BACKGROUND:Biphasic calcium phosphates, consisting of hydroxyapatite and beta-tricalcium phosphate, have been extensively applied as bone graft substitutes due to their similarity with the mineral portion of nature bone. They have been proved to have excellent biocompatibility, bioactivity and osteoconductivity. In recent years, many studies have il ustrated biphasic calcium phosphates perform osteoinductivity both in vitro and in vivo, which is expected to become a good choice for bone graft substitutes. However, the critical factors triggering the osteoinduction process and mechanism of this phenomenon are stil indistinct.
OBJECTIVE:To review the influencing factors and mechanism related to the osteoinductivity of biphasic calcium phosphates.
METHODS:The Ovid Medline database and PubMed database (1985-01/2013-01) were used to search the related articles about the osteoinductive property of biphasic calcium phosphates. The key words were“bone graft substitutes, biphasic calcium phosphates, osteoinduction”. Articles concerning the osteoinductive property of biphasic calcium phosphates were included. The articles that published recently or in the high-impact journals were preferred, and articles with repetitive contents were ruled out. Then 34 articles were suitable for further analysis.
RESULTS AND CONCLUSION:The chemical composition of biphasic calcium phosphates influences the rate of degradation/resorption as wel as bioactivity, which in turn has an influence on the osteoinductivity;the physical properties also play important roles in osteoinductivity by affecting the absorption of bone morphogenetic proteins, vascularization, tissue invasion, microenvironment, and more importantly, triggering the undifferentiated stem cells into osteogenic lineage. What’s more, the species of animals, the implantation-site and the implant size are also critical for osteoinduction. Therefore, through the further study on the influencing factors and mechanism of osteoinduction, biphasic calcium phosphates with stable osteoinductivity, as a promising bone graft substitute, could be synthesized for clinical applications.

Objective: To evaluate the effect of barrier m em brane on guided bone regeneration(GBR) in alveolar cleft. Methods: The alveolar cleft of animal model was established in the maxilla in 10 rabbi ts. The artificial alveolar clefts were treated immediately with following mater ials respectively: (1) PLA+collagen+rhBMP-2 membrane, (2)PLA membrane, (3)colla ge membrane, (4) blank control. All the membranes were fixed by PLA pin and mini -titanium pin. The animals were sacrificed 2 weeks, 1,2,3 and 6 months after su rgery respectively. Samples were studied through macroscopic observation, X-rad iography, histomorphology and enzyme histochemistry analysis. Results: In the clefts covered with the 3 kinds of membrane more bone fromation wa s observed. The compound membrane of PLA+collagen+rhBMP-2 showed the best bone regeneration effects. Conclusion: The GBR technique can be used to repair the bone defect of alveolar cleft.

Calcium phosphates ceramics are frequently used as bone substitute materials in clinics because they are similar to the bone in mineral phase, they are of no antigenicity, and they have good biocompatibility as well as excellent osteoconductivity. The question as to whether calcium phosphate biomaterials possess osteoinductivity has been debated for a long time. Up to now, extensive fundamental studies and clinical application have demonstrated that calcium phosphate ceramics with special structure may induce bone formation in soft tissue. In this paper are reviewed the discovery and confirmation of calcium phosphates ceramics with intrinsic osteoinductivity, the process and mechanism of osteoinduction, and the relationship between osteoinductivity of calcium phosphate materials and animal species, the mesenchymal stem cells related to osteoinduction, the application of osteoinductive biomaterials. The researches directed toward to the osteoinduction of calcium phosphate are prospected.
Biocompatible Materials ; chemistry ; Bone Substitutes ; chemistry ; Calcium Phosphates ; chemistry ; Ceramics ; chemistry ; Guided Tissue Regeneration ; Osseointegration ; physiology ; Tissue Engineering ; trends

BACKGROUND:The phenomenon of osteoinduction by biomaterials has been proven in animal experiments. OBJECTIVE:To investigate whether the ability of a biomaterial to initiate bone formation in ectopic implantation sites improves the performance of osteoinductive biomaterial as a scaffold for tissue-engineered bone. METHODS:We compared ectopic bone formation by combining autologous adipose-derived stromal cells with an osteoinductive and a nonosteoinductive biphasic calcium phosphate ceramic to create a tissue engineering construction in the muscle of dogs. Al implants were implanted in the back muscle of 10 adult dogs for 8 weeks and 12 weeks, including osteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (osteoinductive complex group), osteoinductive biphasic calcium phosphate ceramic (osteoinductive broup), nonosteoinductive biphasic calcium phosphate ceramic+adipose-derived stromal cells (nonosteoinductive complex group), and nonosteoinductive biphasic calcium phosphate ceramic (nonosteoinductive group). Micro-CT analysis and histomorphometry were performed to evaluate and quantify ectopic bone formation. RESULTS AND CONCLUSION:Ectopic bone formation was visible in the osteoinductive complex group and osteoinductive group, and the former group was superior to the latter one in quality of new bone (P<0.05). However, there was no ectopic bone formation in the other two groups. Micro-CT results were consistent with the histomorphological detection. These findings indicate that osteoinductive biphasic calcium phosphate ceramic, as a kind of bone tissue engineering scaffold material, has a better osteogenic capacity, while adipose-derived mesenchymal stem cells serve as seed cells to promote the ectopic bone formation.

