New hope for people with chronic obstructive pulmonary disease (COPD): the transplant of stem cells taken from patients’ own lungs has given very promising results in clinical trials.
COPD, which includes chronic bronchitis and emphysema, is the fourth leading cause of death in Canada. This incurable pathology, which handicaps more than 700 million people around the world, is mainly characterized by shortness of breath which limits the person’s ability to carry out physical activities, as well as a chronic cough. These symptoms result from the destruction of the epithelium that lines the inside of the airways and lungs. This irreversible damage leads to a reduction in gas exchange between the air in the alveoli of the lungs — the microscopic bags located at the end of the bronchioles — and the red blood cells.
Currently, only medications that dilate the bronchial tubes help reduce COPD symptoms. But these do not repair the damage, which is most often caused by smoking. Without curative treatment, patients therefore see their respiratory capacity gradually deteriorate.
A team of Chinese researchers had already experimented with transplanting progenitor cells into the lungs of mice suffering from lung diseases such as COPD. And they then observed that these cells — the first descendants of multipotent stem cells that began to differentiate into specialized cells — successfully incorporated into lung tissue, reconstituted a vascularized epithelium, and improved oxygen concentrations in the lung. blood of mice. Furthermore, this transplantation was found to be safe.
Clinical test
Building on this success, these researchers then attempted a pilot study in two patients suffering from severe COPD. They then found that these progenitor cells had repaired certain regions of their lung tissue.
This time, researchers carried out a clinical trial in which 21 patients suffering from COPD participated. Some 17 patients were randomly assigned to the treatment group; the other three formed the control group which served as a comparison.
Progenitor cells were collected from the lungs of each of the 21 patients during a bronchoscopy, an examination used to visualize the inside of the bronchi. These cells were cultured for three to five weeks to proliferate before transplanting them into the damaged parts of the patients’ lungs. These autologous transplants, that is to say each patient received the progenitor cells which had been drawn from their own lungs, were carried out during another bronchoscopy.
Although this phase 1 clinical trial was primarily intended to verify the safety of such a transplant in humans, the researchers also evaluated the patients’ respiratory capacity 24 weeks after the procedure. In addition to noting any serious side effects, they noted an improvement in the gas transfer capacity in the patients’ lungs. What’s more, they could also travel 30 meters more during the six minutes of a physical test.
In the article they published in the journal Science Translational Medicine, the researchers admit that their study has limitations, particularly due to the small number of participants and the short duration of the follow-up carried out. But to remedy this, they claim to have launched a multicenter phase 2 trial with a larger number of participants, some of whom will unknowingly receive a placebo rather than progenitor cells. These participants will also be followed twice as long, for 48 weeks.