Image: National Cancer Institute/Unsplash/Reproduction
US researchers are testing a new way to treat heart problems and strokes. The bet is on the transplantation of mitochondria – cellular organelles responsible for the production of ATP (adenosine triphosphate). ATP molecules, in turn, function as an energy store for cells. This is what provides the fuel for cellular reactions to take place.
More than a decade ago, researcher James McCully of Boston Children’s Hospital noticed that no drug could save defective mitochondria in damaged heart tissue after ischemia – lack of blood supply. This whole process has been described in this article by the National geographic.
So the idea came up: take healthy mitochondria from the patient himself and put them into the affected cells. Thus, the tissue could be healed without the help of drugs.
Mitochondria transplantation has been performed a few times. A child in the care of surgeon Sitaram Emani at Boston Children’s Hospital underwent the procedure. The operation went as planned, with healthy mitochondria being taken up by the damaged cells and helping the heart tissue to regenerate.
During the procedure, the patient is connected to the ECMO (extracorporeal membrane oxygenation) machine. Healthy mitochondria are collected quickly and are then inserted into the person through the coronary artery, femoral artery or by direct injection into the affected area. This same team has operated on 12 patients since 2015. Of these, eight survived.
The heart is just one of the organs that can benefit from a mitochondrial transplant. Kei Hayashida, a researcher at the Feinstein Institutes of Medical Research in the United States, noticed during tests on rodents that part of the mitochondria injected into the femoral artery reached the brain.
After observation, the researchers were able to treat three stroke patients with the intervention. Two of them showed satisfactory results, while the third did not recover as well – probably due to the large number of strokes he had already suffered.
Either way, there are unanswered questions about mitochondria transplantation. First, researchers don’t know if injection into the femoral vein is enough for mitochondria to reach the heart. It remains to be seen whether or not it is preferable to place them directly on the damaged tissues.
Additionally, it is unclear how many mitochondria need to be transferred for the technique to be successful. In animals, scientists rely on the weight of the guinea pig’s heart, but this does not apply to all tissues. When considering skeletal muscle, for example, you need to inject more mitochondria per gram of muscle tissue.