Svetlana V. Piatnitskaia

Background. The extracellular matrix plays a key role in maintaining homeostasis and bone tissue regeneration by defining the conditions for cell differentiation and intercellular interactions. The native extracellular matrix is a complex three-dimensional network of structural proteins, glycoproteins, and proteoglycans that provide mechanical support to cells and transmit regulatory signals. 2D-culture systems do not reproduce the complex organization of the cellular microenvironment; therefore, the development of 3D-systems for bone tissue differentiation and remodeling in vitro remains an important challenge. Objective. To evaluate the biocompatibility of the hydrogel based on a tissue extract of uterine leiomyoma and its potential to regulate osteogenic differentiation and mineralization of osteoblasts in mono- and co-culture with endothelial cells. Materials and Methods. The tissue extract of uterine leiomyoma was obtained using a modified protocol originally developed for producing Matrigel®. Osteoblasts were cultured within the hydrogel in mono- and co-culture with endothelial cells under osteogenic conditions. Cell viability and morphology were assessed by live-cell microscopy. Mineralization of the extracellular matrix was evaluated using Alizarin Red S staining. Results. The hydrogel based on tissue extract of uterine leiomyoma demonstrated high biocompatibility toward osteoblasts, supporting their viability, promoting differentiation into osteocyte-like cells, and enhancing extracellular matrix mineralization. In co-culture with endothelial cells, these effects were further enhanced, indicating the important role of intercellular interactions. Conclusion. The hydrogel based on tissue extract of uterine leiomyoma represents a promising 3D culture model for the studying osteogenic differentiation of osteoblasts.

Материалы на основе шелка паутины для регенеративной медицины

Monolayer two-dimensional in vitro cell culture systems are unable to fully mimic the native tissue microenvironment, which limits their prognostic value. Threedimensional (3D) culture systems overcome these limitations, ensuring the reproduction of intercellular interactions and tissue architecture characteristic of in vivo models. The most common 3D cell constructs are 3D spheroid models and organoids, the preservation of gene expression in which makes them valuable tools for preclinical research. This work aimed to review the scientific publications on the generation and application of 3D cell cultures in urology and urologic oncology. Analysis of recent publications demonstrates a wide range of applications of these technologies. This review demonstrates that in urologic oncology, patientderived bladder cancer organoids reproduce the molecular profile of tumors, allowing them to be used for testing chemotherapeutic drugs and assessing the cytotoxic activity of T cells. For prostate cancer, 3D cultures are used to evaluate the effectiveness of docetaxel in combination with sildenafil. Kidney cancer organoids reproduce the histological architecture of the original tissues, which facilitates drug screening. In regenerative medicine, 3D spheroid models of bladder smooth muscle cells demonstrate increased deposition of extracellular matrix proteins, which supports their potential for tissue engineering. Thus, 3D cell technologies open up new opportunities for personalized therapy and the development of bioengineered constructs in urology and urologic oncology.

This review examines the use of spider-silk-based materials in regenerative medicine. Spider silk possesses a unique combination of mechanical and biological properties, making it a promising biomaterial for tissue engineering. An analysis of in vivo studies in animal models and the first clinical trials is presented, demonstrating the ability of spider silk to direct cell growth, accelerate wound healing, and promote peripheral nerve regeneration. The prospects for large-scale production of spider silk and its medical applications are discussed.

Introduction. Additive manufacturing of hydroxyapatite (HA) ceramics is considered a promising approach to creating personalized bone implants. However, highly loaded photopolymer suspensions assume precise composition and exposure conditions to ensure stable printing and product quality. The present study aims to develop a photopolymer suspension based on HA of in-house synthesis for the additive production of ceramic implants using DLP 3D printing. Materials and methods. HA is synthesized by coprecipitation and hydrothermal synthesis methods in aqueous solutions of calcium and phosphate salts. The powder is milled and fractionated for assessing the morphology and element composition using scanning electron microscopy and energy-dispersive X-ray fluorescence analysis, respectively. A photopolymer suspension with 60 wt. % of the inorganic phase, developed based on the synthesized HA, contains acrylate monomers, photoinitiating system and dispersing additives. In addition, photopolymerization is studied on a DLP 3D printer at different UV radiation powers and exposure times. Results and discussion. The synthesized well-crystallized HA has lamellar and nanostructured morphology, as well as developed porosity; the predominance of calcium and phosphorus without significant toxic impurities is confirmed. At a radiation power of 40 mW/cm², the optimal exposure time of 6–10 s ensures the formation of uniformly hardened layers with a thickness of about 0.7–0.9 mm and a thickness plateau at a further increase in exposure time. Conclusion. The obtained data indicate that the combination of controlled HA morphology and specially selected photopolymer matrix provides sufficient polymerization depth and layer stability required for DLP printing of complex geometries. High specific surface area and porosity of HA further enhance its potential in tissue engineering. The developed photopolymer suspension based on HA of in-house synthesis demonstrates suitability for DLP 3D printing and can be used as a basis for creating personalized ceramic implants in traumatology, orthopedics, neurosurgery, and maxillofacial surgery.

