immune responses in asthma and viral infections,” said Dr. Huh, “and with several studies using primary human cells taken from lung disease patients.”
BIOLines Laboratory, University of Pennsylvania
A microengineered device designed by Dr. Huh that contains a lung-on-a-chip connected with a bone marrow-on-a-chip. The device was launched to the International Space Station in 2019 for a study of immunosuppression in microgravity.
Among Dr. Huh’s latest devices, built with NIH funding, is an asthma-on-a-chip device. Lung cells isolated from asthma patients are grown in a microfabricated device to create multilayered airway tissue, with airspace, that contains a fully differentiated epithelium and a vascularized stroma. “We can compress the entire engineered area of asthmatic human tissue in a lateral direction to mimic bronchoconstriction that happens during an asthma attack,” he said.
A paper soon to be published will describe how “abnormal pathophysiologic compressive forces due to bronchoconstriction in asthmatic lungs can make the lungs fibrotic, and how those mechanical forces also can induce increased vascularity,” said Dr. Huh, associate professor in the university’s department of bioengineering. “The increased vascular density can also change the phenotype of blood vessels in asthmatic airways.”
Dr. Huh also has an $8.3 million contract with the government’s Biomedical Advanced Research and Development Authority to study how chlorine gas damages lung tissues and identify biomarkers of chlorine gas–induced lung injury, with the goal of developing therapeutics.
Dr. Ingber and associates have developed a device modeling cystic fibrosis (CF). The chip is lined with primary human CF bronchial epithelial cells grown under an air-liquid interface and interfaced with primary lung microvascular endothelium that are exposed to fluid flow.
The chip reproduced, “with high fidelity, many of the structural, biochemical, and pathophysiological features of the human CF lung airway and its response to pathogens and circulating immune cells in vitro,” Dr. Ingber and colleagues reported (J Cyst Fibros. 2022;21:605-15).