Cells respond to the geometric properties of the substrate surface on which they are located and change their shape, orientation and direction of migration in the depending on the type of microrelief or curvature of the contact surface. These cellular responses are called "topographic" responses; they play an important role in the formation of various structures of tissues and organs. Uneven tension of the cytoskeleton in cells can be the cause of topographic reactions of the cell, as an opportunity to realize its compensatory-adaptive reactions, which can lead to cell apoptosis or to maintain further cell viability. The data of these studies may indicate a more correct choice of a method for preserving viable allogeneic transplants (AT) of proper quality, for example, when preserving and transporting DCs, when studying the etiopathogenesis of keratoconus, and creating therapeutic soft contact lenses.

The study of the living cell behavior, depending on the relief of the contacting surface has a rather continuous history. The conclusion that the relief of adhesion to the surface determines the nature of the movement of a living cell along the surface was made in 1911 by Harrison, in England. The researcher placed nerve cells over on the spider's web and found that the cells were stretched out and oriented along its strands. 20 years later, P. Weiss in the United States revealed a similar reaction in the behavior of fibroblasts, which he cultivated on protein filaments from a blood clot. Even later, an exotic substrate with a complex surface, such as fish scales, was used for cell cultivation. It turned out that fibroblasts respond to such a microrelief by stretching and orienting along the folds, but without deepening between the folds. The described phenomenon was called “The cells contact orientation”. So, cells respond to the geometric properties of the substrate surface on which they are placed. Depending on the type of microrelief or the curvature of the substrate surface, cells change their shape, orientation and direction of their migration. These cellular responses are called "topographic" responses; they play an important role in the formation of various structures of tissues and organs. Uneven tension of the cytoskeleton in cells can be the cause of different responses of different living cells, such as the ability to implement their compensatory-adaptive reactions to maintain further cell viability, or turn on the apoptosis mechanism.

It is known that the metabolic background of any cell and the possibility of its self-destruction (apoptosis) depend on the nature of the signals coming from the extracellular matrix. Despite the wide variety of apoptosis inducers, the features of its various pathways of intracellular signaling and changes in intracellular targets contribute to the development of destructive processes in the cell and end with the destruction of genomic DNA followed by cellular phagocytosis. In addition, the transience of the process of self-destruction of cells was noted, for the completion of which several minutes or hours are often sufficient. At the same time, the "early" death of individual cells in the population made it possible to characterize apoptosis as "silent" death. Therefore, it is necessary not only to approach in detail the study and application of methods of visualization of apoptosis in vitro and in vivo, but also to analyze approaches that allow studying the early dynamic processes of apoptosis by alternative methods, outside the scope of experiments on warm-blooded animals. The ability to modify the development of apoptosis and identify the factors and causes of its occurrence is also very important. It is important to register apoptosis as a dynamic process by mean of using the recently novel developed technique of intravital, non-invasive visualization of the state of cells, tissues and organs.

Visualization of morphological changes in apoptotic cells and the role of inducers and blockers of apoptosis are confirmed mainly by histological methods using biopsies and autopsies. A large number ways for detecting apoptotic cells have been described, which are based on different principles and pursue the different goals. Methods for the quantitative determination of apoptotic cells are based on a qualitative and / or quantitative assessment of events caused by changes in the plasma of cells membrane; selective fragmentation of nuclear DNA; changes in the structure of cellular components or their redistribution; lowering the pH in the cytoplasm. It should be noted that the distinctive morphological or biochemical features of apoptotic cells can largely depend on the type of cells, the nature of the inducer, and the stage of apoptosis. The most accessible and simple method for detecting and identification of cells in a state of their apoptotic changes and studying their morphological features is light microscopy. The results of microscopic studies indicate the condensation of cytoplasm and nuclear material in cells after the induction of apoptosis in vitro. Difficulties in identifying apoptotic cells in vivo are mainly due to their rapid destruction and digestion by cells of the environment. Ultrastructural changes characteristic of apoptotic cells can be detected using electron microscopy. This method, which is today the "gold standard", allows for a qualitative analysis of the changes occurring in individual cells during their apoptotic death. Using the method of electron microscopy gives the revelation of differences in ultrastructural changes in cells in the dynamics of apoptosis, initiated by the actions of various inducers of apoptosis. However, the complexity of the methods, the lack of universality of application for any cells types, and the length of time spent on the analysis, significantly limit the possibilities of using this imaging method, as promising and clinically applicable.

