Cloning of human tissues and organs. The use of cloning in medicine Cloning human cells and organs

In October 2001 the company Advanced Cell Technology(AST, USA) succeeded for the first time in obtaining a cloned human embryo consisting of 6 cells. This means that cloning embryos for medical purposes (called therapeutic cloning) is just around the corner.

The purpose of such cloning is to obtain human blastocysts (hollow spherical structures consisting of approximately 100 cells) that contain an internal cell mass. After extraction from blastocysts, the internal cells can develop in culture, turning into stem cells, which, in turn, can turn into any differentiated human cells: nerve, muscle, hematopoietic, gland cells, etc.

The medical applications of stem cells are very promising and extremely diverse. They can be used, for example, to treat diabetes by restoring the population of dead or damaged pancreatic cells that produce insulin. They can also be used to replace nerve cells in case of damage to the brain or spinal cord. In this case, there is no danger of transplant rejection and other undesirable complications that accompany conventional operations involving the transplantation of cells, tissues and organs.

Recently, the term “therapeutic cloning” has also been used to refer to the cloning of embryos intended for implantation into the uterus of a woman, who can then give birth to a cloned child. This is justified by the fact that such cloning will allow infertile couples to have children. However, it has nothing to do with treatment as such. Therefore, most scientists involved in cloning for medical purposes believe that the time for “reproductive” cloning has not yet come; many complex biological, medical and ethical problems still need to be solved.

Many women responded to the ACT company's advertisement with a request to provide material for scientific research in the field of cloning, of whom 12 donors were selected after a thorough check of their health and mental state. Interestingly, the majority of potential donors stated that they would refuse to participate in reproductive cloning experiments.

Donors were given special injections of hormones so that during ovulation, not one, but approximately 10 eggs would be released. Fibroblasts were used as a source of nuclei for transplantation into eggs. Fibroblasts were obtained from skin biopsies of anonymous donors, including patients with diabetes mellitus and patients with spinal cord injuries. After fibroblasts were isolated, cell cultures were obtained from them. cloning egg embryo medicine

In the first experiments, fibroblast nuclei were used. However, after the nucleus transplantation, although the egg began to divide, the process was quickly completed, and not even two separate cells were formed. After a number of failures, American researchers decided to use the approach of T. Wakayama and R. Yanagimachi (the so-called Hawaiian method), with which the first cloned mouse was obtained.

This method consists of transplanting a whole ovarian cell into an egg instead of the nucleus of a somatic cell (fibroblast). Ovarian cells provide nutrition to the developing egg and are so tightly bound to it that they remain on its surface even after ovulation. These cells are so small that a whole cell can be used instead of a nucleus.

However, in this case, significant difficulties arose. It took more than 70 experiments before a dividing egg was obtained. Of the 8 eggs into which ovarian cells were introduced, two formed a four-cell embryo, and one formed a six-cell embryo. After this, their division stopped.

The parthenogenetic approach is based on the fact that the egg does not become haploid immediately, but at a fairly late stage of maturation. If such an almost mature egg could be activated, i.e. stimulated to divide, it would be possible to obtain blastocysts and stem cells. The disadvantage of this approach is that the resulting stem cells will only be genetically related to the egg donor. It is impossible to obtain stem cells for other people in this way; transplantation of nuclei into the egg will be required.

Previously, there were successful attempts to activate the eggs of mice and rabbits using various substances or electric current. Back in 1983, E. Robertson obtained stem cells from a parthenogenetic mouse embryo and showed that they can form various tissues, including muscle and nervous tissue.

With the human embryo, everything turned out to be more complicated. Of the 22 chemically activated eggs, only 6 formed something resembling blastocysts after five days. However, there was no internal cell mass in these blastocysts...

There are three types of mammalian cloning: embryonic cloning, mature DNA cloning (reproductive cloning, Roslin method) and therapeutic (biomedical) cloning.

At embryonic cloning the cells resulting from the division of a fertilized egg divide and continue to develop into independent embryos. This way you can get monozygotic twins, triplets, etc. up to 8 embryos developing into normal organisms. This method has long been used for cloning animals of various species, but its applicability to humans has not been sufficiently studied.

Bio?medical?cloning about?written? higher. It? about?is different from?t reproductive?th? cloning?vaniya only? what? the egg with the transplanted nucleus develops in an artificial environment, then the stem cells are removed from the blastocyst, and the pre-embryo itself dies. Stem cells can be used to regenerate damaged or missing organs and tissues in many cases, however? The procedure for obtaining them is a lot? moral?-ethical problems, and in? In many countries, legislators are discussing the possibility of banning biomedical products. cloning. Nevertheless, research in this area continues, and thousands are incurable. patients (Parkinson's and Alzheimer's diseases, diabetes, multiple sclerosis, rheumatoid arthritis, cancer, as well as spinal cord injuries) with hope? They are waiting for their positive results.

Since cloning of living organisms became possible, there has been debate about the ethics of using clones for organ transplantation. Recently, scientists from Oregon Health and Science University obtained a full-fledged human embryo in the laboratory for the first time. Such embryos are supposed to be used to obtain stem cells.

