Tissue engineering: transplantology of the future. Technologies for manufacturing scaffolds for tissue engineering Manufacturing of material for tissue engineering
Tissue engineering constructs are used to create biological substitutes to restore or improve tissue function. Cells, as a component of the design, can be obtained from different sources and be at different stages of differentiation from poorly differentiated cells to highly differentiated specialized cells. Colonization of a prepared matrix by cells is a pressing problem in modern biomedicine. In this case, the properties of the matrix surface influence cell colonization, including cell attachment and proliferation throughout the matrix.
Currently known methods for obtaining tissue-engineered constructs use the preparation of a suspension of cells and the physical application of this suspension to a biocompatible material through the step-by-step deposition of a suspension culture to form a monolayer and placing the material in solution for a long time, sufficient for the penetration of cells throughout the entire volume of the material, as well as the use 3D bioprinting. Offered various ways formation of tissue-engineered equivalents of hollow internal organs, such as the urethra, bladder, bile duct, trachea.
Clinical studies[ | ]
Tissue engineered constructs based on biocompatible materials have been investigated in clinical studies on patients for urological and dermatological diseases.
See also [ | ]
Notes [ | ]
- , Fox C. F. Tissue engineering: proceedings of a workshop, held at Granlibakken, Lake Tahoe, California, February 26-29, 1988. - Alan R. Liss, 1988. - T. 107.
- Atala A., Kasper F. K., Mikos A. G. Engineering complex tissues // Science translational medicine. - 2012. - T. 4, No. 160. - S. 160rv12. - ISSN 1946-6234. - DOI:10.1126/scitranslmed.3004890.
- Vasyutin I.A., Lyndup A.V., Vinarov A.Z., Butnaru D.V., Kuznetsov S.L. Reconstruction of the urethra using tissue engineering technologies. (Russian) // Bulletin Russian Academy medical sciences. - 2017. - T. 72, No. 1. - pp. 17–25. - ISSN 2414-3545. - DOI:10.15690/vramn771.
- Baranovsky D.S., Lyndup A.V., Parshin V.D. Obtaining functionally complete ciliated epithelium in vitro for tissue engineering of the trachea (Russian) // Bulletin of the Russian Academy of Medical Sciences. - 2015. - T. 70, No. 5. - pp. 561–567. - ISSN 2414-3545. - DOI:10.15690/vramn.v70.i5.1442.
- Lawrence B. J., Madihally S. V. Cell colonization in degradable 3D porous matrices // Cell adhesion & migration. - 2008. - T. 2, No. 1. - pp. 9-16.
- Mironov V. et al. Organ printing: computer-aided jet-based 3D tissue engineering //TRENDS in Biotechnology. – 2003. – T. 21. – No. 4. – pp. 157-161. doi:
Definition One of the areas of biotechnology that deals with the creation of biological substitutes for tissues and organs. Description The creation of biological tissue substitutes (grafts) includes several stages: 1) selection and cultivation of one’s own or donor cell material; 2) development of a special carrier for cells (matrix) based on biocompatible materials; 3) applying a cell culture to the matrix and cell proliferation in a bioreactor with special cultivation conditions; 4) direct introduction of the graft into the area of the affected organ or preliminary placement in an area well supplied with blood for maturation and formation of microcirculation inside the graft (prefabrication). The cellular material can be represented by cells of the regenerated tissue or stem cells. To create graft matrices, biologically inert synthetic materials, materials based on natural polymers (chitosan, alginate, collagen), as well as biocomposite materials are used. For example, equivalents bone tissue obtained by directed differentiation of bone marrow stem cells, cord blood or adipose tissue. Then the resulting osteoblasts are applied to various materials that support their division - donor bone, collagen matrices, porous hydroxyapatite, etc. Living skin equivalents containing donor or own skin cells are currently widely used in the USA, Russia, and Italy. These designs can improve the healing of extensive burn surfaces. The development of grafts is also carried out in cardiology (artificial heart valves, reconstruction large vessels and capillary networks); to restore the respiratory system (larynx, trachea and bronchi), small intestine, liver, urinary system organs, glands internal secretion and neurons. The use of stem cells is widely used in the field of tissue engineering, but has limitations both ethical (embryonic stem cells) and genetic (in some cases, malignant division of stem cells occurs). Research recent years showed that with the help of genetic engineering manipulations it is possible to obtain so-called pluripotent stem cells (iPSc) from skin fibroblasts, similar in their properties and potential to embryonic stem cells. Metal nanoparticles in tissue engineering are used to control cell growth by exposing them to magnetic fields of different directions. For example, in this way it was possible to create not only analogues of liver structures, but also such complex structures as elements of the retina. Nanocomposite materials also provide nano-sized surface roughness of matrices for effective formation bone implants using electron beam lithography (EBL). The creation of artificial tissues and organs will eliminate the need for transplantation of most donor organs and will improve the quality of life and survival of patients. Authors
- Naroditsky Boris Savelievich, Doctor of Biological Sciences
- Nesterenko Lyudmila Nikolaevna, Ph.D.
