The reference cell

Alla Astakhova, "Results"

Everyone has long been accustomed to the fact that in Russia the sensations associated with stem cells are scandalous. Something like magic "injections for all diseases". However, there are exceptions to this rule. As proof, Sergey Kiselyov, head of the Laboratory of Genetic Foundations of Cellular Technologies at the N. I. Vavilov Institute of General Genetics of the Russian Academy of Sciences, shows me a photo of a small gel lump permeated with pink meshes of microscopic capillaries. What's so surprising about that? And the fact that scientists have grown vessels from human stem cells. Moreover, they not only grew it, but also created a standard methodology for this process. There is a chance that the dream of doctors and patients will come true soon and we will still live to the time when it will be possible to manufacture "spare parts for the body".

Cell linesThe specialists of Kiselyov's group began to deal with stem cells quite a long time ago – first in connection with the problems of oncology.

As you know, stem cells play a significant role in the process of the emergence and growth of tumors. "It was in 2001," says Sergey Kiselyov. "There was no boom in stem cells back then."

At first, the researchers "extracted" the material from the bone marrow, fat and pulp of the tooth. However, as stem cells became more and more interesting to them on their own, already out of connection with oncology, they turned their gaze towards human embryos. "By 2002, when the stem cell boom broke out, we had accumulated a lot of experience working with mouse embryonic stem cells," says Sergey Kiselyov. – We, the only ones in Russia, were then able to conduct a "genetic knockout" and raised mice in the laboratory with the gene "turned off", discovered in our own laboratory. So the transition to human embryonic cells did not present any special technical difficulties for us."

Now scientists admit that in order to start working with human embryonic material, they did not have to overcome any special obstacles and seek permission from various authorities – our situation was radically different from what existed in many countries. "When we needed human embryonic stem cells, I had the audacity and called directly to the laboratory of In Vitro Fertilization (IVF) of the Scientific Center of Obstetrics and Gynecology, which was then headed by the late Boris Leonov," Kiselyov says. – It is usually difficult for researchers to find a common language with doctors. However, Leonov was a very erudite man. We didn't have to explain anything to him for a long time." Soon, geneticists received fertilized eggs from the laboratory, which remained unclaimed after implantation of "test tube embryos" to expectant mothers. "According to Russian laws, this material must be either frozen at the request of parents for a fee, or destroyed," Kiselyov says. – I will say right away: we have not received any official permits to work with him. But regulations providing for such permits did not exist in Russia and still do not exist."

However, the doctors still found it necessary to seek the consent of the parents – they signed special papers in which they were allowed to use the embryos for scientific purposes. In 2003, scientists obtained four human stem cell lines from embryos. To do this, the cells of the embryos, from which all the tissues of the body were to develop, were placed in a nutrient medium. They had to share, while retaining the property of being "progenitors", but not to develop into tissue, because then they would quickly die. As it was shown in experiments with mice, only embryonic stem cells, remaining themselves, are able to divide indefinitely in the laboratory, that is, to give offspring almost forever.

Why did scientists need human embryonic stem cell lines? Firstly, in order not to use more and more embryos for experiments. Now all the material for experiments is "supplied" to them by cell lines. In addition, it was important to have cells with the same genetic characteristics and obtained under standard conditions. This is the only way to compare different ways of influencing them. Researchers have a chance to finally get closer to their cherished dream - to grow tissues "to repair" those that have fallen into disrepair.

At the beginning of the XXI century, the boom associated with stem cell research covered both the Old and the New World. However, many countries have imposed strict bans on the use of human embryos. These restrictions were justified – in such a delicate matter as manipulations with human reproductive material, you need to adhere to the rule "measure seven times, cut once". However, the prohibitions had another, less obvious side. In the absence of regulations in this area, our scientists suddenly found themselves in an advantageous position compared to their colleagues. At that time, they were prevented from realizing their advantage by the destroyed scientific infrastructure and the banal lack of money. And after a few years, the bans on experiments with embryos in other countries gradually began to come to naught under the pressure of the pharmaceutical lobby. Now Russians have to promote their developments in fierce competition with others.

Mechanical fillingHowever, years of research have not been in vain.

For example, our scientists are the best in the world at growing endothelial cells from stem cells, that is, the inner surface of human blood vessels. But how to make stem cells change in the right direction?

