Investigation of the blended fibroin/aloe gel extract film on the biomolecular mechanism(s) relating to fibroblast wound healing activity

Abstract

In diabetic patients, the wound healing process is usually delayed or impaired. A primary chronic complication is diabetic foot ulcers. A diabetic environment could be associated with dermal fibroblast dysfunction, reduced angiogenesis, the release of pro-inflammatory cytokines, and senescence features. Alternative therapeutic treatments using natural products are highly demanded for their high potential of bioactive activity in skin repair. In this study, the physicochemical and biological properties of a gamma-irradiated blended fibroin/aloe gel extract film were investigated to support the wound healing efficacy of the prepared film. This work extends our previous studies in vitro and in vivo in the streptozotocin-induced diabetic rat and clinical trials in diabetic foot ulcer patients. In the current study, silk fibroin and aloe gel extract were separately analyzed for their protein content, molecular weight pattern, and chemical characteristics. Both extracts were then dissolved in lactic acid solution and simply cast to obtain the blended fibroin/aloe gel extract film, and the physicochemical and biological properties of the prepared film were determined. We found that gamma irradiation does not affect any physicochemical properties of the prepared film, such as physical appearance (flexibility translucence and yellowish color), surface morphology (non-porous morphology), mechanical properties, and chemical characteristics (presenting of amide I, II, III, glucan units, pyranoside ring, and mannose). The film-treated cells stimulated the proliferation by initiating a shift from G0/G1 phase to S phase and G2/M phase, which were higher than the untreated cells. The film-treated cells provided a completely healed scratch at 36 h after wound creation, while untreated wound was not fully healed, indicating that the biological activity of the prepared film enhances the proliferation and migration of the fibroblast cells and thereby stimulates wound healing improvement in diabetic foot ulcers. The prepared film was also investigated for its beneficial effects on cell biological activities and biomolecular mechanism(s) using normal dermal, diabetic dermal, and diabetic wound fibroblasts. This study aimed to elucidate the possible MAPK/ERK signaling pathway related to the biological effects of the film on fibroblast cells. The biological activities and biomolecular mechanism(s) were determined, including cytotoxicity, cell proliferation, cell cycle, cell migration, VEGF protein secretion, and ERK1/2 signaling pathway assays. The prepared film illustrated the preferential activities to promote cell proliferation and migration, VEGF secretion, and prevention of cell senescence. Furthermore, the prepared film displayed a biological behavior with interesting properties for delayed wound healing. Its mechanism of action is mainly linked to the activation of the MAPK/ERK pathway known to regulate various cellular activities, including proliferation. Therefore, the blended fibroin/aloe gel extract film can be considered as a novel therapeutic approach in treating diabetic non-healing ulcers.

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