- Nanotechnology in tissue engineering / Nanometer. - URL: http://www.nanometer.ru/2007/10/16/tkanevaa_inzheneria_4860.html (access date 10/12/2009)
- Stem cell / Wikipedia - the free encyclopedia. URL: ttp://ru.wikipedia.org/wiki/Stem cells (access date 10/12/2009)
Tags Sections Biomimetic nanomaterials
Formation of nanomaterials using biological systems and/or methods
Bionanomaterials and biofunctionalized nanomaterials
Bionanotechnologies, biofunctional nanomaterials and nanoscale biomolecular devices
Encyclopedic Dictionary of Nanotechnologies. - Rusnano. 2010 .
See what “tissue engineering” is in other dictionaries:
tissue engineering- Methods for controlling body cells in order to form new tissues or express biologically active substances Biotechnology topics EN tissue engineering ... Technical Translator's Guide
The term bioengineering The term in English bioengineering Synonyms biomedical engineering Abbreviations Related terms biodegradable polymers, biomedical microelectromechanical systems, biomimetics, biomimetic nanomaterials, ... ...
The term biomimetic nanomaterials The term in English biomimetic nanomaterials Synonyms of biomimetics, biomimetics Abbreviations Related terms proteins, biodegradable polymers, bioengineering, biomimetics, biocompatibility, biocompatible... ... Encyclopedic Dictionary of Nanotechnology
Vadim Sergeevich Repin Date of birth: July 31, 1936 (1936 07 31) (76 years old) Place of birth: USSR Country ... Wikipedia
- (Latin placenta, “cake”) an embryonic organ in all female placental mammals, some marsupials, hammerhead fish and other viviparous cartilaginous fish, as well as viviparous onychophorans and a number of other groups of animals, allowing ... ... Wikipedia
Contains some of the most outstanding current events, achievements and innovations in various areas modern technology. New technologies are those technical innovations that represent progressive changes within the field... ... Wikipedia
Articlesamphiphilicbiodegradable polymersbiological membranebiological motorsbiologicalatingsbisl... Encyclopedic Dictionary of Nanotechnology
Articles"two-faced" particlesactuamotorsbiological nanomaterialsbiosensbased on nanomaterialshydrogen bond... Encyclopedic Dictionary of Nanotechnology
Articles "soft" chemistrybiological membranebiomimeticsbiomimetic nancoatingsbilayer engineeringhybrid materialsDNADNA microchipgene deliverycap... Encyclopedic Dictionary of Nanotechnology
This is a service list of articles created to coordinate work on the development of the topic. This warning does not apply... Wikipedia
Books
- Tissue engineering, Creative team of the show “Breathe Deeper”. Fundamentally new approach– cell and tissue engineering – is latest achievement in Molecular and Cellular Biology. This approach opened up broad prospects for creating... audiobook
What if we could grow body parts, like a starfish? Is this fantasy or reality? "TO & Z" decided to figure out what it is tissue engineering, and most importantly, is it available in Russia?
What is tissue engineering
In fact, our body is capable of regeneration, moreover, it does this every day: bones are restored every ten years, and skin changes every two weeks. But this, of course, is not enough. Due to diseases, injuries and simply with age, our tissues and entire organs are destroyed and die. How to slow down this process and restore what is no longer there? These issues are addressed by the advanced direction of regenerative medicine - tissue engineering, which makes it possible to increase lost skin and parts of organs, such as the heart or bladder.
