2 种新型骨植入钛合金的细胞生物相容性研究

目的:研究国内2种新研制骨植入钛合金Ti1、Ti2对成骨细胞生物学行为的影响。方法:采用SD乳鼠体外原代分离培养的成骨细胞,将细胞分别接种于新型钛合金表面建立体外共同培养。采用MTT比色试验检测第3天成骨细胞的增殖百分率,采用扫描电镜(SEM)观察细胞形态学变化,并且对培养第5天时细胞碱性磷酸酶(ALP)功能活性进行检测。结果:成骨细胞在新合金表面增殖百分率、碱性磷酸酶活性检测值均高于对照组,细胞增殖百分率及碱性磷酸酶吸光度值与对照组间统计学分析无显著性差异(P>0.05)。扫描电镜观察细胞在新合金表面伸展状况良好、黏附牢固,并具有成骨细胞典型形态特征。结论:2种新型钛合金对成骨细胞学行为无不良影响。     

甲状旁腺激素在体外对破骨细胞分化及骨重吸收能力的影响

目的 探讨甲状旁腺激素(PTH)在体外直接对破骨细胞(OCs)分化及骨吸收能力的影响，以及其与成骨细胞(OBs)中核因子kB受体激活剂受体配体(ligand of receptor activator of nuclear factor kappa B，RANKL)基因和OPG(osteoprotegerin)基因表达的关系。方法体外直接用PTH诱导C3h小鼠全骨髓分化出OCs，用牙片小坑法(pits assayr)观察OCs对骨的重吸收能力。并采用多重RT-PCR方法检测在不同PTH作用浓度和不同作用时间的条件下,OBs中RANKL基因和OPG基因的表达情况。结果(1)PTH在体外可诱导C3h小鼠全骨髓分化出OCs，且在一定浓度范围内，随着PTH增加，OCs的形成数目和骨组织的破坏程度随之增加；(2)在一定PTH浓度和时间范围内，OBs中的RANKL-mRNA及OPG-mRNA表达呈剂量依赖性和时间依赖性。结论 PTH在体外可通过诱导RANKL基因和OPG基因表达而直接影响OCs的分化和骨重吸收功能。     

Cell spreading correlates with calculated logP of amino acid-modified surfaces

The interactions of cells with synthetic surfaces are a critical factor in biomaterials design and it would be invaluable if these interactions could be precisely controlled and predicted. Hydrophobicity or lipophilicity of the surface is commonly used to rationalize cell attachment to materials. In the pharmaceutical sciences it is common practice to use logP, the partitioning coefficient between water and octanol, as a reliable indicator of the hydrophobicity or lipophilicity of (drug) molecules. A number of methods are available to reliably predict logP values directly from molecular structure. In this paper we demonstrate that logP values calculated on the basis of the molecular structure of a range of surface-tethered groups correlate well with cell spreading. To our knowledge this is the first method to predict cell spreading on chemically modified surfaces via nonspecific interactions.     

Effects of vitamin D2 analogs on calcium metabolism in vitamin D-deficient rats and in MC3T3-E1 osteoblastic cells

The effects of 1α-hydroxyvitamin D₂ on calcium metabolism in vivo and of 1α,25-dihydroxyvitamin D₂, which is an active metabolite of 1α-hydroxyvitamin D₂, on bone metabolism in vitro was studied and compared with that of 1α-hydroxyvitamin D₃ or 1α,25-dihydroxyvitamin D₃. 1α-Hydroxyvitamin D₂ and 1α-hydroxyvitamin D₃ was equally potent in stimulating intestinal calcium transport by using the everted sac method and of calcium mobilization from bone in vitamin D-deficient rats. On the other hand, the hypercalcemic activity of 1α-hydroxyvitamin D₂ was much lower than that of 1α-hydroxyvitamin D₃ in normal mice and rats. 1α,25-Dihydroxyvitamin D₂ and 1α,25-dihydroxyvitamin D₃ stimulated alkaline phosphatase activity in ostoblastic MC3T3-E1 cells and bone resorption in newborn mouse calvaria maintained in organ culture. These results show that 1α-hydroxyvitamin D₂ as well as 1α-hydroxyvitamin D₃ promote calcium absorption and may accelerate bone remodelling via direct action on osteoblasts. In addition, they suggest that 1α-hydroxyvitamin D₂ may be more useful than 1α-hydroxyvitamin D₃ for the treatment of senile osteoporosis, because hypercalcemia is one of the major side effects of 1α-hydroxyvitamin D₃.     

The W9 peptide directly stimulates osteoblast differentiation via RANKL signaling

Objective

A RANKL-binding peptide, WP9QY (W9), is known to inhibit mouse osteoclastogenesis by stimulating the production of autocrine factors such as bone morphogenetic proteins (BMPs) to induce osteoblast differentiation. In the present study, we investigated whether osteoblastic differentiation is mediated by RANKL signaling.

