The in vivo and in vitro diabetic wound healing effects of a 2-herb formula and its mechanisms of action

The herbs Radix Astragali (RA) and Radix Rehmanniae (RR) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating diabetic foot ulcer. Diabetic complications, such as foot ulcer, impose major public health burdens worldwide. In our previous clinical studies, two Chinese medicine formulae F1 and F2 have achieved over 80% limb salvage. A simplified 2-herb formula (NF3) comprising of RA and RR in the ratio of 2:1 was used for further study. NF3 was examined for the ulcer healing effect in diabetic rats, and its potential mechanisms of action in fibroblast proliferation, angiogenesis and anti-inflammation in vitro. A chemically induced diabetic foot ulcer rat model was used for studying the wound healing effect. In the in vitro mechanistic studies, human fibroblast cells (Hs27), human umbilical vein endothelial cells (HUVEC) and mouse macrophage cells (RAW264.7) were assessed for tissue regeneration, angiogenesis and anti-inflammatory activities, respectively. Our in vivo results demonstrated a significant reduction of wound area at day 8 in NF3 (0.98 g/kg) group as compared to control (p < 0.01). NF3 could significantly stimulate Hs27 proliferation in a dose dependent manner (p < 0.05). Besides, NF3 could significantly increase the cell migration and tube formation (p < 0.05–0.001) of HUVEC in the angiogenesis study. Furthermore, significant inhibition of nitric oxide production (p < 0.01) was found in NF3-treated macrophage cells, suggesting its anti-inflammatory activity. Our study presents for the first time scientific evidence towards the efficacy of the two-herb formula NF3 in enhancing diabetic wound healing through the actions of tissue regeneration, angiogenesis and anti-inflammation.