The effect of riboflavin-induced collagen photocrosslinking on the scaffold printing accuracy, namely on the area of formed niches and filament thickness, as well as on the degradation time and biocompatibility of scaffolds, has been studied. The thickness of the filaments in the riboflavin-modified scaffolds was 13–29

The aim of the study was to compare type I collagen-based and methacryloyl gelatin-based (GelMA) hydrogels by their ability to form hyaline cartilage in animals after subcutaneous implantation of scaffolds. Materials and Methods Chondrocytes were isolated from the costal cartilage of newborn rats using 0.15% collagenase solution in DMEM. The cells was characterized by glycosaminoglycan staining with alcian blue. Chondrocyte scaffolds were obtained from 4% type I porcine atelocollagen and 10% GelMA by micromolding and then implanted subcutaneously into the withers of two groups of Wistar rats. Histological and immunohistochemical studies were performed on days 12 and 26 after implantation. Tissue samples were stained with hematoxylin and eosin, alcian blue; type I and type II collagens were identified by the corresponding antibodies. Results The implanted scaffolds induced a moderate inflammatory response in both groups when implanted in animals. By day 26 after implantation, both collagen and GelMA had almost completely resorbed. Cartilage tissue formation was observed in both animal groups. The newly formed tissue was stained intensively with alcian blue, and the cells were positive for both types of collagen. Cartilage tissue was formed among muscle fibers. Conclusion The ability of collagen type I and GelMA hydrogels to form hyaline cartilage in animals after subcutaneous implantation of scaffolds was studied. Both collagen and GelMA contributed to formation of hyaline-like cartilage tissue type in animals, but the chondrocyte phenotype is characterized as mixed. Additional detailed studies of possible mechanisms of chondrogenesis under the influence of each of the hydrogels are needed.

3D-bioprinting is a promising technology for a tissue scaffold fabrication in the case of damaged tissue/organ replacement. Collagen is one of the most appropriate hydrogel for the purpose, due to its exceptional biocompatibility. However, the use of collagen with conventionally low concentration makes bioprinting process difficult and does not provide its high accuracy. The purpose of the study was evaluation of suitability of collagen with high concentration in case of chondrocyte-laden scaffold fabrication via 3D-bioprinting for cartilage regeneration in vitro and in vivo. The results of the study showed that inherent porosity of 4% collagen was not enough for cell survival in the case of long-term incubation in vitro. With the beginning of the scaffold incubation, cell migration to the surface and out of the scaffold was observed. The residual cells died mostly within 4 weeks. As for in vivo study, in 2 weeks after implantation of the scaffold, a weak granulomatous inflammation was observed. In 6 weeks, a connective tissue was formed in the area of implantation. In the tissue, macrophages and groups of small cells with round nuclei were found. In accordance with morphological criteria, these cells could be considered as young chondrocytes. However, its amount was not enough to initiate the formation of cartilage.

During biofabrication, a tissue scaffold may require temporary support. The aim of this study was to develop an approach of human thyroid cartilage scaffold temporal support formation. The scaffold 3D-model was based on DICOM images. XY plane projections were used to form scaffold supporting part. To verify the technique, collagen hydrogel was chosen as the main scaffold component. Gelatin was applied for the supporting part. To test the applicability of the approach, a model of thyroid cartilage scaffold with the support was printed. The scaffold corresponded to a given model, although some discrepancy in geometry was observed during verification by computed tomography.

Experiments on F1(CBA×C57BL/6) mice with experimental metastatic melanoma B16 F10 showed that single intravenous injection of xenogeneic bone marrow mesenchymal stromal cells (BM-MSC) in a dose of 106 cells/mouse significantly increased 100-day survival rate of tumor-bearing animals. In contrast, administration of BM-MSC in a dose of 2×106 cells/ mouse reduced survival rates in comparison with the biocontrol (injection of B16 cells alone, 5×105 cells/mouse). This phenomenon can be related to in vivo participation of BM-MSC in reprogramming of resident tissue macrophages, including tumor microenvironment, towards pro- (M1) or anti-inflammatory (M2) phenotype. This is indirectly confirmed by the data on switching from activation to inhibition of ROS-producing activity of blood mononuclears and peritoneal macrophages in tumor-bearing mice in the test of luminol-dependent zymosaninduced chemiluminescence.

Cancer radiotherapy effectiveness largely depends on tumor cells radiosensitivity. Inherent or acquired radioresistance of tumor cells is important challenge in radiation therapy. Response of tumor cells to fractionated radiation therapy has been investigated by many research groups. At present time the use of protons for cancer research and treatment has expanded rapidly. In this connection research on sensitivity of tumor cells to proton beam therapy is an urgent task. The aim of the study was to assess sensitivity of irradiated with electrons or protons B16 melanoma cells to the next electron beam or proton beam irradiation at comparable total doses. Studies with the use of stable tumor cell lines with acquired radioresistance may be useful for the develop-ment of effective treatment plan tailored to the patients with relapses or metastases that have oc-curred after prior unsuccessful radiotherapy with standard types of radiation. Protons were pro-vided by Prometeus installation scanning beam and the electron beam of the accelerator Novac-11. Cells radiosensitivity was measured by clonogenic assay. The resistance of cells first irradiat-ed with protons and electrons to the next irradiation with protons and electrons was estimated by clonogenic assay. DNA damages, cell size, proliferative activity and cell cycle phase distribution were also evaluated. The study demonstrated that fractionated irradiation of B16 cells with elec-trons at the total dose of 60 Gy causes significant reduction of cells radiosensitivity to the next ir-radiation with protons, radiosensitivity of irradiated cells to the second irradiation with electrons remains the same. In contrast, the first fractionated irradiation of cells with protons at the total dose of 50 Gy does not affect the radiosensitivity of the cells to the next irradiation with electrons or protons.