Altered plasma membrane dynamics of bone morphogenetic protein receptor type Ia in a low bone mass mouse model

Bone morphogenetic proteins (BMPs) are growth factors that initiate differentiation of bone marrow stromal cells to osteoblasts and adipocytes, yet the mechanism that decides which lineage the cell will follow is unknown. BMP2 is linked to the development of osteoporosis and variants of BMP2 gene have been reported to increase the development of osteoporosis. Intracellular signaling is transduced by BMP receptors (BMPRs) of type I and type II that are serine/threonine kinase receptors. The BMP type I a receptor (BMPRIa) is linked to osteogenesis and bone mineral density (BMD). BMPRs are localized to caveolae enriched with Caveolin1 alpha/beta and Caveolin beta isoforms to facilitate signaling. BMP2 binding to caveolae was recently found to be crucial for the initiation of the Smad signaling pathway. Here we determined the role of BMP receptor localization within caveolae isoforms and aggregation of caveolae as well as BMPRIa in bone marrow stromal cells (BMSCs) on bone mineral density using the B6.C3H-6T as a model system. The B6.C3H-6T is a congenic mouse with decreased bone mineral density (BMD) with increased marrow adipocytes and decreased osteoprogenitor proliferation. C57BL/6J mice served as controls since only a segment of Chr6 from the C3H/HeJ mouse was backcrossed to a C57BL/6J background. Family of image correlation spectroscopy was used to analyze receptor cluster density and co-localization of BMPRIa and caveolae. It was previously shown that BMP2 stimulation results in an aggregation of caveolae and BMPRIa. Additionally, BMSCs isolated from the B6.C3H-6T mice showed a dispersion of caveolae domains compared to C57BL/6J. The aggregation of BMPRIa that is necessary for signaling to occur was inhibited in BMSCs isolated from B6.C3H-6T. Additionally, we analyzed the co-localization of BMPRIa with caveolin-1 isoforms. There was increased percentage of BMPRIa co-localization with caveolae compared to C57BL/6J. BMP2 stimulation had no effect on the colocalization of BMPRIa with caveolin-1. Disrupting caveolae initiated Smad signaling in the isolated BMSCs from B6.C3H-6T. These data suggest that in congenic 6T mice BMP receptors aggregation is inhibited causing an inhibition of signaling and reduced bone mass.     

白藜芦醇通过上调SOCS-3蛋白抑制脂多糖诱导的成骨细胞表达MIP-2

目的:探讨白藜芦醇是否依赖细胞因子信号转导抑制因子3(suppressor of cytokine signaling-3,SOCS-3)蛋白发挥对牙髓卟啉单胞菌(Porphiyromonas endodontalis,P.e)脂多糖(lipopolysaccharides,LPS)诱导成骨细胞产生巨噬细胞炎性蛋白2(...     

兔骨髓基质细胞向成骨细胞分化过程的超微形态结构观察

目的观察并探讨骨髓基质细胞向成骨细胞诱导分化过程中细胞超微形态结构的变化及相互联系。方法抽取成年兔髂骨骨髓，分离、培养骨髓基质细胞，1周后分别采用含诱导因子的条件培养液和不含诱导因子的标准培养液继续培养，2周后收集细胞，应用透射电镜观察其超微结构；同时分别将上述两组细胞与煅烧骨体外复合并在原培养液中继续培养，分别于复合1、7、14d取出，用扫描电镜观察细胞表面超微形态。结果透射电镜下见诱导前的骨髓基质细胞浆少，核大，细胞器不发达，处于早期幼稚阶段，而诱导2周后的细胞核小、胞浆多，细胞器丰富，处于较为成熟阶段。扫描电镜下见复合培养2周内诱导前后的骨髓基质细胞均由圆盘形向多角形、条带状相互融合、重叠生长，诱导2周后的骨髓基质细胞间可见大量胶原纤维等基质成分以及钙盐颗粒，而诱导前的细胞始终未见基质分泌及钙盐颗粒。结论成骨诱导后，骨髓基质细胞内细胞器等超微结构极为丰富，细胞表面及细胞间有大量细胞外基质分泌和钙盐沉积。透射电镜和扫描电镜可动态观察骨髓基质细胞向成骨细胞分化过程中细胞超微形态结构的变化。     

Effects of Ethyl Acetate Extract of Poncirus trifoliata Fruit for Glucocorticoid-Induced Osteoporosis

Poncirus trifoliata fruit (PTF) affects the digestive and cardiovascular systems, and kidney function. The authors studied the effects of ethyl acetate (EtOAc) extract of PTF on the activities of osteoblasts and in an animal model. The main compounds of the EtOAc extract, naringin and poncirin have been confi rmed by HPLC and NMR analysis. Effects of osteoblastic differentiation were mea-sured by alkaline phosphatase (ALP) activity, osteopontin (OPN) protein expression and osteoprotegerin (OPG) mRNA expression in MC3T3-E1 cells. Also, osteoclast differentiation was measured by multinucleated cells (MNCs) formation through tartrate resistance acid phosphatase (TRAP)-positive staining. Bone mineral density (BMD) was measured before and after treatment with EtOAc extract of PTF in prednisolone-induced osteoporotic mice. Dexamethasone (DEX) decreased OPN and OPG expression level in MC3T3-E1 cells and ALP activity was decreased by DEX dose-dependently. EtOAc extract of PTF recovered the levels of ALP activity, and the expression of OPN and OPG in MC3T3-E1 cells treated with DEX. In osteoclast differentiation, multinucleated TRAP-positive cell formation was significantly suppressed by the EtOAc extract of PTF. Total body BMD was restored by EtOAc extract of PTF in prednisolone-induced osteoporotic mice. In conclusion, EtOAc extract of PTF recovered DEX-mediated deteriorations in osteoblastic and osteoclastic functions, and increased BMD in glucocorticoid-induced osteoporosis.