Optimization and Application of Electrophoretic Mobility Analysis of Human Red Blood Cells to Study Their in Vitro Stability, Interaction with Polycations and Proteolytic Enzymes

in Journal of Biomedical Materials Research, Part A (2008), 84(2), 535-44

Electrophoretic light scattering method has been considered to determine both the mean and polydispersity of electrophoretic mobility of normal human red blood cells. The final goal of our study was to ... [more ▼]

Electrophoretic light scattering method has been considered to determine both the mean and polydispersity of electrophoretic mobility of normal human red blood cells. The final goal of our study was to optimize an in vitro test allowing us to investigate the interaction of xenobiotics, in particular polyelectrolytes, with blood cells. The feasibility of our method has been evaluated based on the reproducibility of our technique to analyze the native electrophoretic mobility of human RBCs, as well as their evolution in the presence of polycationic compounds, i.e. a natural polyamine, spermine, and a synthetic polycation, a polyethylenimine (PEI). Additionally, the follow-up of the human RBCs electrophoretic mobility has been controlled after their incubation with neuraminidase. [less ▲]

In vitro and in vivo analysis of macroporous biodegradable poly(D,L-lactide-co-glycolide) scaffolds containing bioactive glass

in Journal of Biomedical Materials Research, Part A (2005), 75A(4), 778-787

Recent studies have demonstrated the angiogenic potential of 45S5 Bioglass (R). However, it is not known whether the angiogenic properties of Bioglass (R) remain when the bioactive glass particles are ... [more ▼]

Recent studies have demonstrated the angiogenic potential of 45S5 Bioglass (R). However, it is not known whether the angiogenic properties of Bioglass (R) remain when the bioactive glass particles are incorporated into polymer composites. The objectives of the current study were to investigate the angiogenic properties of 45S5 Bioglass (R) particles incorporated into biodegradable polymer composites. In vitro studies demonstrated that fibroblasts Cultured on discs consisting of specific quantities of Bioglass (R) particles mixed into poly(D,L-lactide-co-glycolide) secreted significantly increased quantities of vascular endothelial growth factor. The optimal quantity of Bioglass (R) particles determined from the in vitro experiments was incorporated into three-dimensional macroporous poly(D,L-lactide-co-glycolide) foam scaffolds. The foam scaffolds were fabricated using either compression molding or thermally induced phase separation processes. The foams were implanted subcutaneously into mice for periods Of Lip to 6 weeks. Histological assessment was used to determine the area of granulation tissue around the foams, and the number of blood vessels within the granulation tissue was counted. The presence of Bioglass (R) particles in the foams produced a sustained increase in the area of granulation tissue surrounding the foams. The number of blood vessels surrounding the neat foams was reduced after 2 weeks of implantation; however, compression-molded foams containing Bioglass (R) after 4 and 6 weeks of implantation had significant]), more blood vessels surrounding the foams compared with foams containing no Bioglass (R) at the same time points. These results indicate that composite polymer foam scaffolds containing Bioglass (R) particles retain granulation tissue and blood vessels surrounding the implanted foams. The use of this polymer composite for tissue engineering scaffolds might provide a novel approach for ensuring adequate vascular Supply to the implanted device. [less ▲]

Polylactide implants and bacterial contamination: an animal study

in Journal of Biomedical Materials Research, Part A (2001), 54(3), 335-343

Although bioresorbable aliphatic polyesters derived from lactic acid are now used clinically as sutures, bone-fracture fixation devices and sustained-release drug-delivery systems, very little is known ... [more ▼]

Although bioresorbable aliphatic polyesters derived from lactic acid are now used clinically as sutures, bone-fracture fixation devices and sustained-release drug-delivery systems, very little is known about their behavior in the infected environment. The aim of the present study was to compare the resistance to infection of two polylactide implants with different degradation characteristics, and to evaluate the influence of a bacterial challenge on their mechanical and physicochemical properties. Various quantities of a beta-haemolyzing strain of Staphylococus aureus (V 8189-94) were inoculated into the medullary cavity of rabbit tibiae, and an extruded polylactide rod composed of either P(L)LA (Poly(L-Lactide)) or P(L/DL)LA (Poly(L/DL-Lactide)) was then inserted. Animals were sacrificed four weeks after surgery. The tibiae and implants were removed under sterile conditions and evaluated microbiologically by culturing. The severity of infection was graded according to positive colony-forming units in the bone. The mechanical properties of the retrieved implants were assessed by 4-point bending and shear tests, performed in compliance with the ASTM D790 standard and their physicochemical characteristics also were characterized. P(L)LA and P(L/DL)LA implants were equally resistant to local infection, their mechanical and physicochemical properties being unaffected by bacterial challenge. Hence, once an infection has become established, the release of bactericidal/bacteriostatic by-products during implant degradation does not appear to affect its natural course. The release of bactericidal/bacteriostatic degradation products at the implantation site is unlikely to affect the natural course of an established infection. [less ▲]