Why is tissue engineering necessary?
Tissue necrosis due to disease, injury, or congenital anomalies is the number one health problem worldwide. The need for transplantation is growing in arithmetic progression in all countries. Classical modern medicine cure many chronic diseases on at the moment incapable - only corrective procedures are possible, but to find completely compatible donor- this is also a challenge.
Today, one of the main methods of restoring organs and tissues in cases where transplantation of one’s own material is impossible is its transplantation - from a living donor or a recently deceased person. The main thing in this process is maximum biological compatibility of the donor and recipient. But even in this case, the immune system will resist and interfere with the engraftment of the transplanted organ or tissue. Therefore, patients who have undergone transplantation are prescribed special drugs - immunosuppressants - temporarily or for life. Essentially, they suppress a person's own immune system. But, despite many efforts, very often the transplanted organ does not take root.
Following the principle of “do no harm,” scientists and doctors have long been looking for ways to restore tissues and organs using the patient’s own body. For this purpose, a whole section of reconstructive surgery has appeared, based on microsurgical techniques. Sew or transplant a finger in case of injury, for example, from a foot to an arm, restore the mammary gland after removal of a malignant tumor, and even return a significant part of the patient’s face - after injury, oncology or injury. But microsurgery is not omnipotent. This is how tissue engineering began to flourish, which appeared long before microsurgery.
A little history of the issue
For the first time about this back in late XIX century, the American doctor Leo Loeb thought. In 1897, he conducted an experiment: he observed how cells divided in clotted blood and lymph. Having published his observations, he, however, did not reveal the exact parameters of the experiment, which made this work even more intriguing. Following him to this topic with different sides Many scientists tried to approach, but only ten years later his colleague and compatriot - scientist Ross Harrison - managed to raise and keep alive nerve fibers and cells taken from frog embryonic tissue. And already in 1912, the French surgeon Alexis Carrel and his colleagues were able to support the life of a small section of the heart of a chicken embryo. This biomaterial remained viable and even grew for 24 years!
Tissue Growing Methods
Since then, tissue engineering has come a long way. Currently used to grow tissue different ways, But one of the main ones - scaffold - scaffold technology. Experimenters from different countries have been practicing it since the 90s. According to this technology, cells of a living organism are taken as a sample: a piece of tissue or some separate body. It is then broken down into individual cells using enzymes and cultured for four to six weeks.
The next stage is transplantation of multiplied cells onto a scaffold, special temporary matrix. Externally, the scaffold can be mistaken for cotton fabric, quite suitable for a blouse or shirt, but in fact it is complexly designed artificial material. On such a scaffold, biomaterial intended for transplantation into humans is grown. The structure is implanted where there is no tissue, for example, on the urethra or kidney. The scaffold acts as a kind of courier for new cells. As soon as damaged tissue is restored, the delivery man dissolves, disappearing without a trace.
A striking example of such work is the reconstruction of the bladder by American surgeon Anthony Atala for Luke Massella, a ten-year-old boy with congenital defect development of the spine - cleft. The disease paralyzed bladder child, and by the time the parents turned to the doctor for help, the kidneys were already failing. “For growth” they took bladder tissue the size of half postage stamp. Cell cultivation in laboratory conditions took four weeks. Atala's team then created a bladder-shaped scaffold. inner shell This frame was covered with cells lining the “original” organ, and the outer one with muscle cells. The model was placed in a bioreactor (a medical analogue of an oven) for ripening. After six to eight weeks, the fully formed organ was transplanted. In the same intricate way, Atala managed to grow heart valve and even an ear. By the way, we had to tinker with it: the patient’s cartilage was seeded into the mold, which, after staying in the bioreactor for several weeks, turned into an independent scaffold ear. For more complex organs, such as the heart, Atala's colleague, Chinese scientist Tao Zhu, has developed a technique that uses 3D printers. Instead of ink, human cells are poured into the cartridges, from which a heart is literally printed within an hour, and after 46 hours it is ready for use.