Most of the cells in the body, as the role are in direct contact with the extracellular matrix, a substance secreted by the cells themselves. This applies to different types of cells that are part of various tissues and organs: epithelial, muscle, nerve cells, connective tissue cells that form the basis of most internal organs. All these cells are surrounded by an extracellular matrix, which forms an ordered spatial framework, on the surface and within which cells can move and interact with each other. The only cells: blood cells (erythrocytes and leukocytes), like the malignant cells, are the exception that do not have attachment to the matrix and can circulate freely in the bloodstream or environment. The extracellular matrix consists of protein macromolecules and complex carbohydrates associated with them - glycosaminoglycans. So, cells attach to the extracellular matrix with varying degrees of strength to its surface and move along it. Thus, the matrix serves as a mechanical support for the cells, like a solid support. Cell adhesion to the extracellular matrix is not carried out over the entire basal cell surface, but only in some of its discrete areas. These areas are called focal contacts. They are containing the special proteins - integrins, which have the ability to specifically bind to various protein components of the extracellular matrix - collagens, fibronectin. With the loss of contacts of cells with the extracellular matrix, that is, when they are detached and transferred to a suspended state, the signal chain is interrupted; as a result of which cells cease to function correctly, multiply and even undergo genetically programmed suicide - apoptosis. Thus, focal contacts are not only adhesive structures that mechanically bind cells to the extracellular matrix, but also transducers of various intracellular signals necessary for the cells to maintain their ability to functional activity, proliferation performance and others physiological manifestations inherent in cells.

Depending on the type of microrelief or the curvature of the substrate surface, cells are capable changes their shape, orientation and direction of migration. These are the so-called "topographic" cellular reactions, which must be represented as "volumetric", because this is more correct and accurate, since we are talking about cells of living tissues; which play an important role in the formation of various structures of tissues and organs, and, finally, in order to determine their physiology or pathology. The inhomogeneity of the cytoskeleton's tension in cells can change the mechanisms of living cells reactions.

By creating a simulated matrix geometric configuration by means of experimental surface model with defined surface characteristics, it is possible to obtain new informative results of studies of the cultured cells behavior, their properties and features in vivo, which seems to be very attractive and promising. The application of the deeper knowledge obtained in practice about the behavior of cultured cells, their physiology in the experiment, would make it possible to predict and prevent the course of some pathological processes in living tissues.

The study of "Contact orientation of cells" phenomenon became possible thanks to the use of high advanced technology research, their achievements and developed methods. It is well known that microelectronics is partly the progenitor of nanotechnology. Thus, the use of microelectronics and nanotechnology for the creation of special artificial substrates with surfaces having a certain geometric configuration of specified parameters and specified physicochemical properties of the surface made it possible to conduct a more detailed and effective study of the behavior of cultured cells. Microelectronic techniques have also been used to create discontinuous specialty substrates. The surface of such substrates has a discrete character: the areas of the contact surface are interspersed with empty intervals of the surface with areas of various shapes and sizes free from the substrate. This technique made it possible to obtain not only micro - but also nano - reliefs of a given depth and frequency.

In experiments with studying the behavior of cultured cells on special substrates, cells of two morphologically different types are most often used: fibroblasts and epithelial cells. Fibroblasts belong to cells with polarized pseudopodial activity: the formation of pseudopodia (cell outgrowths in the form of thin filaments - filopodia or lamellar form - lamellipodia) occurs not along the entire cell edge, but only in some of its parts. Such an uneven distribution of pseudopodial activity gives to fibroblasts a characteristic more or less elongated shape and makes them capable of moving over the surface of the substrate. Nerve and muscle cells are also polarized. Epithelial cells are unpolarized: their pseudopodia are formed relatively evenly along the entire periphery of cells, which acquire a characteristic disc-shaped shape and are unable to move along the substrate, like fibroblasts.

