Structural and crystal-chemical characteristics of the apatite deposits from human aortic walls

Thermal behavior of biological apatite is the object of several studies. Crystal size, carbonate content, phase composition, and other parameters change during annealing up to 900 °C in biological minerals with apatite structure. The way these parameters change reflects the specific properties of the initial bioapatite. This work presents data on thermal transformations of pathological bioapatite from the human cardiovascular system, namely aortic wall deposits. Some minor elements, foreign to calcium hydroxyapatite (e.g., Na and Mg), can be both incorporated in the apatite structure and localized in the surface layers of crystals, modifying functions of the mineral. A new approach was proposed to determine the predominant location of minor elements, such as Mg, Na, and K, in the mineral of pathological deposits. Mg and Na in pathological apatite can be in both structurally bound (substituting calcium in lattice) and labile (localized on the crystal surface) states, while K is not able to join the apatite structure in significant amount or be chemically bound to it. This approach, based on atomic spectrometry, can be used effectively in combination with a set of traditional techniques, such as like EDS, IRS, and XRD

Chitosan–hydroxyapatite composite biomaterials made by a one step co-precipitation method: preparation, characterization and in vivo tests

A series of biocompatible chitosan/hydroxyapatite composites has been synthesized in an aqueous medium from chitosan solution and soluble precursor salts by a one-step coprecipitation method. The composite materials were produced in dense and porous variants. XRD and IR studies have shown that the apatite crystals in the composites have structural characteristics similar to those of crystals in biogenic apatite. A study of in vivo behaviour of the materials was carried out. Cylindrical rods made of the chitosan/ hydroxyapatite composite material were implanted into the tibial bones of rats. After 5, 10, 15 and 24 days of implantation, histological and histo-morphometric analyses of decalcified specimens were undertaken to evaluate their biocompatibility and the possibility to apply them in bone tissue engineering. The calcified specimens were examined by scanning electron microscopy combined with X-ray microanalysis to compare the elemental composition and morphological characteristics of the implant and the bone during integration. Porous specimens were osteoconducting and were replaced in vivo by newly formed bone tissue

Adhesion and proliferation of adipose derived mesenchymal stromal cells on chitosan scaffolds with different degree of deacetylation

Aim. Selection of the optimal scaffold for the creation of tissue engineering constructs is a key challenge of biotechnology. In this study we investigated the biocompatibility of human adipose derived mesenchymal stromal cells (MSCs) within the three-dimensional matrices based on the chitosan with a different degree of deacetylation. Methods. MSCs were seeded on the chitosan scaffolds by a perfusion method and cultured for 7 days. The morphology, viability, metabolic activity and distribution of the cells within the matrices were analyzed. Results. The level of MSCs adhesion to the surface of the chitosan scaffolds with low degree of deacetylation (67 %) was insignificant, the cells were round and formed aggregates. In the chitosan scaffolds with a high degree of deacetylation (82 %) the cells attached to the surface of matrices, were able to spread and proliferate. Conclusions. The chitosan scaffolds with a high degree of deacetylation and the human adipose derived MSCs can be used for the creation of bioengineered structures

Особливості морфогенезу опікової рани при застосуванні хітозанових мембран в різні вікові періоди.

Background. The number of research devoted to chitosan application for burn defects treatment has increased during the last decades. However, the age-related features of skin regeneration with chitosan application are still uninvestigated Objective. The aim of our research was to evaluate effectiveness of chitosan coatings application to treat burns in different age periods. Methods. We studied the tissue morphogenesis features of the thermal damaged skin. We modeled the burn wounds of IIIb degree on the rats of experimental and control groups. And then we applied chitosan coatings on the animals of the experimental group to analyze the effectiveness of topical treatment. We analyzed the healing of burn wounds by the following morphological criteria: types of the epidermis and dermis damage; terms and features of wound cleaning; presence and degree of inflammation intensity and blood circulation disorders; quantity and quality of cellular infiltration. Other criteria were terms and degree of connective and epithelial tissue formation and levels of their differentiation and distribution; presence or absence of synchrony regenerative processes in the epithelium and connective tissue (especially features of vessel formation); presence or absence of morphological manifestations of pathological regeneration in the epithelium and connective tissue. Results. We found that the rate of burn healing applying chitosan coatings speeded up as they stimulated both macrophage reaction (with further inflammation reduction); cellular proliferation of fibroblasts and vessel formation. Moreover, granulation tissue and collagen fibers formed faster. Besides, epithelium regeneration and scar formation enhanced. As a result, epithelial cell migration and tissue contraction covered the wound. Conclusion. Application of chitosan membranes to treat thermal burns enhanced wound cleaning from dead tissue and reduced eschar, decreased the intensity of inflammatory reactions and disorders of blood circulation, improved epithelization of the wound and regulated formation of the scar tissue. Nevertheless, application of topical treatment for rats (aged 22 months) changed insignificantly the regenerate structure comparing with the animals from other groups.Применение хитозановых пленок для лечения термических повреждений приводило к ускорению очищения раны от некротических масс и отторжению струпа, уменьшению интенсивности воспалительной реакции и расстройств кровообращения, ускорению эпителизации раны, а также регулировало образование рубцовой тканиу крыс разного возраста.Применение средства местного назначения у животных старческого возраста не приводило к существенным улучшениям морфологии регенерата, что, возможно, связано с низкой чувствительностью эффекторных клеток раны.Застосування хітозанових плівок для лікування термічних ушкоджень призводило до прискорення очищення рани від некротичних мас та відторгнення струпу, зменшення інтенсивності запальної реакції та розладів кровообігу, пришвидшення епітелізації рани, а також регулювало утворення рубцевої тканини у щурів різного віку. Застосування засобу місцевого призначення у тварин старечого віку не призводило до суттєвих покращень морфології регенерату, що, можливо, пов’язане з низькою чутливістю ефекторних клітин рани

New approach to the approximation of «dose – effect» dependence during the human somatic cells irradiation

New data on cytogenetic approximation of the experimental cytogenetic dependence "dose - effect" based on the spline regression model that improves biological dosimetry of human radiological exposure were received. This is achieved by reducing the error of the determination of absorbed dose as compared to the traditional use of linear and linear-quadratic models and makes it possible to predict the effect of dose curves on plateau