This study was aimed to compare the expression of BMP4 mRNA in the in-vivo tissue engineering bone constructed with Ca/P ceramics against the expression of BMP4 mRNA in the naturally healing bone. 20 porous Ca/P ceramics cylinders with Phi 5 mm x 8 mm were made and implanted into the dorsal muscles of 5 dogs. As control, one molar tooth was pulled out from each dog to create bone defect for the naturally healing bone at the same time. The specimens and the naturally healing bone were harvested at 1, 2, 4, 12 and 24 weeks post-implantation. After RNA extraction and reverse transcription, bone morphogenetic protein 4 (BMP4) and GAPDH mRNA were detected by real-time quantitative polymerase chain reaction (PCR) method. The results showed that the expression level of BMP4 mRNA of the in-vivo tissue engineering bone constructed with Ca/P ceramics was higher than that of the naturally healing bone in the period of experiment. However, the in-vivo tissue engineering bone had the same chronological order of BMP mRNA expression that the naturally healing bone did. As a bone substitute analogous to autologous bone, the in-vivo tissue engineering bone constructed with Ca/P ceramics has the potential for clinical application.
Animals ; Bone Morphogenetic Protein 4 ; genetics ; metabolism ; Bone Substitutes ; chemistry ; Calcium Phosphates ; chemistry ; Ceramics ; chemistry ; Dogs ; Humans ; Implants, Experimental ; RNA, Messenger ; genetics ; metabolism ; Tissue Engineering

OBJECTIVETo apply the small interfering RNA (siRNA) targeting survivin to inhibit expression of survivin gene in HSC-3 oral squamous cell carcinoma and to increase the apoptosis of HSC-3 cells.

METHODSsiRNA was synthesized and transfected into oral squamous cell carcinoma HSC-3 cells. Compared with negative control group and blank control group, semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR) was used to detect survivin mRNA. Cellular viability was detected by MTT and HSC-3 cell apoptosis was determined by tunnel and flow cytometry.

RESULTSExpression of survivin mRNA was decreased significantly in siRNA group compared with negative control group and blank control group. Cellular viability was not affected in negative control group and blank control group, but cellular viability in siRNA group was significantly decreased. As to the cellular apoptosis rate, the transfected group (24.99% +/- 1.33%) was significantly higher than negative control group (1.24% +/- 0.13%) and blank control group (0.10% +/- 0.02%).

CONCLUSIONSurvivin gene silenced by siRNA might promote apoptosis of oral squamous cell carcinoma. Survivin siRNA gene therapy would become a new target point for oral squamous cell carcinoma.

Apoptosis ; Carcinoma, Squamous Cell ; Cell Line, Tumor ; Cell Proliferation ; Gene Silencing ; Humans ; Inhibitor of Apoptosis Proteins ; Microtubule-Associated Proteins ; Mouth Neoplasms ; RNA, Messenger ; RNA, Small Interfering ; Transfection

The objective of this study was to learn the property of poly-hydroxybutyrate membrane (PHBm) modified by gamma-radiation and mixture of calcium sulfate, and to explore the possibility of using modified PHBm for guided tissue regeneration (GTR). The PHB was treated by 5 KGy gamma-radiation and mixed with 1/10 calcium sulfate. The modified PHB membrane was prepared by solvent-casting techniques. The mechanical properties and molecular weight of the modified PHBm were tested. Degradability of the modified PHBm was analyzed in vitro in a buffer solution of KH2PO4-Na2HPO4. Biodegradability and biocompatibility of the modified PHBm were inspected 1, 2, 3 and 6 months after the embedding of the modified PHBm into dogs. The morphology was analyzed by scanning electron microscopy (SEM) and molecular weight was tested to evaluate the biodegradability of PHBm. Biocompatibility of the modified PHBm was observed through tissue response by light microscopy. The extension strength and the extension strain at fracture of the modified PHBm were 23.8 MPa and 1.0% respectively. The morphologic observation of the modified PHBm at different terms showed that the modified PHBm was biodegraded gradually in vitro and in vivo. The capsule surrounding the modified PHBm was mainly composed of fibrocytes and few lymphocytes. The longer the time elapsed, the thinner the capsule enveloping the modified PHBm grew. The modified PHBm possesses satisfactory mechanical properties and biocompatibility, and it is biodegradable in vitro and in vivo. The modified PHB membrane could be applied as GTR membrane.
Animals ; Calcium Sulfate ; chemical synthesis ; toxicity ; Dogs ; Gamma Rays ; Guided Tissue Regeneration ; Hydroxybutyrates ; chemical synthesis ; radiation effects ; toxicity ; Materials Testing ; Membranes, Artificial ; Polyesters ; chemical synthesis ; radiation effects ; toxicity

