artificial lung

Researchers from Yale University succeeded in growing lungs in the laboratory using "scaffolds" of an existing lung. It is possible that in the future the research could help patients who need lung and other organ transplants

Noam Levithan and Yonat Ashhar, Galileo

The lungs are essential for breathing, and therefore for life, but their ability to deal with damage and repair themselves is limited. In many cases when the lungs suffer severe damage, for example due to smoking or the hereditary disease cystic fibrosis, the only way to try and save the patient is a lung transplant.

But even when you manage to find a suitable donor in time, most transplant recipients do not survive. Less than 20% of lung transplant recipients survive ten years after transplantation.

One possible way to increase the life expectancy of transplant recipients is to grow a lung from their own cells, so that rejection does not occur. Thomas Petersen (Petersen) and his colleagues from Yale University Recently published in the science weekly Science Research that presents the first step to achieving this goal.

How do you grow a lung?

Since the lung has a complex structure of blood vessels and split airways, Petersen and his colleagues decided not to grow a lung from scratch, but to use an existing lung as a base on which to grow a new lung. The researchers took lungs from adult rats and used a detergent to remove all the cells that make up the lungs and the blood vessels in them.

All that remains after the removal of the cells is the extracellular matrix, which is a kind of scaffolding that gives the lung its shape and spatial structure, and consists mainly of the collagen protein that does not provoke rejection since it is the same in various details.

The researchers scattered on this scaffold cells of blood vessels and lungs that were extracted from the births of rats and transferred the scaffold to a special growth vessel (bioreactor), which imitates some of the conditions in which the lung develops in the fetus, and also flows air into the developing lung.

The cells that the researchers scattered multiplied quickly in the tumor vessel and settled in the right place on the scaffold thanks to the extracellular material. After less than eight days it appears that the cells and the scaffold have developed into a functioning lung.

Like the real thing

In order to check that the created lungs do indeed carry out the work of gas exchange - that is, they absorb oxygen into the blood and release carbon dioxide from it - the researchers removed the left lungs from four adult rats, genetically identical to the dams from which the cells were taken, and implanted the lungs grown in the laboratory in their place.

To the researchers' delight, it was possible to see almost immediately how dark blood (without oxygen) reaches the transplanted lungs and becomes bright when it absorbs oxygen. Blood samples taken by the researchers from the transplanted lungs confirmed that they indeed function similarly to natural lungs.

However, x-rays showed that the transplanted left lungs filled less well with air than the right (natural) lungs. Furthermore, due to small blood leaks and the appearance of blood clots, the researchers had to kill the rats into which the lab-grown lungs were transplanted about two hours after the transplant.

Despite the problems, Petersen and his colleagues showed that it is indeed possible to grow a functioning lung in the laboratory. They even demonstrated, using the lung of a person who donated his body to science and while using umbilical cord blood, that this method could be used to grow a human lung in the laboratory.

But there is no doubt that the road is long until the method is applied in humans. However, researchers in the field of organ growth told the Science news site that the leaks may have occurred because Petersen and his colleagues rushed to transplant the lungs instead of giving them more time to develop, and that the problem would have been solved if they had waited, for example, two months, instead of eight days, before transplanting.

Technologies of growing organs using a scaffold of extracellular material are used not only for lung transplantation in rats. Recently, for example, an article was published in the scientific journal Nature Medicine describing the successful transplantation, also in rats, of a liver grown in the laboratory using the same method.

Thanks to these studies, it is possible that in the future a scaffold from a donor or an animal will be used to grow organs that will not be rejected since they will be built from the cells of the patient waiting for a transplant. And in the event that there are not enough suitable and healthy cells, such as in the case of an adult's lung, other adult cells can be turned into stem cells, made to differentiate into lung cells, and used.