Donor organs are also used as a framework. Let’s take the liver: using special means, all the donor’s cells are removed from it, then the patient’s cells are introduced into the devastated “skeleton” - inside and out. The patient's cells are a guarantee that there will be no rejection by the body. Tissue engineering is still an experimental science, but existing experiments prove that anything can be created using this technique - heart valves, blood vessels, liver, muscles, ears and human fingers. Scientists hope that new technique It will also help to cope with another acute problem of transplantology - the shortage of donor organs.
Autotransplantation in aesthetic medicine
Today, conventional autotransplantation is widely used for burns, injuries of cartilage, tendons and even bones. At the moment, tissue engineering at the level of beauty medicine cannot offer any outstanding things, but there are some things. In aesthetic medicine, autotransplantation of cartilage and fat tissue is widely used. Own cartilage tissue It takes root much better during rhinoplasty and allows flexible modeling of the shape of the nose. With genioplasty, you can easily change the angle of your chin using your own tissue. The installation of cartilage implants is also used in malarplasty to increase the volume of the zygomatic area.
Regenerative medicine in Russia
In Russia, the situation with tissue engineering is not so rosy, no one is growing organs yet, there are regenerative techniques in cardiology, and extracorporeal hematocorrection is used. Experiments are being carried out on 3D printing, but at the moment even with legal point vision, it is impossible to carry out such operations.
Regenerative medicine, in particular growing stem cells outside the human body, is one of the main and important events in world practice. More recently, in 2014, scientists from the Institute of Physical and Chemical Research of Japan managed to restore sight to a 70-year-old woman, and this year the Japanese were able to grow skin, hair follicles and a mini-liver. It is already possible for medicine to grow cartilage, tissues and some whole organs. Not far off - the heart, pancreas and nervous tissue, the brain. So far, the statistics are not encouraging: two people die every minute in the world who could be saved by transplanting their own tissue. Autotransplantation is the future, with the help of which millions of lives can be saved.
Development of modern cell transplantology and its introduction into the clinic in last decades allowed to prolong the lives of many thousands of patients. Currently, the science of cell transplantation remains one of the most rapidly developing areas of biology and medicine. The following methods are already undergoing clinical trials:
– transplantation of one’s own hematopoietic cells when multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis;
– transplantation of hematopoietic cells during treatment malignant tumors kidneys, mammary and pancreas, brain;
– transplantation of donor stem cells to prevent graft-versus-host disease after previous hematopoietic cell transplantation;
– adaptive immunotherapy (cytotoxic T-lymphocytes) in oncology, cellular oncology vaccines;
– transplantation of skeletal myoblasts muscle tissue;
– transplantation of neuronal cells into patients with post-stroke syndrome;
– transplantation of own and donor bone marrow cells to improve bone tissue regeneration after fractures.
Advances in the field of stem cell research are largely due to the increased interest of scientists and clinicians in the prospects for their use in the treatment of diseases currently considered incurable. However, this raises many ethical issues (such as, for example, the use of human embryonic cells as transplant material), as well as issues related to legal regulation cell technologies. In the development of cellular technologies, the following areas are considered the most promising:
– isolation and transplantation of stem cells, including the patient’s own cells;
– identification of subpopulations and clones of stem cells;
– testing the safety of transplantation (infectious, oncogenic, mutagenic), drawing up a “cellular passport”;
– isolation of individual lines of embryonic stem cells by somatic cell nuclear transfer;
– correction of genetic defects by prenatal cell transplantation or a combination of nuclear transfer and genetic therapy.
Tissue engineering
One of the areas of biotechnology that deals with the creation of biological substitutes for tissues and organs is tissue engineering (TI).
Modern tissue engineering began to take shape as an independent discipline after the work of D.R. Walter and F.R. Meyer (1984), who managed to restore the damaged cornea of the eye using plastic material artificially grown from cells taken from the patient. This method is called keratinoplasty. Following a symposium organized by the US National Science Foundation (NSF) in 1987, tissue engineering began to be considered a new scientific direction in medicine. To date, most of the work in this area has been carried out on laboratory animals, but some of the technologies are already used in medicine.
The creation of artificial organs consists of several stages (Fig. 2).
