Papers by Author: Zhong Li Shi

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Authors: Bing Gang Guan, Di Sheng Yang, Zhong Li Shi, Wen Jian Weng, Wei Qi Yan
Abstract: A novel biomimetic composite consisted of nano β-tricalcium phosphate and collagen (n-TCP/Col.), having similar structure with the natural bone, was produced by a wet-chemical method. The biological effect with and without n-TCP/Col on bone repair and regeneration was evaluated by histological and radiological examination in a rabbit femoral condyle model. The results showed that radiopacity of implant decreased gradually and began to increase at 12 weeks, while no obvious changes for the control. Histological results revealed that trabecular bone formed around the implant at 4 weeks and increased at 8 weeks; By 12 weeks, bone filling with Harvard’s system was observed around the implant. By contrast, only loose connective tissue was seen in control group. This was further illuminated by fluorescence microscopy. The results of this study suggested that the novel nano β-tricalcium phosphate and collagen composite possessed good properties of osteoconductivity and degradation in the biological environment, which could have potential application as a promising bone substitute.
Authors: Zhong Li Shi, Wei Qi Yan, Jie Feng, Bing Gang Guan, Yang Bo Liu, Shi Gui Yan
Abstract: To evaluate the effectiveness of the cell-material in situ on joint resurfacing, a woven fabric polyglycolic acid (PGA) treated with fresh chondrocytes was used for repairing cartilage defects. Full-thickness defects were created in the weight-bearing surfaces of the femoral intercondylar fossa in a rabbit model. The defect was filled with and without PGA under surgical condition. Before implantation, chondrocytes were co-cultured with PGA for one day. The animals were sacrificed at eight weeks after implantation and evaluated grossly and histological score. Morphological examination showed that for PGA/chondrocytes group, the repaired tissue appeared similar in color and texture to the surrounding articular surface. While for the untreated control, no cartilage-like tissue was observed at all defects, but connective fibrous tissue. Histological analysis revealed neochondrogenesis and clusters of cartilage matrix with specific safranin-O staining for the PGA/cell group. The Gross and histological evaluation indicated a significantly higher score for PGA/cell group than for PGA and control group. These results suggest that the woven fabric PGA may facilitate the formation of cartilage tissues by providing a biodegradable and good-handle vehicle for the delivery to and retention of organized cell matrix constructs in vivo site. It might therefore enhance neochondrogenesis because of the superior biodegradable and biocompatible of PGA scaffold sheet, while the more suitable biological environment might sustain cell growth and in situ cell function, suggesting a promising candidate for functional tissue engineering of clinical environment.
Authors: Jie Feng, Qiang Zheng, Zhong Li Shi, Hong Liang Jiang, Wei Qi Yan
Abstract: Bone grafts have been used to fill bone defects caused by disease or trauma. The amount of autografts is limited and allogenic bone grafts may transmit diseases and cause immune responses. Numerous materials have been proposed and used as scaffolds for bone tissue reconstruction. In this study, we tested nanophase PLGA/HA composite with mesenchymal stem cells in vitro to examine its biological response and cellular activity. The nanophase composite was compared to conventional polystyrene on cytocompatibility by cell attachment, proliferation, alkaline phosphotase activity test and scanning electron microscopy (SEM) analysis. The results demonstrated that human mesenchymal cells showed more cell attachment and higher cell proliferation rate when growing on nanophase PLGA/HA composite than those growing on polystyrene alone. And the composite also promoted MSC cells differentiate to osteoblast cells as compared with control. It was suggested that the combination of bone marrow mesenchymal cells with artificial materials or differentiation factors may enhance bone formation and regeneration, nanophase PLGA/HA composite might therefore be a promising scaffold material for bone tissue substitute in clinical application.
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