In a breakthrough that could aid in the discovery of a raft of new respiratory treatments, scientists have used microengineering techniques to produce the world's first miniature working lung on a laboratory chip. Harvard researcher Donald Ingber and his colleagues were looking for a way to model lung tissue to make it easier to test different drugs and also to understand how different disease processes, like those resulting from asbestos or pollution-exposure, can damage lung tissue.
To build their lung-on-a-chip, they used a layer of a porous polymer called PDMS to divide in two a channel carved through a block of supporting material. This split the channel into an air compartment and a blood compartment. The polymer itself they initially coated with collagen to make it resemble the tissue matrix upon which cells grow naturally in the body. To each of the appropriate channels they then added either airway or blood cells, which quickly settled down onto the membrane to produce a tissue layer resembling the structure of a real airway. Air passes through the "air" compartment, whilst blood and cells can be pumped through the blood compartment. The lung can also simulate breathing by stretching the supporting block to expand the air channel.
The team have found that their model correctly mimics the process of gas exchange that happens in a real lung and can even respond to bacterial infection! When E. coli bacteria were sprinkled into the air compartment cells, white blood cells from the blood compartment quickly homed in on and neutralised the potential invaders. The team were also able to do some simple tests with nanoparticles, such as those that form components of pollution, in order to show that the model lung responds similarly to real tissue. This means that, rather than using expensive animal models to verify disease processes, discover novel therapies or for safety trials, this new, compact alternative, which is described this week in the journal Science, could provide the answers at a fraction of the cost.