You might remember back in 2008 reading about how scientists had made a breakthrough in regenerative medicine by engineering a human trachea. Since then people have been wondering if the same principles could be applied to more complex body parts. The answer? Yes. Scientists in Texas have grown functioning lungs by using damaged ones as a scaffold to grow new tissue.
Your lungs are the site of gas exchange in your body (general rule of thumb is oxygen in, carbon dioxide out!). To achieve this, they have a huge internal surface area and very thin walls, allowing gases to diffuse in and out of your blood at a very fast rate. But of course we also have to get those gases in and out of the lungs by breathing, which is controlled by your diaphragm contracting and relaxing in coordination with the intercostal muscles between your ribs. Because of the different pressures created during this process, your lungs will be compressed (exhaling) or stretched (inhaling), so it’s really important that your lungs keep their elasticity. There is a lot of stress generated during this process, so it’s also vital that the tissue is strong. All of these features would need to be present in an engineered lung for it to work properly.
Not every person who is signed up to transplant organs is actually able to. If organs are damaged then they have to be discarded, but these tissues have the potential in the future to be used as scaffolding to grow viable lungs fit for transplant. Pretty cool!
Damaged lungs first must be decellularised to form AC (acellular) scaffolds. The difficulty in doing this is that the structure of the lung is highly influenced by the substances found in the extracellular matrix of the lung- during ventilation, collagen I, III and elastin help to form the scaffold that keeps lung structure. So in processing your lungs, you must maintain as many of these materials as possible, but the act of decellularization is very harsh and uses strong detergents so keeping the balance here is tricky business.
Where the process of stripping the cells would once have taken up to four months, the researchers managed to cut this down to only 3 days.
Seeding the Cells
Once your scaffold is complete, it’s time to start attaching your new cells to it. The researchers in Texas coated their lung scaffold in pluripotent stem cells taken from another pair of damaged lungs, before immersing them in a nutrient mix required for the cells to adhere, differentiate and grow.
To see an interview with the researchers from Texas, click here.
And if you want to read more about regenerative medicine and how you can cure you, you might enjoy this article we wrote earlier.
Image from http://www.flickr.com/photos/quinnanya/8371216581/
Nichols JE, Niles JA, & Cortiella J (2012). Production and utilization of acellular lung scaffolds in tissue engineering. Journal of cellular biochemistry, 113 (7), 2185-92 PMID: 22573544