The effect of ingested copper on the structural and cytotoxic properties of Steatoda grossa (Theridiidae) spider silk.

Spiders, assigned to macroconcentrators of heavy metals, are particularly threatened by the toxic effects of these chemicals. Until now, it has not been specified to what extent metals alter the processes proceeding in silk glands and if such changes could consequently influence the chemical and structural properties of the spun web threads. In the present study selected biological properties of Steatoda grossa (Theridiidae) silk yarn after nutritional exposure to copper at sublethal doses (0.234 mM CuSO4) were assessed. It was determined both changes in ultrastructure of ampullate glands and hunting web's architecture as well the cytotoxic effect in model cells (fibroblasts: line ATCC® CCL-1 NCTC clone 929), that were in contact with the analyzed biomaterial. The exposure of spiders to copper caused the occurrence of apoptotic cells in the ampullate glands as well as a significant reduction in the diameter of single fibers in double and multiple connection complexes as compared with control. At both 24 and 72 h of incubation, intensification of apoptotic and necrotic processes was observed in the fibroblast cultures that were remaining in indirect contact with the webs produced by copper-contaminated individuals. In the case of fibroblasts in direct contact with silk from the copper group, a clear cytotoxic effect resulting in an increased frequency of necrosis was observed after 72 h of incubation. The results indicated that copper may change the biological properties of spider silk and compromise its biomaterial properties.

Effect of the Thickness of TiO2 Films on the Structure and Corrosion Behavior of Mg-based Alloys.

This article discusses the influence of the thickness of TiO2 films deposited onto MgCa2Zn1 and MgCa2Zn1Gd3 alloys on their structure, corrosion behavior, and cytotoxicity. TiO2 layers (about 200 and 400 nm thick) were applied using magnetron sputtering, which provides strong substrate adhesion. Such titanium dioxide films have many attractive properties, such as high corrosion resistance and biocompatibility. These oxide coatings stimulate osteoblast adhesion and proliferation compared to alloys without the protective films. Microscopic observations show that the TiO2 surface morphology is homogeneous, the grains have a spherical shape (with dimensions from 18 to 160 nm). Based on XRD analysis, it can be stated that all the studied TiO2 layers have an anatase structure. The results of electrochemical and immersion studies, performed in Ringer's solution at 37 °C, show that the corrosion resistance of the studied TiO2 does not always increase proportionally with the thickness of the films. This is a result of grain refinement and differences in the density of the titanium dioxide films applied using the physical vapor deposition (PVD) technique. The results of 24 h immersion tests indicate that the lowest volume of evolved H2 (5.92 mL/cm2) was with the 400 nm thick film deposited onto the MgCa2Zn1Gd3 alloy. This result is in agreement with the good biocompatibility of this TiO2 film, confirmed by cytotoxicity tests.

Biomechanical properties of hybrid heart valve prosthesis utilizing the pigs that do not express the galactose-α-1,3-galactose (α-Gal) antigen derived tissue and tissue engineering technique.

The aim of the study was to estimate the biomechanical properties of heart valves conduit derived from transgenic pigs to determine the usefulness for the preparation of tissue-engineered heart valves. The acellular aortic and pulmonary valve conduits from transgenic pigs were used to estimate the biomechanical properties of the valve. Non-transgenic porcine heart valve conduits were used as a reference. The biomechanics stability of acellular valve conduits decreased both for the transgenic and non-transgenic porcine valves. The energy required to break the native pulmonary valve derived from transgenic pigs was higher (20,475 ± 7,600 J m(-2)) compared with native non-transgenic pigs (12,140 ± 5,370 J m(-2)). After acellularization, the energy to break the valves decreased to 14,600 and 8,800 J m(-2) for the transgenic pulmonary valve and non-transgenic valve, respectively. The native transgenic pulmonary valve showed a higher extensibility (42.70 %) than the non-transgenic pulmonary valve (35.50 %); the extensibility decreased after acellularization to 41.1 and 31.5 % for the transgenic and non-transgenic valves, respectively. The pulmonary valves derived from transgenic pigs demonstrate better biomechanical properties compared with non-transgenic. Heart valves derived from transgenic pigs can be valuable for the preparation of tissue-engineered bioprostheses, because of their biomechanical properties, stability, reduced immune response, making them safer for clinical applications.

Age-related changes in biomechanical properties of transgenic porcine pulmonary and aortic conduits.

The limitations associated with conventional valve prosthesis have led to a search for alternatives. One potential approach is tissue engineering. Most tissue engineering studies have described the biomechanical properties of heart valves derived from adult pigs. However, because one of the factors affecting the function of valve prosthesis after implantation is appropriate sizing for a given patient, it is important to evaluate the usefulness of a heart valve given the donor animal's weight and age. The aim of this study was to evaluate how the age of a pig can influence the biomechanical and hemodynamical properties of porcine heart valve prosthesis after acellularization. Acellular porcine aortic and pulmonary valve conduits were used. Hearts were harvested from animals differing in weight and age. The biomechanical properties of the valves were then characterized using a uniaxial tensile test. Moreover, computer simulations based on the finite element method (FEM) were used to study the influence of biomechanical properties on the hemodynamic conditions. Studying biomechanical and morphological changes in porcine heart valve conduits according to the weight and age of the animals can be valuable for developing age-targeted therapy using tissue engineering techniques.