Papers by Keyword: Osteoinduction

Abstract: In this paper, we report the initial research to obtain hybrids (PU@Hap-1%, PU@Hap-2% and PU@Hap-3% compound by hydroxyapatite (Hap) synthesized by coprecipitation (CP) method, with monoglycerides (MG) of castor oil (Ricinus communis) polymerized with hexamethylene diisocyanate (HDI). Hap, was characterized by X-ray diffraction (XRD), Rietveld refinement, Fourier transform infrared (FTIR), RAMAN spectroscopy and X-ray fluorescence (XRF). Hybrids, MG and castor oil, were characterized by Fourier transform infrared (FTIR). XRD patterns and Rietveld refinement analysis confirmed that hexagonal phase for nanostructure for Hap, with average size particles D  12 nm, obtained by Scherrer equation and ration Ca/P = 2.13 (m/m) confirmed that XRF spectroscopy. FTIR and RAMAN spectra exhibited all active modes for vibrational stretches (1, 2, 3 and 4) of the phosphate groups () and vibrational modes of O-H bonds, present in the hexagonal structure for Hap in a ranger from 400 to 4000 cm-1 and 400 to 1100 cm-1, respectively. The conversion of castor oil (triglyceride) to MG, was monitored by FTIR spectroscopy, confirmed that increase of intensity active modes in 3317 cm-1 and 1741 cm-1, corresponding to the vibrations modes of O-H and C=O, respectively. Finally, we observed that all active modes in FTIR spectroscopy, corresponding to the hybrids: PU@Hap-1%, PU@Hap-2% and PU@Hap-3%, and Polyurethanes – PU (standard), confirmed the increase of intensity mode of the phosphate group with the increase of Hap in the polymerization of the mixture MG with HDI.

Abstract: In an In vivo study the full synthetic bone substitute NanoBone^® S (NBS) was analyzed using a standardized bone defect (6 x 12 x 24mm) model in the ovine tibial metaphysis. The defect on the left side was filled with NBS granules and on the right side, autologous bone, harvested from the hip of the same animal, was inserted. After six, 12 and 26 weeks sheep were sacrificed and the tibiae analyzed. Quantitative histomorphological analysis after six weeks showed a resorption of biomaterial from over 60 to 24 percent. In contrast the bone formation after 6, and 12 weeks revealed an osteoneogenesis of 19%, and 34%, respectively. Hematoxylin and eosin sections demonstrated multinucleated giant cells on the surface of the biomaterial and resorption lacunae, indicating osteoclastic resorptive activity.

Abstract: Various kinds of materials have been found to bond to living bone and some of them are clinically used as important bone substitutes. However, they can not be used under load-bearing conditions, since their fracture toughness are not so high as that of human cortical bone. All of them are based on calcium phosphate or silicate. The present authors recently showed that even Ti metal and its alloys having high fracture toughness can show bone-bonding bioactivity, if they are subjected to simple chemical and heat treatments to form some kind of titanium oxide or titanates on their surfaces. They can show not only bone-bonding property, but also novel functions such as osteoinduction, release of antibacterial or bone-growth promoting ions etc.

Abstract: Use of ready-made marine skeletons is one of the simplest possible remedies to major problems hindering the future development of regenerative orthopaedics- such as, providing a richness of framework designs and now a potentially rich, accessible source of osteopromotive analogues and biomineralisation proteins. It has already been shown that coral and marine sponge skeletons can support self-sustaining musculoskeletal tissues and that extracts of spongin collagen and nacre seashell organic matrices promote bone mineralisation. This should not be surprising given that the pivotal biomineralisation proteins, which orchestrate bone morphogenesis are also found in the earliest calcifying marine organisms. This is because they are representatives of the first molecular components established for calcification, morphogenesis and wound healing. In support of this notion, it has emerged that BMP molecules- the main cluster of bone growth factors for human bone morphogenesis- are secreted by endodermal cells into the developing skeleton. In addition, the regenerative signalling proteins, TGF-b and Wnt-prime targets in bone therapeutics- are also present in early marine sponge development and instrumental to stem cell activation in Cnidarians. Based on this match between vertebrate and invertebrate main developmental proteins, we review the nature and extent of this evolutionary relatedness and use it to support the development of a new strategy, which is to mine selected marine origin organic matrices for novel metabolic, signalling and structural proteins/peptides and protein analogues to apply in regenerative orthopaedics, particularly when using adult stem cells. To support such a proposal we show early stage evidence-gathered in our own laboratory- of the presence of fibrinogen fragments and early osteopromotive effects of a coral organic matrix extract on stem cells. In practice the discovery of new osteopromotive and osteo-accelerant protein analogues will require use of traditional chromatography techniques, osteoactivity assays to hone in on potential proteins of significance and advanced proteomic tools to provide accurate sequencing, determine the mechanisms and molecular pathways involved in osteoactivation and determine the efficiency and effectiveness of marine skeleton-derived protein modulation of the stem cell (MSC) proteome. As more analogues are discovered using proteomic tools, skeletal organic matrices may have ever increasing utility for regenerative orthopaedics.