In other words, cells respond to surface geometry not only with morphological changes, but also with pronounced shifts in intracellular signaling pathways that can lead to changes in the synthetic and functional activity of cells.

Have been responding to nanorelief, the cellular reactions to the geometric configuration of the surface are based on the isometric tension of the cell created by the interaction of actin and myosin molecules in the cell cytoskeleton. Due to the tension of the bundles of actin microfilaments connected to the focal contacts, the cell is constantly in a tense, stretched state. The tensile force of microfilament bundles can depend on their shape: straight bundles develop a stronger tension than bundles under flexion (when the cell is deformed). As shown by the experiments of G. Dan in England, fibroblasts cultivated on a glass substrate in the form of a prism are unable to move from one face to another through the edge of the prism; if the angle of convergence of the two faces is less than 164 °. The fibroblast migration is obviously hindered by the stronger tension of the straight bundles of actin microfilaments, which are associated with focal contacts on the surface of the prism face, as compared to ring-shaped bundles that could help overcome this face. As a result, the fibroblast exhibits rigidity to change in shape at an angle of critical value. If this is the case, then the migration of fibroblasts can be explained by the inability of fibroblasts to such as plasticity, because fibroblasts move only along flat areas of the substrate surface. As for the epithelial cells, which are more characteristic of not straight, but circular bundles of actin microfilaments, which is also typical for tumor cells in which the actin cytoskeleton is significantly reduced. Accordingly, epithelial cells are less resistant to deformation and can overcome any surface relief, multiply over the entire surface of migration, which is inaccessible and impossible for the function of stromal cells! Unlike fibroblasts, epithelial cells do not lose contact over the entire migration surface; they evenly stretch above and below any obstacle, gradually covering it entirely, in such cells the tensile forces are much weaker than in fibroblasts, and, accordingly, such cells are more plastic to change the shape of the cell and, therefore, can multiply, as well as concentrate in any inaccessible for fibroblasts niche.

The amazing ability of cells to respond to micro- or nanoreliefs such as parallel grooves remains largely enigmatic. One of the assumptions is that the so-called stretch receptors are involved in the reactions of cells to the surface relief of the substrate. These receptors of the plasma membrane of cells, possibly, react to the curvature or microroughness of the substrate surface, causing a reorganization of the actin cytoskeleton and an uneven redistribution of tension forces in the cell. As a result, the cells begin to stretch and orient themselves in a certain direction (for example, along micro- or nanotrenches). The behavior of a fibroblast crawling along the edge of a prism: with a decrease in the angle of convergence of two edges, the leading edge of the cell is gradually shortened; therefore, at an angle of less than 164 °, the fibroblast unfolds in the opposite direction, continuing to move towards a flatter and more uniform surface. The activation of stretch receptors triggers intracellular signaling that causes the phosphorylation of certain proteins and changes in gene expression. One of the probable candidates for the role of stretch receptors are chloride ion channels in the cell membrane: in an environment with a chloride deficiency, the elongation of cells forward to the microdeepening sharply decreases.

The use of microelectronics and nanotechnology makes it possible to model a wide variety of geometric configurations of substrates, allowing a more detailed and efficient study of the behavior of cultured cells on these surfaces with infinitely variable relief properties and physicochemical characteristics of the migration surface. ...

The study of the mechanisms of development of pathological dystrophic processes in the cornea and the possibilities of their correction remains an important medical and biological problem. The cornea is a unique biological structure that ontogenetically develops from 3 different germ layers, which give rise to all somatic cells of organs and systems of the body develop. Indeed, the induction of degenerative changes in the cornea, to one degree or another, involves all tissue, cellular and molecular structures in the pathological process. The level of development of modern biomedical allows us to obtain more and more data on the living cells and tissues. In the currently used modern ways of learning of the cornea, various principles of obtaining information can be used: microscopic, optical, topographic, mechanical, metric, tomographic, but most often several research principles are simultaneously included in the diagnostic technology.

The experience of clinical application of modern research methods to assess the properties and structure of the cornea has some peculiarities.

