Papers by Author: Di Sheng Yang

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Authors: Yan Bo Feng, Wei Qi Yan, Di Sheng Yang, Jie Feng, Xiao Xiang Wang, Sam Zhang
Abstract: The objective of this study was to evaluate the interface shear strength and the responses of osteoblast-like cells to titanium implants with a sandblasted and acid-etched surface modified by alkali and heat treatments (SLA-AH). The implants with machined and SLA surface served as controls. Each type of implant was characterized by scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis. In vitro assays were made using human osteoblast-like cell culture on different surfaces. The rectangle plates were also transcortically implanted into the proximal metaphysis of New Zealand White rabbit tibiae. After 4, 8 and 12 weeks implantation, mechanical and histological assessments were performed to evaluate biomechanical and biological behavior in vivo. By SEM examination, SLA surface combined with AH treatments revealed a macro-rough surface with finely microporous structure. The in vitro assays showed that the SLA-AH surfaces exhibited more extensive cell deposition and improved cell proliferation as compared with controls. Pull-out test demonstrated that the SLA-AH treated implants had a higher mechanical strength than the controls at all interval time after implantation. Histologically, the test implants revealed a significantly greater percentage of bone-implant contact when compared with controls. The results of this study suggest that a useful approach by combined processes could optimize implant surfaces for bone deposition and produce distinct biological surface features.
Authors: Zhi Jun Pan, Xin Huang, Di Sheng Yang, Hidero Unuma, Wei Qi Yan
Abstract: Hydroxyapatite (HA) coatings were introduced onto Poly L-lactic Acid (PLLA) polymer in a controlled manner by immobilized urease method with a shortened precipitation time. Osteoblastic-like cellular responses to the composite were examined in terms of cell proliferation, differentiation and cell morphology, as well as the expression of bone-associated genes. The cells exhibited higher cellular proliferation at 2 and 4 days on the HA/PLLA composite compared to PLLA scaffold, while no significant difference was observed later at 6 days. The alkaline phosphatase (ALP) activity by cells at 7 days was statistically higher on HA/PLLA scaffold than on PLLA. Moreover, the gene expression of ALP and osteocalcin (OC) was up regulated on HA/PLLA composite by RT-PCR analysis. The preliminary study suggested that the use of the controlled modification of hydroxyapatite coating on PLLA scaffold to produce HA/PLLA composite might enhance cellular activity, indicating the potential use for bone substitute in tissue engineering.
Authors: Bing Gang Guan, Wei Qi Yan, Di Sheng Yang, Chao Zou, Wen Jian Weng
Abstract: A novel porous beta-tricalcium phosphate /collagen fibers (β-TCP/CF) composite, having a well-dispersed nano-sized β-TCP in collagen matrix, was developed by a wet-chemical method. The nano-composite was compared to conventional β-TCP on cytocompatibility by cell attachment, proliferation, alkaline phosphotatse (AKP) activity and scanning electron microscopy (SEM) analysis. These in vitro assays showed that the β-TCP/CF composite elicited cell adhesion and proliferation better then controls. Moreover experiments on osteoblast-like cells showed improved cell growth with the highly characterized nanophase structure. SEM micrographs also showed that the nano-sized composite exhibited much more viable cells in attachment on the surface compared with the controls. At 1, 3 and 5 days, AKP activity was not significant different for the tested and control samples, while at 7 day after culture, significantly increased AKP activity was observed for β-TCP/CF than for the control. The in vitro results obtained confirmed the remarkable improvement of cell adhesion and proliferation of the nano-sized β-TCP/CF composite, which may be a new promising candidate for tissue engineered bone substitute.
