A simple plasma spraying method was employed in coating hydroxyapaptite (HA) on to carbon/carbon composites (C/C composites). The morphology of the coating was examined under scanning electron microscope (SEM). The phase constitutions of the HA coating were determined by X-ray diffractometer (XRD). The shear strength of the HA coating-C/C composite substrates was detected. A hydroxyapatite coating with rough surface was observed. A considerable amount of amorphous phase appeared as a result from the coating process, which could be transformed into the morphous phase crystalline HA after subsequent heat treatment. The shear strength between the HA coating and C/C composite substrates was 7.15 MPa.
Bone Substitutes ; chemistry ; Carbon ; chemistry ; Carbon Compounds, Inorganic ; chemistry ; Coated Materials, Biocompatible ; chemistry ; Durapatite ; pharmacology ; Humans

New bone formation in long-term intramuscle implant of Ca-P biomaterial was investigated in this experiment. After implanting into dog dorsal muscle for 15 months, a thin fibrous membrane that wrapped HA/TCP implant was still observed obviously. Three types of tissues, i.e. mesenchymal tissue, bone and bone marrow, regularly distributed in different pores of implant. Nearly all the pores of implants were occupied by bone. Bone in the pores located in the central region of implant was matured lamellar bone characterized by obvious lacuna and rich bone marrow. However, bone in the peripheral pores was immature woven bone without bone marrow formation. Furthermore, mesenchymal tissues only exist in the peripheral pores and usually were connected with immature woven bone. It was demonstrated that porous HA/TCP has bone inductivity and it could induce new bone formation at non-osseous site. Well-regulated distribution of mesenchymal tissue, bone and bone marrow in the pores suggest bone morphogenesis in the implant must obey a specific space-time program.
Animals ; Biocompatible Materials ; Bone Substitutes ; pharmacology ; Ceramics ; pharmacology ; Dogs ; Hydroxyapatites ; pharmacology ; Implants, Experimental ; Materials Testing ; Osteogenesis ; drug effects

*Absorbable Implants ; Biocompatible Materials/*pharmacology ; Bone Regeneration/*drug effects ; Bone Regeneration/physiology ; Bone Substitutes/*pharmacology ; Calcium Phosphates/*pharmacology ; Structure-Activity Relationship

OBJECTIVESr-HA, a new type of hydroxyapatite biomaterial, was implanted into animals to study the bioreaction and character, which would be helpful for the further clinical applications in the future.

METHODSTotally 24 rabbits were divided into 3 groups. The bone defect of 6 mm x 12 mm x 4 mm was made at both mandibular angles of rabbits and Sr-HA of different proportion (10%, 5%, 0) was applied to reform the defects. One group of animals were killed randomly at 1, 3 and 6 months after operation to evaluate the material biological compatibility using anatomic, X-ray examination, histological and ECT methods.

RESULTSThe histological photographs showed that Sr-HA caused little infection around implanted area and, almost was not repulsed by hosts. With the degradation of biomaterial, there was more apparent new bone growth in the area around Sr-HA than that around HA and some ossification can be found in soft tissue nearby. Also a tight osteointegrity was gradually got after the operation, according to the results of X-ray and, the border between Sr-HA and bone was hardly discovered at the 6th month after the operation. A more obvious nuclide assembling was observed at the side of Sr-HA by ECT images. With the biodegradation of Sr-HA, more new bone was intruded into the spare space of the biomaterial.

CONCLUSIONSr-HA has better biocompatibility and higher biodegradation than that of pure HA. It holds an excellent osteoinductivity and fair osteoconductivity to some degree too. So a more satisfying effect of bone defect rehabilitation was gained with the increasing new bone depositing in the free space of the material, when it degraded gradually.

