A technology of bone tissue cultivation on a thin scaffold in a rotational bioreactor is developed. An optimal regime of cell material cultivation is determined for testing the method, and an optical method for diagnostics of the bone growth dynamics during its cultivation is found. Numerical simulations of the fluid flow in the bioreactor make it possible to significantly simplify the medical experiment and to choose the optimal values of the rotation frequencies and shear stresses acting on the cell material placed on the scaffold. The optical diagnostics of the scaffold samples in the course of dynamic cultivation in the bioreactor is performed by the method of laser-induced fluorescence. An algorithm based on the principal component analysis is applied to analyze the spectral data; as a result, the spectra of excitation and fluorescent emission of the basic fluorescent substances in the sample (tyrosine and tryptophan amino acids, structural protein (collagen), and fluorescent structures of polycaprolactone) are calculated. It is found that the contribution of the component corresponding to collagen in the samples increases in the process of dynamic cultivation, which testifies to effective formation of the extracellular matrix of the bone.

The developed mathematical model was applied for study of fluid dynamics in a rotational bioreactor for bone tissue engineering by in vitro technology. The research goal is finding an optimal mode for rotation ensuring proper cyclic loading from fluid upon the cell-seeded biomaterial. The basis for developing a mathematical model of a bioreactor was a design of rotational type biological reactor used in medical research; the liquid flow is generated through viscosity mechanism due to surface rotation. Mathematical description of flow in a reactor cavity was performed with Navier—Stokes equations. It was assumed that flow regime in the boundary layer is laminar. Numerical algorithm was accomplished using a fluid flow solver “Fluent” in the code package ANSYS-12. Four variants of generating the rotational motion in the reactor cavity were considered. A series of parametric computations was performed for the rotation frequency f in the range 0.05 ≤ f ≤ 0.25 Hz. The paper offers visualization of velocity fields in the vertical plane. The distributions for shear stress and pressure in the working zone of reactor were calculated and analyzed. Simulations demonstrated that a method of fluid rotation by driving the outer cylinder with an offset axis is the best for arranging a cyclic pressure and cyclic shear stress on the biological material.

Scaffold technology is a new method for replacement of damaged tissues in a living organism using patient's own cells. A new rotational bioreactor was designed for the task of cell-seeded scaffold cultivation for the restoration of critical bone defects. The numerical simulation of fluid flow in the rotational bioreactor was performed. The calculated shear stress and static pressure values acting on the stein cells at different rotational frequencies allow selection of operating modes depending on the desired conditions. Optical control of stem cells differentiation was worked out. The obtained laser-induced fluorescence excitation-emission matrices of investigated samples were analyzed using principal component method. The spectra of fluorophores were reconstructed by combining positive narrow linear combinations from alternating principal components. Evaluating the ratio of narrow component contributions allows distinguish seeded and unneeded by stem cells scaffolds, as well as scaffold samples exposed by shear stress in the rotational bioreactor.

The technology using for the replacement of damaged tissues the own cells of the patient, which are placed in a three-dimensional frame - scaffold, is promising for solving the problem of the bone tissue regeneration. A new biological reactor of the rotational type, in which the scaffold tissue rotates in a medium for cultivating the cells, was designed for the development of this technique. A numerical algorithm based on the ANSYS program was developed, which enables one to estimate in a new bioreactor the level of the mechanical load on the cells, which affects their pro-perties. The algorithm enables the computation of the values of the shear stress and static pressure acting on the scaf-fold surface. The computations have shown that the necessary shear stress is reached in the proposed rotational biore-actor on the outer side of the inner cylinder (0.002−0.1 Pa) in the range of rotation frequencies 0.083 < f < 0.233 Hz. At the same time, computational results have revealed the presence of an inhomogeneity in the mechanical action distribution along the scaffold tissue, which is due to the appearance of two Taylor vortices with opposite rotation directions in the gap between the cylinders. The experiments on the flow field visualization inside the rotational bio-logical reactor have shown a qualitative agreement of the flow character with computational results. The proposed numerical algorithm may simulate with sufficient accuracy the fluid flow in a real system. The obtained dependencies can be used in practice for creating an optimal microenvironment of the cells cultivated in the biological reactor.

