Heart from a bioreactor

Scientists have grown a human heart in the laboratory

Anna Govorova, Infox.ru

Bioengineers from Massachusetts General Hospital, Harvard Medical School and the Harvard Stem Cell Institute (USA) have grown a human heart, reports Infox. This is another important step in the development of regenerative medicine.

However, it is still unclear whether such a heart will work in the body. But already now it can be used for the development and testing of new drugs for the treatment of cardiovascular diseases. But before such a heart or pieces of heart tissue can be used for transplantation, it will take at least another ten years, the authors say.

They report on their achievement in the latest issue of the journal Circulation Research (Guyette et al., Bioengineering Human Myocardium on Native Extracellular Matrix).

Scientists have learned to grow heart cells from stem cells for a long time. For example, cardiomyocytes are already able to grow from animal and human skin cells. From cardiomyocytes grown in the laboratory, they learned to obtain both pieces of heart tissue and small organoids.

But there is a huge distance from these studies to the creation of an entire organ – a functional heart.

The first difficulty is getting a "skeleton". The authors of the current study, led by associate Professor Dr. Harald Ott, began working on this problem back in 2008. During this time, they managed to develop a method for obtaining a skeleton (scientists call it a scaffold) for the lungs and kidneys of rats and larger animals.

In their current work, scientists have used this technique for the first time to create a "skeleton" for the human heart.

As a source material in the New England Organ Bank, the authors took the hearts of 73 deceased people whose organs were unsuitable for transplantation. Then they got rid of the heart cells – this process is called "decellurization". After that, there was a "skeleton" consisting of collagen and elastin – the main proteins of connective tissue.

It is very important that the technique developed by scientists allowed to preserve not only the "skeleton", but also the blood vessels penetrating the heart. The problem of creating such a network of vessels, or vascularization of grown organs, is one of the most difficult in regenerative medicine.

The "skeleton" itself was seeded by scientists with cardiomyocytes obtained by direct reprogramming from human fibroblasts – skin cells. In total, they placed about 500 million of these cardiomyocytes in the area of the wall of the left ventricle.

Then, for 14 days, the "skeleton" with cardiomyocytes was placed in a bioreactor with a nutrient and oxygen-containing medium that resembled the environment in which the human heart works. After 14 days, the cells formed a three-dimensional structure and began to contract in response to electrical impulses.

As the authors say, this is certainly a great success.

Nevertheless, it remains a big problem to "force" the transplanted cells to develop into different functional types. Recall that in addition to cardiomyocytes (they are the main cells of the heart muscle), there are epithelial and smooth muscle cells in the heart. In general, stem cells are characterized by the so-called "site-specificity" when they develop into different types depending on the position in the organ. But it is very difficult to achieve this from them in laboratory conditions.

"Creating heart muscle tissue from patients' own skin cells is a very important step. This will allow to grow models of the heart for the selection of therapy individually for each patient with cardiovascular diseases. Such models are also very important in the development of drugs and new treatment methods. We will work on it. In the future, pieces of grown heart tissue can be used for transplantation into a damaged area of the heart, for example, after a myocardial infarction. But it should take at least ten years for this to happen. A fully grown organ for transplantation is already a reality of the distant future," says Dr. Ott (in a press release from Massachusetts General Hospital Functional heart muscle regenerated in decellularized human hearts – VM).

Portal "Eternal youth" http://vechnayamolodost.ru  16.03.2016