Bioceramics 17

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Authors: Oliver Malard, Jean Michel Bouler, Jerome Guicheux, Olivier Gauthier, E. Lerouxel, G. Daculsi
Abstract: Bone invasion is common in case of Squamous Cell Carcinomas (SCC) of the upper aero-digestive tract. Radiotherapy is required in addition to large surgical tumor removal. This treatment usually generates irreversible injuries on the reparation properties of the tissues, especially on bone. The quality of life of patients undergoing major surgery and radiotherapy in maxillary and mandible areas is reduced, but could be improved by bone reconstruction. The aim of this study was to evaluate the bone reconstruction possibilities by Macroporous Biphasic Calcium-Phosphate (MBCPÔ). The MBCP substitute was evaluated as granules and associated to autologous bone marrow (BM) graft in irradiated areas, in an inbreeding rodent model. Radiation sequels were created on inferior members of half of the rats. 3 weeks later, 3-mm osseous defects were created on each animal. The inbreeding model allows BM to be grafted without graft-versus-host reaction. Defects were filled either with MBCP alone, BM alone or a mixture of MBCP and BM. Six weeks after implantation, animals were sacrificed: bone repair and ceramic degradation were evaluated by qualitative and quantitative study. Results showed that bioceramics were well osteointegrated. Filling the defects with BM alone showed a significant increased of newly-formed bone formation but only after irradiation, whereas filling defects with MBCP alone increased new-bone formation only without previous irradiation. Associating MBCP to BM provided the best new-bone formation rates after irradiation. Degradation of the ceramic was the most important in case of BM grafting. This study demonstrated that BM added to MBCP constitute an appropriate material to be considered in case of bone defect occurring in irradiated tissue, and could be foreseen for use after bone removal for oncologic obligations.
285
Authors: Ji Yong Chen, You Rong Duan, Xing Dong Zhang
Abstract: Two sets of porous biphasic calcium phosphate ceramics (BCP) were prepared for dynamic SBF experiment: porous BCP with micropores on the walls of macropores( set A) and porous BCP with dense walls of macropores (set B). Apatite layer could only formed on the macropore walls with micropores. Four groups of specimens were prepared for animal experiments. Group A was porous BCP ceramics with micropores on the walls of macropores; group B was porous BCP with dense walls of macropores; group C was porous BCP ceramics with apatite layers formed by static SBF[2]on their surfaces; group D was porous BCP ceramics with apatite layers formed by dynamic SBF on their walls of macropores. The result of dynamic SBF animal experiments showed that microstructure of BCP played an important role in the bone-like apatite formation and osteoinductiion in biomaterials. Apatite formation may be the prerequisite of osteoinductive formation of new bone.
289
Authors: C.Y. Bao, P. Li, Yan Fei Tan, Y. Cao, X.Y Ling, Chun Lin Deng, Xu Dong Li, W.C. Chen, Hong Song Fan, Xing Dong Zhang
Abstract: The purpose of this study was to evaluate the response of osteoblasts to the calcium phosphate with different surface modification, and to evaluate the osteoinductive capabilities of these biomaterials. 60HA/40α-TCP ceramics sintered at 1250oC was applied in this study. The ceramic cylinder with F5mm×8mm and slice with F10mm×1mm were prepared respectively. One thirds of the ceramics were formed bone-like apatite (BLA), and the surface of another one thirds was modified with collagen. Osteoblasts (1×106/ml) were co-cultured with the three kinds of thin slices for 12h, 24h and 48h. SEM observation was applied to evaluate if the surface modification and BLA formation could affect the attachment and proliferation of osteoblast in vitro. The three kinds of cylinder samples were implanted in dog muscle to evaluate their differences in osteoinduction. Cells grew in multi-layers and well attached to the surface and proliferated well in the group of collagen and HA/TCP. In untreated and BLA precipitated group, cells did not attach to the surface well. Osteoinduction was good in BLA precipitated group and the amount of bone formed was higher; in untreated group and collagen-treated group, no bone formation was observed in the tested period. This result indicated that the scaffold used in cell-materials composites in vitro and that in osteoinductive material based tissue engineering in vivo was not same.
293
Authors: Dorota Nowak, M. Florek, J. Nowak, Wojciech Kwiatek, Janusz Lekki, E. Zięba, P.G. Romero, Besim Ben-Nissan, A. Kuczumow
Abstract: The distribution of about twenty inorganic elements was traced in the skeletons of black corals of the Antipathes salix species. Electron microprobe and PIXE mappings revealed the peculiar structure of this material, composed of the large cells (arranged in annual rings), surrounded by thin layers with an elevated level of iodine (up to 5%). Our current knowledge of the chemical composition of these corals’ skeleton is not complete. Essentially the organic skeleton is saturated with inorganic elements and several of these could be commercially important. In fact, they have never been investigated for biomedical applications. In this preliminary current work, black corals from the Antipathes salix species were studied with the aim of detecting the inorganic components of their matrix and their suitability as biomedical materials.