Проведен сравнительный анализ эффективности ферментативного и детергентного способов децеллюляризации сердечных аллографтов. Показано, что после децеллюляризации детер-гентным методом достигается наибольшая степень очистки клапана от клеток при сохранении его исходной механической прочности и пространственной структуры каркаса. На сновании полученных данных детергентный метод может быть рекомендован в качестве предпочтительного при приготовлении аллографтов для последующего использования в кардиохирургической практике с целью уменьшения постимплантационных побочных эффектов.

The purpose of the simulated reactor is a production of tissue-engineered structures, designed for regeneration of bone tissue outside the body. The rotational reactor used in clinical practice is taken as a basis. Its geometric data, the mathematical model and the results of the computation experiments are given in [1, 2]. In [3], a comparison is made between the results of a numerical calculation and the experimental data on laser visualization of a flow in the rotational reactor. In the present paper, the modification of rotational reactor is considered, which makes it possible to change the hydrodynamic flow regime around the biological material. In the new setup the rotation axis of the inner cylinder is parallel shifted from the axis of symmetry of the outer cylinder at a distance of 12.5% of the radius. As a result, the radial gap between the outer stationary and inner rotating cylinders depends on the circumferential coordinate phi. The variable gap has become a factor determining the formation flow fields in reactor working one. The effect of the fluid flow on the cellular material adhered on the scaffold surface, which in turn is fixed on the surface of the rotating cylinder, has become variable in magnitude and cyclic in shape. The computational algorithm for solving the problem is based on packet technology. The numerical solution is based on the gas-dynamic solver FLUENT of the ANSYS 12 software package. The flow regime in the boundary layer is postulated to be laminar. A series of parametric calculations was performed for the rotation frequency of the inner cylinder f in the range 0.083 <= f <= 0.167 Hz. The work presents visualization of the velocity fields and distribution of shear stress and static pressure on the rotating cylinder surface. It is shown that the cyclicity of the hydrodynamic effect on the working zone expands the range of possibilities of rotational bioreactors for the bone tissue cultivation.

. A scaffold usage for the cell culturing is a widespread tissue engineering approach, including culturing in a bioreactor, however the effective use of a bioreactor requires adaptation of the scaffold at the stage of its design. In our opinion, this means assessment of the perfusion properties of the scaffold. Aim of the study: Aim of the study was the assessment of the perfusion properties of a scaffold sheet made of 11% w/v polycaprolactone (PCL) composite material with gelatinization of 0.5%, 2%, and 4% w/v and fabricated with different electrospinning parameters and hydrostatic pressure (5, 10, and 15 mm Hg). Materials and methods : To produce composite material, polycaprolactone, gelatin (type B), and solvents: 1,1,1,3,3,3-hexafluoroisopropanol, 2,2,2-trifluoroethanol and chloroform were used. Three composite variants of 11% w/v PCL with gelatinization of 0.5%, 2%, and 4% w/v were prepared. Perfusion properties of the scaffold sheet were assessed with an original experimental equipment. Structural analysis was carried out using the laser confocal microscopy. Results : Polymer scaffold sheet fabricated with electrospinning demonstrated the possibility of the transverse and longitudinal perfusion through the sheet under hydrostatic pressure of 5, 10, and 15 mm Hg. Also was found what time of 1 mL saline transverse and longitudinal perfusion through a PCL electrospun sheets depends from gelatinization and electrospinning parameters (transverse perfusion time of the sheet fabricated with the electrospinning collector speed of 450 rpm was 10 times lower than sheets fabricated with speed 90-180 rpm), with equal samples thickness and perfusion pressure. Conclusion : An obtained results allows to optimize the polymer scaffold fabrication process with electrospinning to achieve the optimal characteristics of the perfusion through the scaffold.

