The response of osteoblasts to nanocrystalline silicon-substituted hydroxyapatite thin films

Magnetron co-sputtering has been employed to fabricate thin nanocrystalline coatings of silicon-substituted hydroxyapatite (SiHA) of different Si compositions: 0.8 wt%, 2.2 wt%, and 4.9 wt%. A human osteoblast-like (HOB) cell model was used to study the long-term interaction between the HOB cells and coatings in vitro. Results showed that the number of cells growing on all coated titanium (Ti) samples were statistically significantly higher than on uncoated Ti. In addition, HOB cells growing on all SiHA surfaces displayed enhanced cell spreading, with extensive extracellular matrix synthesis. DNA staining revealed normal phenotype nuclear morphology for HOB cells, with several dense chromosomes surrounded by a periphery of intact nuclear membrane. Furthermore, immunofluorescent staining indicated that cells showed improved adhesion on the coated surfaces with increasing Si content, developing mature cytoskeletons with numerous distinct and well-defined actin stress fibres in the cell membranes. Results also demonstrated that the bone mineralisation process was greatest in the presence of the highest Si level (4.9 wt%). However, at very early culturing time point, cells did not attach so readily on the surface of this coating due to rapid dissolution. Thus, this work suggests that a Si content of 2.2 wt% may be the optimum loading to improve the bioactive property of HA thin films.     

豚鼠骨髓间充质干细胞与纳米羟基磷灰石体外构建组织工程人工听骨

背景：人工合成的纳米羟基磷灰石具有良好的生物活性和相容性,植入体内后能在短时间内与体内的软硬组织形成紧密结合,因此成为广泛应用的骨组织工程材料。 目的：观察豚鼠骨髓间充质干细胞与纳米羟基磷灰石复合多孔陶瓷材料体外复合培养的结合程度,并分析其构建组织工程人工听骨的可行性。 方法：采用细胞差速贴壁法分离培养豚鼠骨髓间充质干细胞,使用流式细胞仪检测CD29、CD45、CD44进行间充质干细胞表面标记物鉴定,并检测其骨细胞分化能力。将骨髓间充质干细胞与纳米羟基磷灰石复合多孔陶瓷共培养1,3,5,7,10 d,电镜观察骨髓间充质干细胞与此种支架材料的复合情况。 结果与结论：培养3 d后,可见大量骨髓间充质干细胞贴附在材料表层,并且形态稳定,生长旺盛,增殖力强,具有极佳的延伸性;培养5 d后可见材料表面已全部覆盖骨髓间充质干细胞,细胞结合紧密,细胞表面可见大量分泌颗粒,胞体明显增大,边缘完整,呈纤维样伸长;7 d后细胞逐渐从材料表面脱落,仍附在材料表面的细胞出现“星形”改变,“伪足”增多;10 d后细胞呈片状脱落。说明纳米羟基磷灰石材料保持了它良好的生物相容性,利于细胞黏附、增殖,可结合大量的骨髓间充质干细胞,用于构建组织工程人工听骨。     

羧乙基壳聚糖-纳米羟基磷灰石复合材料细胞相容性和生物力学性能的实验研究

制备羧乙基壳聚糖-纳米羟基磷灰石(NCECS/nHA)复合材料,研究其生物力学性能以及与气管软骨细胞的生物相容性。方法 气管软骨片段取自8周龄大耳白兔,Ⅱ型胶原酶消化,将所获得软骨细胞传代培养。将体外制备的NCECS/nHA复合材料分别进行干态标本和湿态标本的生物力学检测。将第3代软骨细胞种植到NCECS/nHA复合材料,分别计算材料表面软骨细胞在2h、6h、12h细胞贴壁率,并用噻唑蓝(MTT)法测定细胞增殖活性。结果 NCECS/nHA复合材料具有良好的生物力学性能。兔气管软骨细胞在NCECS/nHA复合材料表面上12h的贴壁率达(88.4±2.1)％,与其他组差异无统计学意义(P＞0.05)。同时MTT显示气管软骨细胞在NCECS/nHA复合材料表面生长状态良好。扫描电镜结果显示软骨细胞在NCECS/nHA薄膜上增殖和分化良好。结论 NCECS/nHA复合材料具备良好的细胞相容性和适宜的生物力学强度,作为一种具有开发潜力的生物材料,可用于组织工程气管的体外构建。     

