Expression of osteoblastic markers in cultured human bone and fracture callus cells

We compared the expression of osteoblastic markers in cultured human cells isolated from fracture calluses of various histological states of development with that in cells from adult and fetal bone. Adult osteoblasts and all callus cells produced almost exclusively type I collagen, whereas fetal osteoblasts produced also considerable amounts of type III collagen in vitro. 1,25-Dihydroxyvitamin D₃ induced the synthesis of osteocalcin in all bone and callus cells but to varying extents. Fetal bone cells and early-stage callus cells synthesized less than 10% the amount of osteocalcin produced by adult bone cells. Late-stage callus cells produced intermediate levels of osteocalcin. Fetal bone cells and early-stage callus cells responded to parathyroid hormone with a less pronounced increase in intracellular cAMP than did adult bone cells. Late-stage callus cells showed the best response to parathyroid hormone. The activity of alkaline phosphatase was highest in fetal bone cells. These observations show that cells isolated from fetal bone and from fracture callus tissues express a pattern of markers clearly relating them to the osteoblastic lineage. On the basis of the different patterns of osteoblastic markers expressed in vitro we conclude that functionally distinct subtypes of osteoblasts do exist in different mineralized tissues and at different developmental stages.Abbreviations DMEM Dulbecco's modified Eagle's medium - FCS Fetal calf serum - PTH Parathyroid hormone - 1,25D ₃ 1,25-Dihydroxyvitamin D₃ - AP Alkaline phosphatase     

捆绑带束缚压力对骨折模型动物骨痂形成及愈合的影响

背景：有些观点认为捆绑带的使用会影响骨折部位的血运甚至造成骨折延迟愈合与骨折不愈合。 目的：观察3种不同束缚压力捆绑带对骨折动物模型骨痂形成及愈合的影响。 方法：建立新西兰大白兔股骨干非负重骨折动物模型,髓内固定后随机分为3组,分别在骨折部位加用200,150,100 N束缚压力的捆绑带固定,术后2,4,6周观察骨痂形成及愈合。 结果与结论：200 N压力组骨折固定牢固,但骨折断端外骨痂形成受限,无骨愈合,影响断端远期稳定性。100 N压力组早期骨折断端不稳定,虽不影响骨折愈合,但容易出现畸形愈合。150 N压力组压力适中,骨折固定与愈合均良好。提示在保持适当束缚压力的情况下,捆绑带可以有效维持骨折部位稳定,避免骨折移位或畸形愈合,保障骨折正常愈合,对骨折部位骨膜血运无异常影响,有助于促进骨折早期愈合。     

Loss of Smad3 gives rise to poor soft callus formation and accelerates early fracture healing

Smad3 is an intracellular signaling molecule in the transforming growth factor β (TGF-β) pathway that serves as a regulator of chondrogenesis and osteogenesis. To investigate the role of the TGF-β/Smad3 signaling in the process of fracture healing, an open fracture was introduced in mouse tibiae, and the histology of the healing process was compared between wild-type (WT) and Smad3-null (KO) mice. In KO mice, the bone union formed more rapidly with less formation of cartilage in the callus and eventually the fracture was repaired more rapidly than in WT mice. Alkaline phosphatase staining showed that osteoblastic differentiation in the fracture callus was promoted in KO mice. Additionally, TRAP staining and the TUNEL assay revealed that the induction of osteoclasts and apoptotic cells was significantly promoted in the healing callus of KO mice. Sox9 expression clearly decreased at both mRNA and protein levels in the early stage of fracture in KO mice. In contrast, the expression of genes for osteogenesis and osteoclast formation increased from day 5 until day 14 post-fracture in KO mice compared to WT mice. From these results, we concluded that the loss of TGF-β/Smad3 signaling promoted callus formation by promoting osteogenesis and suppressing chondrogenesis, which resulted in faster fracture healing.     

