Interpenetrating polymer networks containing gelatin modified with PEGylated RGD and soluble KGF: Synthesis, characterization, and application in in vivo critical dermal wound

The purpose of this study was to evaluate the biocompatibility and the efficacy in wound healing of a gelatin-based interpenetrating polymer network (IPN) containing poly(ethylene glycol) (PEG)-ylated RGD and soluble KGF-1 (RGD-IPN+KGF). IPNs were applied to full-thickness wounds on a rat model. Wound healing was assessed through histological grading of the host response and percent area contraction at 2 days, 1 week, 2 weeks, and 3 weeks. A control IPN containing unmodified gelatin (unmod-IPN) and a conventional clinical bandage were applied to similar wounds and also evaluated. During the first week of healing, the unmod-IPN and conventional dressing wound showed a greater amount of contraction than that of RGD-IPN+KGF. However, by 3 weeks the extent of wound contraction was comparable between treatments. The RGD-IPN+KGF treated wound demonstrated lower macrophage and fibroblast densities at 3 weeks as compared to unmod-IPN treated wounds. RGD-IPN+KGF acted as a tissue scaffold while preventing the entry of foreign bodies, advantages not seen with the conventional dressing. The extent of cellularity and extracellular matrix organization was higher for wounds healed with RGD-IPN+KGF than those healed with unmod-IPN. These results indicate that both soluble and immobilized bioactive factors can be incorporated into our IPN platform to enhance the rate and the quality of dermal wound healing. © 2007 Wiley Periodicals, Inc.Link_to_subscribed_fulltex

Biofilm formation on nanostructured hydroxyapatite-coated titanium

Biofilm formation on medical devices is a common cause of implant failure, especially regarding implants that breach the epithelial tissue, so-called transcutaneous implants. Nanotechnology and the development of new nanomaterials have given the opportunity to design nanotextured implant surfaces. Such surfaces have been studied using various in vitro methods showing that nanosized features strongly benefit bone cell growth. However, little is known on how nanostructured features affect biofilm formation. The aim of this study was therefore to examine the shape- and chemical-dependent effect of a nanostructured hydroxyapatite (HA) coating on the degree of Staphylococcus epidermidis biofilm formation. Three different types of nanosized HA particles having different shapes and calcium to phosphate ratios were compared to uncoated turned titanium using safranin stain in a biofilm assay and confocal laser scanning microscopy (CLSM) for assessment of biofilm biomass and bacterial volume, respectively. No difference in biofilm biomass was detected for the various surfaces after 6 h incubation with S. epidermidis. Additionally, image analysis of CLSM Z-stacks confirmed the biofilm assay and showed similar results. In conclusion, the difference in nanomorphology and chemical composition of the surface coatings did not influence the adhesion and biofilm formation of S. epidermidis

Degradation and biocompatibility of photoembossed PLGA-acrylate blend for improved cell adhesion

We have shown previously that PMMA–acrylate photopolymers are biocomopatible and can exhibit improved cell adhesion compared to PMMA, due to an increase in negative surface charge caused by UV radiation PLGA has been used widely in soft tissue regeneration due to its high biocompatibility and cell adhesion. This polymer is also biodegradable and can be utilised in the field of vascular regeneration. In this study, PLGA is blended with a triacrylate monomer (TPETA) to create a degradable photopolymer blend. Surface relief structures are formed on this PLGA–TPETA by photoembossing. An optimum height of 950 nm was achieved for a 10 µm pitch with the height of these relief structures being controlled by changing UV intensity, processing temperature and time. Degradation studies of this blend revealed a bulk degradation mechanism with PLGA–TPETA degrading slower compared to pure PLGA. We also evaluated the adhesion of human umbilical vein endothelial cells (HUVECs) on both smooth and textured PLGA–TPETA films. Embossed PLGA–TPETA films showed improved cell adhesion compared to smooth substrates. Furthermore, HUVECs proliferated faster on the embossed surface compared to their smooth counterparts