In vitro and in vivo evaluation of the chitosan/Tur composite film for wound healing applications

We have developed tourmaline/chitosan (Tur/CS) composite films for wound healing applications. The characteristics of composite films were studied by optical microscope, infrared spectra and X-ray diffraction. Tur particles were uniformly distributed in the CS film and the crystal structure of CS was not remarkably changed except the decrease of crystallinity. The influence of Tur on wound healing applications was characterized by modulating Tur concentrations in the Tur/CS composite film prepared by loading Tur powder into CS matrix with different proportion (0, 1/40 and 1/10). Then L929 cells were co-cultured on the composite films to access the cytotoxicity in vitro. Tur concentrations strongly influenced cell process extension. Tur/CS composite film with 1/40 mass ratio could promote the cell adhesion and proliferation. Fewer and shorter processes were observed at high Tur density. When the composite films were transplanted on porcine full-thickness burn wounds, histological results demonstrated that the Tur/CS group with 1/40 mass ratio had a significantly higher number of newly-formed and mature blood vessels, and fastest regeneration of dermis. Based on the observed facts these films can be tailored for their potential utilization in wound healing and skin tissue engineering applications.     

Development of a functional wound dressing composed of hyaluronic acid spongy sheet containing bioactive components: evaluation of wound healing potential in animal tests

This study aimed to develop a novel wound dressing composed of hyaluronic acid (HA) spongy sheet containing bioactive components. The wound dressing prepared by the freeze-drying method has a two-layered structure: an upper layer composed of cross-linked high-molecular-weight HA (HMW-HA) and a lower layer composed of low-molecular-weight HA (LMW-HA) containing arginine (Arg), magnesium ascorbyl phosphate (vitamin C derivative: VC), and epidermal growth factor (EGF) (referred to as EGF-dressing). A wound dressing containing only Arg and VC was prepared in a similar manner (referred to as EGF-free-dressing). The potential of each wound dressing was evaluated in animal tests using Sprague Dawley (SD) rats and diabetic mice. In the first experiment, each wound dressing was applied to a full-thickness skin defect in the abdominal region of SD rats. Wound conditions after 1?week and 2?weeks of treatment were evaluated based on macroscopic and histological appearance. A commercially available non-woven alginate wound dressing (Alg-dressing) was used in a control group. Both EGF-free-dressing and EGF-dressing decreased wound size and promoted granulation tissue formation associated with angiogenesis more effectively when compared with Alg-dressing. In particular, EGF-dressing promoted re-epithelialization. In the second experiment, each wound dressing was applied to a full-thickness skin defect in the dorsal region of diabetic mice. Wound conditions after 1?week and 2?weeks of treatment were evaluated based on macroscopic and histological appearance. A commercially available Alg-dressing was used in a control group. Both EGF-free-dressing and EGF-dressing decreased wound size and promoted granulation tissue formation associated with angiogenesis more effectively when compared with Alg-dressing. These findings indicate that EGF-free-dressing and EGF-dressing have the potential for more effective wound healing when compared with Alg-dressing. In particular, EGF-dressing has a higher potential for wound healing when compared with EGF-free-dressing.     

Characterization of extracellular matrix proteins during wound healing in the lamina propria of vocal fold in a canine model: A long-term and consecutive study

The characterization of vocal fold wound healing can be reflected by the changes of extracellular matrix (ECM) proteins in the lamina propria. Although the expression of ECM proteins after vocal fold injury has been widely studied, such observations have lacked time continuity and integrity of marker proteins. In this study, we observed the morphology of injured vocal folds in a canine model. We used immunofluorescence staining to evaluate the expression and distribution of ECM proteins, such as collagen, elastin, hyaluronic acid, decorin and fibronectin, from 15 days to 6 months after injury. The results showed that large amounts of ECM proteins were secreted 15–40 days after injury. Collagen and fibronectin secretion increased significantly, and were disorderly deposited. The secretion of decorin and elastin increased slightly, while hyaluronic acid decreased. The 15–40 day post-injury period may be the critical intervention stage in wound healing of vocal folds. From 3 to 6 months after injury, the secretion of ECM proteins declined. However, collagen and fibronectin secretion were still significantly higher than normal with irregular arrangement, while the secretion of elastin, hyaluronic acid and decorin decreased significantly at 6 months. This led to vocal fold inelasticity and stiffness, which required effective long-term interventions to treat scar formation.