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At present there is a growing need for tissue engineering products, including the products of scaffold-technologies. Biopolymer hydrogel scaffolds have a number of advantages and are increasingly being used to provide means of cell transfer for therapeutic treatments and for inducing tissue regeneration. This work presents original hydrogel biopolymer scaffolds based on a blood plasma cryoprecipitate and collagen and formed under conditions of enzymatic hydrolysis. Two differently originated collagens were used for the scaffold formation. During this work the structural and mechanical characteristics of the scaffold were studied. It was found that, depending on the origin of collagen, scaffolds possess differences in their structural and mechanical characteristics. Both types of hydrogel scaffolds have good biocompatibility and provide conditions that maintain the three-dimensional growth of adipose tissue stem cells. Hence, scaffolds based on such a blood plasma cryoprecipitate and collagen have good prospects as cell carriers and can be widely used in regenerative medicine., Graphical abstract Image 1, Highlights • Original hydrogel scaffolds based on a blood plasma cryoprecipitate and collagen. • Depending on the origin of collagen, scaffolds possess differences in their properties. • Scaffolds can provide the conditions needed to maintain growth of stem cells.

To make ceramic antibacterial biocompatible material, we synthesized mixed calcium–bismuth oxophosphate (CaBiPO-apatite) with apatite structure. A mixture of CaBiPO-apatite and ammonium carbonate was used to prepare ceramic material in tablet form. Qualitative and quantitative phase analyses using powder XRD combined with IR spectroscopy shown the absence of any phase or chemical changes in the material during the process of making ceramics. In vitro experiment with human mesenchymal stromal cells showed high biocompatibility of the material caused by structural type and high porosity of material, despite the presence of bismuth in composition of the substance.

The activity of stem cell processes is regulated by internal and external signals of the cell &ldquo, niche&rdquo, In general, the niche of stem cells can be represented as the microenvironment of the cells, providing a signal complex, determining the properties of the cells. At the same time, the &ldquo, concept implies feedback. Cells can modify their microenvironment, supporting homeostasis or remodeling the composition and structure of the extracellular matrix. To ensure the regenerative potential of tissue engineering products the &ldquo, concept should be taken into account. To investigate interactions in an experimental niche, an original hydrogel biopolymer scaffold with encapsulated mesenchymal adipose-derived stem cells (ASCs) was used in this study. The scaffold provides for cell adhesion, active cell growth, and proliferative activity. Cells cultured within a scaffold are distinguished by the presence of a developed cytoskeleton and they form a cellular network. ASCs cultured within a scaffold change their microenvironment by secreting VEGF-A and remodeling the scaffold structure. Scaffold biodegradation processes were evaluated after previous culturing of the ASCs in the scaffolds for periods of either 24 h or six days. The revealed differences confirmed that changes had occurred in the properties of scaffolds remodeled by cells during cultivation. The mechanisms of the identified changes and the possibility of considering the presented scaffold as an appropriate artificial niche for ASCs are discussed.

The aim of the study was to develop a technology for repairing an osteomyelitic bone defect using autologous adipose tissue mesenchymal stromal cells (MSCs) bound to a collagen matrix and to test the efficacy of this technique. Materials and Methods. The study was carried out with 17 rabbits. A bone defect was created using a milling cutter applied to the proximal third of the leg. The wound (8.0×4.0 mm and a depth of 4.0 mm) involved the periosteum, cortical layer, and cancellous substance. Staphylococcus aureus strain was used as an infectious agent. After the development of chronic osteomyelitis, the animals underwent osteonecrectomy. In the study group, autologous MSCs in Collatamp EG collagen carrier were placed into the bone defect. MSCs were obtained from adipose tissue and cultured in the matrix for 5 days. In control, the defect was filled with the collagen matrix without cells. Results. On day 14 upon the initiation of chronic osteomyelitis, bacteriological examination of the discharge from the fistula showed the presence of mixed bacterial flora (Staphylococcus aureus and Escherichia coli) in all operated animals. Results of X-ray, laboratory, and histological tests confirmed the formation of a focus of chronic osteomyelitis. Two months after the treatment (collagen with or without MSCs) began, all animals of the study group showed mature bone tissue regenerated in the affected zone. In the control group, proliferation of osteoblasts on the surface of the bone trabeculae was also observed; however, mature osteoid tissue was more often detected in the study group (35.0 vs 20.0% in control). In the study group (MSCs + collagen matrix), there was a decrease in bone marrow fibrosis (50.0 vs 100.0% in control) and cartilage formation (30.0 and 66.7%, respectively). After full treatment, newly formed bone trabeculae were detected more often (100.0 vs 60.0% in control); they were more mature and filled the defect area more efficiently. Conclusion. Our results indicate that the use of a collagen matrix with autologous MSCs is a promising plastic material for repairing osteomyelitic defects following necrectomy. The MSCs were able to increase the density of the filling material in the bone cavity, significantly accelerate the formation of bone beams around the matrix, and increase the tissue volume around the implant. The presence of MSCs significantly decreased the interference of a connective tissue component with osteogenesis and chondrogenesis.