Animals ; Biocompatible Materials ; Biodegradation, Environmental ; Bone Substitutes ; Hydroxyapatites ; chemistry ; pharmacology ; Implants, Experimental ; Mandible ; surgery ; Osteogenesis ; physiology ; Rabbits ; Strontium ; chemistry ; pharmacology

OBJECTIVESTo construct new type of bone graft material by combining calcium phosphate cement (CPC) with bone morphogenetic protein (BMP), and then to detect its osteogenic activity.

METHODSThe surface of CPC and CPC/BMP composite were observed by scanning electron microscope (SEM). CPC and CPC/BMP pellets were separately implanted into the thigh muscle pouches of mice. Samples obtained at different times were tested by histological analysis, SEM, organic substance detection, and alkaline phosphatase (ALP) measurement to observe the induced ectopic bone formation.

RESULTSUnder SEM, the CPC and CPC/BMP composite was found to consist primarily of platy crystals, granular crystals and some small rod-like crystals with micropores about 10-50 microm in size. BMP about 1-5 microm in size was seen like micro globules distributing evenly in the micropores. Newly formed cartilage or bone was not found in the CPC group. In the CPC/BMP group, mesenchymal cells were proliferated and abundant cartilage was found in one week. Woven bone appeared at 2 weeks. New bone formation increased with bone marrow at 4 weeks. At 8 weeks, the implanted CPC/BMP became heterogeneous and a lot of collapsed granules were observed. At the end of 16 weeks, mature lamellar bone appeared and the volume of the implanted CPC/BMP became smaller. One week after implantation, the ALP increased evidently in the CPC/BMP groups and reached the highest level at the 4th week, which was about 168 U/L. The content of organic substance in specimens increased from 22% to 39% by the end of the 16th week, showing the continuous calcification and formation of new bone. SEM also showed that the CPC/BMP composite had good potentiality of ectopic bone induction, and the new bone formed accompanied by the slow degradation of the material.

CONCLUSIONThe results of this study suggested that the CPC/BMP composite could be used as material for bone graft substitute.

Animals ; Bone Cements ; Bone Morphogenetic Proteins ; pharmacology ; Bone Substitutes ; chemical synthesis ; pharmacology ; Calcium Phosphates ; Male ; Materials Testing ; Mice ; Mice, Inbred Strains ; Osteogenesis ; drug effects ; Prosthesis Implantation

Compound membranes of chitosan/hydroxyapatite were prepared by blending. The physical performance showed that the air-water contact angles decreased from chitosan's 103 degrees to chitosan/hydroxyapatite's 57 and the water adsorption rate increased slightly. When immersed into culture medium, the materials adsorbed Ca2+, and low crystalline hydroxyapatite deposited on the surface of the membranes. Chitosan/hydroxyapatite compound membranes could enhance the attachment and proliferation of mescenchymal stem cells (MSCs). After 12 days' induction on the materials, the alkaline phosphatase (ALP) activity value of MSCs on the compound membrane was 10.1, being much higher than 1.6 on chitosan membrane (P<0.01). All these results indicate that chitosan does not have very good affinity for MSCs, but the biocompatibility of chitosan can be apparently enhanced after mixing with hydroxyapatite. The compound membrane stimulates MSCs to differentiate into osteoblasts and it may be a good potential material for bone substitution.
Alkaline Phosphatase ; metabolism ; Animals ; Bone Substitutes ; pharmacology ; Cell Proliferation ; drug effects ; Cells, Cultured ; Chitosan ; chemical synthesis ; pharmacology ; Durapatite ; chemical synthesis ; pharmacology ; Membranes, Artificial ; Mesenchymal Stromal Cells ; cytology ; Rats

OBJECTIVETo study the ectopic osteogenesis of tissue engineered bone with recombinant human bone morphogenetic protein/transforming growth factor-beta (rhBMP/TGF-beta) or WO-1 slow-released factors.