The development of biomedical cell products for damaged cartilage recovery is an important direction of regenerative medicine. The review examines the main issues related to biodegradable tissue scaffold and hydrogel properties: selection of appropriate biomaterials, cells loaded and other supplements that could provide the best conditions for cartilage recovery. The results of in vitro and in vivo studies, as well as clinical trials registered at the National Institutes of Health database (ClinicalTrials.gov), are considered.

Опыт применения портативного отечественного нейтронного генератора в схемах гамма-нейтронной терапии домашних животных со злокачественными новообразованиямиКорякин С.Н. 1 , Кайдан Н.А. 2 , Исаева Е.В. 1 , Ульяненко Л.Н. 1 , Лычагин А.А. 1 , Ульяненко С

The study was aimed to the biological effectiveness of the proton scanning beam of the first Russian medical facility. The clonogenic assay of B-16 tumor cells was used as a test system. Cell irradiation was carried out in a suspension condition in a water phantom. Single and three-field exposures were studied. The dose interval was 2-8 Gy. The energy range from 47.5 to 92.0 MeV was used for the Bragg peak formation. The relative biological effectiveness of protons comparing to gamma-rays was 1.2 for single-field and 1.5 for three-field irradiation. The results obtained agree with literature data related to the used cell culture (B-16) and linear energy transfer range (3÷8 keV/µm).

Эффективность фотон-захватной терапии с использованием золотосодержащих соединений на основе гиалуроновой кислоты (экспериментальные исследования) Корякин С.Н. 1 , Ульяненко С.Е. 1 , Исаева Е.В. 1 , Бекетов Е.Е. 1 , Ульяненко Л.Н. 1 , Успенский С.А. 2,3, Селянин М.А. 2 , Зеленецкий А

We describe a technique for attaining extended transversally-flat paraxial dose fields with the intermediateenergy carbon beam slowly extracted at the magnetic-field flat-bottom from the IHEP U-70 synchrotron. To this end, a fixed-radius circular beam sweep with the aid of a compact electromechanical wobbler with rotating permanent dipole magnets is applied. A technique for tuning the beam transfer line and the irradiation facility proper at the interim radiobiological workbench with an external fixed target is substantiated. A brief description of its engineering implementation is presented. Results of the successful experimental verification of the technique in question with a carbon nuclear beam from the U-70 machine are reported, in particular, results of the primary radiobiological exercises accomplished in cooperation with the scientists at the MRRC of the Russian Ministry of Healthcare.

The study was carried out using compact neutron generators with a sealed tube operating in pulsed (neutron generator ING-031) and continuous (NG-14) modes. Neutron radiation was formed due to reaction T(d,n)He-4. The average flow of 14-MeV neutrons was 6.6x10(9) ns(-1) for ING-031 and 1.2-1.6x10(10) n s(-1) for NG-14. Duration of an impulse was similar to 1 ms and pulse frequency of 50 Hz. The gamma rays of Co-60 source with an average energy of 1.25 MeV were standard radiation. Biological efficacy was estimated using the clonogenic activity of mice melanoma B-16 cells. Comparison of biological effects of neutron irradiation in pulse and continuous modes showed no significant difference between them. RBE values of pulse (ING-031) and continuous (NG-14) neutron radiation were equal-in the range of 2.4-2.6. According to the clonogenic activity of melanoma B-16 cells no dose rate effect was observed within the studied range of neutrons doses and dose rates.

The technology of solid-state modification of hyaluronic acid (HA) with sodium decahydroborate by deformation in Bridgman anvils was developed. The deformation was carried out at a pressure of 1 GPa and a rotation angle of 500°. The structure of the obtained complexes was studied. It was shown using Raman and IR-Fourier spectroscopy that HA and the polyborates could form a network of cyclic polymeric chelate complexes in which HA acted as a multidentate ligand. The biodistribution of the HA-based B-containing compound in organs and tissues of mice with B-16 melanoma was studied after a single intratumoral administration. The maximum B content in the tumor was observed 15 min after administration. However, it was halved after 1 h and decreased by 5 times by 3 h. The most opportune time for performing a boron-neutron-capture therapy session was 30 min after administration when the tumor B concentration was >30 μg/g and exceeded the content in surrounding tissues. The tumor/muscle and tumor/blood ratios reached 3 and 5, respectively. Use of this non-toxic compound for neutron-capture therapy was deemed promising based on preclinical studies.

The technology of solid-state modification of hyaluronic acid with sodium decahydroborate by deformation in Bridgman anvils has been developed. The deformation was carried out at a pressure of 1 GPa and a rotation angle of 500 degrees. The structure of obtained complexes has been studied. According to the Raman and infrared spectroscopy data, hyaluronic acid and polyborates are capable of forming a network of cyclic polychelate complexes with hyaluronic acid as polydentate ligands. The distribution of hyaluronic acid-based boron compound in organs and tissues in mice with melanoma B-16 has been studied after single intratumor administration. The maximum boron content in tumor was observed 15 min after drug administration, but decreased two times already in 1 h and more than 5 times in 3 h upon administration. The optimum time for BNCT session is 30 min after compound administration, when boron concentration in tumor is greater than 30 μg/g and exceeds that in the surrounding tissues. During this time, the tumor/muscle and tumor/blood concentration ratios were 3 and 5, respectively. The first stage of investigation shows that the proposed compound is non-toxic and has good prospects for use in BNCT.