When the airways in the lungs are blocked by thick fluids, breathing causes hissing sounds named “crackles”. In some pulmonary diseases such as cystic fibrosis, these crackles are rather common, since the body suffers from a deficiency in the protein which makes these fluids less gluey. When people who suffer from a pulmonary disease inhale, the plugs “explode”, causing the crackling sound. Until now, these sounds were considered as symptoms of the disease. However, the latest experiments conducted by the University of Michigan scientists imply that the crackles themselves damage the lung. If the plugs rupture, they cause a stress wave, similar to an explosion, damaging the surrounding cells.
In order to see the crackles’ progression, the researchers created the “lung on a chip”. Two rubber sheets were connected, with a groove carved across them. A porous polyester sheet was placed between the grooved sides, causing the rubber sheets to attach and creating two chambers, which were then filled with a nourishing liquid. When the lung cells began to grow, the top chamber was emptied to simulate an airway. This caused the cells to develop further than they do in a Petri dish. The cells began acting in a lung-like way in terms of protein secretion, tissue connections, and overall function. The device is exactly the size of the smallest airway branches in human lungs.
When the cell development was complete, the researchers ran the control part of the experiment. The team observed that liquid followed by air passing through the channels did not damage the cells. The team then turned on a “microfabricated plug generator”, which is a vial of liquid attached to the cell culture chamber on the chip and pumped air through it. Drops of liquid from the vial entered the simulated airways of the chip and due to the pressure, burst, creating “crackles”. Testing revealed that at least 24% of the lung cells die as a result of the bursts. The more frequent the plug bursts were, the more damage the surrounding cells suffered. Further research is necessary in order to fully understand the crackles’ effects and in order to explore more research possibilities of the “lung on a chip”. The chip’s developers hope their device will lead to the development of new treatments for respiratory diseases.
TFOT recently covered the use of artificial body parts in research, including a bionic eye capable of restoring the eye sight of people who suffer from age-related blindness, developed by the Boston Retinal Implant Project. Another related TFOT story focused on the creation of an artificial arm by the German company Festo. We have also covered a “blood test on a chip” device. The micro-sized laboratory is capable of analyzing minute blood samples, and was developed in Caltech (California Institute of Technology).
More information regarding the lung on a chip can be found on the University of Michigan News Service webpage.