Urtica extracts induce periosteal cell proliferation and differentiation:tissue-engineered bone construction and ultrastructural changes

Xu Bing; Liu Yuan

doi:10.3969/j.issn.2095-4344.0196

Abstract：BACKGROUND: Urtica, a traditional Chinese herbal, holds anti-inflammatory and anti-rheumatic effects, but its influence on periosteal cells is little reported. OBJECTIVE: To investigate the proliferation and differentiation of human periosteal cells induced by urtica and to construct tissue-engineered bone by periosteal cells in vitro,thereby providing theoretical basis for the application of urtica in bone tissue engineering. METHODS:Human clavicle periosteum was obtained.Primary periosteal cells were cultured by tissue culture method in vitro,passaged,and the 3 generations of periosteal cells were seeded into cell culture plate, and treated with urtica extracts (10-6, 10-5and 10-4g/L, experimental group), 50 μg/L bone morphogenetic protein-7 (positive control group) or purified water (control group). The absorbance values of periosteal cells were measured by MTT assay, and the expression levels of alkaline phosphatase and calcium nodules were detected by alkaline phosphatase staining and Von Kossa staining at 1, 4, 7 and 9 days after culture. 10-4g/L urtica extracts and bone morphogenetic protein-7 were added into the three-dimensional polyclonal lactone scaffold and periosteal cells to construct tissue-engineered bone. After 24 days of culture, the morphological changes of periosteal cells were observed under electron microscope. RESULTS AND CONCLUSION: MTT results revealed that the absorbance values of periosteal cells in the experimental and positive control groups were significantly higher than those in the control group at different time points (P < 0.05); the order of absorbance values was as follows: 10-4group > 10-5group > 10-6g/L group (P < 0.05), suggesting 10-4g/L was the optimal concentration. The positive rates of alkaline phosphatase and calcium nodules in the experimental and positive control groups were significantly higher than those in the control group (P< 0.05), but the experimental and positive control groups did not differ significantly (P > 0.05). In the experimental group, there were abundant microvilli on the cell membrane, the mitochondria matrix was dense and appeared with crista, and active proliferation and differentiation of cells were detected. The number of mitochondria in the experimental and positive control groups was significantly more than that in the control group (P < 0.05). These findings indicate that periosteal cells can be induced by urtica to amplify and differentiate into osteoblasts, and construct tissue-engineered bone in the three-dimensional polyclonal lactone scaffold.