Hydroxyapatite nanoparticles were synthesized using modified sol–gel approach. Its biocompatibility was proved by in vitro experiments with diploid fibroblasts. The experiment showed that the presence of hydroxyapatite in the environment of cells does not reduce their viability. The observed phase transition of hydroxyapatite was explained as order/disorder transition, saving the crystal structure symmetry. Organo–inorganic composites of chitosan and hydroxyapatite were obtained by preparing a joint solution and pouring onto a glass substrate. According to XRD and DTA data, addition of hydroxyapatite reduces the softening and decomposition temperature of chitosan. This information is necessary to optimize the manufacturing processes of organo–inorganic scaffolds.

The success of the regenerative process resulting from the implantation of a scaffold or a tissue-engineered structure into damaged tissues depends on a series of factors, including, crucially, the biodegradability of the implanted materials. The selection of a scaffold with appropriate biodegradation characteristics allows for synchronization of the degradation of the construct with the processes involved in new tissue formation. Thus, it is extremely important to characterize the biodegradation properties of potential scaffold materials at the stage of in vitro studies. We have analyzed the biodegradation of hybrid fibrin–collagen scaffolds in both PBS solution and in trypsin solution and this has enabled us to describe the processes of both their passive and enzymatic degradation. It was found that the specific origin of the collagen used to form part of the hybrid scaffolds could have a significant effect on the nature of the biodegradation process. It was also established, during comparative studies of acellular scaffolds and scaffolds containing stem cells, that the cells, too, make a significant contribution to changes in the biodegradation and structural properties of such scaffolds. The study results also provided evidence indicating the dependency between the pre-cultivation period for the cellular scaffolds and the speed and extent of their subsequent biodegradation. Our discussion of results includes an attempt to explain the mechanisms of the changes found. We hope that the said results will make a significant contribution to the understanding of the processes affecting the differences in the biodegradation properties of hybrid, biopolymer, and hydrogel scaffolds.

The aim of the study is to evaluate biocompatibility of a novel hybrid polyoligomer in in vitro and in vivo models. Materials and Methods Cytotoxicity of the material was investigated using the MTT assay with human dermal fibroblasts as test cultures. To study direct interaction of the hybrid polyoligomer with cells, the fibroblasts were cultured on the polymer samples for 96 h, the cultures were assessed every 24 h using fluorescence microscopy. To study the tissue reaction in the area of contact with the donor bed and the morphological features of the implanted sample restructuring, a case-control study was performed using a rabbit model. Samples of hybrid polyoligomer were implanted into the bone defect formed in the left iliac crest in 10 rabbits. In the control group, the prepared allograft samples were transplanted into similar defects in 10 animals. The rabbits were sacrificed 4 and 8 weeks after the operation. The standard morphological methods with hematoxylin and eosin staining and immunohistochemical Ki-67 proliferation marker evaluation were used to assess the state of tissues in the defect area. Results The results demonstrate that the hybrid polyoligomer is not cytotoxic (cytotoxicity score 0-1), cells adhere well to its surface, retain their viability and typical morphology throughout the entire observation period. No negative impact of material implantation on the health state and behavior of animals was detected. Morphological examination showed the absence of inflammatory changes, formation of thin-walled capillary vessels, and considerable proliferative activity of mesenchymal cells in the defect area, even though it was more intense than in the control group. Conclusion No inflammation signs were detected by 8th week of the experiment. It was defined that new bone was beginning to form. The results of analysis support the conclusion that the developed hybrid materials are prospective for further research as potential bone substitute.

Polymer monoliths containing open interconnected pores were synthesized by a visible-light induced polymerization of oligocarbonatedimethacrylate (OCM-2) in the presence of dialkylphthalates (C6H4[C(O)OR]2, R = C2H5, n-C4H9, n-C8H17 and n-C9H19) as porogenic agent. A closeness of the refractive indices of the forming polymer and dialkylphthalates provides for the formation of transparent porous monoliths, thus making manufacture of thick porous polymeric materials using visible light possible. The porous polymers derived from OCM-2 can sorb water and benzene. The filling of pores by water increases with an increase of a number of carbon atoms in the ester groups from 0.65 for diethyl phthalate to 1.0 for dinonyl phthalate. Experimentally defined value of Hildebrand solubility parameter δ for poly-OCM-2 is 24.9 MPa1/2. A closeness of the solubility parameters of the polymer (δp) and porogenic agent (δs) guarantees the porous architecture of the polymer formed. The porous polymeric materials have been studied in vitro using a culture of human dermal fibroblasts (HDF) of four passages. The MTT test (MTT is 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) has shown that the materials are not cytotoxic. During long-term cultivation of the cells on the material surface a pronounced cell adhesion as well as cell viability and proliferative activity have been detected.