Therapy of the future: see you again!
Results of the conference "Therapy of the future"
The conference was attended by professors of the Skolkovo Institute of Science and Technology (Raj Rajagopalan), professors of the Massachusetts Institute of Technology (Bruce Tidore, Daniel Andreson, Rudolf Janisch, Peter Reddin, etc.), professors of the European Institute of Aging Biology (Gerald de Haan, Evgeny Berezikov, Peter Landsdorp). But, of course, the focus was on two invited Nobel laureates: Philip Sharp, Professor, winner of the Nobel Prize in Physiology and Medicine in 1993 (David Koch Institute for Integrative Cancer Research, Massachusetts University of Technology) and Shinya Yamanaka, Professor, winner of the Nobel Prize in Physiology and Medicine in 2013, Director of the iPS Center for Cell Research and applications, Senior researcher at the Gladstone Institute of Cardiovascular Diseases and researcher at the L.K. Weiter Foundation in Stem cell biology.
In the introductory part of the conference, the pressing issue of the future of biomedical research in the Russian Federation was discussed. The discussion was attended by Anton Burns, Professor, Director of the Skoltech Research Center "Center for Stem Cell Research", Viktor Kotelyansky, Professor, Director of the Skoltech Research Center "Center for RNAi Therapy and Functional Genomics", Daniel Anderson, Professor of the Department of Chemical Engineering at the David Koch Institute for Integrative Cancer Research of the Massachusetts Institute of Technology, Viktor Vekselberg, President of the Foundation Skolkovo, Lyudmila Ogorodova, Deputy Minister of Education and Science of the Russian Federation, Andrey Ivanov, Deputy Minister of Finance of the Russian Federation, Rudolf Janisch, founder of the Whitehead Institute, as well as Nobel laureates (where without them).
We listened with interest to a lecture by Alexander Kabanov, a former graduate of Moscow State University, and now a professor at the University of North Carolina, director of the Center for Nanotechnology and co-director of the Karolinska Institute of Nanomedicine. In his lecture, he talked about the possibilities of using polymer micelles for drug delivery. This is one of the most promising areas in the development of targeted delivery of antitumor drugs. The shell of a hydrophilic polymer makes it possible to successfully transport insoluble drug molecules in the blood plasma. Kabanov noted that until now, polyethylene glycol was considered the gold standard in this area. However, recently, it has been replaced by polymer shells of a new generation based on polyoxazolines. They are characterized by greater hydrophilicity and increased chemical stability of micelles. Further prospects for the development of this direction are promising: nanoparticles can be embedded in the gel shell of drugs that ensure selective penetration of the drug into the tumor cell.
I remember a lecture by Peter Redin, professor of biology at the Massachusetts Institute of Technology, on the cellular and molecular foundations of regeneration in Planaris flatworms. The professor has long wondered how the body "understands" which tissue needs regeneration after damage. The studies were conducted on planarians capable of reproducing body parts or even an entire organism from small fragments. To suppress the ability of worm cells to divide, the researchers exposed planaria to radiation; at the same time, the selected dose of radiation allowed some neoblasts (cells that migrate to the affected areas and restore healthy tissue) to survive. Such neoblasts in cell culture demonstrated all the properties of stem cells, forming cells of various tissues. Some of the neoblasts (they were called clonogenic) were able to transform into all the tissues of an adult worm. To confirm the universality of clonogenic neoblasts, scientists transplanted them to worms exposed to a lethal dose of radiation when the planaria had no cells capable of dividing. What happened next, the researchers themselves call nothing but a science fiction movie: a single cell is able to completely restore the tissues of the irradiated planaria. At the end of the process, the worm consisted of cells genetically identical to the original donor clonogenic cell. At the same time, the animal felt normal, ate, grew and multiplied. This is the first time that an adult animal carries pluripotent stem cells. The study means a possible breakthrough in regenerative medicine: if it is possible to find human genes similar to those that control neoblasts in worms, it will be possible to create similar cells on human material.
Professor Olga Dontsova also spoke at the conference with a lecture on RNA polymerases. To study the dynamic contacts formed by mRNA and 5S rRNA molecules during translation, a chemical crosslinking method was developed. The combination of chemical crosslinking technology, chemical "footprinting" and molecular biology methods made it possible to investigate new functions of the ribosome E-site, identify interactions between ribosome functional centers, and trace the fate of tmRNA inside the ribosome. In the course of studies of chemical modifications of RNA in the ribosome, several new methyltransferases have been discovered and described. This made it possible to develop a unique high-performance screening system for new ribosomal antibiotics.
But most of all, the conference was waiting for a lecture by Nobel laureate Shinya Yamanaki. A wave of interest in his recent discovery of a method for reprogramming somatic cells into stem cells has not yet passed. Let me remind you how the professor and his team gradually came to this discovery.
It is interesting that an outstanding scientist could not have taken place at all: the young Dr. Yamanaka initially chose the path of surgery, but, having a fine sense (which, by the way, then played a big role in his life), he left this field in time. According to the professor himself, he sent his resume to several universities in the USA, but received a response from only one. So in 1991, Shinya Yamanaki met Dr. Tom Innerarity (Gladstone University, San Francisco), where Shinya began to participate in scientific work devoted to the study of the effect of APOBEC1 gene expression in the liver on plasma cholesterol levels.