壳聚糖/纳米羟基磷灰石分层复合支架的生物相容性研究

制备壳聚糖/纳米羟基磷灰石(CS/nHA)分层复合支架,对其进行细胞毒性评价.分离培养大鼠软骨细胞接种于支架,相差显微镜和扫描电镜观察细胞的黏附及生长情况.动物皮下埋植试验观察其组织相容性.实验结果证实壳聚糖/纳米羟基磷灰石分层复合支架具有良好的生物相容性,有望成为较好的骨软骨组织工程支架.     

Cellular biocompatibility and biomechanical properties of N-carboxyethylchitosan/nanohydroxyapatite composites for tissue-engineered trachea

To prepare an NCECS/nHA composite for tissue-engineered trachea and investigate its biomechanical and biocompatibile properties. Biomechanical tests were performed on dry and wet NCECS/nHA composite specimens prepared in vitro. The cell adhesion rate on each composite surface after 2, 6, and 12 hours of culture was calculated, and cell proliferation activity was measured using an MTT assay. NCECS/nHA composites exhibited satisfactory tensile strength and Young's modulus values. The adhesion rate of rabbit tracheal chondrocytes on NCECS/nHA surfaces reached 88.4% after 12 hours of culture. NCECS/nHA composites are promising scaffold materials for tissue-engineered trachea owing to satisfactory biocompatible and biomechanical properties.     

Primary human osteoblasts grow into porous tantalum and maintain an osteoblastic phenotype

Porous tantalum (Ta) has found application in orthopedics, although the interaction of human osteoblasts (HOB) with this material has not been reported. The aim of this study was to investigate the interaction of primary HOB with porous tantalum, using 5-mm thick discs of porous tantalum. Comparison was made with discs of solid tantalum and tissue culture plastic. Confocal microscopy was used to investigate the attachment and growth of cells on porous Ta, and showed that HOB attached successfully to the metal "trabeculae," underwent extensive cell division, and penetrated into the Ta pores. The maturation of HOB on porous Ta was determined in terms of cell expression of the osteoblast phenotypic markers, STRO-1, and alkaline phosphatase. Despite some donor-dependent variation in STRO-1/AlkPhos expression, growth of cells grown on porous Ta either promoted, or did not impede, the maturation of HOB. In addition, the expression of key osteoblastic genes was investigated after 14 days of culture. The relative levels of mRNA encoding osteocalcin, osteopontin and receptor activator of NFkappaB ligand (RANKL) was not different between porous or solid Ta or plastic, although these genes were expressed differently by cells of different donors. However, bone sialoprotein and type I collagen mRNA species showed a decreased expression on porous Ta compared with expression on plastic. No substrate-dependent differences were seen in the extent of in vitro mineralization by HOB. These results indicate that porous Ta is a good substrate for the attachment, growth, and differentiated function of HOB.     

电纺纳米羟基磷灰石/聚酯酰胺复合支架材料的制备及其细胞相容性

背景：采用静电纺丝技术将功能性无机纳米微粒复合高分子超细纤维,形成类细胞外基质结构和功能的复合支架材料是骨组织工程支架领域一个新的研究方向。 目的：通过静电纺丝法构建纳米羟基磷灰石/脂肪族聚酯酰胺复合纤维支架材料,并初步考察其细胞相容性。 方法：以静电纺丝法制备纳米羟基磷灰石/脂肪族聚酯酰胺超细纤维支架材料,通过扫描电镜、原子能谱等表面形貌的物相分析,进行细胞在复合材料上的形态学观察。 结果与结论：通过静电纺丝法成功制备出纳米羟基磷灰石/脂肪族聚酯酰胺超细纤维复合材料,成骨细胞直接培养于材料上呈现良好生长行为,初步证实了复合支架材料的细胞相容性。说明静电纺丝技术在构建类骨细胞外基质结构和功能的仿生复合材料方面具有独特优势,电纺超细纤维复合材料有望成为新型的骨组织工程支架。     

