Papers by Author: Hong Song Fan

Abstract: Collagen has been widely used in biomedical field, such as scaffolds for tissue engineering. However, the rapidly biodegradation and weak mechanical strength of collagen limited its application. In this study, an insoluble collagen extracted from cattle hide was designed as scaffold to act as a three-dimensional substrate for tissue engineering. The received insoluble collagen sponge was analyzed by scanning electron microscopy, infrared spectroscopy, mechanical testing and thermogravimetric-differential thermal analysis. In addition, the degradation was performed in vitro using collagenase. The results showed that the insoluble collagen had the same triple helical domain as acid-soluble collagen, while the compression strength was greatly improved and the degradation rate was reduced. The insoluble collagen sponge with good stability should be promising in tissue engineering scaffold applications.

Abstract: In the present study, three types of tetracalcium phosphate (TTCP) were prepared by solid-solid reaction or co-precipitation method and by different cooling modes. The effect of TTCP on the performance of calcium phosphate cement (CPC) was investigated. The result showed that the characteristic of TTCP varied with preparation method and played an important role in CPC performance. A solid-solid reacted TTCP yielded smaller particle size and resulted in bad workability and mechanical strength of CPC. The fast cooling of sintering TTCP by liquid nitrogen could avoid the decomposition of TTCP and make pure TTCP. TTCP prepared by wet-precipitation could improve performance of CPC and was promising to optimization of CPC.

Abstract: With good biocompatibility, collagen is often used in cartilage tissue engineering. Collagen/alginate composite was hoped to improve the poor mechanical property of pure collagen but the biocompatibity was decreased. In this study, hydroxyapatite (HA) particles were used to get collagen/alginate/HA (CAHA) composite film to enhance the bioactivity properties. The bioactivity of the composite was investigated by in vitro co-culture with chondrocytes. During the 6-day cell culture in vitro, the composite showed a significant improvement in promoting proliferation and maintaining morphology/phenotype of the chondrocytes over collagen/alginate composite by MTT, SEM, fluorescent and immunohistochemical assays. Cytocompatibility and cytoviablility of CAHA even come up to that of collagen film alone. The results indicated that the composite film may provide an appropriate environment for the proliferation and maintaining the morphology and phenotype of chondrocytes and have a potential clinical application in the cartilage tissue engineering field.

Abstract: It is well known that the cellular responses are related with both physical and chemical characteristics of substrate, including surface topography. In the present study，the effect of surface topography of hydroxyapatite (HA) on rat bone marrow cell (rBMCs) response was investigated. HA disc-shaped pellets with various topography were manufactured by single-axis pressing methods. The rBMCs responses on materials including cell morphology and proliferation were evaluated by SEM and MTT methods respectively, and the differentiation potential was assessed by total protein content and alkaline phosphatase (ALP) activity testing. The results showed that the cell porliferation was higher on HA surfaces with macropore structure, while ALP activity was lower. No significant difference in the cellular responses on the pore distribution and orietation was observed. However, the pore structure had a potential to guide cell orientation by gathering the cells inside the pores rather than on the ridges. Since ALP served as an indicator of early osteoblast differentiation, in this study its higher expression on HA surface with micropores suggested that surface microtopograhy exhibited an important effect on early osteoblast differentiation process.

Abstract: As a natural biomaterial, collagen especially pepsin-solubilized collagen (type I) has been used widely in biomedical fields due to its excellent biocompatibility. In this preliminary study, we investigate the effect of some inorganic ions which are frequently utilized in the preparation of collagen on the morphology and crystallinity of fibrils. The scanning electron microscope and x-ray diffraction were applied to analyze the morphology and the crystallization of the reconstituted collagen fibrils, respectively. Although further studies are needed, these initial results indicate that by controlling the self-assembly conditions of collagen molecules, we may achieve the desired properties of fibrillar collagen products.

Abstract: This study was carried out to investigate the effect of acid-alkali treatment and alkaliheat treatment on the push-out strength and tissue response of the porous titanium in vivo. Porous titanium with different treatment was implanted in dog bony site for 2 months and 5 months and the push-out strength was tested. At 2 months, the mean push-out strengths of the acid-alkali treated and alkali-heat treated porous titanium were 11.3 and 15 MPa, respectively. At 5 months, the values reached 29.8 and 35 MPa, respectively. Histological observation showed a close contact between implants and bone, and more bone tissue filled inside the pores of porous titanium increasing with implantation time. The results indicated higher bonding strength between bone and porous titanium in alkali-heat treated samples. Therefore, alkali-heat treatment can provide porous titanium implants with better fixation as a bone substitute for clinical use under load-bearing conditions.

Abstract: The study is aimed at to explore the construction of bone graft with calcium phosphate ceramics implanted in subcutaneous fat, and provide applying technique for the in vivo bone tissue engineering. Forty-eight calcium phosphate ceramics (Ca-P ceramics) columns with Φ 5×8 mm were prepared, and eight dogs were used in this experiment. Six samples were implanted in each dog. Three in dorsal muscles while the others in subcutaneous fat. The specimens were harvested at 4, 6, 12 and 24 weeks post operation, for gross observation, SPECT and histological studies. The osseous or osteoid tissue formation at different times in the two non-osseous sites was compared and the new bone grafts in subcutaneous fat and intramuscular implantations were evaluated. The results demonstrated that the bone graft could be constructed not only in muscle but also in subcutaneous fat. Compared to that in muscle, constructing bone graft in subcutaneous fat could have brighter prospect to clinical application.

Abstract: Hydroxyapatite/polymer scaffolds with proper biomechanical properties and stable 3-D porous structure were fabricated by combining gas foaming with solvent-casting/particle-leaching technique, in which novel solid H2O2 were used as a porogen. During the manufacturing process, we found that the porosity, compressive strength and microstructure of the composites are varied from each other while different solvents (dichloromethane, acetone, chloroform and 1,4-dioxane) were used. Porosities of the specimens increase from 72±5 to 87±5% in accordance with the increase of boiling point from 39.75 to 101.32 °C, while compressive strength decreased (4.8±0.7- 0.5±0.3 MPa). Interactions of HA/solvent and PLA/solvent together with evaporation dynamic tests of different solvents were investigated. The results show that the evaporation rate of the solvents is the most important factor affecting the final properties of the scaffolds.

Abstract: Dense HA/TCP bioceramics were immersed in pure bovine serum, rabbit serum and dog serum to observe apatite formation. Deposited crystals were examined using SEM. Results showed that some needle-like crystals formed on surface of sterilized HA/TCP, and needle crystals developed into sheet crystals and stick crystals after ceramics were immersed in bovine serum and rabbit serum respectively. The growth of crystals was maybe affected by the content of calcium, various kinds of albumen and alkaline phosphatase in different serums and the different pH of serum.

Abstract: Porous tricalcium phosphate ceramics were immersed in static and dynamic revised simulated body fluid (RSBF) at 37°C. Morphology, composition and phase of precipitates on TCP were identified by SEM, FTIR and TEM methods. FTIR and TEM results indicated the deposits on the inner pore walls of TCP were OCP, and SEM results implied that the deposited way of precipitates in static system was different from that in dynamic system.