The latest advances in science have opened access to the holy of holies for man - to the "code of life", or DNA, providing almost limitless opportunities for restructuring any living organism. Are we ready to accept such a gift from scientists?
Taking a quick glance at Anthony James's office, it's easy to guess what he is doing - all the walls are covered with images of mosquitoes, and the shelves are lined with books about these insects.
Above the work table is a poster that clearly shows all stages of the development of the Aedes aegypti mosquito: hatching of the larva from the egg, its subsequent pupation and transformation into an adult. The scale of the image will make even inveterate fans of thrillers about bloodthirsty giant insects shudder. On the license plate of Anthony's car is also proudly stamped with an incomprehensible combination of letters - AEDES.
“For three decades I have been literally obsessed with mosquitoes,” says Anthony James, a molecular geneticist at the University of California, Irvine. There are about 3.5 thousand species of real mosquitoes in nature, but Anthony is only interested in the most deadly of them. One of the striking examples is the Anopheles gambiae mosquito, a carrier of a disease that kills hundreds of thousands of people every year.
Biogeographers believe that these mosquitoes came to America from Africa on the ships of slave traders in the 17th century and brought with them yellow fever, which killed millions of people in the New World at that time. Today, these insects have also become carriers of dengue fever, which infects about 400 million people every year, chikungunya, West Nile and Zika viruses. (The latter raged in 2015 in Brazil and Puerto Rico, which led to the outbreak of a number of diseases of the nervous system, including a rather rare ailment - microcephaly: children are born with a disproportionately small head and an underdeveloped brain.)
Using CRISPR technology, Anthony edited the genome of the individual on the right so that the adult mosquito could no longer spread the parasites. Fluorescent protein markers confirm the operation was successful. If now the "edited" insects are released into the natural environment, their descendants will gradually replace the usual carriers of the infection. But the matter has not yet reached practical action.
Mosquito larvae from the Anthony James laboratory at the University of California, Irvine, demonstrate how malaria can be eradicated once and for all. Both belong to the species Anopheles stephensi, the main distributor of Plasmodium malaria in Asian cities.
The main goal set by Anthony's group is to find the key to the mosquito genome and make it so that they cannot spread dangerous diseases. Until recently, his team was practically alone on the thorny path of theoretical research. Everything changed with the advent of a new revolutionary technology - CRISPR / Cas9: Anthony's research finally found a practical basis.
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CRISPR / Cas9 are two components of the bacterial gene system responsible for the immunity of these tiny creatures. The first consists of short palindromic DNA repeats (in English, cluster regularly interspaced short palindromic repits, or abbreviated CRISPR) located in regular groups, between which there are spacers (literally: "separators").
Spacers, in fact, represent sections of the genes of viruses and act as a kind of card index of genetic "fingerprints" of these main enemies of bacteria. And Cas9 is a protein that, using a guide RNA - a copy of one or another spacer - checks the viral DNA fragments already in the "card index" with foreign molecules trapped in the cell. And, if a match is found, it cuts the DNA of the virus trying to invade the cell, making it impossible for it to multiply.
It turned out that Cas9 can be adapted to work with any guide RNA, which means that this protein can be targeted to cut any DNA sequence that is an analogue of this RNA. When a cut in a given part of DNA is made, all that remains is to insert the required gene into the gap (or you can not insert anything new, just delete the unnecessary old one). Then the cell itself (and not only the bacterial one!) Does everything: for it, the elimination of such breaks is a routine work.
Having mastered the weapons of bacteria against viruses, geneticists have learned to quickly and accurately change the DNA of any living organism on the planet, and man is no exception. In fact, CRISPR technology is a scalpel in the hands of a geneticist, sharper and safer than a surgeon's steel scalpel. With the help of a new method of genetic engineering, specialists can correct some genetic ailments - edit mutations that lead to muscle dystrophy, cystic fibrosis, and even defeat one of the forms of hepatitis. Recently, several groups of scientists have tried to use a new method to "cut" the genes of the immunodeficiency virus (HIV) embedded in the chromosomes of human cells - lymphocytes. It is too early to talk about a new miracle cure for AIDS, but, according to many experts, it will be found precisely thanks to CRISPR technology.