Molecular basis of osteoclastogenesis induced by osteoblasts exposed to wear particles

In this study, we investigate the molecular mechanisms by which human osteoblasts (HOB) challenged with wear debris promote the differentiation of osteoclast precursors. HOB were obtained from trabecular bone and exposed to alumina (Al(2)O(3)) or 'ultra-high molecular weight polyethylene' (UHMWPE) particles for 24h. The supernatant (HOB-CM) was used for the immunoenzymatic detection of receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG), as well as for inducing the osteoclast differentiation from peripheral blood mononuclear cells (PBMC). The OPG-to-RANKL ratio was significantly decreased in the conditioned medium of UHMWPE-challenged HOB. Morphological and cytochemical analysis showed that HOB-CM induced by itself the osteoclast formation, but a large amount of multinucleated tartrate-resistant acid phosphatase (TRAP)-positive giant cells were obtained when PBMCs were cultured with 1 microg/mL UHMWPE HOB-CM. The expression of genes involved in osteoclast differentiation and activation was evaluated, i.e. c-fms, RANK, c-src, c-fos, cathepsin-K (CATK), TRAP, and calcitonin R (CTR). The UHMWPE HOB-CM increases c-src expression, suggesting that polyethylene debris favour the paracrine activity of HOB in inducing the pathway involved in osteoclast polarization and adhesion. On the contrary, Al(2)O(3) HOB-CM downregulates c-fos expression, suggesting that the passage from macrophages into the osteoclast lineage is deviated. These results show that Al(2)O(3) wear debris is less active than UHMWPE in inducing osteoclast differentiation. Moreover, they provide new insight into the molecular basis of particle-induced osteoclastogenesis, that is the starting point for planning mode-specific targeting of periprosthetic osteolysis.     

Superior in vitro biological response and mechanical properties of an implantable nanostructured biomaterial: Nanohydroxyapatite–silicone rubber composite

A potential approach to achieving the objective of favorably modulating the biological response of implantable biopolymers combined with good mechanical properties is to consider compounding the biopolymer with a bioactive nanocrystalline ceramic biomimetic material with high surface area. The processing of silicone rubber (SR)–nanohydroxyapatite (nHA) composite involved uniform dispersion of nHA via shear mixing and ultrasonication, followed by compounding at sub-ambient temperature, and high-pressure solidification when the final curing reaction occurs. The high-pressure solidification approach enabled the elastomer to retain the high elongation of SR even in the presence of the reinforcement material, nHA. The biological response of the nanostructured composite in terms of initial cell attachment, cell viability and proliferation was consistently greater on SR–5 wt.% nHA composite surface compared to pure SR. Furthermore, in the nanocomposite, cell spreading, morphology and density were distinctly different from that of pure SR. Pre-osteoblasts grown on SR–nHA were well spread, flat, large in size with a rough cell surface, and appeared as a group. In contrast, these features were less pronounced in SR (e.g. smooth cell surface, not well spread). Interestingly, an immunofluorescence study illustrated distinct fibronectin expression level, and stronger vinculin focal adhesion contacts associated with abundant actin stress fibers in pre-osteoblasts grown on the nanocomposite compared to SR, implying enhanced cell–substrate interaction. This finding was consistent with the total protein content and SDS–PAGE analysis. The study leads us to believe that further increase in nHA content in the SR matrix beyond 5 wt.% will encourage even greater cellular response. The integration of cellular and molecular biology with materials science and engineering described herein provides a direction for the development of a new generation of nanostructured materials.     

