Biomedicine

The mainstream in Leonid and Natalia Gavrilovy’s investigations is the search for longevity factors acting at early stages of human life. For example, young dump men stand considerably less chance to become a centenarian than persons of the same age having thin or normal constitution. Living conditions in early childhood (for example, childhood spent at a farm) also affect longevity. Some factors may be changed only while planning a child. It was found that one of those factors was mother’s age at childbirth. At present, the researchers have started a large-scale project aiming to study longevity in the USA. That project will allow to ascertain more carefully how living conditions in childhood, youth and middle age affect achieving of exceptional longevity (100 years). Besides factors connected to living conditions, Gavrilovy’s project also includes the search for biological factors of longevity using population data — that is the subject of a science called biodemography. Particularly, creation of an extensive database of long-lived Americans (several thousands of people lived till their centenary) will allow to clarify the type and mode of life span inheritance, the influence of parent’s longevity at the pathway of descendants’ mortality. It will also allow to ascertain the role of parents' reproductive age in the achieving of exceptional longevity by their descendants. One of Leonid and Natalia Gavrilovy’s investigations was devoted to different demographic scenarios and population size forecasts. The aim of the investigation was to clarify demographic consequences of the successful biomedical struggle against aging. It led to a very important conclusion which can change current public opinion claiming that life extension obviously results in overpopulation. People born from young mothers (20–25 years) have twice better chance to live till 100 years than people born from older mothers. The researchers found that a victory over aging, joy of contact with children and stable population size are not incompatible.

In Dr. A. Ben-Yakar’s laboratory, microsurgery probe (10×15×40 mm) was developed using femtosecond laser nanotechnology and two-photon fluorescent microscopy. In the future, it can be used as an endoscope allowing to obtain two-photon picture from operation site having 340 nm in diameter. Future development of the metal covered mirrors with enhanced reflection power and objective microlenses will allow to get images of cell autofluorescence. The probe may be used in oncology, dermatology and neurosurgery. The other novel product is a «lab on a chip» microchip that allows to carry out axotomy in Caernorhabditis elegans using femtolaser. After nanocutting of nerve endings innervating moving back (while the ability of moving forward was preserved), functional resroration of the nerve fibers cut was shown using fluorescent proteins for neuron labelling. In the future, development of this method will allow to study the influence of genes and drugs at nerve tissue development and regeneration.

This method has allowed to create a new class of matrices on the basis of biocompatible cross-linked hydrogels which imitate extracellular matrix. It should be noted that the tissues of blood vessels with high cell density could be created without the use of any bioreactor. Those investigations has got further advance in the use of the laser for acellular framework perforation. That allows to obtain micropores of optimal size and density without changing mechanical properties of structures. Using acellular small-intestinal submucosa as a framework, the scientists have obtained micropores which are 50 µm in diameter, when distances between the pores are 714 µm. To achieve recellularization of that matrix, rotary filling of living cells suspended in hyaluronic hydrogel is used. The next stage in bioengineering of vascular tissue will be connected with the use of nanotechnological methods. The method allows to obtain bioengineered tough tubular constructions without using any reactor.

R. Hass’s group has made essential contribution in the understanding of cell aging as works of that group have shown that metalloproteinase-7 and 20S proteasome directly participate in the signal transmission to PARP-1 protein which plays key role in hemopoietic cell rejuvenation. Moreover, experiments have shown that the decrease in the activity of metalloproteinases is linked directly to how rapidly cells become senescent, as well as to the tissue aging in general. At R. Hass’s laboratory, primary stem cells, obtained from the umbilical cord of newborns, are mainly used. Undoubtedly, this fact has great advantage in terms of subsequent use of the scientific data obtained for medical purposes. Particularly, the scientists from R. Hass’s laboratory have formulated a hypothesis about cell rejuvenation by means of their possible dedifferentiation.

A. Bronikowski’s laboratory studies mechanisms of action of «aging genes» in reptiles, and mechanisms allowing reptiles avoid physiological aging. The research on widely distributed reptile species, which belong the family Colubridae, was aimed at finding out whether physiological parameters and the level of locomotor activity (this level correlates with survival rate of young snakes) reflected the evolution of life span in those reptiles. It should be noted that general metabolic level and mitochondrial efficiency did not depend on the life span. Further researches have revealed that innate immunity was higher in snakes of short-living ecotype. And that difference could not be explained by the state of parasitic invasion in those ecotypes. Moreover, both ecotypes revealed positive correlation between immunity and body size/age. It was found that long-living snakes (more than 15 years) had higher locomotor activity and lowered level of peroxide production as compared to short-living ones (less than 10 years).

