Excessive skin scars due to elective operations or trauma represent a challenging clinical problem. Pathophysiology of hypertrophic scars entails a prolonged inflammatory and proliferative phase of wound healing. Over expression of TGF-β1 and COX-2 play key regulatory roles of the aberrant fibrogenic responses and proinflammatory mediators. When we silenced TGF-β1 and COX-2 expression simultaneously in primary human fibroblasts, a marked increase in the apoptotic cell population occurred in contrast to those only treated with either TGF-β1 or COX-2 siRNA alone. Furthermore, using human hypertrophic scar and skin graft implant models in mice, we observed significant size reductions of the implanted tissues following intra-scar administration of TGF-β1/COX-2 specific siRNA combination packaged with Histidine Lysine Polymer (HKP). Gene expression analyses of those treated tissues revealed silencing of the target gene along with down regulations of pro-fibrotic factors such as α-SMA, hydroxyproline acid, Collagen 1 and Collagen 3. Using TUNEL assay detection, we found that the human fibroblasts in the implanted tissues treated with the TGF-β1/COX-2siRNAs combination exhibited significant apoptotic activity. Therefore we conclude that a synergistic effect of the TGF-β1/COX-2siRNAs combination contributed to the size reductions of the hypertrophic scar implants, through activation of fibroblast apoptosis and re-balancing between scar tissue deposition and degradation.

Terrestrial snail could intelligently employ elastic fibers clinging itself onto the inverted smooth plate.

Hydrogels had been prepared by blending PLA-PEG-PLA copolymer with Bombyx mori silk fibroin (SF) solution. Copolymers were synthesized by ring opening polymerization of L-lactide in the presence of dihydroxyl PEG with molar mass of 400 and 1000, and characterized by using (1)H NMR and DSC. Hydrogels formed leaf-like lamellar structures with many nanoglobules which may reserve drugs or growth factors more effectively. Rheological measurements indicated that the adding of copolymer significantly accelerated the hydrogelation of silk fibroin solution which leads to orders-of-magnitude increase in the complex shear modulus to form rigid hydrogel. Hydrogelation kinetics could be controlled easily by changing the concentration ratio, kinds of copolymer and hydrogelation temperature, suggesting the hydrogels could be formed in situ under physiological conditions with suitable mechanical properties. Furthermore, Fourier transform infrared, X-ray diffraction, and differential thermal analysis were employed to study the structure of hydrogels. The copolymer and SF in blend hydrogels were phase separation. There was an increase of β-sheet content and formation of silk II structure during hydrogelation. These results may indicate that copolymer/SF hydrogels could be a valuable candidate scaffold as in situ-forming hydrogels for drug/growth factor release in tissue engineering.

No abstract

Flexible silk fibroin gel-like films with microporous morphology were prepared from B. mori silk fibroin fibers directly solubilized in formic acid/CaCl 2 solvent. These films were characterized by several analysis techniques to determine the structure and properties of films. The pore size of gel-like films can be adjusted through SF concentration and Ca ions concentration. The controllable pore size in gel-like films was grew from 3-5 lm to 100 lm under the increase of fibroin concentration from 1.0 wt % to 8.0 wt %. At the same time, the water content of silk fibroin gel-like film decreased from 83.5 6 3.4% to 68.2 6 2.6%. With increasing Ca ions contents from 2.0 wt % to 10.0 wt % in dissolution process, the pore size and water content of silk fibroin gel-like films grew larger, especially its water content values reached 86.2 6 4.0% at 10.0 wt % Ca ions concentration. At wet condition, the gel-like film with b-sheet structure showed higher breaking stress (4.26 6 0.31 MPa) and elongation (45.45 6 15.79%) at 8.0 wt % concentration. With the preparation method, the membrane is hydrophilic and the pore size is adjustable, which contributes to high toughness and favorable cell growth environment, suggesting that these silk fibroin gel-like films can be a potential candidate scaffold for biomedical applications, such as wound dressing, facial mask, contact lenses, etc.