The musculoskeletal system, consisting of bones and cartilage of various types, muscles, ligaments, and tendons, is the basis of the human body. However, many pathological conditions caused by aging, lifestyle, disease, or trauma can damage its elements and lead to severe disfunction and significant worsening in the quality of life. Due to its structure and function, articular (hyaline) cartilage is the most susceptible to damage. Articular cartilage is a non-vascular tissue with constrained self-regeneration capabilities. Additionally, treatment methods, which have proven efficacy in stopping its degradation and promoting regeneration, still do not exist. Conservative treatment and physical therapy only relieve the symptoms associated with cartilage destruction, and traditional surgical interventions to repair defects or endoprosthetics are not without serious drawbacks. Thus, articular cartilage damage remains an urgent and actual problem requiring the development of new treatment approaches. The emergence of biofabrication technologies, including three-dimensional (3D) bioprinting, at the end of the 20th century, allowed reconstructive interventions to get a second wind. Three-dimensional bioprinting creates volume constraints that mimic the structure and function of natural tissue due to the combinations of biomaterials, living cells, and signal molecules to create. In our case—hyaline cartilage. Several approaches to articular cartilage biofabrication have been developed to date, including the promising technology of 3D bioprinting. This review represents the main achievements of such research direction and describes the technological processes and the necessary biomaterials, cell cultures, and signal molecules. Special attention is given to the basic materials for 3D bioprinting—hydrogels and bioinks, as well as the biopolymers underlying the indicated products.

The current paper highlights the active development of tissue engineering in the field of the biofabrication of living tissue analogues through 3D-bioprinting technology. The implementation of the latter is impossible without important products such as bioinks and their basic components, namely, hydrogels. In this regard, tissue engineers are searching for biomaterials to produce hydrogels with specified properties both in terms of their physical, mechanical and chemical properties and in terms of local biological effects following implantation into an organism. One of such effects is the provision of the optimal conditions for physiological reparative regeneration by the structural components that form the basis of the biomaterial. Therefore, qualitative assessment of the composition of the protein component of a biomaterial is a significant task in tissue engineering and bioprinting. It is important for predicting the behaviour of printed constructs in terms of their gradual resorption followed by tissue regeneration due to the formation of a new extracellular matrix. One of the most promising natural biomaterials with significant potential in the production of hydrogels and the bioinks based on them is the polymer collagen of allogeneic origin, which plays an important role in maintaining the structural and biological integrity of the extracellular matrix, as well as in the morphogenesis and cellular metabolism of tissues, giving them the required mechanical and biochemical properties. In tissue engineering, collagen is widely used as a basic biomaterial because of its availability, biocompatibility and facile combination with other materials. This manuscript presents the main results of a mass spectrometry analysis (proteomic assay) of the lyophilized hydrogel produced from the registered Lyoplast^® bioimplant (allogeneic human bone tissue), which is promising in the field of biotechnology. Proteomic assays of the investigated lyophilized hydrogel sample showed the presence of structural proteins (six major collagen fibers of types I, II, IV, IX, XXVII, XXVIII were identified), extracellular matrix proteins, and mRNA-stabilizing proteins, which participate in the regulation of transcription, as well as inducer proteins that mediate the activation of regeneration, including the level of circadian rhythm. The research results offer a new perspective and indicate the significant potential of the lyophilized hydrogels as an effective alternative to synthetic and xenogeneic materials in regenerative medicine, particularly in the field of biotechnology, acting as a matrix and cell-containing component of bioinks for 3D bioprinting.

Aim – to study the immunomodulator-induced individual cytokine production by peripheral blood mononuclear cells (PBMCs) and to evaluate the potential of using this approach as a universal cellular test system in personalized medicine. Material and methods. The peripheral blood mononuclear cells given by donors were cultured in vitro in the presence of immunomodulators Imunofan and Polyoxidonium. After incubation, the enzyme-linked immunosorbent assay (ELISA) of the culture medium for the presence of pro-inflammatory cytokines IL-6, IL-8/CXCL8, MCP-1/CCL2, and IFN-α cytokines was performed. Results. The results of the experiment have demonstrated the absence of spontaneous or immunomodulator-induced production of IFN-α by PBMCs. These data correspond to the information presented earlier in the scientific literature. We also observed a pronounced inhibitory effect of both immunomodulators on the production of cytokines MCP-1/CCL2, IL-6, IL-8/CXCL8 by PBMCs, along with the individual variability of their production and the cumulative effect of production over time. Conclusion. The features of the production of pro-inflammatory cytokines by PBMCs into the medium in the presence of immunomodulators, revealed by the in vitro screening, can be used to develop universal in vitro cellular test systems for personalized diagnosis of a number of socially significant inflammatory and autoimmune diseases.

Objective a retrospective assessment of the bedsores' features, the optimization of treatment tactics, evaluation of long-term treatment results. Material and methods.The study group included 38 patients with stage IV decubitus ulcers according to the classification of AHCPR localized in the sacral region, the area of the ischial tuberosity and the greater trochanter. Results.We determined the critical time intervals for the decubitus ulcers occurrence. It has been found that in most patients bedsores are remaining for a long period of time. The modern complex methods for the IV stage decubitus ulcers treatment with the plastics of the soft tissue defects revealed their reliably higher effectiveness. Conclusion.The formation of bedsores most often occurs during the first month after the injury and three years after the injury. The treatment of patients with this pathology should be comprehensive and carried out in the well-equipped purulent surgery department by the specialists experienced in treating such patients. The plastic surgery by displaced blood-supplying flaps contributes to success in the treatment of stage IV bedsores.

Aim – to evaluate in vitro the biocompatibility and osteoconductivity of a hybrid graft based on a bioorganic matrix, human bone marrow mesenchymal stromal cells (BM-MSC) and osteogenic growth factors. Material and methods. Bioorganic matrices were studied for biocompatibility with human BM-MSC culture used in traumatology and orthopedics. For promoted osteogenic differentiation of BM-MSCs, allogeneic plasma enriched with soluble platelet factors was used. The osteogenic potential of BM-MSCs by the synthesis of mRNAs of early (transcription factor 2 (Run X2), alkaline phosphatase (ALP)) and late genes (osteopontin (OSP)) of osteogenesis was analyzed. The properties of cell adhesion and proliferation of MSCs in the conditions of a three-dimensional hybrid graft by the MTT test and fluorescence microscopy were assessed. Results. The biocompatibility of the studied bioorganic matrices with human BM-MSCs was established. The collagen matrix promoted rapid cell adhesion and proliferation between the scaffold fibrils. It has also been established that allogeneic platelet-rich plasma affects the osteogenic differentiation of human BM-MSCs in vitro, increasing the expression of marker genes RunX2, ALP, OSP. When modeling a hybrid graft in vitro, the formation of a tight contact between the alloimplant and collagen biopolymer using MSCs was shown. Conclusion. The biological properties of the developed hybrid cell-tissue graft characterize its biocompatibility and osteoconductivity of its constituent components, which makes it promising for use in regenerative medicine, especially in reconstructive surgery of bone defects.