Another area of active search is the fight against pig viruses, because of which it is still impossible to put organ transplants from animals to humans on stream. They are trying to find an application of CRISPR technology to protect endangered species. They began to conduct experiments to remove genes from the DNA of cultivated plants in order to ward off insect pests from them. If this can be achieved, humanity will no longer rely entirely on poisonous pesticides.
None of the scientific discoveries of the last century promised so many benefits - nor did it raise so many ethical issues. For example, can sex cells be edited? After all, they contain genetic material that is passed on to the next generations - children, grandchildren and great-grandchildren of genetically modified individuals - and so on ad infinitum. It doesn't matter what intentions genetics will be guided by in this case - whether the desire to correct a congenital ailment, or the desire to enhance some useful property - but who will dare to predict all the consequences of interference with the very foundations of life?
“If someone suddenly dares to transform germ cells, he should think three times,” reflects Eric Lander, director of the Broad Institute of Cambridge, who led the not so long ago sensational Human Genome project. - And until this daredevil proves to the general public that there are good reasons for such an intervention in human nature, and society does not accept his evidence, there can be no question of any deep change in the genome. However, scientists have not yet managed to find answers to many ethical questions. And I don't know who and when will be able to give them."
And delay in this case is similar to death in the truest sense of the word. Thus, according to forecasts of the US Centers for Disease Control and Prevention, by the time the raging Zika epidemic in Puerto Rico subsides, more than a quarter of the 3.5 million population of the island will become carriers of this disease (based on models of the spread of other pathogens, which are carried by mosquitoes). This means that thousands of pregnant women are at risk of giving birth to a terminally ill or unviable child.
A truly effective solution to the problem at the moment is one - to flood the entire island with insecticides that will destroy the insect vectors. [This is what the USSR did in due time during the construction of the Bratsk hydroelectric power station. - Russian editorial note (RRP).] However, Anthony James suggests another way to eradicate the disease once and for all. To do this, you just need to edit the mosquito genome using CRISPR technology.
Directed editing of the genome allows you to bypass the "immutable" laws of heredity. In nature, it is so established that during sexual reproduction, parents pass on to their offspring one copy of genes each. However, some lucky genes have received a "gift" from evolution: their chances of being inherited exceed 50 percent. True, the owners of such genes are unlikely to be happy with such a gift of fate: as a rule, these are genes that carry serious diseases. Now, at least in theory, scientists can use CRISPR technology to cut defective genes from a DNA strand. Further, the altered genotype will spread in the population naturally (sexually).
A staff member at the Shenzhen International Center for Regenerative Medicine before entering a sterile room where pig's eye corneal cells are modified to be transplanted into humans.
Long Haibin of the Guangzhou Institute of Pharmaceutical Research strokes the Tiangu beagle, one of two dogs raised from embryos, whose genome has been edited to double its muscle mass. Such experiments allow scientists to better understand the mechanisms of muscular dystrophy in humans.
In 2015, the journal Proceedings of the National Academy of Sciences published an article by Anthony James, in which he described the use of the CRISPR method to genetically modify the malaria mosquito. “By inserting certain genes, mosquitoes will not be able to spread the causative agents of the deadly disease,” explains James. "But at the same time, nothing else in their lives will change."
“I worked in peace and quiet for decades, no one knew about me. Now my phone is ringing,”he adds, nodding his head at the stack of letters piled up on his desk. But Anthony is well aware that the launch of an artificially created mutation, designed to spread rapidly in a population of wild animals, can lead to unpredictable consequences and, possibly, to irreversible changes in nature. "The spread of insects with a genome edited in the laboratory in the natural environment is certainly associated with a certain risk," says the scientist. "However, in my opinion, inaction is even more dangerous."