The main approach to tissue engineering involves the use of scaffolds seeded with cells, followed by culturing in a bioreactor. However, the effective use of a bioreactor requires adaptation of the scaffold at the stage of its design. In our opinion, this means assessment of the perfusion properties of the scaffold. Transverse and longitudinal perfusion under hydrostatic pressure of 5, 10, and 15 mmHg, as well as the significance of electrospinning parameters for fabrication of a scaffold sheet and the composition of composite material—11% w/v polycaprolactone with gelatinization of 0.5%, 2%, and 4%, were demonstrated.

AIM:Тo evaluate renal morphological changes in the early stages of lithogenic processes and during urinary correction of urine with oxalate-chelating compounds (sodium citrate).MATERIAL AND METHODS:An experimental model of oxalate nephrolithiasis was performed on 80 male Wistar rats weighing 180 to 250 g. Rat kidneys were morphologically and ultrastructurally studied. Immunohistochemical techniques were applied to study the features of development of endoplasmic reticulum stress.RESULTS:There were histotopographic changes in the renal tissue elements in the early stages of development of lithogenic processes accompanied by characteristic ultrastructural changes in the epithelium of the renal tubules and collecting ducts: by expansion of elements in the granular endoplasmic network, by mitochondrial damage with formation of large, ampullary extended cristae, and by emergence of autolysosomes. Signs of development of endoplasmic reticulum stress with activation of protein GADD153 were found, which deteriorated the cell lining of the nephron tubules and collecting ducts.CONCLUSION:In the early stages of development of lithogenic processes, there are stereotypic ultrastructural and histotopographic changes in the epithelium of the nephron tubules and collecting ducts, which contribute to the progression of stone formation processes and to the disruption of cellular homeostasis with activation of endoplasmic reticulum stress, synthesis impairment, or post-translational modifications in modulator proteins of lithogenesis.

Development of cell-mediated scaffold technologies for the treatment of critical bone defects is very important for the purpose of reparative bone regeneration. Today the properties of the bioreactor for cell-seeded scaffold cultivation are the subject of intensive research. We used the mathematical modeling of rotational reactor and construct computational algorithm with the help of ANSYS software package to develop this new procedure. The solution obtained with the help of the constructed computational algorithm is in good agreement with the analytical solution of Couette for the task of two coaxial cylinders. The series of flow computations for different rotation frequencies (1, 0.75, 0.5, 0.33, 0.125 Hz) was performed for the laminar flow regime approximation with the help of computational algorithm. It was found that Taylor vortices appear in the annular gap between the cylinders in a simulated bioreactor. It was obtained that shear stress in the range of interest (0.002-0.1 Pa) arise on outer surface of inner cylinder when it rotates with the frequency not exceeding 0.8 Hz. So the constructed mathematical model and the created computational algorithm for calculating the flow parameters allow predicting the shear stress and pressure values depending on the rotation frequency and geometric parameters, as well as optimizing the operating mode of the bioreactor.

Application of scaffold technology for the problem of bone tissue regeneration has great prospects in modern medicine. The influence of fluid shear stress on stem cells cultivation and its differentiation into osteoblasts is the subject of intensive research. Mathematical modeling of fluid flow in bioreactor allowed us to determine the structure of flow and estimate the level of mechanical stress on cells. The series of computations for different rotation frequencies (0.083, 0.124, 0.167, 0.2 and 0.233 Hz) was performed for the laminar flow regime approximation. It was shown that the Taylor vortices in the gap between the cylinders qualitatively change the distribution of static pressure and shear stress in the region of vortices connection. It was shown that an increase in the rotation frequency leads to an increase of the unevenness in distribution of the above mentioned functions. The obtained shear stress and static pressure dependence on the rotational frequency make it possible to choose the operating mode of the reactor depending on the provided requirements. It was shown that in the range of rotation frequencies chosen in this work (0.083 < f < 0.233 Hz), the shear stress does not exceed the known literature data (0.002 - 0.1 Pa).