METHODSPartial demineralized freeze-dried bone (PDFDB) of pig was used as scaffold material. rhBMP/TGF-beta or WO-1 were pre-coated on the surface of material by means of vacuum negative pressure absorption, and then coated with polylactic acid (PLA) to make slow-released material. There were six group: PDFDB material (group A); PDFDB combined with osteoblasts (group B); PDFDB material with rhBMP/TGF-beta slow-released system (group C); PDFDB material combined with rhBMP/TGF-beta slow-released system osteoblasts (group D); PDFDB with WO-1 slow-released system (group E); PDFDB material combined with WO-1 slow-released system and osteoblasts (group F) were implanted in bilateral lower limbs of 36 Newzealand rabbits respectively (6 rabbits in each groups). Histological, histochemical and biochemical analysis were detected 2, 4, 6, 8 weeks after operation.

RESULTSWithin the observation periods, no osteogenesis was observed in group A. The osteogenesis in group B, D, F were superior to that of group C and E (P < 0.05). The osteogenetic activity in group C and E was delayed. The quantity and quality of osteogenesis in group D and F were 2 weeks ahead of time compared with group B, and 4 weeks to that of group C and E. The newborn calcification content was superior to that of group A, C, and E (P < 0.05).

CONCLUSIONSThe osteogenesis of PDFDB materials with BMP/TGF-beta or WO-1 is slower than that of which combined with osteoblasts. Simple material PDFDB has no ectopic osteogenesis.

Animals ; Bone Morphogenetic Proteins ; pharmacology ; Bone Substitutes ; pharmacology ; Child ; Drug Synergism ; Female ; Humans ; Lactic Acid ; pharmacology ; Osteogenesis ; drug effects ; Polyesters ; Polymers ; pharmacology ; Rabbits ; Recombinant Proteins ; pharmacology ; Swine ; Tissue Engineering ; Transforming Growth Factor beta ; pharmacology

BACKGROUND: Distraction osteogenesis (DO) is a promising tool for bone and tissue regeneration. However, prolonged healing time remains a major problem. Various materials including cells, cytokines, and growth factors have been used in an attempt to enhance bone formation. We examined the effect of percutaneous injection of demineralized bone matrix (DBM) during the consolidation phase on bone regeneration after distraction. METHODS: The immature rabbit tibial DO model (20 mm length-gain) was used. Twenty-eight animals received DBM 100 mg percutaneously at the end of distraction. Another 22 animals were left without further procedure (control). Plain radiographs were taken every week. Postmortem bone dual-energy X-ray absorptiometry and micro-computed tomography (micro-CT) studies were performed at the third and sixth weeks of the consolidation period and histological analysis was performed. RESULTS: The regenerate bone mineral density was higher in the DBM group when compared with that in the saline injection control group at the third week postdistraction. Quantitative analysis using micro-CT revealed larger trabecular bone volume, higher trabecular number, and less trabecular separation in the DBM group than in the saline injection control group. Cross-sectional area and cortical thickness at the sixth week postdistraction, assessed using micro-CT, were greater in the regenerates of the DBM group compared with the control group. Histological evaluation revealed higher trabecular bone volume and trabecular number in the regenerate of the DBM group. New bone formation was apparently enhanced, via endochondral ossification, at the site and in the vicinity of the injected DBM. DBM was absorbed slowly, but it remained until the sixth postoperative week after injection. CONCLUSIONS: DBM administration into the distraction gap at the end of the distraction period resulted in a significantly greater regenerate bone area, trabecular number, and cortical thickness in the rabbit tibial DO model. These data suggest that percutaneous DBM administration at the end of the distraction period or in the early consolidation period may stimulate regenerate bone formation and consolidation in a clinical situation with delayed bone healing during DO.
Animals ; Bone Regeneration/*drug effects ; Bone Substitutes/*administration & dosage/*pharmacology ; Disease Models, Animal ; Humans ; Injections ; Male ; Osteogenesis, Distraction/*methods ; Rabbits ; Tibia/radiography/surgery