This requires a sample of the original skin, as well as a donor egg obtained from a healthy woman. The DNA is removed from the egg, and then one of the skin cells is injected inside it. After this, an electric discharge is applied to the cell, causing it to begin to divide. Within six days, an embryo develops from it, from which stem cells can be taken for implantation. According to scientists, with the help of such technologies it will be possible to treat such serious illnesses as Alzheimer's disease, various brain pathologies and multiple sclerosis.

“Our discovery makes it possible to grow stem cells for patients with serious diseases and organ damage,” said one of the authors of the development, Dr. Shukharat Mitalipov. “Of course, a lot still needs to be done before there is a safe and reliable method of treatment with stem cells. But our work “This is a confident step towards regenerative medicine.”

Until recently, a surrogate mother was required to carry a cloned embryo. Now it will be possible to obtain clones in the laboratory without the participation of female volunteers. Meanwhile, many see this latest discovery as a threat to humanity. Or rather, the prospect for illegal and uncontrolled human cloning.

Cloning is a rather slippery topic. If people are born artificially, can they be considered human? Recently, many science fiction works and films have appeared, the plot of which is the discrimination of clones, as well as their use for organ transplants. Organ transplantation has always been a problem, as it is difficult to find a suitable donor. If there was an entire army of clones grown specifically for the purpose of donation, people's chances of receiving healthy organs to replace sick ones would increase dramatically. Moreover, if these organs were taken from their completely identical counterparts. Over time, it would be possible to “transplant” even damaged limbs or, say, eyes...

But what about the clones themselves? So far we are talking only about embryos, from which there are no plans to grow real people. But in principle they could become them. Another option is to grow clones with defective brains - it seems like you wouldn’t mind them... But again, how ethical is this? The hero of Nancy Farmer's book "House of Scorpio", a clone of a major drug lord, unlike his "brothers" in misfortune, retains his mind, but he manages to save his life only by a miracle...

The fantastic film “The Island” depicts a future society where there are entire settlements of human clones who are grown only to later receive organs from them... And in the novel “Never Let Me Go” by Kazuo Ishiguro and in the film of the same name, clones are taught in special schools , from childhood, being taught the idea that sooner or later they will become donors and give away their organs to save the lives of other people, so that practically none of them will live to see the age of thirty...

It would seem that in reality such a scenario is simply impossible: not a single country in the world can legalize the killing of living people for medical purposes. But who knows... After all, the prospects that cloning opens up are quite tempting. And why not sacrifice an underdeveloped “copy” to save the life of, say, a famous scientist, artist or politician? The more global the scale, the less valuable the life of a clone will seem...

Messages about the permission of cloning of human organs that flashed in the media sound intriguingly fantastic. Everyone seems to have become accustomed to cloned frogs and sheep.

Is the stamping of the liver, kidneys, heart and lungs on the way? Let's figure it out.

You can suppress the recipient's immunity with special medications - immunosuppressants.

Not bad for preventing rejection, but then the patient will suffer from unwanted side effects. In particular, if the immune system is “turned off,” all sorts of pathogenic microorganisms are activated, which are abundant in the body of any person. Each of us is a real walking zoo, where various bacteria, viruses, and all kinds of fungi sit in cells. They are constantly kept under control by the immune system.

The second option is to select an organ from a donor whose cells will resemble the recipient’s cells in a number of ways.

In other words, you need to find a double organ. For this purpose, entire data banks are being created in developed countries of the world. The chances of success are still slim.

The idea that if an organ for transplantation cannot be obtained, then it must be done was expressed back in the late 1980s. Director of the liver transplant program at Boston Children's Hospital, Dr. Charles Vacanti. However, an organ is a very complex system: it includes many different tissues, it is penetrated by blood vessels and nerves. How to recreate this system and how to reproduce the desired shape of the organ in the laboratory? This is the second and so far practically unsolved problem in the creation (cloning) of organs for transplantation.

Some approaches to solving it, however, are being outlined. Take the nose and ears for example. Their shape is created by cartilage, and cartilage is structured quite simply. It has no blood vessels or nerve endings. To get an artificial ear, do the following. The desired shape is cast from a porous polymer and “populated” with chondrocytes - cells that create natural cartilage. Chondrocytes themselves can be grown outside the body, but ears and noses do not grow in plastic cups. Chondrocytes themselves cannot create such complex spatial forms.

However, they can be helped by arranging them in the space in the right way. After some time, the polymer fibers from which the template was made dissolve, and “living” cartilage of the desired shape is obtained.

Finally, there is another way to develop transplantology. Have you noticed that humanity has learned to fly, but it does it completely differently from birds. Airplanes don't flap their wings. This path is also possible in medicine. Moreover, it is already gradually being implemented. The “artificial kidney” device has been created and is working. There are no living cells in it yet. But perhaps in the future it will be possible to create a kind of “centaur” - an organ filled with electronics, which will include living tissue. It will not be a copy of a natural kidney, but it will perform its functions perfectly.