Excitation–emission matrices of laser-induced fluorescence of lens capsule epithelium, the lens nucleus, and the lens capsule are investigated. A solid-state laser in combination with an optical parametric generator tunable in the range from 210 to 350 nm was used for excitation of fluorescence. The spectra of fluorescence of all three types of tissues exhibit typical features that are specific to them and drastically differ from one another. This effect can be used for intrasurgical control of presence of residual lens capsule epithelium cells in the capsular bag after surgical treatment of a cataract.

One of the main unsolved problems in traumatology and orthopedics is reconstruction of critical-sized segmental bone defects. We believe that implementation of noninvasive monitoring of the bioengineering stages for cellmediated bone scaffold by laser-induced fluorescence (LIF) can become a positive aspect in mastering this technique. An electrospun scaffold model (parameters: 10 wt. % polycaprolactone; 5% wt type A gelatin; mean fiber diameter 877.1 +/- 169.1, and contact angle 45.3 degrees) seeded with BHK IR cell culture (182 +/- 38 cells/mm(2)) was used to show the principal possibility of differentiating between the scaffold seeded and unseeded with cells. First of all, the fluorescence spectra of the cell-seeded scaffold contain a peak at 305 nm for the excitation range of 230-290 nm, which can be used to differentiate between the samples. An increase in fluorescence intensity of the cell-seeded scaffold in the range of 400580 nm upon excitation at 230-340 nm is also noticeable. The wavelength of 250 nm is characterized by high signal intensity and is most suitable for differentiation between the samples.

The aim of the study was to compare the efficacy of different techniques of indirect myocardial revascularization: transmyocardial laser revascularization and concomitant injection of mononuclear fraction of red bone marrow in laser canals during surgical treatment of ischemic heart disease. The efficacy was evaluated on the basis of echocardiography and perfusion scintigraphy data obtained in two weeks, 6 months, 12 months and 3 years after operation. Implantation of a mononuclear fraction of red bone marrow into laser canals proved to be the most effective technique. It was confirmed by a significant decrease in angina functional class and a more pronounced increase in myocardial perfusion and contractility.

Bone tissue engineering looking for an alternative solution to the problem of skeletal injuries. The method is based on the creation of tissue engineered bone tissue equivalent with stem cells, osteogenic factors, and scaffolds - the carriers of these cells. For production of tissue engineered bone equivalent is advisable to create scaffolds similar in composition to natural extracellular matrix of the bone. This will provide optimal conditions for the cells, and produce favorable physico-mechanical properties of the final construction. This review article gives an analysis of the most promising materials for the manufacture of cell scaffolds. Biodegradable synthetic polymers are the basis for the scaffold, but it alone cannot provide adequate physical and mechanical properties of the construction, and favorable conditions for the cells. Addition of natural polymers improves the strength characteristics and bioactivity of constructions. Of the inorganic compounds, to create cell scaffolds the most widely used calcium phosphates, which give the structure adequate stiffness and significantly increase its osteoinductive capacity. Signaling molecules do not affect the physico-mechanical properties of the scaffold, but beneficial effect is on the processes of adhesion, proliferation and differentiation of cells. Biodegradation of the materials will help to fulfill the main task of bone tissue engineering - the ability to replace synthetic construct by natural tissues that will restore the original anatomical integrity of the bone.

We studied structural changes in the prostate gland, thymus, and lymph nodes in CBA mice after transplantation of Ehrlich ascites tumor cells into the prostate gland. On experimental day 5, the number of blood and lymph vessels decreased in the gland; the percentage of connective tissue elements and glandular tissue and the number of immunoblasts in the thymus increased. On day 18, the number of blood vessels in the tumor decreased; the width of the cortex and glandular tissue increased in the thymus, while the number of immunoblasts was reduced. On day 28, tumor infiltration and increased number of lymphatic vessels in its stroma were observed; parenchyma was reduced, and the area of the connective tissue increased in the thymus. These structural changes indicated the development of accidental involution of the thymus during carcinogenesis of the prostate.