Delayed healing remains a major clinical problem and here we have sought to develop an improved dressing film comprising 1.95% w/v fibroin and 0.05% w/v aloe gel extract. The tensile strength of dry film was 21.1 ± 0.5 MPa and broke at 1.1 ± 0.2% elongation; corresponding values for wet film were 18.3 ± 1.3 MPa and 1.9 ± 0.1%. The film maintained its shape upon water immersion and the swelling ratio of the dry film was 0.8 ± 0.1 while the water uptake was 43.7 ± 2.6%. After 28 days of incubation in phosphate buffered saline (1 M, pH 7.4, 37 °C), the weight of film was reduced by 6.7 ± 1.1% and the tensile strength and elongation at breaking point (dry state) were 15.4 ± 0.6 MPa and 1.5 ± 0.2%, respectively. Compared to aloe-free fibroin film (2.0% fibroin extract only), the blended film enhanced the attachment and proliferation of skin fibroblasts. The bFGF immunofluorescence of fibroblasts cultured on the blended film appeared greater than those cultured on tissue culture plate or on aloe-free fibroin film while α-smooth muscle actin was maintained. In streptozotocin-induced diabetic rats, the wounds dressed with the blended film were smaller (p <0.05) by day 7 after wounding, compared to untreated diabetic wounds. Histology of repaired diabetic wounds showed the fibroblast distribution and collagen fiber organization to be similar to wounds in normal rats, and this was matched by enhanced hydroxyproline content. Thus, such accelerated wound healing by the blended fibroin/aloe gel films may find application in treatment of diabetic non-healing skin ulcers.
ABSTRACT:The aim of this study was to determine the properties of β-glycerol phosphate (GP)/collagen/chitosan blended films for the potential application to skin tissue engineering. Various ratios of collagen to chitosan (8:2 and 7:3) and amounts of GP (0.5, 1, and 1.5% w/w) of total polymers were blended in solution form and cast into films. According to SEM images, the casted films showed a non-porous surface. For the mechanical properties, the prepared scaffolds exhibited the maximum elongation ranging from 15-23%, which is lower than those found by other researchers. However, the maximum tensile strength values of the scaffolds made from the collagen/chitosan (ratios 7:3) crosslinked with 0.5 or 1% w/w GP were in the range of 8-10 MPa which achieve the recommended values for application in skin tissue engineering. The scaffolds showed ability to retain their structure after immersion in phosphate buffer saline solution (pH 7.4) for 1 h, and their volume increased about 20%. After incubation in collagenase solution (200 U of collagenase/5 g of collagen) at 37°C, the scaffolds were degraded within 24 to 26 days which coincides very well with the healing time of acute wounds (about 25 days). FT-IR studies revealed the possibility of an interaction of GP with collagen/chitosan via ionic interaction that enhances the strength and stability of the prepared scaffold. The results from an in vitro culture study showed that the keratinocyte HaCaT culture could adhere well and grow on the selected scaffold with a typical morphology at 98.1 ± 1.8% of the control (cells growth on tissue culture plate) after cultivation for 5 days. The results suggest the potential of the GP/collagen/chitosan blended films for use as skin scaffolds.
In present study, the chitosan/starch/β-glycerol phosphate hydrogel was investigated as an effective carrier for chondrocytes and delivery of transforming growth factor-β1. In vitro study indicated that transforming growth factor-β1 was released sustainably for 14 days with its biological activity to stimulate chondrocyte functions, as indicated by the strong expression of type II collagen protein. Subcutaneous implantation to rats revealed the strong expressions of type II collagen and aggrecan messenger ribonucleic acids, and also type II collagen protein was observed in the hydrogel in combination with transforming growth factor-β1 within 2 weeks. Our collective results showed the potential of chitosan/starch/β-glycerol phosphate hydrogel for effective delivery of chondrocytes and transforming growth factor-β1, and preserve chondrocytes' phenotype and functions in vitro.
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