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: I.V. Antonova, Andrzej Misiuk, Adam Barcz, Di Sheng Yang, V.P. Popov
Authors: Zhi Jun Pan, Bing Gang Guan, Di Sheng Yang, Jie Feng, Wei Qi Yan
Abstract: Biomimetic nanoapatite coatings was developed by functionally modified methods with a combination of topographic, chemical and biomimetic treatments on the surface of titanium (Ti) substrate. The biological behavior and bioactivity of functionally modified SLA implants with chemical and biomimetic treatments (SCB-treated Ti) using body like solution were investigated to compare with untreated Ti and SLA Ti plates as controls. The cell attachment, proliferation, alkaline phosphotatse (AKP) activity, cell morphology and differentiation were evaluated by using MTT, RT-PCR, scanning electron microscopy (SEM) and confocal laser-scanning microscope (CLSM) analysis system. The results showed that the cell adhesion and proliferation was enhanced on functionalized titanium surface with nano-scale apatite compared to the controls. SEM micrographs also revealed that the osteoblast-like cells spreadly grew along the surface. Cell morphology and differentiation could be further observed distinctly by CLSM graphs. Moreover, mRNA expression of alkaline phosphotatse in nucleus on the SCB-treated Ti increased obviously on the third day compared with the controls. The in vitro results demonstrated the remarkable improvement on cell adhesion and proliferation of the biomimetic nanoapatite on SCB-treated Ti, which could be used for orthopaedic/dental implants.
Authors: Xin Huang, Wei Qi Yan, Di Sheng Yang, Jie Feng, Yan Bo Feng, Yan Bo Gao, Wen Jian Weng
Abstract: A novel composite of biodegradable Poly-L-lactic acid (PLLA) with the deposition of the nanosized amorphous calcium phosphate (NCP) particles was developed as tissue engineering scaffold. To improve the minor intrinsic healing capacity of cartilage tissue, the porous composite with desired degradation rate was incorporated with basic fibroblast growth factor (bFGF) and evaluated in the in vivo environment. Full-thickness defects were created in the weight-bearing surface of the femoral condyles in a rabbit model. The defect was filled with and without NCP/PLLA scaffold as a carrier of bFGF. Gross morphology for the test implant showed that the defect was filled with regenerated tissue. It resembled cartilaginous tissue and restored the contour of the condyle at 8 weeks after operation. For the untreated control, no cartilage-like tissue was observed at all defects. Histological analysis revealed neochondrogenesis and clusters of cartilaginous extracellular matrix observed with safranin-O staining at 4 weeks for the NCP/PLLA with bFGF treated defects. At 8 weeks after operation, well-formed and mature cartilage was resurfaced the defects. While only fibrous tissue replacement was observed for the control either at 4 or 8 weeks. Special staining for cartilage indicated the presence of highly sulfated glycosaminoglycans and collagen, which were the major extracellular matrices of cartilage. This investigation showed the potential of NCP/PLLA loaded with bFGF in the study of in situ-transplantable carrier to improve healing of cartilage tissue lesion.
Authors: D. Sun, Yu Zhu, Di Sheng Yang, R. Zhu
Authors: Wei Qi Yan, Jie Feng, Q. Chen, Di Sheng Yang, Ying Zhao, Shi Gui Yan
Abstract: Stimulation of bone healing through local application of growth factors from implants may improve the clinical outcome in fracture treatments. However, the growth factors in reconstructive application require supraphysiologic dosing and considerable expense while hampering their clinical application. Genetic modification of mesenchymal stem cells (MSCs) to both produce and respond to osteogenic factors may have potential for use in enhancing bone healing. In this study, MSCs were genetically modified by a recombinant adenoviral containing the gene for human bone morphogenetic protein 2 (hBMP-2). The gene-transduced cells were incorporated with a porous beta-tricalcium phosphate (TCP) as a novel complex. We investigated osteogeneic potential of gene-transduced MSCs/ceramic and the ability of the complex on facilitating bone formation in a radius segmental defect of rabbits. In vitro results showed that there were apparent hBMP2 gene expression and protein synthesis in MSCs with hBMP2 stably transfection, whereas negative expression of hBMP2 in controls. Histological studies demonstrated that gene-transfected MSCs/ceramic composite appeared an ability of heterotopic osteogenesis. In the segmental bone defects, endochondrial ossification at fracture sites was found in both transfected and untransfected MSCs-ceramic composites. While the composite with hBMP2 transfection showed the earliest and the most effective healing of the segmental bone defects both radiographically and morphologically. Our results show that genetically modified MSCs/ceramics had enhanced osteogeneic capacity relative to unmodified MSCs or only ceramic implants. This study suggests that use of cell-and gene-activated bioceramics may offer promise for molecular design of implants to induce osteogenesis and enhance bone regeneration.
Authors: Di Sheng Yang, J. Lu, L. Li, H. Yao, Duan Lin Que
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