Papers by Author: Zhi He Zhao

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Authors: Juan Li, Zhi He Zhao, Guo Ping Chen, Hai Tang, Zhi Hua Li, Jun Zeng, Song Jiao Luo, Yi Zheng, Zheng Zhou
Abstract: We have designed a new four-point bending system by combination of integrate circuit and beam-deflection theory, and conducted a series of experiments concerning cell morphology and proliferation. The system was proved to be able to supply the cultured anchorage-dependent cells with cyclic uniaxial stretching strain and compressive stress easily, precisely and effectively.
Authors: Qi Feng Zhang, Shu Juan Zou, Meng Chun Qi, Yang Xi Chen, Zhi He Zhao
Abstract: Cranial sutures produce new bone at the sutural edges of the bone fronts in response to external stimuli. Little is known regarding the mechanism of osteogenesis in cranial sutures. Ets1 and Cbfa1 are two important osteogenic transcription factors regulating the differentiation and maturation of osteoblasts. But their function in cranial sutures is not still elucidated. We have investigated the gene expression of Ets1 and Cbfa1 in rat’s calvarial sutural osteoblast-like cells under a single period of mechanical strain. The cells were isolated from the cranial suture of SD rats and cultured in vitro, and subjected to a single 40 minutes mechanical strain using a four-point bending apparatus. The gene expression patterns of Ets1 and Cbfa1 were examined by RT-PCR. Both mRNA levels of Ets1 and Cbfa1 have increased significantly within 6 and 12 hours respectively after mechanical strain were applied, and the increase returned to control level thereafter. However, Ets1 and Cbfa1 exhibited different temporal expression patterns: Ets1 expressed immediately after the mechanical loading and reached the maximum transcription at 0.5h; whereas Cbfa1 experienced a latency period first, then increased slowly within 2 hours, and reached the maximum transcription at 6 h. The maximum transcription of Cbfa1 was about 2.58 fold of that of Ets1. Ets1and Cbfa1 may play different roles in regulating bone matrix protein expressions in osteoblast-like cells during suture distraction and their function is time-dependent. High frequency distraction (>2times/24h) is favourable to the maximal expression of the two genes.
Authors: Zhi He Zhao, Jun Wang, Yu Bo Fan, Song Jiao Luo, Ling Yong Jiang
Abstract: It was well recognized that mechanical strain plays a crucial role in periodontal tissues remodeling. The aim of this study was to investigate the effect of mechanical strain on osteoblastic precursor cells in a collagen type I gel scaffold. Rat MSCs were isolated and cultured according to the established method. Cells were induced with osteogenic medium, then seeded in a collagen type I gel and mechanically stretched by application of cyclic biaxial strain 24h later. Strain cycle was set to 1 cycle/min (0.017Hz), and strain magnitude was set to 2%, 5%, 7% elongation. Cells were collected in 0h, 3h, 6h, 9h, 12h, 24h and 48h respectively. ODF and ICAM-1 mRNA were analyzed by RT-PCR assay. The results shown that 2-7% elongation strain, either dynamic or static, inhibited ICAM-1and ODF expression of osteoblastic precursors, and the effects were relative tightly to strain magnitude. The inhibition effects of dynamic strain loading group exceeded the corresponding static strain. This work suggested that appropriate mechanical strech may suppress differentiation of osteoclasts through inhibiting expression of ICAM-1 and ODF. Application of mechanical stress might have a beneficial effect on quantity of generated bone tissue and might be a important factor in tissue engineering of periodontal tissues.
Authors: Zhi Qiang Wang, Zhi He Zhao, Jin Lin Song, Yu Bo Fan, Song Jiao Luo
Abstract: The purpose of this study is to study the proliferous effect of mandibular condylar chondrocytes given static tension-stress and/or transforming growth factor-β1 (TGF-β1) in vitro. The fourth-passage condylar chondrocytes were harvested for this study, and a pulsatile cellular mechanical system was used to apply stress on cells. The proliferous effect of condylar chondrocytes given continuous static tension-stress and/or TGF-β1 were examined by using flow cytometry. The experiment was divided into two parts. The first part was divided into 20 groups according to different TGF-β1 dosage (0ng/ml, 0.1ng/ml, 1ng/ml and 10ng/ml) for 0, 6, 12, 18 and 24 hours respectively. The second part was divided into eight groups under continuous static tension-stress (0 or 5kPa) and different TGF-β1 dosage (0ng/ml, 0.1ng/ml, 1ng/ml, 10ng/ml) for 12 hours. Experimental data was analyzed with repeated interclass analysis of variance The results showed that chondrocytes which were cultured under different TGF-β1dose combined with 5kPa static tension-stress had multi-horn morphological characters, including a great quantity of chondrocytes with division growth.TGF-β1 had a mitogenic effect on rat mandibular condyle chondrocytes at the concentrations of 0.1 , 1 and 10ng/ml , and the mitogenic effect of TGF-β1 to condylar chondrocytes were demonstrated after 12 to 18 hours, and the peak of mitogenic effects appeared at the 18th hour (P <0.05) . The most active mitogenesis happened in the group whose chondrocytes was under continuous static tension-stress (5kPa) combined with TGF-β1. These results proved that mechanical stimulus and TGF-β1 in vitro could influence and regulate the growth of condylar chondrocytes.
Authors: Qi Feng Zhang, Shu Juan Zou, Hai Xiao Zhou, Yang Xi Chen, Meng Chun Qi, Zhi He Zhao
Abstract: The purpose of the present study was to observe the response and changes of cranial suture to the distraction forces in growing goats and to examine the expression patterns of TGF-β and BMP during suture distraction.Twenty growing goats were divided into three groups: control (n=4), experimental (n=12), and sham (n=4). A pure titanium distractor was placed in the coronal suture in both the sham and experimental groups. After healing, the distractor was activated for distraction of the coronal suture at a rate of 0.5 mm/day for 8 days in the experimental group. Three animals were killed respectively, at 0,2,4 and 8 weeks after completion of suture distraction. No force was applied in the sham group. X- Ray examination was taken and the coronal suture samples were harvested and processed for histological analysis and scanning electron microscopic analysis and immunohistochemistry of TGF-β and BMP. The coronal sutures of experimental group were separated successfully. Signs of intramembranous bone formation and remodeling were found in the distracted suture,and the sutural structure almost return to its normal state at 8 weeks after end of distraction. At 0 and 2 weeks after completion of suture distraction, the collagen fiber bundles were strengthened and aligned in the direction of the distracted forces. Strong expression of BMP and TGF-β were detected in the fibroblast-like cells and the active osteoblasts. At 4 weeks after suture distraction, signs of intramembranous ossification were found in the edge areas of the distracted suture, and the positive staining of BMP and TGF-β was still noted in the osteoblasts around the newly formed bone trabeculae. This study suggests that cranial suture expansion can be achieved in growing animal by distraction osteogenesis. Mechanical strain resulted from distractor can induce the adaptive remodeling in the cranial suture of growing goats. It also suggests BMP and TGF-β may play very important roles in the process of bone formation and remodeling during suture distraction osteogenesis.
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