Structural and in vitro adhesion analysis of a novel covalently coupled bioactive composite

The interfacial adhesion between a restorative composite and tooth is one of the major factors that determine the ultimate performance of composite restoration. A novel polyurethane (PU) composite material was prepared by chemically binding the nano-hydroxyapatite (nHA) to the diisocyanate component in the PU backbone by utilizing solvent polymerization. The procedure involved stepwise addition of monomeric units of the PU and optimizing the reagent concentrations. The resultant materials were characterized structurally (Raman Spectroscopy) and in vitro bioactive analysis was conducted in modified-simulated body fluid for periodical time intervals. The in vitro study evaluated the push-out bond strength of existing obturating material and novel covalently linked PU/nHA composites to dentin after long-term storage in deionized water and artificial saliva. Human extracted molar roots were filled with experimental samples and analyzed at predetermined time intervals. The shear bond strength of samples was measured and surface morphologies were evaluated. Covalent bond formation was achieved between PU and nHA without intermediate coupling agent. With the increase in concentration of nHA, the composite showed more bioactivity and adhesion toward tooth structure. Bond strength of this new composite were in accordance with obutrating material, therefore, the material can be used as an obturating material because of its direct adhesion with tooth structure.     

Polyurethane/nano-hydroxyapatite composite films as osteogenic platforms

A wide variety of biomaterials are utilized in tissue engineering to promote cell proliferations in vitro or tissue growth in vivo. The combination of cells, extracellular matrices, and biocompatible materials may make it possible to grow functional living tissues ranging from bone to nerve cells. In bone regeneration, polymeric scaffolds can be enhanced by the addition of bioactive materials. To this end, this study designed several ratios of polyurethane (PU) and nano-hydroxyapatite (nHA) composites (PU-nHA ratios: 100/0, 90/10, 80/20, 70/30, 60/40 w/w). The physical and mechanical properties of these composites and their relative cellular compatibility in vitro were determined. The chemical composition and crystallinity of the composites were confirmed using X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analyses. Atomic force microscopy, nano-indentation, and contact angle measurements were used to evaluate surface properties. The results showed a significant increase in surface roughness and a decrease in contact angle when the nHA concentration increased above 20%, resulting in a significant increase in hydrophilicity. These surface property changes influenced cellular behavior when MC 3T3-E1 cells were seeded on the composites. All composites were cytocompatible. There was a linear increase in cell proliferation on the 80/20 and 70/30 composites only, whereas subjective evaluation demonstrated noticeable clusters or nodules of cells (considered hallmarks of osteogenic differentiation) in the absence of any osteogenic inducers only on the 90/10 and 80/20 composites. Cellular data suggests that the 80/20 composite was an optimal environment for cell adhesion, proliferation, and, potentially, osteogenic differentiation in vitro.     