B. Best was one of the initiators of the Hippocampal Slice Cryopreservation Project (HSCP). For work at this project, Dr. Yuri Pichugin was specially invited from Ukraine. The aim of the project was vitrification (cooling accompanied with liquid vitrescence without formation of ice crystals) of hippocampal slice obtained from the rat brain. That hippocampal slice was firstly frozen to −130 С, then it was heated up and tested for vitality. Though great attention is now given to cryopreservation of immature neurons for the needs of following therapeutic intracerebral transplantation, there is no scientific publications devoted to cryopreservation of mature arranged brain tissues which have potential interest for pharmaceutical industry. Y. Pichugin’s group has reported about first experiments in cryopreservation of cross sections of mature rats’ hippocamps. Microscopic examination has shown serious damages in frozen thawed slices; however, the state of their ultrastructural and histological preservation was evaluated as good and perfect. Research results have firstly shown that complicated neuronal networks can be well preserved by vitrification. Moreover, vitrification mixture, that has appropriate K/Na ratio and causes minimal damages, was developed. Those results can help in psychoneurological drug development and transplantation of complex brain areas for cure of brain diseases and injuries.

Hematopoietic stem cells usually divide several times in an adult organism. It is still unclear which factors determine the number of stem cell divisions during the lifetime. Scientists analyzed the process of stem cell self-renewal and found out that stem cells isolated from three-week-old or younger newborns had definite advantage over the cells isolated from the adult human organism. After three weeks, embryonal stem cells lose their ability to divide well and generate new cells which will differentiate into specialized tissue cells afterwards. Moreover, scientists created time scale of age-related stem cells behavior. It will become the basis for further investigations aimed at finding the initial cause of the age-related restriction in the number of stem cell divisions. Those results are of considerable value for clinical therapy — cells from three-week-old or younger newborns are the most appropriate for transplantation into adult organism.

Contrary to the widespread opinion about static nature of the mammalian brain, processes of neurogenesis in the adult, mature brain were found to be objective reality. Only some brain areas, such as olfactory bulb and fascia dentata hippocampi, are capable of neurogenesis in the adult organism. At the same time, quite a few stem cell precursors can exist in different parts of the mature brain. J. Emsley has taken part in the investigations demonstrated that new neurons could be added to the mature neocortical neuronal networks. That fact can be connected to the transplantation of neurons derived from nerve cell precursors or via manipulation with endogenous precursors (including induction of limited neurogenesis in long-distant projections of cortical neurons observed in adult mice). Taking into consideration neuron heterogeneity and complexity of links between neurons in the mammalian cerebral cortex, trials aimed at reconstruction of functional neuronal network require detailed understanding of the significance of signals pointed at neuron differentiation, neuron junctions and survival of certain types of neurons. Developmentally regulated transcription factors for definite types of neurons were marked out; those transcription factors for motor and corticotectal neurons, and neurons of the corpus callosum differed one from another. Gene-specific analysis for neuronal subtypes in the cerebral cortex determined existence of a program combining molecular genetic control with precise development of key cortical neuronal projections. Scientists hope that subsequently, it will be able to stimulate neuron differentiation from progenitors in other brain areas, expecting local therapeutic effect, which does not contradict heterogeneity of the source material, for neurodegenerative diseases and brain injuries treatment. Results of those investigations are important for the directed control of neural progenitor (stem cell) differentiation concerning functional restoration of the central nervous system.

The area of A. Kompaniets’s scientific interest is the investigation of homological series of chemical compounds — polyols, amides and their derivatives, products of the directed synthesis; the ascertainment the type of a relation between cryoprotective activity, cytotoxicity, compound toxicity, structure and physicochemical properties. She realizes in her work one of the ways of creation and obtaining of new cryoprotectors — chemical modification of the known compounds. Research areas linked to phase transition and development of methods allowing to direct it, so that it is possible to optimize the technology of low-temperature conservation of different cell suspensions and tissues, are also an important part of A. Kompaniets’s investigations. In A. Kompaniets’s laboratory, data allowing to handle recrystallization processes, such as «crystal-crystal», «vitrification-devitrification», in the media with various cryoprotectors (such additives as carbohydrates, proteins, surfactants etc.) were obtained. At present, solutions containing cryoprotectors and bioactive substances, which will allow to freeze bodies of warm-blooded animals to ultralow temperatures, are tested in the department led by A. Kompaniets.

Teeth develop as the result of interaction between mesenchymal cells and epithelium where epithelium provides instructive information for initiation. Basing on those initial tissue interactions, the group headed by prof. P. T. Sharpe replaced mesenchymal cells with mesenchyme created as agglomeration of mouse cultivated non-teeth stem cells. Recombination between non-teeth mesenchyme obtained from mesenchymal cells and embryonal epithelium of the oral cavity stimulates odontogenous answer in stem cells. Embryonal stem cells, nervous stem cells and adult cells obtained from the bone marrow — all induced odontogenous gene expression. Moreover, relocation of the embryonal tooth germ into adult jaw resulted in the development of tooth structures. This indicates that the embryonal tooth germ can become fully developed in the adult environment. Relocation of the recombination into adult renal capsules resulted in the development of tooth structures and associated bones. Thus, those results provide considerable progress towards creating of the artificial embryonal tooth germ derived from cultured cells. Such artificial embryonal tooth germs can be used in adults for the replacement of lost teeth by new ones after oral transplantation.