Utilizing human lung and blood vessel cells, researchers have created a device mounted on a microchip that mimics a living, breathing human lung. About the size of a rubber eraser, the device was developed by a team from the Wyss Institute for Biologically Inspired Engineering at Harvard University, Harvard Medical School and Children's Hospital Boston. Because it’s translucent, researchers can watch the processes taking place inside of it – kind of difficult to do with an actual lung. It will be used for testing the respiratory effects of environmental toxins, aerosolized therapeutics and new drugs. Using conventional models, such tests can cost over US$2 million.

In our lungs, oxygen passes through a thin membrane of cells to enter the bloodstream. This membrane consists of an inner layer of lung cells, a permeable matrix in the middle, and capillary blood vessel cells on the outside. Not only is this membrane responsible for getting oxygen out of the air we breathe, but it also recognizes inhaled foreign bodies such as toxins, and activates an immune response.

The lung-on-a-chip simulates this membrane. It utilizes a porous, flexible rubbery matrix, with lung cells on one side and blood vessel cells on the other. A culture medium flows past in a channel on the blood cell-side, simulating blood flow, while a vacuum sucks air in and out of a channel on the lung cell side, simulating the expansion and contraction of the lungs’ air sacs.

To test the device, researchers introduced E. coli bacteria on the lung cell side, while having added white blood cells to the medium flowing past on the other side. The lung cells detected the bacteria, activated the blood vessel cells through the membrane, which in turn triggered an immune response, bringing the white blood cells in to kill the bacteria.

In another experiment, the team introduced various nanoparticles into the air channel. Some of the particles got into the lung cells and caused them to overproduce free radicals, while others passed through the membrane and entered the blood channel. The mechanical act of “breathing” greatly increased the absorption of the particles. The same results were obtained when the nanoparticles were tested on mice.

The Harvard scientists are now working on demonstrating the device’s ability to replicate gas exchange between lung cells and the bloodstream. They are also looking into creating other organs-on-chips, and linking their device to the already-existing beating-heart-on-a-chip.

All images courtesy the Wyss Institute.

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