Neovascularization of poly(ether ester) block-copolymer scaffolds in vivo: long-term investigations using intravital fluorescent microscopy.

Item does not contain fulltextPoly(ether ester) block-copolymer scaffolds of different pore size were implanted into the dorsal skinfold chamber of balb/c mice. Using intravital fluorescent microscopy, the temporal course of neovascularization into these scaffolds was quantitatively analyzed. Three scaffold groups (diameter, 5 mm; 220-260 thickness, microm; n = 30) were implanted. Different pore sizes were evaluated: small (20-75 microm), medium (75-212 microm) and large pores (250-300 microm). Measurements were performed on days 8, 12, 16, and 20 in the surrounding normal tissue, in the border zone, and in the center of the scaffold. Standard microcirculatory parameters were assessed (plasma leakage, vessel diameter, red blood cell velocity, and functional vessel density). The large-pored scaffolds showed significantly higher functional vessel density in the border zone and in the center (days 8 and 12) compared with the scaffold with the small and medium-sized pores. These data correlated with a larger vessel diameter and a higher red blood cell velocity in the large-pored scaffold group. Interestingly, during the evaluation period the microcirculatory parameters on the edge of the scaffolds returned to values similar to those found in the surrounding tissue. In the center of the scaffold, however, neovascularization was still active 20 days after implantation. Plasma leakage and vessel diameter were higher in the center of the scaffold. Red blood cell velocity and functional vessel density were 50% lower than in the surrounding tissue. In conclusion, the dorsal skinfold chamber model in mice allows long-term study of blood vessel growth and remodeling in porous biomedical materials. The rate of vessel ingrowth into poly(ether ester) block-copolymer scaffolds is influenced by pore size and was highest in the scaffold with the largest pores. The data generated with this model contribute to knowledge about the development of functional vessels and tissue ingrowth into biomaterials

Long-term evaluation of porous PEGT/PBT implants for soft tissue augmentation.

Item does not contain fulltextPorous PEGT/PBT implants with different physico-chemical characteristics were evaluated to identify its potential as biodegradable and biofunctional soft tissue filler. Implants (50 x 10 x 5 mm3) were implanted subcutaneously in mini-pigs and tissue response, tissue volume generated and its consistency were assessed quantitatively with a 52 weeks follow-up. The absence of wound edema, skin irritation, and chronic inflammation demonstrated biocompatibility of all implants evaluated. The hydrophobic implants induced the mildest foreign body response, generated highest amount of connective tissue and demonstrated a decrease in copolymer MW of 34-37% compared to 90% decrease of the hydrophilic implants. The rate and extent of copolymer fragmentation seems to be the determining factor of success of soft tissue augmentation using porous PEGT/PBT copolymer implants

Cobalt-Releasing 1393 Bioactive Glass-Derived Scaffolds for Bone Tissue Engineering Applications

Loading biomaterials with angiogenic therapeutics has emerged as a promising approach for developing superior biomaterials for engineering bone constructs. In this context, cobalt-releasing materials are of interest as Co is a known angiogenic agent. In this study, we report on cobalt-releasing three-dimensional (3D) scaffolds based on a silicate bioactive glass. Novel melt-derived "1393" glass (53 wt % SiO2, 6 wt % Na2O, 12 wt % K2O, wt % MgO, 20 wt % CaO, and 4 wt % P2O5) with CoO substituted for CaO was fabricated and was used to produce a 3D porous scaffold by the foam replica technique. Glass structural and thermal properties as well as scaffold macrostructure, compressive strength, acellular bioactivity, and Co release in simulated body fluid (SBF) were investigated. In particular, detailed insights into the physicochemical reactions occurring at the scaffold-fluid interface were derived from advanced micro-particle-induced X-ray emission/Rutherford backscattering spectrometry analysis. CoO is shown to act in a concentration-dependent manner as both a network former and a network modifier. At a concentration of 5 wt % CoO, the glass transition point (T-g) of the glass was reduced because of the replacement of stronger Si-O bonds with Co-O bonds in the glass network. Compressive strengths of gt 2 MPa were measured for Co-containing 1393-derived scaffolds, which are comparable to values of human spongy bone. SBF studies showed that all glass scaffolds form a calcium phosphate (CaP) layer, and for 1393-1Co and 1393-5Co, CaP layers with incorporated traces of Co were observed. The highest Co concentrations of similar to 12 ppm were released in SBF after reaction for 21 days, which are known to be within therapeutic ranges reported for Co2+ ions