Angiogenesis, the growth of new blood vessels from preexisting vasculature, plays an important role in physiological and pathological processes such as embryonic development and wound healing. This study investigated the effects of methanol extracts of Stewartia koreana leaves (SKE) on angiogenesis. Stewartia koreana significantly promoted the proliferation and migration of human umbilical vein endothelial cells in a dose-dependent manner. The SKE induced endothelial cell proliferation in the range of 50 microg/mL without cytotoxicity. Treatment of HUVECs resulted in the activation of the mitogen-activated protein kinases that was correlated with endothelial cell proliferation and migration. SKE also stimulated angiogenesis in a chick chorioallantoic membrane assay, demonstrating promotion of new blood vessel formation in vivo. Local administration of SKE onto skin punched wounds resulted in increased von Willebrand Factor antigen, indicating that it stimulated neovasculization in the wound region. The results suggest that Stewartia koreana extracts may potentially be useful for the development of agents to accelerate vascular wound healing or to promote the growth of collateral blood vessels in ischemic tissues.

Stewartia koreana (S. koreana) has been used in the treatment of inflammatory diseases, such as acute gastroenteritis and aches, in Korean folk medicine and has been reported to have a number of biological activities, such as anti-inflammatory activity and the promotion of angiogenesis. In this study, we aimed to determine the effects of S. koreana extract (SKE) and its components on dermal fibroblast growth and migration, and to investigate the wound healing activity of the extract in mice. In vitro experiments revealed that the numbers of SKE-treated cells increased by approximately 2.5-‑ and 3.7-fold with 50 and 100 µg/ml of SKE, respectively. 5-bromo-2'-deoxy-uridine (BrdU) incorporation was also increased in the SKE-treated cells by 2.3-fold. SKE promoted the migration of human skin fibroblasts and, among the isolated compounds, hyperin increased the proliferation and migration of the fibroblasts to almost the same degree as SKE. Western blot analysis demonstrated that SKE stimulated the MEK/ERK1/2 and PI3K/Akt signaling pathways. In in vivo experiments, the SKE-treated wound lesions of mice decreased by approximately 7% in diameter after 2 days of treatment with SKE compared with the wound lesions on the 1st day of the experiment. On the 9th day of treatment, the diameter of the lesions was further reduced by approximately 83% in the SKE-treated wound areas compared with the wound areas on the 1st day of treatment. Our results demonstrate that methanol extracts of S. koreana leaves promote the proliferation and migration of skin fibroblasts and possess effective wound healing activity through the activation of the MEK/ERK1/2 and PI3K/Akt signaling pathways. Hyperin was identified as an active compound responsible for the stimulation of fibroblast growth and migration.

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