297
Authors: Hirotaka Maeda, Noriko Miura, Toshihiro Kasuga, Masayuki Nogami
Abstract: Novel hollow spheres for bone fillers incorporating cells were prepared using composites consisting of poly(lactic acid) and calcium carbonates. An open channel of ~800 µm in diameter was easily formed using a chemical etching method to provide a pathway to the interior of the sphere. Cells could migrate through the open channel into the interior of the sphere. Bonelike apatite coating on the surface of the sphere was prepared by soaking in calcium chloride solution to supply excess Ca2+ ions on the surface and subsequently by soaking in simulated body fluid. The hollow spheres with an open channel may be one of the great potential candidates as novel bone fillers combined with a cell-delivery system.
301
Authors: Y.H. Hsu, I.G. Turner, A.W. Miles
Abstract: The aim of this study was to fabricate porous Hydroxyapatite/Tricalcium phosphate (HA/TCP) bioceramics with an adequate degree of interconnected porosity combined with optimal mechanical properties. Porous HA/TCP bioceramics with interconnected porosity and the controlled pore sizes necessary to simulate natural bone tissue morphology were fabricated by a novel technique of vacuum impregnation of reticulated polymeric foams with ceramic slip. By varying the characteristics of the slips and using foams of different pores per inch (ppi), samples of porous HA/TCP, blocks and granules, with a wide range of pore sizes were successfully manufactured. Functionally gradient materials (FGM) with porosity gradients were also made and no weakness was found at the interface. The pore size of the HA/TCP bioceramics was in the range of 197 – 254 µm (for 20 ppi foam), 143 – 182 µm (for 30 ppi foam) and 105 – 127 µm (for 45 ppi foam). The compressive strengths and the apparent densities of the HA/TCP samples were in the range of 30 –170 MPa and 2.34 – 2.76 g/cm3 respectively. These results indicate that it is possible to manufacture open pore HA/TCP bioceramics with compressive strengths comparable to human bone which could be of clinical interest.
305
Authors: A.F. Lemos, J.H.G. Rocha, J.M. Ventura, José Maria F. Ferreira
Abstract: Hydroxyapatite (HA) is the calcium-phosphate material with composition closest to that of human bone, what makes it suitable for osseous implant purposes, namely as fillers, spacers and bone grafts substitutes. This study is aimed at the development of a method to produce porous spherical hydroxyapatite granules. The process involves the spraying of a suspension with different amounts of a setting agent to a setting media. The tailor and the control of the morphology, size and porosity of the granules were attained by adjusting the nozzle diameter, the pressure of air flow and the distance between the nozzle and the setting media.
309
Authors: Yeon Ung Kim, Min Chul Kim, Kyoung Nam Kim, Kwang Mahn Kim, Seong Ho Choi, Chong Kwan Kim, Racquel Z. LeGeros, Yong Keun Lee
Abstract: This study presents the manufacture of macroporous hydroxyapatite scaffolds with a small amount of calcium phosphate glass powder as sintering additives. Hydroxyapatite slurry was prepared by suspending the hydroxyapatite and glass powder in water. Polyurethane sponge was used to produce highly macroporous scaffolds. The rheological characteristic of the slurry was measured to identify the effect of adding calcium phosphate glass powder into hydroxyapatite slurry. Sintered scaffolds could be repeatedly coated to improve mechanical properties. Scaffolds prepared by single and double replication cycle process were characterized by density, porosity and compressive strength measurements by increasing amount of the calcium phosphate glass powder to the hydroxyapatite slurry, viscosity by increased more than same amount of pure hydroxyapatite, and the capillary force was similar to pure hydroxyapatite slurry. The compressive strength of the macroporous hydroxyxapatite scaffold containing the calcium phosphate glass powder showed higher value than that of pure hydroxyapatite at single replication cycle. SEM demonstrated that the microstructure of the scaffold became denser with the introduction of the calcium phosphate glass powder. The pore struts were thicker as replication cycle was increased.
313
Authors: A. John, H.K. Varma, T.V. Kumari, V.R. Nisha, D. Narayanan
Abstract: Cytotoxicity and cytofunctionality of the in-house prepared novel bioactive glass coated hydroxyapatite (BGHA) is described here as a first step in characterizing the biocompatibility of the material for orthopaedic application. Sintered hydroxyapatite was coated with bioactive glass by a sol-gel method. The BGHA granule was 2 - 4 mm in size with a pore size in the range of 50 – 150 µm. FT-IR spectrum depicted the functional groups and XRD spectrum defined the crystallinity of the material. MTT assay proved high cellular activity and morphologically the cells showed normal proliferation with the expression of actin and vimentin network in the cytoplasm. In the resin sections, cells were found located on the walls of the pores while in osteoblast-cultured granules, cellular matrix was also observed along the pore interconnections. Recrystallization on the surface of the cultured granules did not support the adhesion of cells. The electron diffraction pattern displayed the high crystallinity of the raw granule while a diffused pattern of amorphous apatite like crystallites was observed for the cultured granules. High calcium and low phosphorous concentration was observed in the medium of the cells simultaneously with ALP and osteocalcin production. This pre-clinical evaluation proved BGHA, as a promising material for bone scaffolds.
317
Authors: Masataka Yoshikawa, Norimasa Tsuji, Tadao Toda, Hiroko Machida, Hajime Ohgushi
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