[PROSPECTIVE SYNTHETIC MATRICES FOR THE RECONSTRUCTION OF TRACHEAL DEFECTS IN CANCER PATIENTS].

A replacement of major defects of the trachea remains a challenge despite numerous attempts to use for this purpose various options of autologous and allogeneic implants as well as synthetic matrixes. The most prospective direction is to create tracheal matrixes based on biocompatible porous or fibrous materials that mimic native tissues and provide the proliferation of multipotent cells. This review summarizes current data regarding the development of experimental research and clinical testing of biocompatible tracheal matrixes, which were created using innovative technologies.

Fabrication method, structure, mechanical, and biological properties of decellularized extracellular matrix for replacement of wide bone tissue defects.

The present paper was focused on the development of a new method of decellularized extracellular matrix (DECM) fabrication via a chemical treatment of a native bone tissue. Particular attention was paid to the influence of chemical treatment on the mechanical properties of native bones, sterility, and biological performance in vivo using the syngeneic heterotopic and orthotopic implantation models. The obtained data indicated that after a chemical decellularization treatment in 4% aqueous sodium chlorite, no noticeable signs of the erosion of compact cortical bone surface or destruction of trabeculae of spongy bone in spinal channel were observed. The histological studies showed that the chemical treatment resulted in the decellularization of both bone and cartilage tissues. The DECM samples demonstrated no signs of chemical and biological degradation in vivo. Thorough structural characterization revealed that after decellularization, the mineral frame retained its integrity with the organic phase; however clotting and destruction of organic molecules and fibers were observed. FTIR studies revealed several structural changes associated with the destruction of organic molecules, although all organic components typical of intact bone were preserved. The decellularization-induced structural changes in the collagen constituent resulted changed the deformation under compression mechanism: from the major fracture by crack propagation throughout the sample to the predominantly brittle fracture. Although the mechanical properties of radius bones subjected to decellularization were observed to degrade, the mechanical properties of ulna bones in compression and humerus bones in bending remained unchanged. The compressive strength of both the intact and decellularized ulna bones was 125-130 MPa and the flexural strength of humerus bones was 156 and 145 MPa for the intact and decellularized samples, respectively. These results open new avenues for the use of DECM samples as the replacement of wide bone tissue defects.

UHMWPE-based nanocomposite as a material for damaged cartilage replacement.

In the present work dispersion-strengthened nanocomposites based on ultra-high molecular weight polyethylene (UHMWPE) after mechanical activation were studied. Mechanical activation was performed for hardening of the boundaries between the polymer particles, reducing the fusion defects and increasing of wear-resistance. Three types of samples were prepared: UHMWPE, UHMWPE/Al2O3 nanocomposite and UHMWPE/Al2O3 nanocomposite after mechanical activation. UHMWPE/Al2O3 nanocomposites prepared with mechanical activation show the best mechanical properties in compression and higher wear-resistance. UHMWPE/Al2O3 nanocomposites prepared with mechanical activation were chosen for in vivo study by orthotopical transplantation in rats. Animals' activity has been being monitored for 60days after surgery. No signs of inflammation, cellular infiltration, destruction of material or bone-cartilage defect were found. Implanted sample has not changed its position of implantation, there were no any shifts. Obtained data shows that UHMWPE-based nanocomposite is a promising material for creating bioimplants for cartilage defect replacement.

Growth-dependent release of carbohydrate metabolism-related and antioxidant enzymes from Staphylococcus aureus strain 6 as determined by proteomic analysis.