According to the results of studies conducted by Julie Albon, Andrew B. Tallot, 2000, it was found that the loss of endothelial cells of the donor cornea during its conservation occurs as a result of cell apoptosis, while the number of apoptotic cells and their accumulation in the endothelial layer correspond to folds donor cornea.

While dealing with the topic of preservation of allogeneic grafts using the achievements of nanotechnology in the polymer materials surface nanomodofication, we were also interested in studies of apoptosis, which takes place in the development of degenerative diseases of the cornea, during surgical interventions, as well as the cornea deformation, if this occurs during its storage.

Apoptosis and necrosis play a leading role in degenerative diseases of the cornea. Living cells are very sensitive to curvature, microrelief and all kinds of disturbances in the surface relief. By creating special artificial substrates with specified parameters and characteristics, it would be possible to study in detail, model and predict the behavior of various cells under different conditions.

Many cellular reactions to the geometric configuration of the surface are based on the isometric tension of the cell, created by the interaction of actin and myosin molecules in the cytoskeleton. The surprising ability of cells to respond to microrelief or nanorelief, such as parallel alternation: depressions and elevations, remains largely enigmatic. How does a cell determine irregularities on the surface of a substrate, the dimensions of which are tens of thousands of times smaller than the dimensions of the cell itself, if we talk about the nanoscale surface relief? One of the assumptions is that the so-called elongation receptors are involved in cell responses to the geometric configuration of the substrate surface. These receptors of the cell plasma membrane able react to the curvature or microroughness of the substrate surface, causing a reorganization of the actin cytoskeleton and an uneven redistribution of tension forces in the cell. As a result, may be cells begin to stretch and orient themselves in a certain direction (for example, along micro- or nanochannels). Stretch receptor activation involves intracellular signaling, which determines the appropriate orientation of the cell in its behavior with changes in its functions.

The corneal stroma, as the structural basis of the cornea, is the most powerful layer, consisting of the thinnest plates formed by strictly oriented protein collagen fibers, which provides tissue strength with an extremely strict periodicity and regularity of collagen fibers, which also provides the cornea transparency. It contains special fibroblasts - keratocytes, formed mainly by collagen fibers and other elements of the extracellular matrix, the stroma is 85-90% of the thickness of the cornea; Keratocytes play an important role in maintaining transparency and healing damage. In a healthy cornea, keratocytes are in a stable state, and if their integrity is violated, they are activated and begin to repair damage; herewith the some keratocytes are damaged by apoptosis. The endothelial cells of the cornea require even more "inviolability" and the prevention of the slightest damage, such as deformation. Violations of the physiological processes in the cells of the cornea, as well as during the healing of the cornea, can lead to irreversible degenerative changes in the cornea.

The cells in the body subordinate their shape and functional activity in accordance with the requirements of such characteristics of the extracellular matrix as its chemical properties and / or geometric configuration. The anisotropy of the chemically mediated adhesive properties of the matrix, as well as the curvature of its surface or nanorelief, various discontinuities of the matrix - all these serve as distinctive features for choosing the direction of cell migration, their behavior, the concentration of certain types of cells in places of regeneration (for example, during wound healing) or laying of future organs (in embryogenesis), regulation of cell reproduction and their activity. The medical aspect of this problem is very important in practice, as the study of the patterns and mechanisms of attachment and movement in the extracellular matrix of living cells, as an opportunity to program the behavior of a living cell. In vitro modeling for a detailed and more effective investigation of the behavior of cultured fibroblast and epithelial cells using the example of already well working the detailed experimental models, for more in-depth research of the behavior of various cells, the possibilities of controlling and predicting their functions, presents great opportunities in the study of cell apoptosis and its regulation, of an essential interest for ophthalmology as well. Investigations data of the cells physiology, depending on the surface relief, could clarify the keratoconus etiopathogenesis, methods of its prevention and treatment, for example, based on the development and use of therapeutic soft contact lenses, etr. (The Application of Nanostructured Surface for the Recovering of the Cornea;1st International Conference for Ocular Cell Biology, Conference Proceedings, p.40, Homerton College, Cambridge, UK, 2006.)