A donor for himself

How to grow stem cells

What are stem cells, how do they affect human life and what diseases can be cured with their help? Derrick Rossi, professor of the Departments of Stem Cells and Regenerative Biology at Harvard Medical School, told RIA Novosti about these and other questions in an interview with the Social Navigator project.

© MIPT Press Service

– What are stem cells?

– There are many different stem cells. For example, embryonic: they are responsible for the formation of the human body. Such cells are also called pluripotent stem cells, which means that they can transform into any kind of tissue in our body.

This type of cell exists only at very early stages of embryonic development of the organism. However, this does not mean that the history of stem cells ends there.

For the formation of various tissues of the body during life, a person also needs stem cells. To do this, there are special stem cells that create a replacement for old or dead cells in our body.

I work with those stem cells that form blood, or rather, those of its components that move oxygen through our body, fight infections and so on. There are about 200 different blood cells that are responsible for different functions, and they all come from just a stem cell – a hemocytoblast – that lives in the bone marrow. There are not so many of them, but still they are there.

These cells have a huge potential. For example, they can be used to cure leukemia – blood cancer. You may have heard of bone marrow transplantation. However, today it is used as a means of last resort.

– Why?

– The fact is that this procedure is quite dangerous in itself. In 10% of cases, bone marrow transplantation is fatal for the patient. After all, first a person is subjected to harsh chemotherapy or radiation with radioactive or gamma rays to kill all blood cells, and then new ones are introduced that can restore the bone marrow and start blood reproduction anew. At the same time, it should be understood that if at least one cell remains in the human body, the disease will return.

New blood stem cells are taken from a donor. More precisely, part of his bone marrow is transplanted to the patient. The donor does not even have to be a close relative: the main thing is that he and the recipient have a high level of compatibility. More precisely, the higher, the better.

However, it should be understood that high compatibility is still not ideal, so there will be elements of discrepancy. Because of this, the donor's cells can begin to attack the recipient's body, which will lead to such a disease as a "graft versus host" reaction. This is a very terrible disease. The worse the compatibility, the worse the disease. That is why initially, more than half a century ago, transplantation was performed only among identical twins who have perfect compatibility.

– How to determine the degree of compatibility?

– It is determined by genetic analysis of the tissue compatibility system, which in the body is represented by a set of proteins located on the surface of almost all cells of the body. With their help, the latter determine their own and others'.

– How difficult is it to find a donor with a high level of compatibility?

– In different ways, it is difficult for someone, for someone it is not. Some types are more common, some less common. In the study of the human tissue compatibility system, ten parameters are checked. In general, everything is simple: the more donors, the greater the chance to find a high level of compatibility.

– How do they take bone marrow from a donor and how much of it is needed for a successful operation?

– In this procedure, it is not the amount of bone marrow that is important, but the number of stem cells. In the bone marrow, as I have already said, there are not so many of them: about one cell out of 20 thousand will be a stem cell. But, for example, there are about 10 billion cells in the femur, so there are enough stem cells there.

As for the amount needed for the operation, one true hematopoietic stem cell is enough to restore the process of blood formation, but until the stem cell accelerates and gives all the precursors, months may pass! Therefore, it is necessary to transfer not only stem cells, but also progenitors differentiating from them, which can restore the hematopoiesis system for a short time, but very quickly. It's like baking: you can buy a finished product, a semi-finished product, a source product or build a farm. Hematopoietic cells are a farm, and while it is working at full capacity, you will starve to death.

The necessary stem cells are also in the umbilical cord blood, but there are too few of them there: not enough even for a large child, and what can we say about an adult.

Therefore, for this operation, cells are taken from the bone marrow. There are two ways to get them. The first is when a part of the bone marrow is sucked out of the iliac bone, more precisely, from its crest, under general anesthesia with the help of a special huge needle.

The second is when, with the help of certain proteins that are given to the donor, stem cells are removed from the bones into the blood. Then, with the help of a special device, they are taken from there. But in order to get enough stem cells in this way, you need to carry out the procedure for five consecutive days.

– Can this somehow harm the donor?

- no. During the procedure with proteins, there may be a slight short-term pain in the bones. If we talk about the procedure with a needle, it will be a little painful and uncomfortable after the procedure. However, what is a little discomfort and pain compared to the fact that you can give someone a life?

– In July, news agencies wrote about an experiment when mice, if I'm not mistaken, were injected with stem cells into the hypothalamus, which increased the rate of regeneration of all cells in the body and, accordingly, slowed down aging. Have you heard about it?

– To be honest, no. However, sometimes in science some seemingly fantastic things turn out to be true. And in general, science is the discovery of the unknown, and nature surprises us all the time. Never say never. This is especially true for biology and science in general. If someone has succeeded in something, someone will definitely try to repeat the experiment. That's how science works. That's the beauty of her: she always checks herself.

For example, the Japanese scientist Shinya Yamanaka discovered that you can take any cell in the body and turn it into a stem cell. He took a small piece of mouse skin, got a separate cell from it, a fibroblast. Then Yamanaka realized that if a series of genetic manipulations were carried out, it could be reprogrammed into a stem cell that could turn into any kind of tissue. In fact, he received pluripotent stem cells, but called them induced stem cells.

Thanks to this discovery, scientists have learned how to turn any cell in the body into a pluripotent one, which in turn can transform into any other.

Before this discovery, any scientist would have said that a skin cell is a skin cell and will never be anything else. A kind of dogma. But Yamanaka denied it. He published his report in 2006, and in 2012 he received the Nobel Prize for this discovery.

– If it is possible to turn any cell into any, then why is this technology not used in the treatment of the same leukemia?

– We can take any cell and turn it into a pluripotent stem cell, yes. However, making a blood stem cell out of it is a much more difficult task. Many laboratories in the world are now working on how to "persuade" a pluripotent stem cell to turn into the right one. We just don't know yet the rules that will allow us to do this.

– What can you say about the use of stem cells in cosmetology?

– The only clinically proven procedure with stem cells is a bone marrow transplant. That's it!

There are a lot of pseudoscientific clinics in the world that promise to restore youth, beauty and a lot of things with the help of stem cells. Clinically, nothing like this has been proven. This is complete nonsense! They just want to breed you for money.

The only thing you can hope for when going to such a procedure is that you will not be harmed. You'll be lucky if they give you a saline solution. Believe me, you don't want them to give you stem cells, because these would-be doctors don't know what they are doing.

Don't believe what you read on the Internet.

– What do you think are the prospects for stem cells in medicine?

– But who knows, the real potential? Until 2006, everyone thought that it was impossible to get another cell from one cell. How soon will stem cells be used on a daily basis in medicine? At the moment, about 40 thousand bone marrow transplants are performed per year. We are trying to increase this indicator. If the operation is made safer, then in the future it will be possible to treat other diseases, for example HIV.

Have you heard about the "Berlin patient"? This is the only person on earth who could be cured of HIV infection. His name is Timothy Brown. Twice he was very unlucky, and once incredibly lucky. In 1995, a man was found to have HIV, in 2006 - leukemia. A donor was found for him with a mutation of the CCR5 gene, which makes a person immune to HIV. This mutation occurs in a small number of Europeans (about 10% have a variant of the delta32 gene, and only 1% have it in a double set, which makes such people resistant to HIV-1). In 2007, Timothy Brown underwent a bone marrow transplant, thanks to which he defeated leukemia, and then HIV. This fact has been repeatedly confirmed.

Konstantin Ermolaev talked

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