Photosynthesis against heart attack

Heart attacks will be treated with photosynthetic bacteria

Anna Kaznadzei, N+1

Biologists from Stanford University have managed to reduce heart failure in rats using photosynthetic bacteria injected into the heart. When illuminated, such bacteria produced oxygen, and the cardiac activity of rats with blocked heart vessels improved significantly. The study is published in Science Advances (Cohen et al., An innovative biologic system for photon-powered myocardium in the ischemic heart).

Synechococcus elongatus bacteria on rat cardiomyocyte

A heart attack, or myocardial infarction, occurs due to necrosis of a section of the heart muscle. This, in turn, happens due to a lack of blood supply, namely, a lack of oxygen in this area. For example, thrombosis, arterial spasm or overstrain of the heart can cause a heart attack. This is one of the most common causes of death on Earth, along with oncological diseases.

In order to establish blood flow in the heart, in addition to prescribing medications, doctors perform operations that allow the release of "blocked" vessels (they may be narrowed, for example, due to cholesterol plaques). At the same time, expanding structures – stents are inserted into the vessel, or interfering clots are removed. Scientists decided to look at the treatment from the other side – oxygen could be produced directly in the heart, and surgery could be avoided.

At first, they tried to work with plants – spinach and fodder cabbage (common in America as a symbol and standard of healthy nutrition "kale"). Organelles responsible for oxygen production – chloroplasts - were isolated from them and tried to use them as separate functional units. This experiment, however, was not crowned with success, chloroplasts without cells could not work effectively. Then the researchers decided to switch to photosynthetic bacteria.

Synechococcus elongatus bacteria are able to convert carbon dioxide into oxygen under the influence of light, the way plants do, while in terms of size and structure they themselves are something like separate chloroplasts (it is believed that chloroplasts were once free-living bacteria for a long time, and then switched to a symbiotic existence). By placing them in a Petri dish next to the rat's heart cells, the scientists made sure that the bacteria emit oxygen in the light, which is successfully used by their neighbors. The bacteria were able to live in the physiological conditions necessary for the heart cells, and those, in turn, were not hindered, but helped by their presence.

After that, the culture of these bacteria was injected into the heart of rats. Some of the vessels of these rats were artificially blocked, causing the rats to have a heart attack. When the areas of the myocardium began to become dead, the rats were illuminated with bright light. The bacteria began to release oxygen, which was effectively used by the surrounding tissues. The oxygen level in them increased by 25 times, and the cardiac activity of the rats improved. Such rats survived longer, and their hearts contracted better and more powerfully compared to the control sample, which was kept in the dark. After blocking the vessels, the temperature of the cardiac tissues of all rats initially fell, but in rats with bacterial culture, after twenty minutes it rose back, which indicated an effective course of internal metabolic processes.

The effect of improving cardiac activity persisted even four weeks after the start of the experiment. Separately, scientists note that a day after the artificial attack, the level of troponin (a biomarker of heart disease) in rats whose cardiac bacteria were exposed to direct illumination decreased significantly.

The immune system of rats did not reject bacteria, but it should be borne in mind that in humans this process can become an obstacle to such therapy. The positive point is that, on the contrary, the immune response can be used – and bacteria could be injected not directly into the heart, but into any vessel. To do this, they must be provided with the appropriate antibodies, the target of which are heart cells. Another problem is lighting – you need to "punch" the human chest with light to achieve the desired effect without surgery.

If successful, such therapy could help, if not avoid heart attacks, then at least postpone them, giving more time for treatment. The next stage of the scientists' work will be the genetic modification of bacteria in order to increase the efficiency of their oxygen production, as well as experiments with larger animals – sheep and pigs.

Portal "Eternal youth" http://vechnayamolodost.ru  15.06.2017