Rice. 2. Processing scheme for tissue-engineered structures
At the first stage, one’s own or donor cell material is selected (biopsy), tissue-specific cells are isolated and cultivated. The tissue-engineered structure, or graft, includes, in addition to the cell culture, a special carrier (matrix). Matrices can be made of various biocompatible materials. The cells of the resulting culture are applied to the matrix, after which such a three-dimensional structure is transferred to a bioreactor1 with a nutrient medium, where it is incubated for a certain time. The first bioreactors were created to produce artificial liver tissue.
For each type of graft being grown, select special conditions cultivation. For example, to create artificial arteries, a flow-through bioreactor is used, in which a constant flow of a nutrient medium is maintained with variable pulse pressure, simulating the pulsation of blood flow.
Sometimes, when creating a graft, prefabrication technology is used: the structure is first placed not on permanent place, but to an area well supplied with blood, for maturation and formation of microcirculation inside the graft.
Cell cultures that are part of the regenerated tissue or are their precursors are used as cellular material for creating artificial organs. For example, when obtaining a graft for reconstructing the phalanx of a finger, techniques were used that caused directed differentiation of bone marrow stem cells into bone tissue cells.
If the patient’s own cellular material was used to create the graft, then almost complete integration of the graft occurs with a rapid restoration of the function of the regenerated organ. When using a graft with donor cells, the body switches on mechanisms for inducing and stimulating its own reparative activity, and within 1–3 months the body’s own cells completely replace the decaying graft cells.
Biomaterials used to obtain matrices must be biologically inert and, after grafting (transferred into the body), ensure localization of the cellular material applied to them in a specific place. Most tissue engineering biomaterials are easily destroyed (resorbed) in the body and replaced by its own tissues. In this case, intermediate products that are toxic, change the pH of the tissue or impair the growth and differentiation of the cell culture should not be formed. Non-resorbable materials are almost never used, because they limit regenerative activity, cause excessive formation connective tissue, provoke a reaction to foreign body(encapsulation).
To create tissues and organs, mainly synthetic materials, materials based on natural polymers (chitosan, alginate, collagen), as well as biocomposite materials are used (Table 3).
Table 3. Classes of biomaterials used in tissue engineering.
Biomaterial |
Biocompatible |
Toxicity |
Resorption |
Scope of application |
Synthetic: Polymers based on organic acids Hydroxyapatite |
Full to CO 2 and H 2 O Non-resorbable |
Surgery, in tissue engineering as a carrier matrix for almost all cell cultures. Bone tissue |
||
Natural: Alginate |
Dressing materials, in tissue engineering in the form of hydrogels (chondroblasts, nerve cells) |
|||
Dressing materials, in technical equipment in the form of films, sponges; in combination with collagen (reconstruction of bone, muscle, cartilage tissue, tendons) |
||||
Collagen |
Replacement with own proteins, enzymatic lysis |
Dressing materials, in TI (sponges, three-dimensional models, films) as a carrier matrix for almost all cell cultures. |
||
Extracellular matrix (natural biological membranes) |
++++ |
Remodeling with replacement by own proteins |
Suture material, in TI (three-dimensional models, films) as a carrier matrix for almost all cell cultures |
Biodegradable synthetic biomaterials based on polymers of organic acids, such as lactic acid (PLA, polylactate) and glycolic acid (PGA, polyglycolide), were among the first to be used in tissue engineering. In this case, the polymer may contain either one type of acid residue or their combinations in various proportions. Matrices based on organic acids formed the basis for the creation of organs and tissues such as skin, bone, cartilage, tendon, muscles (striated, smooth and cardiac), small intestine, etc. However, these materials have disadvantages: changes in the pH of surrounding tissues when broken down in the body and have insufficient mechanical strength, which does not allow their use as a universal material for matrices and substrates.
A special place among materials for biomatrix carriers is occupied by collagen, chitosan and alginate.
Collagen has virtually no antigenic properties. Used as a matrix, it is destroyed by enzymatic hydrolysis and structurally replaced by its own proteins synthesized by fibroblasts. Matrices with specified properties can be made from collagen for the reconstruction of almost any organs and tissues. Being a natural tissue (intercellular) protein, it is optimally suited as a cell culture carrier, ensuring tissue growth and development.
Alginate is a polysaccharide from seaweed that can be used as a carrier matrix, but does not have sufficient biocompatibility and optimal mechanical properties. It is commonly used in the form of hydrogels to restore cartilage and nerve tissue.