Geneticists more than 40 years ago learned to remove certain nucleotide sequences from the genome of some organisms and transfer them to others in order to change the nature of new owners. Molecular biologists were anticipating the tremendous opportunities the recombinant DNA method promises for them - this is the name of the new technology. However, enthusiasm diminished when they realized that the transfer of DNA between different species can lead to the uncontrolled spread of viruses and other pathogens, and subsequently to the emergence of diseases from which there is no natural defense mechanism. This means that there will be no ready-made vaccines for these diseases.
The unpredictable future frightened the scientists themselves above all. In 1975, at the Asilomar Conference in California, molecular biologists from around the world discussed the risks posed by genetic engineering and formed a working group to develop a series of measures to improve safety in genome experiments.
It soon became clear that an acceptable level of security was achievable, and the capabilities of the new applied science exceeded the wildest expectations. Genetic engineering began to gradually change the lives of millions of people for the better. Diabetes sufferers received a stable source of insulin: scientists transferred genes responsible for the synthesis of insulin in the human body to bacteria, and giant colonies of genetically modified bacteria turned into real insulin factories.
Thanks to genetic modification of plants, new high-yielding crops resistant to herbicides and insects have appeared - a new round of the green revolution has begun.
Before the embryos enter the uterus, a thorough preimplantation genetic diagnosis (PGD) was carried out - a test that allows you to select only healthy embryos. Ilan Tur-Kasp, a doctor at the Ohio Institute of Reproductive Genetics and Reproduction, who performed the operation, estimated that PGD would help reduce the cost of treating cystic fibrosis by $ 2.2 billion a year.
Both parents of 16-month-old Jack are carriers of the same defective gene, which means that there is a 25 percent chance of their children inheriting cystic fibrosis. Fortunately, Jack himself is not susceptible to this ailment, but over time he can also transmit the disease by inheritance.
Has become widespread and treated with genetic engineering. Only the food industry has faced public opposition to the same scientific methods. Numerous studies showing that eating foods derived from genetically modified organisms (GMOs) are no more dangerous than traditional food did not help either. The hysteria around GMOs confirms that people are ready to give up even those foods that have been recognized as safe by the scientific community. [And this despite the fact that accidents related to the consumption of "healthy" organic products have been recorded, and no one has suffered from the use of genetically modified foods! However, thanks to poorly educated politicians, whose statements are instantly picked up and disseminated in the media,ordinary people have the opposite impression. - CONTACT]
At the dawn of the application of the method of recombinant DNA, the terms "transgenic" and "genetically modified" referred to organisms created by combining the DNA of a modified organism with DNA fragments taken from other species. Perhaps CRISPR technology will help scientists to convince the layman: in some cases, genetic engineering is not only needed - it is necessary. After all, this technology allows you to change the genome of a certain species without the participation of foreign DNA.
A striking example of this is golden rice. The only difference between this genetically modified rice variety from the original species is that its grains, thanks to the modification, are rich in vitamin A. Every year in developing countries, up to half a million children lose their sight due to a lack of vitamin A, but activists opposing GMOs, still blocked both scientific research and commercial production of golden rice. Now, genetics have changed tactics and started working on altering the properties of ordinary rice using CRISPR in order to achieve the same result by editing the plant's genes. And a group of scientists led by Kaisia Gao from the Chinese Academy of Sciences succeeded, having removed all three copies of one of the wheat genes, to bring out a plant variety that is resistant to a dangerous fungal disease - powdery mildew.
For millennia, agronomists have been sifting through - of course, unconsciously - the genes of representatives of a particular species, crossing different varieties. CRISPR technology, in fact, is a more economical selection method - highly accurate and fast. In some countries, the differences between GMO varieties and varieties obtained using CRISPR technology have already been officially confirmed by regulators, as have been done by the governments of Germany, Sweden and Argentina.