Abstract: The comparative investigation of a highly nanoporous bone grafting material (NanoBone S, NBS) and a sintered hydroxyapatite ceramic (Cerabone, CB) aimed to show the influence of the structure of the material on osteoinductivity.NBS consists of synthetic nanocrystalline hydroxyapatite embedded in a porous silica gel matrix. Its specific surface amounts 206 m²/g in contrast to CB with a specific surface of 0.4 m²/g.The biomaterials were implanted in the neck region of 18 sheep and left there for the periods of 6, 12 and 26 weeks. In each case granulate was implanted superficially into the trapezius muscle and into the subcutaneous adipose tissue respectively. The samples were analysed by micro-CT, histochemistry, immunohistochemistry and histomorphometry. In the case of NBS ossicles had developed. An intensive remodelling process was verifiable. The bone formation in CB was marginal.As a basic phenomenon in NBS, the substitution of the original SiO₂ gel matrix by organic molecules forming an organic matrix around the embedded hydroxyapatite seams to be the key event causing these results.

Abstract: Various bone graft substitutes were used in clinical practise in the treatment of bone defects after trauma or osteoporosis. Many synthetic biomaterials were developed in recent years primarily based on hydroxyapatite (HA). NanoBone^® is a nanocrystalline hydroxyapatite (HA) embedded in a porous matrix of silica (SiO₂). The ratio of HA:SiO₂ varied between 76:24 (wt%; NanoBone^®) and 61:39 (wt%; Nanobone^® S). The two bone substitutes NB and NB S and a natural bovine bone substitute Bio-Oss^® (BO) were evaluated by means of implantation in the tibia of the rat. The aim of this study was to analyze the remodelling process and to measure new bone formation and degradation after implantation of these biomaterials. A tibia defect model was used for all investigations with testing periods of 12, 21 and 84 days. (n=5 for each time point). The results showed, that all bone grafts were well accepted by the host tissue without inflammatory reactions. In comparison to the biomaterial BO, NanoBone^® and NanoBone^® S were quickly degraded, whereas autologous proteins were incorporated into nanopores. New bone formation was statistically higher in NanoBone^® S compared to Bio-Oss^® in defect area after 84 days implantation. The presence of osteoclasts in tissue sections were demonstrated by TRAP- and ED1-immunohistology.

Abstract: The combined chemical-hydrothermal synthesis of TiO2 and CaTiO3 films on pure Ti substrates was examined with a focus on film crystallinity and surface morphology. Pure Ti disks were chemically treated with H2O2/ HNO3 aqueous solutions at 353 K for 20 min in order to form a TiO2 gel layer on the surfaces. The samples were then hydrothermally treated in an autoclave at 453 K for 12 h or 24 h. Anatase-type TiO2 and perovskite-type CaTiO3 films with high crystallinity were obtained upon treatment with distilled water or aqueous NH3 and aqueous Ca(OH)2, respectively. Uniform, crack-free films were obtained. The surfaces showed excellent attachment of osteoblast-like MC3T3E1 cells in an incipient stage. Furthermore, the cells showed satisfactory proliferation, though at a slightly lower rate than on Ti. In addition, the samples were immersed in SBF (Simulated Body Fluid), adjusted to 310 K. A light hydroxyapatite (HAp) precipitate was observed on the unmodified Ti surface after 6 days of immersion. In contrast, precipitation was observed only after 2 to 4 days on the present oxide films. Thus, these oxide films are non-toxic and enhance the deposition of HAp.

Abstract: The interconnected porous scaffolds are crucial to support the attachment, differentiation, proliferation of cells so to construct 3-dimensional (3-D) tissues. Up to now, there are several approaches to prepare porous scaffolds. In our experiments, we designed a novel porous bioceramic scaffold, called the hydroxyapatite (HA) spherule scaffold, by accumulating HA spherules in an HA porous tube to establish an interconnected porous structure which can be reconstructed exactly. The porous HA tube was manufactured by polymer sponge template while HA spherules were prepared by sol-gel process. In the animal experiment, the HA spherule scaffolds were implanted at 2 different non-osseous sites such as muscle and abdominal cavity in dogs. The new bone growth was investigated after six months. The preliminary results demonstrated that the proliferation of osteocytes on the scaffolds in muscle was obviously better than in abdominal cavity, and about ten times more blood vessels (BVs) were appeared in the former site than those in the latter site. This study presents an alternative way to reveal the relationship between the porous structure of scaffolds and ectopia bone growth because the interconnection and porosity can be controlled easily by the size and porosity of HA spherules.

Abstract: Material-induced osteoinduction has been reported in comparatively large animals such as dogs and pigs; however, it does not often occur in small animals such as rodents. In this study, we implanted the porous calcium-deficient hydroxyapatite (CDHA) in the dorsal muscles of dogs and rats, and compared cellular events occurred in 2 species with particular emphasis on the osteoclast-like multinucleated cells. In the CDHA extracted from dogs, many tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells were detected after 2 weeks, and new bone formation was observed after 4 weeks. In contrast, in rats, only a small number of TRAP-positive cells were detected and no bone formation was observed before 6 weeks. Transmission electron microscopy (TEM) revealed that multinucleated cells in the CDHA from dogs after 2 weeks showed osteoclast-like structures such as ruffled borders. However, in the CDHA from rats, there were no osteoclast-like structures observed. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that the expression of cathepsin K in dogs was higher than that in rats. These results indicate that TRAP-positive cells might be one of main factors responsible for the cross-species difference in material-induced osteoinduction.

Abstract: Several kinds of biomaterials are known to possess osteoinductive ability without bone inductive substances in ectopic implantation. β-TCP is one such material that has been reported to exhibit this ability in a canine model. In addition, prostaglandin E2 has been proved to accelerate osteogenesis in a rodent model, and one of its receptors EP4 has been considered to play a particularly important role. We examined that the EP4 agonist accelerates β-TCP-induced osteoinduction in a canine model. The results suggested that the EP4 agonist accelerated not only osteoinduction but also osteoclastogenesis prior to bone formation.