Effects of Drynariae rhizoma on the proliferation of human bone cells and the immunomodulatory activity

Drynariae Rhizoma (DR), a traditional Korea medicine, which is known for its effect to strengthen myoskeletal systems, frequently appears as the main ingredient in prescriptions for bone injuries. However, it is unclear how it pharmacologically contributes to the reformation of bone. In this study, the effect of DR on bone cells was investigated in vitro for the first time. The human osteoprecursor cells (OPC-1) were incubated in the medium with different concentrations of DR and the cell proliferation was studied. When the concentration of DR was ≤120 μg ml−1, the proliferation of OPC-1 was enhanced. However, the proliferation of OPC-1 was inhibited by DR with the concentrations of >250 μg ml−1. Under most treatments, the cells presented very pale expression for cyclooxygenase-2 (Cox-2) protein; slightly intensified band showed at the highest DR concentration, 120 μg ml−1 during the course of culture. On the other hand, we investigated the immunomodulatory activity of DR on cellular and humoral immunity. When different doses of ethanolic and water extracts of DR was administerd to mice, it was dose-dependently potentiated the delayed-type hypersensitivity reaction induced by both sheep red blood cells (SRBC) and oxazolone. It significantly enhanced the production of circulating antibody titre in mice in response to SRBC. But, DR did not any effect on macrophage phagocytosis. Prolonged administration of DR significantly ameliorated the total white blood cell count and also restored the immunosuppressive effects induced by cyclophosphamide. The present investigation reveals that DR possesses immunomodulatory activity. From the results, it was concluded that DR directly stimulated the proliferation, alkaline phosphatase activity, protein secretion and particularly type I collagen synthesis of OPC-1 at dose-dependent manner, and stimulated both the cellular and the humoral immunity.