Bone formation on hydroxyapatite (HA) coating in the presence of gaps is important for clinical application. Pure Ti and hydroxyapatite coated by plasma sprayed samples were implanted in dog respectively. The implants were surrounded by gaps of 2 mm, and the follow-up period was 12 weeks. Histological examination and histomorphometry revealed that gaps could be bridged by bone provided the hydroxyapatite coating was applied, and that pure Ti implants were surrounded by fibrous tissue with no bone contact at all.
Animals ; Bone Substitutes ; Coated Materials, Biocompatible ; pharmacology ; Dogs ; Femur ; injuries ; surgery ; Hydroxyapatites ; pharmacology ; Implants, Experimental ; Male ; Osseointegration ; Osteogenesis ; drug effects ; Titanium

The aim of this study was to develop a bioactive membrane for inducing bone regeneration. The membrane was composed of polylactic acid, collagen, recombinant human bone morphogenetic protein-2 (rhBMP-2). The PLA + collagen + rhBMP-2 membrane was fabricated by solvent-casting and cool-drying. The mechanic properties of this compound membrane were tested. The two surfaces of membrane were observed by SEM. Degradability of PLA was evaluated by SEM observation and molecular weight measure in vitro and in vivo. The compound membranes were implanted in rabbit muscles. The samples were obtained when animals were sacrificed at different periods: 2 weeks, 1, 2, 3, 6 months after surgery. The biodegradability and biocompatibility of the membrane were evaluated. The heterotopic bone inducing activity of BMP was identified. The results indicated that the strength at extension to failure of the compound membrane was 36.4MPa at 2.3% strain. The compound membrane was found bearing active factor on its coarse side, which can induce bone regeneration. After implantation in vivo, the membrane maintained the structure for three months and degraded in 6 months. Based on histological analysis, there was no obvious inflammation. Heterotopic bone was induced. We could conclude that the PLA + collagen + rhBMP-2 membrane is an absorbable compound membrane that possesses good biocompatibility, adequate mechanic properties and excellent property of bone induction. It could be applied as an ideal membrane for inducing bone regeneration.
Animals ; Biocompatible Materials ; Biodegradation, Environmental ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; administration & dosage ; pharmacology ; Bone Regeneration ; drug effects ; Collagen ; administration & dosage ; pharmacology ; Guided Tissue Regeneration ; Lactic Acid ; administration & dosage ; pharmacology ; Male ; Membranes, Artificial ; Polyesters ; Polymers ; administration & dosage ; pharmacology ; Rabbits ; Transforming Growth Factor beta ; administration & dosage ; pharmacology

OBJECTIVES: To summarize the open-eruption technique of impacted anterior maxillary teeth, this study reports a technically improved operation on surgical exposure based on dental follicles and evaluates post-treatment periodontal health considering the effect of dental follicles. METHODS: Patients who underwent open-eruption technique with unilateral labially impacted maxillary central incisors were selected. The impacted teeth were assigned to the experimental group, and the contralateral unimpacted maxillary central incisors were assigned to the control group. In the surgical exposure, the new technique makes use of dental follicles to manage the soft tissue, so as to preserve soft tissue for better aesthetic results and healthier periodontal tissue. Tooth length, root length, alveolar bone loss, and alveolar bone thickness were recorded after the therapy. RESULTS: A total of 17 patients with unilateral maxillary central incisor impaction were successfully treated. The tooth length and root length of the two groups showed a statistically significant difference between the impacted and homonym teeth, with a shorter length in the impacted tooth (P<0.05). More labial alveolar bone loss was found in the experimental group compared with that in the control group (P<0.05). The outcomes of the cementoenamel junction width, pa- latal alveolar bone loss, and alveolar bone thickness did not indicate statistical significance between the experimental and control groups (P>0.05). CONCLUSIONS In the surgical exposure, the new technique uses dental follicles to manage the soft tissue and preserve it for better aesthetic results and healthier periodontal tissues.
Humans ; Tooth, Impacted/surgery* ; Incisor ; Alveolar Bone Loss/diagnostic imaging* ; Tooth Root ; Dental Sac ; Maxilla/surgery* ; Esthetics, Dental