The cornea and the skin are two organs that form the outer barrier of the human body. When either is injured (e.g., from surgery, physical trauma, or chemical burns), wound healing is initiated to restore integrity. Many cells are activated during wound healing. In particular, fibroblasts that are stimulated often transition into repair fibroblasts or myofibroblasts that synthesize extracellular matrix (ECM) components into the wound area. Control of wound ECM deposition is critical, as a disorganized ECM can block restoration of function. One of the most abundant structural proteins in the mammalian ECM is collagen. Collagen type I is the main component in connective tissues. It can be readily obtained and purified, and short analogs have also been developed for tissue engineering applications, including modulating the wound healing response. This review discusses the effect of several current collagen implants on the stimulation of corneal and skin wound healing. These range from collagen sponges and hydrogels to films and membranes.
Aging is a complex physiological process that can be accelerated by chemical (high blood glucose levels) or physical (solar exposure) factors. It is accompanied by the accumulation of altered molecules in the human body. The accumulation of oxidatively modified and glycated proteins is associated with inflammation and the progression of chronic diseases (aging). The use of antiglycating agents is one of the recent approaches in the preventive strategy of aging and natural compounds seem to be promising candidates. Our study focused on the anti-aging effect of the flavonoid hesperetin, its glycoside hesperidin and its carbohydrate moieties rutinose and rhamnose on young and physiologically aged normal human dermal fibroblasts (NHDFs). The anti-aging activity of the test compounds was evaluated by measuring matrix metalloproteinases (MMPs) and inflammatory interleukins by ELISA. The modulation of elastase, hyaluronidase, and collagenase activity by the tested substances was evaluated spectrophotometrically by tube tests. Rutinose and rhamnose inhibited the activity of pure elastase, hyaluronidase, and collagenase. Hesperidin and hesperetin inhibited elastase and hyaluronidase activity. In skin aging models, MMP-1 and MMP-2 levels were reduced after application of all tested substances. Collagen I production was increased after the application of rhamnose and rutinose.
Myricetin (MYR) and dihydromyricetin (DHM) are classified as natural flavonoids. Both substances are known for their anti-inflammatory and antioxidant properties. In this study, an in vitro model of inflammation was demonstrated on monolayers of scratched fibroblasts or keratinocytes exposed to LPS from Pseudomonas aeruginosa for six hours. MYR and DHM were subsequently applied to the cells for 24 hours at sub toxic concentrations (5-15 µM). Inflammatory parameters were analysed in collected cell medium and lysate after the incubation period using the Enzyme-Linked ImmuneSorbent Assay (ELISA) and Western blot. Both flavonoids inhibit the production of pro-inflammatory cytokines (IL-6, IL-8) in LPS-stimulated skin cells as well as the decreased level of MMP-1 in fibroblasts. However, the application of MYR and DHM dose dependently increased the level of MMP-1 in keratinocytes. In our experiments, we focused on the anti-glycation activity of MYR and DHM, where the higher concentration of MYR seems to be more effective.
Hyaluronic acid (HA) has attracted the attention of scientists for its application in many medical fields owing to its intrinsic properties such as biodegradability, biocompatibility, and nontoxicity. Poor stability and antibacterial activity are the most significant drawbacks of using HA in preparing a wound dressing. The wound dressing should be able to swell and absorb exudates from the wound, as well as possess antibacterial activity. Herein, we successfully prepared an HA-based antibacterial wound dressing that can swell more than 500 times and with good mechanical properties. HA was used both as reducing and stabilizing agents, and zinc oxide nanoparticles (ZnO-NPs) were incorporated via in situ synthesis. The uniform spherical shape of ZnO-NPs (50 ± 10 nm) was synthesized and assembled on a hyaluronan/polyvinyl alcohol matrix (HA/PVA), forming stable and evenly distributed ZnO-NPs, which interacted with the HA/PVA. Such a hybrid nanostructure prevented ZnO-NPs from dropping off the PVA/HA network and thus minimized the toxicity of NPs. Concerning the slow release of NPs, the nanocomposite membrane still exhibited significant antibacterial activity against different types of bacteria (G+/−). The ZnO-NPs/HA/PVA composite membrane allows the attachment and growth of normal human dermal fibroblasts and human primary osteogenic sarcoma (Saos-2) without exhibiting toxicity. In vivo measurements showed that the nanocomposite PVA/HA/ZnO-NP membrane promoted infected wound healing compared with the control sample. The results obtained suggest that the investigated nanocomposite has reasonable potential as an antibacterial wound dressing material.
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