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Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects. In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing. A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control. Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C. In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous). Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.

An auxetic polyurethane (PU) scaffold was prepared to investigate chondrocyte proliferation under compressive stimulation for cartilage regeneration. To give a negative Poisson’s ratio to the PU scaffold, volumetric compression with a 3 : 1 ratio was applied during heat treatment. For the control PU scaffold, the Poisson’s ratio was 0.9 ± 0.25 with elongation at 20% of the strain range. Poisson’s ratio for experimental specimens was approximately −0.4 ± 0.12 under the same conditions. In cell proliferation tests, cells were cultivated within the prepared scaffold under compression with a 20% strain range. With a 20% strain range elongation, the compressive load was approximately 0.3 N. The experimental group showed a 1.3 times higher cellular proliferation rate than that of the control group after 3 days in culture. At day 5 of culture, however, the rate of proliferation of the control group increased so that there was no significant difference between groups. However, collagen content (produced by the cells) in the cell-proliferated medium was 1.5 times higher in the experimental group after 5 days in culture. This may have been due to the effectiveness of the auxetic structure of the scaffold. An isotropic compressive load was transmitted to the cells due to the negative Poisson ratio of the scaffold.

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PurposeThis study aimed to develop an anti-inflammation system consisting of epigallo-catechin-3-gallate (EGCG) encapsulated in poly(lactide-co-glycolic acid) (PLGA) particles to promote wound healing.MethodsNano- and microscale PLGA particles were fabricated using a water/oil/water emulsion solvent evaporation method. The optimal particle size was determined based on drug delivery efficiency and biocompatibility. The particles were loaded with EGCG. The anti-inflammatory effects of the particles were evaluated in an in vitro cell-based inflammation model.ResultsNano- and microscale PLGA particles were produced. The microscale particles showed better biocompatibility than the nanoscale particles. In addition, the microscale particles released ~60% of the loaded drug, while the nanoscale particles released ~50%, within 48 hours. Thus, microscale particles were selected as the carriers. The optimal EGCG working concentration was determined based on the effects on cell viability and inflammation. A high EGCG dose (100 μM) resulted in poor cell viability; therefore, a lower dose (≤50 μM) was used. Moreover, 50 μM EGCG had a greater anti-inflammatory effect than 10 μM concentration on lipopolysaccharide-induced inflammation. Therefore, 50 μM EGCG was selected as the working dose. EGCG-loaded microparticles inhibited inflammation in human dermal fibroblasts. Interestingly, the inhibitory effects persisted after replacement of the drug-loaded particle suspension solution with fresh medium.ConclusionThe EGCG-loaded microscale particles are biocompatible and exert a sustained anti-inflammatory effect.