Chitosan is a nitrogen-containing polysaccharide, which is the main component of the outer covering of insects, crustaceans and arachnids. This biomaterial is obtained from the chitinous shells of crustaceans and mollusks. Currently, a drug with a combined composition – a collagen-chitosan complex – deserves attention. In the course of laboratory and clinical studies, its inertness and ability to maintain the viability of cell culture as in vitro, so in vivo. This complex is approved by the Ministry of Health of the Russian Federation as a dressing and wound healing agent and is already used in clinical practice in surgery and dentistry.
Modern possibilities of tissue engineering
Most research in the field of tissue engineering is aimed at obtaining tissue equivalents of one kind or another. The most studied area of tissue engineering is the reconstruction of connective tissue, especially bone. The first work in this area described the reconstruction of an osteochondral fragment femur rabbit The main problem faced by the researchers was the choice of biomaterial and the interaction of bone and cartilage tissue in the graft. Bone tissue equivalents are obtained by directed differentiation of stem cells from bone marrow, umbilical cord blood or adipose tissue. Then the resulting osteoblasts are applied to various materials that support their division - donor bone, PGA, collagen matrices, porous hydroxyapatite, etc. The graft is immediately placed at the site of the defect or previously kept in soft tissues. Researchers believe that the main problem with such structures is the discrepancy between the rate of formation of blood vessels in new tissue and the lifespan of cells deep in the graft. To solve this problem, the graft is placed near large vessels.
The histogenesis of muscle tissue largely depends on the development of neuromuscular interactions. The lack of adequate innervation of muscle tissue structures does not yet allow the creation of functioning tissue equivalents of striated muscle tissue. Smooth muscle less sensitive to denervation, because has some capacity for automaticity. Smooth muscle tissue structures are used to create organs such as the ureter, bladder, and intestinal tube. IN lately More and more attention is being paid to attempts to reconstruct the heart muscle using grafts containing cardiac myocytes obtained by targeted differentiation of poorly differentiated bone marrow cells.
One of the most important areas in tissue engineering is the production of skin equivalents. Living skin equivalents containing donor or own skin cells are currently widely used in the USA, Russia, and Italy. These designs can improve the healing of extensive burn surfaces.
The main applications of tissue engineering in cardiology can be considered the creation of artificial heart valves, reconstruction of large vessels and capillary networks. Implants made from synthetic materials are short-lived and often lead to blood clots. When using tubular (vascular) grafts on biodegradable matrices, positive results were obtained in animal experiments, but an unsolved problem remains the controlled strength and resistance of the graft walls to blood pulse pressure.
The creation of artificial capillary networks is important in the treatment of pathologies of blood microcirculation in diseases such as obliterating endarteritis, diabetes mellitus, etc. Positive results here obtained using biodegradable grafts made in the form of a vascular network.
Restoration of respiratory organs, such as the larynx, trachea and bronchi, is also possible using tissue structures made of biodegradable or composite materials coated with epithelial cells and chondroblasts.
Diseases and malformations of the small intestine, accompanied by its significant shortening, lead to the fact that patients are forced to receive special nutritional mixtures And parenteral solutions. In such cases, lengthening the functional part of the small intestine is the only way to alleviate their condition. The graft manufacturing algorithm boils down to the following: cells of epithelial and mesenchymal origin are applied to a biodegradable membrane and placed in the omentum or mesentery of the intestine for maturation. Later certain time your own intestine is connected to the graft. Experiments on animals have shown an improvement in absorption activity, however, due to the lack of innervation, the artificial intestine does not have the ability to peristalsis and regulate secretory activity.
The main difficulty in liver tissue engineering is the formation of a three-dimensional tissue structure. The optimal biomatrix for cell culture is the extracellular matrix of the liver. Researchers believe that the use of porous biopolymers with specified properties will lead to success. Attempts are being made to apply permanent magnetic field for three-dimensional organization of cell culture. The problems of blood supply to large-sized grafts and bile drainage remain unresolved, since the grafts lack bile ducts. However, existing techniques already make it possible to compensate for some genetic abnormalities liver enzyme systems, as well as reduce the manifestations of hemophilia in laboratory animals.