The RGD-containing peptide was used to modify the surface of porous PLGA-[ASP-PEG], and was incubated in the modified simulated body fluid (mSBF) for two weeks. The mineralization of PLGA-[ASP-PEG] was explored. The active peptide was used to modify PLGA-[ASP-PEG] through cross-linker (Sulfo-LC-SPDP), characterized by X-ray photoelectron spectroscopy (XPS) the peptide-modified PLGA-[ASP-PEG] (Experiment group, EG) and PLGA-[ASP-PEG] without modification (Control group, CG) were all incubated in mSBF for two weeks, confirmed by observation of Scanning electron microscope(SEM) and measurements of Energy dispersive analysis system of X-ray (EDS) and X-ray diffractometry (XRD). XPS indicated that the binding energy of sulphur in EG was 164eV, and the ratio of carbon to sulphur in EG was 99.746 : 0.1014, however, sulphur was not detected in CG; SEM analysis demonstrated that the mineralization layers were more consecutive and compact in EG than in CG. The results of EDS and XRD indicated that the main component of mineral was hydroxyapatite, and the ratio of Ca/P was 1.60 in EG, and 1.52 in CG. RGD-containing peptide provided enough functional groups for mineralization; the mineralized peptide- modified PLGA-[ASP-PEG] possessed the bonelike microstructure.
Biocompatible Materials ; chemistry ; Bone Substitutes ; Bone and Bones ; metabolism ; Calcification, Physiologic ; Lactic Acid ; chemistry ; Oligopeptides ; chemistry ; Osteogenesis ; drug effects ; Peptides ; chemical synthesis ; pharmacology ; Polyglycolic Acid ; chemistry ; Surface Properties

OBJECTIVETo determine the osteogenic capacity of autologous bone marrow mesenchymal stem cells (BMSCs)-calcium phosphate ceramic composites in vitro and implanted as a bone graft substitute for lumbar anterior interbody fusion in rhesus monkeys.

METHODSFrom March 2003 to April 2005, 9 adult rhesus monkeys underwent lumbar L(3 - 4) and L(5 - 6) discectomy and interbody fusion via an anterior retroperitoneal approach. Two fusion sites in each animal were randomly assigned to two of three treatments: autogenous tricortical iliac crest bone graft (autograft group, n = 6) or cell-free ceramic graft (ceramic group, n = 6) or BMSCs-ceramic composite graft (BMSCs group, n = 6). Autologous BMSCs were culture-expanded and stimulated with osteogenic supplement. The cell-ceramic composites were constructed in a rotary dynamic cell culture system. The spinal fusion segments were evaluated by radiography, biomechanical testing, histologic analysis and histomorphometric analysis at 3 months post-surgery.

RESULTSBiomechanical testing showed that spinal segments from the autograft group and the BMSCs-ceramic group were statistically and significantly stiffer than the cell-free ceramic group. The BMSCs-ceramic group and the autograft group showed equivalent biomechanical stiffness by statistical analysis. Histologically, both the autograft group and the BMSCs-ceramic group achieved osseous union, but the cell-free ceramic group had a fibrous union. Quantitative histologic analysis showed that the amount of bone formation was significantly greater in the autograft group and the BMSCs-ceramic group compared with the cell-free ceramic group. However, the amount of ceramic residue was significantly greater in the cell-free ceramic group versus the BMSCs-ceramic group.

CONCLUSIONSThe results indicate that BMSC-ceramic composites can enhance bone regeneration and achieve osseous spinal fusion 3 months after the implantation in rhesus monkey interbody fusion model. Cell-free ceramics has an unsatisfactory efficacy in spinal fusion due to its tense fibrous fusion.

Animals ; Bone Regeneration ; drug effects ; Bone Substitutes ; pharmacology ; Calcium Phosphates ; Ceramics ; Female ; Macaca mulatta ; Male ; Mesenchymal Stromal Cells ; cytology ; Spinal Fusion ; methods ; Tissue Engineering