So far, everything that has been said is only a distant prospect, which, however, can be outlined with cautious optimism. Before “cloning”, i.e. mass production of complex organs such as kidneys, liver or spleen is still a long way off. Therefore, take care of your health!

Of particular interest in the bioethical context is the problem of cloning. There are several cloning methods:

Stem cell manipulation;

Cell nucleus transplantation.

The uniqueness of stem cells lies in the fact that when they enter damaged areas of various organs, they are able to turn into cells of exactly the type that are necessary for tissue restoration (muscle, bone, nerve, liver, etc.). That is, using cloning technology, it is possible to grow the necessary human organs “to order”. The real fantasy, however, is where to get stem cells? The results of many years of experiments are as follows:

Abortive material for natural and artificial insemination;

Extraction of stem cells from the corners and grooves of the brain, bone marrow and hair follicles of the adult body and other tissues;

Blood from the umbilical cord;

Pumped out fat;

Lost baby teeth;

Studying adult stem cells is certainly encouraging and does not raise the ethical concerns that embryonic stem cells do. It is generally accepted that the best source of stem cells for therapeutic cloning (i.e. obtaining embryonic stem cells) is embryos. However, in this regard, we cannot turn a blind eye to potential dangers. The European Ethics Panel has highlighted the issue of women's rights, which could come under intense pressure. In addition, experts note the problem of voluntary and informed consent for the donor (as well as anonymity) and for the recipient of the cells. Questions about acceptable risk, the application of ethical standards in human research, the safety and security of cell banks, confidentiality and protection of the private nature of genetic information, the problem of commercialization, the protection of information and genetic material when moving across borders, etc. remain controversial.

Most countries in the world have a complete or temporary ban on human reproductive cloning. The UNESCO Universal Declaration on the Human Genome and Human Rights (1997) prohibits the practice of cloning for the purpose of human reproduction.

Another cloning method is cell nuclear transfer. At the moment, in this way, many clones of various types of animals have been obtained: horses, cats, mice, sheep, goats, pigs, bulls, etc. Scientists note that cloned mice live shorter lives and are more susceptible to various diseases. Research into cloning living beings continues.

Chapter 7. Bioethical problems of genetic engineering technologies

7.1 Biotechnology, biosafety and genetic engineering: history and modernity

For a long period of time, biotechnology was understood as microbiological processes. In a broad sense, the term biotechnology refers to the use of living organisms to produce food and energy. The last years of the twentieth century were marked by great achievements in molecular biology and genetics. Methods have been developed for isolating hereditary material (DNA), creating new combinations of it using manipulations carried out outside the cell, and transferring new genetic constructs into living organisms. Thus, it has become possible to obtain new breeds of animals, plant varieties, and strains of microorganisms with traits that cannot be selected through traditional breeding.

The history of the use of genetically modified organisms (GMOs) in practical activities is short. In this regard, there is an element of uncertainty regarding the safety of GMOs for human health and the environment. Therefore, ensuring the safety of genetic engineering work and transgenic products is one of the pressing problems in this area.

The safety of genetic engineering activities or biosafety provides for a system of measures aimed at preventing or reducing to a safe level the adverse effects of genetically engineered organisms on human health and the environment when carrying out genetic engineering activities. Biosafety as a new area of ​​knowledge includes two areas: the development and application of methods for assessing and preventing the risk of adverse effects of transgenic organisms and the system of state regulation of the safety of genetic engineering activities.

Genetic engineering is a technology for obtaining new combinations of genetic material by manipulating nucleic acid molecules outside the cell and transferring the created gene constructs into a living organism. The technology for producing genetically engineered organisms expands the capabilities of traditional breeding.

The production of transgenic medicines is a promising area of ​​genetic engineering activity. If previously, for example, frequent transfusions of donor blood (a risky and expensive procedure) were considered an effective method of treating anemia, today modified microorganisms and animal cell cultures are used to produce transgenic medications. The effectiveness of using transgenic organisms in the service of medicine can be examined using several examples of solving human health problems. According to WHO, there are about 220 million people with diabetes in the world. For 10% of patients, insulin therapy is indicated. It is impossible to provide all those in need with animal insulin (probability of transfer of viruses from animals to people; expensive medicine). That is why the development of technology for the biological synthesis of hormones in microbial cells is the optimal solution to the problem. Insulin obtained at a microbiological factory is identical to natural human insulin, is cheaper than animal insulin preparations, and does not cause complications.

A pronounced slowdown in the growth of children, leading to the appearance of midgets and dwarfs, is another human health problem associated with disruption of the endocrine glands (lack of growth hormone somatotropin, which is produced by the pituitary gland). Previously, this disease was treated by injecting growth hormone into the blood of patients, isolated from the pituitary gland of deceased people. However, there were a number of technical, medical, financial and ethical problems. Today this problem has been resolved. The gene encoding the production of human growth hormone is synthesized and inserted into the genetic material of E. coli.