"There are three things to do. I call this principle the "3D rule," says Sergey Kiselyov. – First, we need to get cells that would function in the same way as cells of a certain tissue, in this case, the vascular endothelium. Secondly, these cells in their genetic portrait should be identical to what we want to get. And thirdly, we need to be sure that the genetic changes in them are irreversible."

Scientists began to grow vessels not immediately. This was preceded by the experience of joint research on the treatment of lower limb ischemia with cells taken from the patient's own bone marrow. When they were injected into patients, the growth of new small vessels began, and blood circulation improved. (The picture on the left shows the vessels of the lower leg before treatment, on the right – 6 months after the introduction of stem cells.)

However, scientists honestly admit: they do not yet know what factors contributed to this growth. These mechanisms have yet to be explored. With embryonic stem cells, things were different. To begin with, it was necessary to find means that allowed them to be affected in such a way that they developed into vessels. To do this, we had to constantly experiment, changing the composition of the nutrient medium in which they grew many times in order to either "let go" or "slow down" their development in the right direction. Gradually, scientists have achieved that the cells, undergoing a series of successive changes, could form vascular structures directly "in vitro". Success meant that colonies of stem cells in laboratory cups, the division of which had to be so carefully monitored, could become natural factories of "spare" tissues. However, for this it was necessary to overcome a number of difficulties. After all, scientists have never been able to obtain pure cultures consisting entirely of vascular endothelium. However, their results turned out to be an order of magnitude better than those of competing scientific groups from other countries: while other researchers usually manage to "reorient" only 5 percent of stem cells towards "vascular" specialization, this figure reached 50 percent for the Russian team. However, the ratio had to be changed radically: it was the Russians who had previously been involved in stem cells in oncology, who knew how dangerous any "extra" cell could become for the body, the development of which got out of control... The scientists decided to "sort" the resulting mass by the method of immune-magnetic separation. Magnetic particles "sewn" to antibodies that interact with vascular endothelial proteins according to the "key – lock" principle help to select the necessary cells. When the sample is then placed in an electromagnetic field, the "necessary" and "unnecessary" cells move away from each other. The "necessary" cells are later additionally checked for the presence of genetic mutations.

Now scientists are able to pick up a "clean" sample with vascular cells grown in a test tube. "Without being particularly modest, we can say today that we have a reliable standard technique for obtaining vascular tissues from human stem cells, which is already ready for clinical use," Sergey Kiselyov admits. What's next? The answer suggests itself: having accumulated the necessary number of vascular cells, proceed to animal testing. Firstly, human vascular cells grown in the laboratory are practically ready–made material for drug testing without risk to patients. Secondly, only the lazy do not talk about the epidemic of cardiovascular diseases today. Shunts, artificial heart valves, and other means of "repair" are in demand as never before. However, the compatibility of synthetic materials with the tissues of a living organism has always been a problem. It is not for nothing that the famous transplantologist Valery Shumakov, working on an artificial heart, dreamed of a hybrid organ in which the mechanical filling would be placed in a shell of living human cells created in a test tube...

Waiting for a breakthroughOf course, no one today dares to say that there is one step left before the realization of this bold dream.

At least because vessels grown in a test tube from someone else's embryonic cells, as well as organs taken for transplantation, can be rejected. "As in the case of a transplant, a person who has received "spare parts" for the cardiovascular system will most likely have to take drugs that suppress immunity," says Academician Rem Petrov.

However, there is no doubt that whoever is the first to be able to put the production of "spare parts" for vessels on stream will still render humanity a huge service. But will this fabulous plot continue? So far, Russian investors, who have heard mostly only about "golden" injections of stem cells, are afraid to invest in expensive and "long-lasting" serious scientific research related to this topic. Scientists don't have to rely on the state's money either – our country has not even joined the International Stem Cell Initiative program initiated by the UK, which already includes a dozen and a half scientific academies and research institutes from different countries. "I'm afraid that very soon we will lose that small "point" advantage over other teams that we still have," Sergey Kiselyov admits. This state of affairs can be understood: all over the world, the attitude of the permitting authorities to the problem of stem cells is wary. However, experts are confident: this will be the case only until the moment when there is no serious breakthrough in stem cell research associated with the real success of new treatment methods. Experts predict this event by 2010. And someone will definitely be the first...

Portal "Eternal youth" www.vechnayamolodost.ru
14.04.2008