3D打印羊椎骨粉/聚乙烯醇支架、纳米级羟基磷灰石/聚乙烯醇支架、羊椎骨粉/聚乙烯醇无孔骨板的性能比较

BACKGROUND: With the promotion of 3D printing technology, 3D printing scaffolds for bone tissue engineering have become the new ideas for jaw bone repair. OBJECTIVE: To compare the physical and biological properties of sheep vertebral bone meal/polyvinyl alcohol (PVA) scaffold, nano-hydroxyapatite (nHA)/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. METHODS: 3D printing technology was used to print sheep vertebral bone meal/PVA scaffold, nHA/PVA scaffold, and sheep vertebral bone meal/PVA nonporous bone plate. Porosity, morphology, water absorption rate and mechanical properties of different scaffolds were detected. Three kinds of scaffolds were all used to culture bone marrow mesenchymal stem cells, and cell proliferation ability was detected using cell counting kit-8 at 1, 4, 7 days of culture. RESULTS AND CONCLUSION: Under scanning electron microscope, the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold exhibited regular and interconnected pores with good continuity and clear network structure; the sheep vertebral bone meal/PVA nonporous bone plate had no obvious pores; however, it had dense and evenly distributed micropores with different sizes on its surface. The porosity of nHA/PVA scaffold was lower than that of the sheep vertebral bone meal/PVA scaffold (P < 0.05). The water absorption rate was highest for the nHA/PVA scaffold followed by the sheep vertebral bone meal/PVA scaffold and the sheep vertebral bone meal/PVA nonporous bone plate (P < 0.05). In contrast, the scaffold toughness was highest for the sheep vertebral bone meal/PVA nonporous bone plate, followed by the sheep vertebral bone meal/PVA scaffold and nHA/PVA scaffold. In addition, the cell proliferation activity of cells cultured on the sheep vertebral bone meal/PVA scaffold was significantly higher than that cultured on the other two kinds of scaffolds. Taken together, the 3D printing sheep vertebral bone/PVA scaffold has good physical and chemical performance.     

Fabrication of nano-hydroxyapatite on electrospun silk fibroin nanofiber and their effects in osteoblastic behavior

In this study, a novel tissue engineering scaffold material of electrospun silk fibroin/nano-hydroxyapatite (nHA) biocomposite was prepared by means of an effective calcium and phosphate (Ca-P) alternate soaking method. nHA was successfully produced on regenerated silk fibroin nanofiber as a substrate within several minutes without any pretreatments. The morphologies of both nonmineralized and mineralized nanofibers were analyzed using a field-emission scanning electron microscopy (FESEM). The crystallographic phases of the nHA were analyzed using X-ray diffraction (XRD). Fourier transform infrared (FTIR) spectrophotometer and thermogravimetry analyses (TGA) were employed to determine the type of functional groups and the amount of nHA presenting in the silk/nHA biocomposite nanofibers, respectively. The osteoblastic activities of this novel nanofibrous biocomposite scaffold were also investigated by employing osteoblastic-like MC3T3-E1 cell line. The cell functionality such as alkaline phosphatase (ALP) activity was ameliorated on mineralized nanofibers. All these results indicated that this silk/nHA biocomposite scaffold material may be a promising biomaterial for bone tissue engineering.     

Osteoblasts on rod shaped hydroxyapatite nanoparticles incorporated PCL film provide an optimal osteogenic niche for stem cell differentiation

After the clinical insertion of a bone biomaterial, the surrounding osteoblasts would migrate and attach to the implant surface and foster a microenvironment that largely determines the differentiation fate of the comigrated mesenchymal stem cells. Whether the fostered microenvironment is suitable for osteogenic differentiation of mesenchymal stem cells is critical for the subsequent osseointegration. In this study, we determined (1) how the spherical or rod-shaped hydroxyapatite nanoparticles (nHA) incorporated poly(?-caprolactone) (PCL) films (PCL-spherical nHA, PCL-rod nHA) interact with primary human osteoblasts (HOBs); (2) how the microenvironment rendered by their interaction affects osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ASCs). HOBs were seeded on PCL, PCL-spherical nHA, and PCL-rod nHA films, respectively. When cultured alone, the HOBs on PCL-rod nHA films showed most efficient osteoblastic differentiation compared with those on PCL or PCL-spherical nHA films. When cocultured with ASCs in an indirect coculture system, only the HOBs on PCL-rod nHA films up-regulated the gene expression of Runx2, bone sialoprotein, and osteocalcin of ASCs. Additionally, the HOBs on PCL-rod nHA films showed significant up-regulation of bone morphogenic protein 2 gene and protein expression and induced highest phosphorylated Smad1/5 protein level in ASCs. Treatment of the coculture medium with bone morphogenic protein 2 inhibitor (Noggin) largely abolished the osteogenic differentiation of the ASCs induced by the HOBs on PCL-rod nHA films. In conclusion, HOBs can not only best display their osteoblastic phenotype by culturing on PCL-rod nHA films but also render an optimal osteogenic niche for the differentiation of stem cells.     