The Department of Cardiovascular Diseases, where Sinya was working at that time, was actively engaged in the problem of treating atherosclerosis. As is known, the body synthesizes two isoforms of the protein APS (the only apolipoprotein of low-density lipoproteins, the carrier of "bad cholesterol", which causes the accumulation of cholesterol in the walls of blood vessels): ApoV-100 and ApoV-48. ApoV-100 is synthesized in the liver and corresponds to the full 100% of the ApoV gene. An isoform corresponding to only half (more precisely, about 48% – hence the name) of the ApoV – ApoV-48 gene is synthesized in the intestine and is a much less harmful product. Yamanaka set out to develop a method for transforming a harmful isoform into a safe one for the body. Thus, the enzyme APOBEC1, responsible for the synthesis of intestinal aroV 48, was discovered. This enzyme is also present in the liver, but in an inactive form. Tom Innerarity, the head of the study, suggested that the activation of the enzyme APOBEC1 in the liver will promote the synthesis of a less harmful isoform of APS, which means it will lead to a decrease in plasma cholesterol.
Shinya Yamanaka's role in this work was to create a line of transgenic mice with the APOBEC1 gene. The future Nobel laureate brilliantly coped with the task, the necessary gene was really expressed. But the result of this stage of work turned out to be completely unpredictable. Over time, the mice became noticeably bulging of the anterior abdominal wall, which at first caused Yamanaki's assistant to assume that the animals were pregnant. But due to the fact that this could not happen physiologically – all the mice were males – they began to look for an explanation of this pathology. It turned out that all mice developed liver cancer, and after several years of studying this phenotype in 1997, a new gene was discovered – NAT1 (Novel APOBEC1 Target No1). The enzyme APOBEC1 changed the structure of the protein NAT1, which led to the development of a tumor.
Next, Shinya Yamanaka decided to study whether the absence of the NAT1 gene affects the appearance of a cancerous tumor. This experiment required transgenic mice, which could be obtained using embryonic stem cells (ESCs). Observing ESCs with the knockout NAT1 gene, Yamanaka discovered that cells do not differentiate, but divide endlessly. So the professor discovered a gene that ensured the differentiation of ESCs.
Returning to his laboratory in Japan with the valuable results of many years of work, Yamanaka continued to study the pluripotency of cells. The first reprogramming of a cell with the help of genetic factors took place back in 1987, when muscle cells were made from skin cells. The researchers introduced a gene into the fibroblasts of the skin that determines the development of the muscle cell ("master gene"), and thus reprogrammed the cell. Professor Yamanaka led a team of researchers analyzing the influence of 24 factors on the development of pluripotency in somatic cells. One of his assistants once suggested analyzing the factors not individually, but all together. As Yamanaka himself says, this idea seemed absurd to him, but still decided to try this method. We all already know the result of the experiment – in 2006, Professor Shinya Yamanaka and his team, together with Professor John Gordon, discovered 4 genes: Oct3/4, Sox2, c-Myc and Klf4, under the influence of which the somatic cell becomes a pluripotent stem cell.
It is worth noting that during the first experiments of obtaining iPS cells, the C-Myc factor with oncogenic activity and retrovirus vectors were used, which are not capable of independent replication, but provide effective embedding of foreign DNA into the genome and the constancy of genetic changes. However, these vectors are embedded only in dividing cells, can cause insertion mutations, give relatively low titers of the recombinant virus, and the expression of the embedded gene often decreases to a very low level after a few months.
Now the technology for obtaining iPS has become safer: oncogenic factors are not used, and retrovirus vectors have been replaced with plasmids that are not embedded in the genome. This method of obtaining cells proved itself in the phase of preclinical animal studies. It has also been found that fewer genes are required to reprogram some types of adult cells. For example, mouse neurons can be turned into pluripotent stem cells with just one gene – Oct4. In addition, data have been obtained that under certain conditions, when reprogramming cells, some genes can be replaced with small molecules of chemical compounds, as in conventional medicines.
In his lecture, Yamanaka highlighted the latest iPS cell research that has already begun and is planned to be conducted. Having received the approval of the Ministry of Health of Japan, scientists led by Dr. Masayo Takahashi from the RIKEN Center for Developmental Biology are studying the effectiveness of iPS cells isolated from the skin and reprogrammed into epithelial pigment cells of the human retina in the treatment of age-related macular degeneration (chronic progressive dystrophic disease of the central region of the retina (macula), which leads to the gradual loss of the central vision required for a clear perception of objects). This work was the first clinical study of the use of iPS.
iPS has been found to be used in the treatment of amyotrophic lateral sclerosis (ALS). The institute headed by Professor Yamanaka managed to obtain iPS of healthy people and ALS patients. No differences were found in the stem cells themselves. But after these cells turned into motor neurons, the differences were found. It turned out that the processes of neurons in ALS patients were two times shorter than in healthy people. Now, substances that may be able to reverse the process of shortening of neural processes are being tested on neurons grown in the laboratory.
The professor also noted that since the first presentation of obtaining iPS cells, results have been achieved to improve the method. If in 2006 the percentage of iPS cells obtained from fibroblasts was 0.1% or less, then in 2009 the percentage was increased to 20, and in 2013 a team of Israeli scientists reported 100% transformation. Important advantages of iPS cells over other cell lines are reproducibility and compatibility with ES.
If after the lecture the picture of the further future of iPS in medicine was more or less outlined, then vague impressions remained from a personal conversation with the Nobel laureate. When asked what is still better than iPS or ES cells, the professor was slightly confused in his answers: at first he confirmed that both cell lines are used for different purposes, but then changed his mind and said that his brainchild iPS, of course, is much better and more efficient. The professor also found it difficult to answer the question whether stimulation of iPS differentiation is possible, for example, with retinol. Nevertheless, there is one very pleasant moment: a keepsake photo with a Nobel laureate :)
As a result, the conference left very good impressions: a rich program, bright personalities, interesting communication. We are waiting for new meetings!
Portal "Eternal youth" http://vechnayamolodost.ru16.06.2014