Electrochemical and cellular behavior of ultrafine-grained titanium in vitro.

The electrochemical and cellular behavior of commercially pure titanium (CP-Ti) with both ultrafine-grained (UFG) and coarse-grained (CG) microstructure was evaluated in this study. Equal channel angular pressing was used to produce the UFG structure titanium. Polarization and electrochemical impedance tests were carried out in a simulated body fluid (SBF) at 37°C. Cellular behaviors of samples were assessed using fibroblast cells. Results of the investigations illustrate the improvement of both corrosion and biological behavior of UFG CP-Ti in comparison with the CG counterpart.

Development of a compliant and cytocompatible micro-fibrous polyethylene terephthalate vascular scaffold.

Bioengineering approaches have been intensively applied to create small diameter vascular grafts using artificial materials. However, a fully successful, high performing and anti-thrombogenic structure has not been achieved yet. In this study, we have designed and fabricated a novel non-woven fibrous vascular graft with biomechanical properties closely resembling those of native vessels. Vascular cell growth, preservation of cell phenotype, retention of vasoactive properties, as well as the effect of gelatin coating on the cellular interaction with the scaffolds under static and shear stress conditions were investigated. The non-woven fibrous scaffolds were made from melt blown polyethylene terephthalate fiber webs stacked by means of a consolidation technique. The scaffold variables were fiber diameter distribution and the number of consolidated web stacks. SEM analysis confirmed various fiber diameter and pore size ranges corresponding to the different conditions. The scaffolds showed burst pressure values of ∼1500 mmHg and compliance (8.4 ± 1.0 × 10(-2) % mmHg(-1) ) very similar to those of native arteries (∼8 × 10(-2) % mmHg(-1) ). The structure with the smallest fiber diameter range (1-5 µm) and pore size range (1-20 µm) was the most suitable for the growth of human brain endothelial cells and aortic smooth muscle cells. The cells maintained their specific cell phenotype, expressed collagen and elastin and produced cAMP in response to α-calcitonin gene-related peptide. However, under shear stress conditions (0.9 dyne cm(-2) ), only 30% of the cells were retained in both uncoated and gelatin-coated scaffolds indicating the need for improving the cell retention capacity of these structures, which is our future research direction. This study indicates that the biomechanical and biocompatible properties of this novel vascular scaffold are promising for the development of a vascular graft with similar characteristics to those of native vessels.