成骨诱导人脐带间充质干细胞与纳米羟基磷灰石/聚酰胺66支架材料的生物相容性☆

背景：纳米羟基磷灰石/聚酰胺66材料有利于成骨细胞的长入和新生骨的形成、且抗弯强度、抗压强度等各项参数与正常骨组织的力学性能相接近,能满足实验动物硬组织修复的要求。 目的：分析成骨诱导后人脐带间充质干细胞与纳米羟基磷灰石/聚酰胺66复合支架的生物相容性。 方法：体外培养人脐带间充质干细胞,纯化增殖,成骨诱导。取成骨诱导后的第3代人脐带间充质干细胞接种于纳米羟基磷灰石/聚酰胺66支架材料上,观察细胞的生长、增殖情况及材料细胞毒性。 结果与结论：成骨诱导后人脐带间充质干细胞在复合支架上生长分化良好,增殖活性不受材料影响。成骨诱导14 d内,可见碱性磷酸酶活性随着培养时间延长而逐渐增高。MTT法检测细胞无毒性。扫描电镜观察,1 d后可见细胞在支架表面附着生长;7 d后可见细胞在材料上生长良好,材料空隙有大量充填。说明纳米羟基磷灰石/聚酰胺66支架可作为骨组织工程中人脐带间充质干细胞的细胞载体,具有良好的生物相容性,能满足骨组织工程的需要。关键词：羟基磷灰石/聚酰胺66;人脐带间充质干细胞;细胞培养;骨组织工程;支架;生物相容性 缩略语注释：nHA/PA66：nano-hydroxyapatite crystals and pnolyamide 66,羟基磷灰石/聚酰胺66;hUCMSCs：human umbilical cord mesenchymal stem cells,人脐带间充质干细胞 doi:10.3969/j.issn.1673-8225.2012.16.019     

Involvement of tissue transglutaminase in the stabilisation of biomaterial/tissue interfaces important in medical devices

Tissue transglutaminase (tTG) has recently been established as a novel cell surface adhesion protein that binds with high affinity to fibronectin in the pericellular matrix. In this study, we have made use of this property to enhance the biocompatibility of poly(epsilon-caprolactone) (PCL), a biomaterial currently used in bone repair. Poly(epsilon-caprolactone) discs were first coated with fibronectin and then tTG. The surface localisation of the two proteins was confirmed using ELISA and the tTG shown to be active on the surface by incorporation of biotin cadaverine into the fibronectin coating. When human osteoblasts (HOBs) were seeded onto the coated polymer surfaces in serum free medium, the surface coated with fibronectin and then tTG showed an increase in the spreading of the cells as compared to the surface coated with fibronectin alone, when analysed using environmental scanning electron microscopy. The presence of tTG had no effect on HOB cell differentiation when analysed by determining alkaline phosphatase activity. The use of tTG as a novel adhesion protein in this way may therefore have considerable potential in forming a stable tissue/biomaterial interface for application in medical devices.     