The construction of endocrine glands is at the stage of experimental testing of methods on laboratory animals. The greatest success has been achieved in tissue engineering of the salivary glands; constructs containing pancreatic cells have been obtained.
Malformations of the urinary system account for up to 25% of all malformations. Tissue engineering in this area of medicine is in great demand. Creating kidney tissue equivalents is a rather difficult task, and attempts are being made to solve this problem using direct organogenesis technologies using embryonic renal tissue anlages. The possibility of restoring various organs and tissues of the urinary system was shown in laboratory animals.
One of most important tasks is the restoration of organs and tissues nervous system. Tissue engineered structures can be used to restore both the central and peripheral nervous systems. Olfactory bulb cells and three-dimensional biodegradable gels can be used as cellular material for spinal cord repair. For the peripheral nervous system, biodegradable tubular grafts are used, within which axon growth is carried out by Schwann cells.
The creation of artificial organs will eliminate the need for transplantation of most donor organs and will improve the quality of life and survival of patients. In the near future, these technologies will be introduced into all areas of medicine.
Based on materials from the journal “Cellular Transplantology and Tissue Engineering”, 2005, No. 1
- Zarui Ivanovna, they say that tissue engineering brings science fiction to life. What fantastic projects is your lab working on today?
Tissue engineering is the design and growth of living functional tissues or organs outside the body for subsequent transplantation into a patient. The three-dimensional structure of the tissue must be restored at the site of the defect. The goal is to regenerate tissue, not simply replace it with synthetic material. The main focus of our laboratory is the creation of a collection of mesenchymal stem cells obtained from adipose tissue of adult people. Embryonic stem cells are released from the inner cell mass of the embryo at early stage, and adults - from different tissues of the adult body. Exists ethical problem, associated with the inevitable destruction of the human embryo when obtaining embryonic stem cells. Therefore, it is preferable to obtain cells from adult tissue. Perhaps 20 years ago this could really be perceived as science fiction, but today it is modern innovative technology. This is exactly what we do. Protocols brought from the USA (and I worked for ten years in the laboratory of George Washington University) allow us not to develop a technique from scratch, but to continue working in this direction.
- What tasks does the laboratory at the Institute of Physiology face?
The Institute of Physiology has been conducting research at the level of organisms and extracellular models for quite some time. Cell culture and tissue engineering provide an opportunity to develop this field, to study the molecular mechanisms of transformation of cells into tissues grown specifically for further transplantation. We (and this is me and three of my young employees) work in the laboratory with adipose (adipose) tissue, from which stem cells are relatively easily isolated. From them it is possible to grow cardiac tissue cells - cardiomyocytes with a given structure, functionally active, capable of contraction, as well as nerve and skin cells, depending on the purpose of the study. Our laboratory does not yet have all these methods, but they have been published, so it is a matter of time.
There are two main components to tissue engineering. These are the cells and the environment in which they must grow. Suppose we already know how to make a muscle cell and a cardiac muscle cell from a stem cell, which differs from ordinary muscle, as well as skin and liver cells. But this is not enough, they need a habitat. And not just liquid medium, A three dimensional space, in which cells can grow to create artificial tissue. A special cell carrier, the so-called matrix, is also required. To create matrices, biological inert materials are used, one of which is collagen. In the last five to six years, the creation of natural or, as they are also called, cell-free matrices has become widespread. I'll explain what it is. Each of our tissues, each of our organs has its own architecture. Studies conducted in large scientific centers The USA and Japan have shown that it is possible to take an organ and wash it of all cells, while preserving its architecture. The main thing is to provide conditions under which the solution prepared in advance, the main component of which is detergent (soap), flows through all the vessels feeding this organ, dissolving the cell membranes and leaving only the protein core. To make sure we could do this too, we took a rat's heart, treated it with a detergent solution, and at the end of the experiment, all that was left was the frame - a marble heart. The entire architecture of the organ, which is built from protein, has been preserved. Soap, as you know, has no effect on proteins. The cells, which then dig up from the inside, get stuck in this already folded heart, create their own feedback connections and the heart begins to work.