In addition to the upcoming changes in the food industry, it is difficult to overestimate the potential of the CRISPR method in medicine. The technology has already greatly simplified research in oncology - now it is much easier for scientists to create experimental clones of cancer cells in the laboratory and test various drugs on them in order to identify the most effective in the fight against a developing tumor.
Doctors will soon be testing the CRISPR method to treat certain diseases directly. For example, stem cells from people suffering from hemophilia can be edited outside the patient's body to correct the mutant genes that cause the disease.
The new healthy cells will then need to be injected back into the patient's bloodstream.
More amazing scientific breakthroughs await us in the next few years. For example, in the United States, about 120 thousand people are registered for organ transplants, and this line is only growing. Thousands of people die without waiting for the rescue operation. (And this is without taking into account those hundreds of thousands of people who, for various medical reasons, cannot even get on the list for organ transplants!) For many years, scientists have been trying to solve the problem - including through the use of animal organs. Pigs are among the candidates for donation, but their DNA contains endogenous porcine retroviruses (PERVs), similar to HIV and potentially capable of infecting human cells. No government regulator will under any circumstances allow the transplant of infected organs, and until recently, no one has succeeded in completely eliminating retroviruses from pig cells.[Pig organs are used as potential transplants because they are comparable in size to humans and are easier to raise than chimpanzees and gorillas (not to mention ethical concerns), and not because they are genetically closer to humans than apes. - CONT'D.] It is hoped that editing the porcine genome with CRISPR will allow geneticists to provide transplants for humans.
A group led by George Church, a professor at Harvard Medical School and the Massachusetts Institute of Technology, has already managed to cut out all 62 genes of PERV viruses from the DNA of a pig kidney cell - a complex operation with a simultaneous editing of several genome regions performed for the first time. When the modified cells were mixed with human cells in the laboratory, none of the human cells became infected. The same specialists were able to successfully edit other types of pig cells, removing 20 genes from them that cause the rejection of foreign tissues by the human immune system. This is another important component of successful animal organ transplantation to humans.
George is now engaged in cloning modified cells to grow full-fledged pig embryos from them. In a year or two, he expects to begin experiments on primates, and if, after test transplants, the organs begin to function without interruption, and rejection does not occur, then at the next stage it will be possible to conduct experiments with the involvement of volunteers. According to Church's optimistic forecasts, such human surgeries will become real in a year and a half, given that the alternative to risk for many patients is inevitable death.
Throughout his scientific career, George has been looking for a way to help people who have been refused transplants by doctors because of their low success rate. “The organ transplant decision is one of the most difficult for doctors,” he explains. - It is necessary to take into account many factors: the presence of infectious diseases, alcohol abuse and, in general, everything that is “wrong” with a potential recipient. The refusal is usually supported by the words that the transplant will not bring significant benefits to the patient. But this is fundamentally wrong: of course, transplantation gives a second chance to any person! You just need to provide a sufficient number of donor organs!"
Another unplowed field for CRISPR technology is the restoration of populations of endangered species. For example, bird populations on the Hawaiian Islands are rapidly declining - it's all to blame for a special type of malaria plasmodium that affects birds. Until the beginning of the 19th century, whaler ships brought mosquitoes to the islands, the local birds had never encountered diseases carried by dipterans, and did not have time to develop immunity to them. Only 42 endemic Hawaiian species have survived to this day, and three quarters of them are already endangered. The American organization for the conservation of birds managed to assign Hawaii the status of "the world capital of endangered species of birds." If avian malaria is not stopped by editing the mosquito genome, the islands are likely to lose all their own species.
The gut of this mosquito from Anthony James's lab is filled with the blood of a cow. Such insects are capable of transmitting Zika virus and dengue fever, but their genome can be modified using CRISPR technology so that the offspring of the altered individuals will be sterile.