纳米晶重组类人胶原基/聚乳酸复合支架材料的表征及细胞相容性研究

目的　制备纳米羟基磷灰石/重组类人胶原基/聚乳酸复合支架材料 (nano-hydroxyapatite/ recombinant human- like collagen/polylactic acid,nHA/RHLC/PLA),观察材料的形貌特征,探讨材料对骨髓基质干细胞(BMSCs)增殖、黏附及分化等生物学行为的影响。 方法　制备nHA/RHLC/PLA复合支架材料,应用X 光衍射分析（XRD）、红外光谱分析（FTIR）、ZWICK Z005 测试机对样品的化学成分、机械性能测试和压缩强度进行测试,通过扫描电镜检查等方法观察材料的表征;将犬骨髓基质细胞（BMSCs）接种在支架材料上培养,检测材料-细胞的黏附情况及材料对细胞生长增殖的影响。 结果　nHA/RHLC/PLA复合支架材料压缩强度均大于1MPa,达到了天然松质骨的最低强度。扫描电镜结果显示：支架材料呈三维多孔结构,孔为不规则多边形,孔的走向多样,纵向和横向孔隙互为交通,孔径在几十微米到300微米不等,孔隙率为75%~83%。nHA/RHLC/PLA复合支架材料表面BMSCs的黏附、生长良好;而BMSCs的增殖能力与对照组相比,差异无显著性意义(P>0.05)。 结论　nHA/RHLC/PLA复合支架材料符合组织工程骨支架的力学要求,具有良好的微观结构,无细胞毒性,细胞与支架生物相容性良好。利用重组类人胶原代替动物源性胶原制备纳米晶骨修复材料,规避了动物胶原交叉感染的风险,有望成为一种理想的骨组织工程支架材料。     

In vitro evaluation of nanosized carbonate-substituted hydroxyapatite and its polyhydroxyethylmethacrylate nanocomposite

Nanometer scale carbonate-substituted hydroxyapatite (nanoCHA) particles were prepared and examined using transmission electron microscopy, which revealed their polycrystalline nature with a rod-like morphology (20-30 nm in width and 50-80 nm in length). In vitro cytotoxicity study showed that there was some evidence of lactate dehydrogenase (LDH) release when macrophages were in contact with high concentrations of nanoCHA particles. The levels of LDH release decreased significantly with a reduction in nanoCHA concentration. A similar trend was observed for the inflammatory cytokine TNF-alpha. nanoCHA particles with high carbonate content induced a high level of TNF-alpha release. Biological testing using a human osteoblast (HOB) cell model found that HOB cells were able to grow and proliferate on a nanoCHA deposited surface. Well organized actin fibers were observed for HOB cells in contact with nanoCHA particles with low carbonate content and the cell proliferation rate was higher on these particles in comparison with those of high carbonate nanoCHA particles. Therefore, low carbonate nanoCHA particles were incorporated into poly-(2-hydroxyethylmethacrylate) matrix to make a nanocomposite. It was found that the nanoCHA composite was hydrophilic and became rubber-like after hydration. Both 20 wt % and 40 wt % composites were able to induce the formation of bone-like apatite after immersion in simulated body fluid. A high bioactivity of the composite was obtained with high loading of the nanoCHA filler. These results demonstrate the potential of formulating nanocomposites for biomedical applications.     

Human osteoblast cultures from osteoporotic and healthy bone: biochemical markers and cytokine expression in basal conditions and in response to 1,25(OH)2D3

The development of methods to culture bone cells has enhanced in vitro studies and allowed researchers to investigate bone cell metabolism in healthy tissue and in various different bone diseases. Greater knowledge of cultures of pathologic bone tissue-derived osteoblasts may be helpful in performing in vitro experiments that test biomaterials and therapies to be used in the orthopedic field, since this kind of approach better reflects the conditions of clinical relevance to many patients. In the present study primary cultures of human osteoblastic cells were isolated from donors with osteoporosis (HOB, Human Osteopenic Bone) and their respective controls (HNB, Human Normal Bone). They were then characterized in baseline conditions and after stimulation with 10(-9) M 1,25(OH2)D3. Specific biochemical markers of bone cells and cytokines involved in bone turnover were evaluated to assess cell metabolism and any possible differences between osteoblasts derived from healthy and osteopenic bone tissue. Under baseline conditions, HNB and HOB in vitro cultures showed some differences in proliferation (MTT test), PICP, OC and IL-6. The HNB response to 1,25-(OH2)D3 stimulation differed significantly from that of the HOB cultures but only with regard to the MTT test, and ALP and PICP levels; the other selected parameters showed a similar behavior for both cultures. The current findings should be taken into account when cultures derived from human bone are used for in vitro experiments.