The choice of the sterilization method for ceramic implants is critically important, as it can affect the chemical and physico-mechanical properties of the material and its biocompatibility. Higher cytotoxicity, which is a possible side effect of sterilization, hinders osseointegration. This study aimed to determine the cytotoxicity of porous ceramic samples after sterilization using the most common methods. Samples of hydroxyapatite (HA), tricalcium phosphate (TCP), and aluminum oxide (AO) were prepared by stereolithography, and bone allograph samples were made using the DLP method. The annealing lasted for 4 hours, with a peak temperature of 800 °C and the temperature increment of 3 °C per minute; the sintering temperature was up to 1200 °C. We used the following sterilization methods: autoclaving at 1 atmosphere, 120 °C, for 45 minutes; radiation sterilization, 25 seconds with an absorbed dose of 25 kGy; plasma peroxide sterilization, 42 minutes; dry heat sterilization at 180 °C, for 60 minutes. Cytotoxicity was determined with the help of an MTT assay (24-hour exposure in a CO2 incubator). The results of the study: for HA, high porosity means growth of values in transition from autoclaving (0.1115) to plasma peroxide sterilization (0.2023). Medium and low porosity show similar results, with peaks in dry-heat sterilization (0.4954 and 0.4505). As for for AO, it exhibited high viability when subjected to this method. The TCP samples have shown stable results, but their low-porosity variation had the values growing after autoclaving (0.078 to 0.182, dry-heat sterilization). The study forms the basis for optimizing the ceramic implants manufacturing technology and sterilization methods to ensure their high biocompatibility.

Organs-on-chips (OOC) refer to microfluidic devices used to create biomimetic systems of physiological organs. The system contains engineered or natural miniature tissues grown inside microfluidic chips. Organ-on-a-chip technology enables numerous human pathologies to be reproduced, since classical animal models may fail to adequately predict the therapeutic response in humans. This technology can be an intermediate link in the animal-human research system. Moreover, in cancer studies, OOC simulate the three-dimensional hierarchical complexity of tumors in vivo and the tumor microenvironment, being an efficient and cost-effective solution for tumor growth studies and cancer drug screening. Organs-on-chips represent compact and easy-to-use microphysiological functional units simulating physical and biological processes in human body. This extends the possibility of preclinical studies, such as disease modeling or even the development of diagnostic devices. In this regard, the present study is aimed at reviewing the scientific literature in the field of microfluidic devices intended for use in urology and oncourology.

The centrepiece of this analytical review is the metabolism of hydroxyapatite in its natural, bone, and synthetic forms, where the mitochondria-mediated mechanism may serve as the leading mechanism. The possibility that osteoblast mitochondria play an important role in the initial stages of bone mineralisation is discussed. Furthermore, the paper highlights the key role of mitochondria in the metabolism of synthetic hydroxyapatite.Differences between the results of in vivo and in vitro studies using synthetic hydroxyapatite of different morphologies are also detailed. It is noted that long-term infiltration with immune cells and in vivo studies are necessary to adequately evaluate hydroxyapatite as a bone-plastic material.Particular attention is given to the interaction of hydroxyapatite with immune cells and its ability to affect the ribosomes and mitochondria of cells. Due to its mechanical properties, scalability and potential use for the treatment of extensive bone defects of tumor origin, hydroxyapatite is a promising material.This study also highlights the importance of further development of in vitro research methods in the context of their biomimeticity. Overall, this work offers a theoretical direction for future studies of hydroxyapatite as a bone grafting material and emphasises the value of in vivo studies.

The immuno-compatibility of implant materials is a key issue for both initial and long-term implant integration. Ceramic implants have several advantages that make them highly promising for long-term medical solutions. These beneficial characteristics include such things as the material availability, possibility to manufacture various shapes and surface structures, osteo-inductivity and osteo-conductivity, low level of corrosion and general biocompatibility. The immuno-compatibility of an implant essentially depends on the interaction with local resident immune cells and, first of all, macrophages. However, in the case of ceramics, these interactions are insufficiently understood and require intensive experimental examinations. Our review summarizes the state of the art in variants of ceramic implants: mechanical properties, different chemical modifications of the basic material, surface structures and modifications, implant shapes and porosity. We collected the available information about the interaction of ceramics with the immune system and highlighted the studies that reported ceramic-specific local or systemic effects on the immune system. We disclosed the gaps in knowledge and outlined the perspectives for the identification to ceramic-specific interactions with the immune system using advanced quantitative technologies. We discussed the approaches for ceramic implant modification and pointed out the need for data integration using mathematic modelling of the multiple ceramic implant characteristics and their contribution for long-term implant bio- and immuno-compatibility.