Of course, now new technologies have arrived, bioprinting is developing, so-called 3D printing, which allows you to print a matrix or heart. But for this you need to give the printer special, expensive “ink”. Making it out of paper won’t work either; the matrix won’t stick. To keep it in place, it is necessary to isolate or synthesize specialized proteins, mainly collagens, which create the architecture of any organ. In our conditions, this is a very expensive task; it is easier to obtain a cell-free organ. But suppose we collected all this and retransplanted it, for example, put a patch on the skin, but here we may encounter the classic problem of transplantation - rejection. Therefore, we are a laboratory not just of tissue engineering, but also of immunology.
Theoretically, all cells of any organism are similar and differ only in surface molecules, which are encoded by molecules known to the given immune system. If these molecules are washed away along with the cells that carry them, then theoretically the matrix should not cause immune reaction body. But no one has done this research yet.
The next stage is to determine the most easily accessible, cheap, but working matrices. This is the second direction of our research activity. We are trying to combine both directions into one in order to study the fundamental aspects of tissue regeneration. Sometimes basic science is considered out of touch with reality, but the results of our laboratory's research have a specific application. Fragments of tissue grown primarily from skin are the easiest to take root during transplantation. In the USA, Japan, Europe they are widely used for burns, plastic surgery etc., which will be done in our country over time. But this will be outside the academic organization.
- Science in Armenia is financed on a residual basis. Creating a new immunology and tissue engineering laboratory requires considerable investment. How did this happen?
Of course, we have to get out of it. The idea of creating a laboratory arose thanks to the initiative of the Institute of Physiology and collaboration with the University. George Washington in the USA, where I remain a member of the faculty. American collaborators help with everything they can, sharing equipment and reagents. The head of the laboratory of cardiac physiology of this university, a world-famous scientist and our compatriot, Professor Narine Sarvazyan, is interested in making sure everything happens here, helping not only financially, but also intellectually. We discuss ideas, look for options in order to get results with very modest financial resources. Sometimes she even repeats our experiment in her laboratory to clarify the result. To grow cells, we use an old Soviet-style incubator. The institute provided us with two computers, renovated rooms, allocated laboratories, provided a couple of old sterile boxes, although not of the level required, so we often use the equipment of Naira Ayvazyan’s laboratory, with whom we actively collaborate. We bought the refrigerator ourselves. In terms of equipment, we still have many problems, especially the need for new tools. Due to the lack of a flow cytometer device, it is not possible to cooperate productively with our collaborator - the Avangard cosmetic center in Avan. But we are expanding contacts and research opportunities.
My friends, Moscow biologists, assured me that cells are capricious ladies, and you need to talk to them, otherwise they will get offended and stop growing. The cells usually come from females and need to be loved. Arriving at the laboratory in the morning, you need to go up to the incubator and wish the cells good morning, say something pleasant, and talk. You laugh, but that's how it is. At the University. George Washington, I had a colleague who ignored this rule, and his cells did not grow. He had to oblige his graduate students to go to the incubator every morning and compliment the cells. In addition, the cell needs our protection. By taking a cell from the body, we deprive it of its immunity; now it relies only on us and sterile equipment. Surgeons never even dreamed of the sterility that we must ensure.
- Who else does the laboratory collaborate with?
Within the institute, we collaborate with the laboratories of Naira Ayvazyan and Armen Voskanyan. They conduct their research at the biochemical level or synthetic substrates - they separate fat, create an artificial cell from it, form vesicles and study the influence of various toxins on them. It is better to do this on growing cells. Therefore, another area of activity of the laboratory is studying the influence of our endemic poisons on actively growing cells. It doesn’t matter whether they are cancerous, embryonic or cardiac cells. Without knowing the molecular physiology of the action of poisons, without knowing molecular mechanism, creating a specific antidote is difficult. Only by understanding which molecule influences this mechanism can an antidote be used. Therefore, it is necessary to answer the question of why this particular molecule was taken at the molecular level.
- Biotechnology is a very expensive science, but usually scientists are helped out by grants...
We received a grant from the State Committee for Science, it is valid for two years. But the amount is not very significant. We hoped to receive an ISTC grant. We established a collaboration with colleagues from Kazakhstan, where the ISTC is now based, created a connection, but it didn’t work out. Why, I don't know. No feedback. And we were counting on this money.