Proteins released into the culture medium by Staphylococcus aureus (S. aureus) strain 6 were determined at the end of the exponential growth phase (4.5 h). Eleven proteins were identified by liquid chromatography coupled with mass spectrometry. Three proteins were predicted to have signal peptides indicating their extracellular localization. The other proteins were presumably located in the cytoplasm of the bacteria. Five out of the 11 proteins were involved in carbohydrate metabolism. Other intracellular proteins of S. aureus were not detected in the culture medium. This indicates that the release of these 11 proteins was specific and that unspecific protein release due to damaged or dying bacteria did not play a role. It is suggested that enzymes associated with carbohydrate metabolism may provide the energy necessary for the transition of bacteria from a resting to a proliferative state. Another enzyme released by S. aureus, superoxide dismutase, may catalyze redox reactions in this context. The production of other proteolytic enzymes and toxins may take place at later stages of bacterial growth. A cocktail of these 11 proteins was used for the immunization of mice. Indeed, vaccination with these proteins prolonged the survival times of mice upon infection with S. aureus strain 6. Therefore, these proteins may have implications for the development of novel strategies for the prevention and therapy of S. aureus infections.

Optimization of a method for preparation and repopulation of the tracheal matrix for allogenic transplantation.

A method for decellularization of the trachea for subsequent repopulation with allogenic MSC was optimized. Tracheas from C57BL/6 mice were devitalized and repopulated with MSC from BALB/c mice. The tracheal matrix with devitalized mucosa and intact cartilaginous structure, fit for repopulation with allogenic MSC, was obtained by chemical treatment with NaClO4. This approach seemed to be promising for transplantation of allogenic trachea.

Possibility of microorganism elimination from the blood using modified coal hemosorbents.

We studied the possibility of using coal hemosorbents for elimination gram-positive and gram-negative microorganisms from the blood. After hemosorption, the number of S. aureus and K. pneumoniae pneumoniae colony-forming units significantly decreased. The obtained results indicate that coal sorbents can bind and probably eliminate gram-positive and gram-negative bacteria from the blood.

Hemoglobin-associated proteins isolated from blood serum of Ehrlich carcinoma-bearing mice.

In the present study, we analyzed differential composition of blood serum from Ehrlich carcinoma-bearing and healthy male C57Bl/6 mice by isolating complexes of hemoglobin and other serum proteins by a proteomic approach (gel filtration, gel electrophoresis, and mass spectrometry). The hemoglobin fractions isolated from the serum of mice- bearing tumors contained several proteins with molecular weights of 15, 65, 68, and 100 kDa, while hemoglobin fractions isolated from the serum of healthy mice did not contain additional protein bands. These bands were identified by MALDI-TOF as haptoglobin, serum albumin, a homologue of alpha-fetoprotein, and hemoglobin-alpha. Ion exchange chromatography indicated complex formation of these proteins. Injection of hemoglobin-associated blood serum proteins (HAP) isolated from tumor-bearing animals, leads to tumor regression. Intraperitoneally injected HAP-induced apoptosis in Ehrlich carcinoma cells but not normal peritoneal cells and led to a complete regression of the ascitic or solid Ehrlich carcinoma. A one-year follow up of the animals did not reveal any signs of tumor growth. In conclusion, HAP might be a novel principle of tumor regression. The clinical relevance of these findings with Ehrlich carcinoma should be investigated in the future.

Cytotoxic protein from human platelets.

The 14 kDa protein was purified from human platelets. It displays high cytotoxic activity to the human ACL cells at 10 M concentration (21.8+/-7.1%). Its N-terminal sequence is YAPQXQFGP-, being highly homologous to region 241-249 residues of the human Cls complement component.

Platelet-mediated cytotoxicity and its enhancement by platelet activating factor.

Platelet cytotoxicity was assessed in 70 cancer patients with various tumor localizations and in 30 normal donors. The data presented reveal that the ACL cell line displays the highest sensitivity to platelet cytotoxicity. Using the ACL cells, we discovered that platelets from oncological patients and normal donors display comparable cytotoxicity. The level of platelet lytic activity is irrelevant to tumor localisation; however, it appears to be dependent on the stage of tumor growth. Incubation of platelets, both from donors and patients, with PAF (concentration range 10 pM to 10 nM) results in a significant rise of the killing activity of platelets. PAF induces greater cytotoxicity enhancement for platelets with lower initial activity, this pattern appearing to be the specific feature of the PAF mediated effect. Hence, platelets can be considered as effector cells relevant to antitumor immunity; PAF-mediated enhancement of platelet cytotoxicity can appear to be useful in the search for new immunotherapeutic drugs.