Jack Newman, former Chief Scientist at Amyris, which pioneered synthetic artemisinin, the only effective drug for treating malaria in humans, is now focusing on fighting mosquito-borne avian diseases. The only relatively effective method of protecting birds today is the complete elimination of vectors, which requires the use of toxic agents to be sprayed over a huge area. Relative - because even with this approach, success is not at all guaranteed. “For a mosquito to die, the insecticide must hit it directly,” explains Newman. But bloodsuckers spend most of their lives hiding in the crowns of trees and hiding in depressions of rocks or between stones. To poison the bulk of the mosquito population, all Hawaiian islands will have to be flooded with chemicals. If we follow the path of changing the genome and sterilize the mosquitoes, then the birds can be saved without destroying their habitat. “Genetic engineering is an incredibly accurate solution to several problems in Hawaii,” Jack says. “Avian malaria is steadily destroying the ecosystem of the islands, but we have the ability to stop it. Are we just going to sit back and watch how nature is dying before our eyes?"
True, not everyone is happy about the rapid progress. For example, in February 2016, US Director of National Intelligence James Klepper warned in his annual speech to the Senate that genetic engineering technologies like CRISPR could be used to create weapons of mass destruction. However, the scientific community immediately pointed out the groundlessness of such statements, recognizing them as too radical. Terrorists have much easier and cheaper ways to attack civilians than infecting farm fields with a new disease or developing a deadly virus.
Of course, one should not completely exclude the possible harm from the use of new gene technologies. "What can be the consequences of reckless handling of the genome?" - asks Jennifer Doudna, professor of chemistry and molecular biology at the University of California (Berkeley).
In 2012, Jennifer, together with her colleague Emmanuelle Charpentier from the Institute for Infectious Biology in Berlin (one of the Max Planck network of research institutes), first applied CRISPR technology for DNA editing, answers this question: “I don’t think we know enough about the human genome, and the genome of other animals, but people will still use this technology - no matter how well it is studied."
The faster science develops, the more frightening the technological threats facing humanity seem. Biology is becoming simpler and more accessible, and soon anyone will be able to experiment with a home CRISPR kit - like radio amateurs collecting all kinds of receivers and transmitters at home. So the concern about what hobbyists can do in home labs if they get their hands on a tool to change the fundamental foundations of animal and plant genetics is justified.
And yet, the amazing possibilities of genetic engineering should not be missed. After all, if, for example, mankind can be forever rid of malaria and other diseases carried by bloodsuckers, this will undoubtedly become one of the greatest achievements of modern science. And although it is still too early to talk about the use of CRISPR technology for editing human embryos, there are other ways of transforming the genome of germ cells that can heal diseases without affecting the DNA of future generations.
For example, children with Tay-Sachs disease lack the enzymes necessary for the breakdown of gangliosides, fatty acids accumulating in the nerve cells of the brain, which leads to the death of these cells and, as a result, to inhibition of mental and physical development, and then to early death of a child. The disease is extremely rare and only in cases where both parents pass on to their children a defective copy of the same gene (which is typical for closed human groups with closely related crossbreeding). Using CRISPR technology, you can correct the genetic material of one of the parents - for example, the sperm of the father - and the child will probably not inherit both defective copies at once.
In the future, such gene therapy may save lives and reduce the likelihood of disease. A similar effect can already be achieved - with artificial insemination: the choice of an embryo without a defective gene copy ensures that the newborn does not inherit the disease to his offspring.
“Gene transfer technology and CRISPR are providing us with the broadest possibilities that no one could have dreamed of before,” summarizes Hank Greeley, director of the Center for Law and Life Sciences at Stanford Medical School. - With their help, we are able to do a lot of good. But it is important to realize that we have acquired power of a completely different order, and it is necessary to make sure that we use it wisely. So far we are not ready to take on such responsibility, but not a day should be lost - there is a lot to be done to guarantee ourselves a peaceful life in the future”