“Lung on a chip” could reduce the use of animals
Scientists have invented a device that mimics the air pockets of the human lung, allowing them to study lung disease and test new therapies without using animals.
The lung-on-a-chip is a clear, flexible thumb-sized box containing two tiny channels separated by a thin membrane. One channel is lined with human lung cells and has air flowing through it, while a nutrient-rich liquid that acts as a blood substitute flows through the other, which is lined with blood-vessel cells. A vacuum applied to the chip moves the channels to re-create the way human lung tissues expand and contract when breathing.
The device can replace animals in some experiments and has also led to new findings that would not have been possible using an animal. The accessibility of the clear device allows scientists to study the air-blood membrane at a microscopic level and under many different controlled conditions.
Using their new invention, the scientists studied pulmonary oedema, a condition in which fluid and blood clots fill the lungs. It can be caused by heart failure and is also a side effect of a common cancer chemo-therapy. The researchers injected the cancer drug into the blood-vessel-like channel and found that fluid and blood proteins leaked across the membrane into the air channel, similar to the side effect in patients.
This led to two surprising discoveries. The first was that the immune system, which was not represented in the chip, was not required to cause the leakage side effect as had been previously thought. The team also found that when they turned on the vacuum system to create breathing-like movements, the leakage worsened another unknown aspect of pulmonary oedema. A new treatment which is known to prevent pulmonary oedema in mice also worked in the device, showing that it did so by prevented the leakage between channels.
Bodies are complicated systems of connected organs and tissues that are incredibly hard to replicate. It’s important that drugs are tested in whole animals and not isolated parts. Nonetheless, the new chip can be used in some early experiments and is the first of a set of “organ-mimicking chips” that are aimed at reducing the numbers of animals used in medical research.