Extract of Polygala tenuifolia, Angelica tenuissima, and Dimocarpus longan improve skin wound healing in streptozotocin-induced diabetic mouse

Abstract

Objective : Chronic skin wounds caused by diabetes, peripheral artery disease, pressure ulcers, and venous insufficiency do not fully recover anatomically and functionally. We previously found that topical application of 3% WIN-1001X cream reduces skin inflammation. In this study, we investigated whether 3% WIN-1001X cream alleviates chronic skin wounds exhibiting prolonged and extensive inflammation using streptozotocin-induced diabetic mouse. Methods : WIN-1001X contained 20% ethanol extracts of three botanical drugs: Polygala tenuifolia Willd., Angelica tenuissima Nakai, and Dimocarpus longan Lour. Streptozotocin-induced diabetic mice were used as a chronic wound model. After making full-thickness excision wounds were made on shaved dorsal skin, 3% WIN-1001X cream was topically applied daily for 12 days. The wound area was measured, and histology was performed to detect granulation tissue and collagen deposition. Quantitative real-time PCR and immunohistochemistry were performed to measure expression of RNA and proteins related to wound healing such as pro-inflammatory cytokines, growth factors, anti-microbial peptides, cell proliferation, keratinocyte differentiation, myofibroblast formation, and macrophage infiltration. Results : Topical application of 3% WIN-1001X cream suppressed infiltration of neutrophils and monocytes as well as pro-inflammatory cytokine gene activation in diabetic mouse skin. It also promotes M1 to M2 macrophage polarization. Interestingly, 3% WIN-1001X cream activated the gene expression of anti-microbial peptides. Furthermore, It up-regulated gene expression of PDGFβ, HGF, KGF, and TGFβ, resulting in the promotion of cell proliferation, granulation tissue formation, myofibroblast formation, and keratinocyte differentiation. Conclusion : 3% WIN-1001X cream suppressed skin inflammation through decreased cytokine gene expression, immune cell infiltration, and increased macrophage polarization. It also promoted cell proliferation, granulation tissue formation, and myofibroblast transition. Furthermore, 3% WIN-1001X cream promoted keratinocyte re-epithelialization and differentiation as well as increased collagen deposition in chronic skin wounds. Thus, our results suggest that 3% WIN-1001X cream may help alleviate chronic skin wounds.