The use of quantitative ultrasound to monitor fracture healing: a feasibility study using phantoms

Fracture healing has traditionally been monitored subjectively using manual manipulation of the fracture site and evaluation of radiographic images. A more objective method of monitoring would provide obvious advantages, allowing healing progress to be quantitatively assessed and so providing the opportunity for early detection of problems. A tibia phantom was used to investigate whether the longitudinal propagation velocity of ultrasound across a fracture site could be used quantitatively to assess fracture healing. The characteristic of fracture healing simulated by the phantom was the changing gap between the bone ends at the fracture site. The ultrasound velocity was measured using a recently developed machine, the SoundScan 2000 (Myriad Ultrasound Systems Ltd, Israel). The precision of the SoundScan 2000 was found to be 0.4% in vitro. Ultrasound velocity predicted the simulated fracture gap with a high degree of accuracy (R²=0.994). The measured and the theoretically calculated velocity for different widths between the simulated bone ends was found to be highly correlated with a coefficient of determination of 0.998. This result shows that the use of quantitative ultrasound to monitor fracture healing warrants further investigation in vivo.     

The use of quantitative ultrasound to monitor fracture healing: a feasibility study using phantoms

Fracture healing has traditionally been monitored subjectively using manual manipulation of the fracture site and evaluation of radiographic images. A more objective method of monitoring would provide obvious advantages, allowing healing progress to be quantitatively assessed and so providing the opportunity for early detection of problems. A tibia phantom was used to investigate whether the longitudinal propagation velocity of ultrasound across a fracture site could be used quantitatively to assess fracture healing. The characteristic of fracture healing simulated by the phantom was the changing gap between the bone ends at the fracture site. The ultrasound velocity was measured using a recently developed machine, the SoundScan 2000 (Myriad Ultrasound Systems Ltd, Israel). The precision of the SoundScan 2000 was found to be 0.4% in vitro. Ultrasound velocity predicted the simulated fracture gap with a high degree of accuracy (R2 = 0.994). The measured and the theoretically calculated velocity for different widths between the simulated bone ends was found to be highly correlated with a coefficient of determination of 0.998. This result shows that the use of quantitative ultrasound to monitor fracture healing warrants further investigation in vivo.     

Diminished callus size and cartilage synthesis in alpha 1 beta 1 integrin-deficient mice during bone fracture healing

Integrins mediate cell adhesion to extracellular matrix components. Integrin alpha 1 beta 1 is a collagen receptor expressed on many mesenchymal cells, but mice deficient in alpha 1 integrin (alpha1-KO) have no gross structural defects. Here, the regeneration of a fractured long bone was studied in alpha1-KO mice. These mice developed significantly less callus tissue than the wild-type (WT) mice, and safranin staining revealed a defect in cartilage formation. The mRNA levels of nine extracellular matrix genes in calluses were evaluated by Northern blotting. During the first 9 days the mRNA levels of cartilage-related genes, including type II collagen, type IX collagen, and type X collagen, were lower in alpha1-KO mice than in WT mice, consistent with the reduced synthesis of cartilaginous matrix appreciated in tissue sections. Histological observations also suggested a diminished number of chondrocytes in the alpha 1-KO callus. Proliferating cell nuclear antigen staining revealed a reduction of mesenchymal progenitors at the callus site. Although, the number of mesenchymal stem cells (MSCs) obtained from WT and alpha 1-KO whole marrow was equal, in cell culture the proliferation rate of the MSCs of alpha 1-KO mice was slower, recapitulating the in vivo observation of reduced callus cell proliferation. The results demonstrate the importance of proper collagen-integrin interaction in fracture healing and suggest that alpha1 integrin plays an essential role in the regulation of MSC proliferation and cartilage production.     

骨膜在骨折愈合及骨组织修复过程中的作用

背景:骨膜因含有成骨潜能的细胞而参与骨折愈合及骨组织修复的过程,其在修复骨缺损方面的作用是目前研究的热点。目的:对骨膜在骨折愈合及骨组织修复过程中所发挥的作用进行综述。方法:第一作者应用计算机检索1964年1月至2019年12月PubMed、中国知网数据库等中英文期刊全文数据库有关骨膜在骨折愈合及骨组织修复过程中作用的文章,英文检索词periosteum,bone healing,periosteum cells;中文检索词骨膜,骨折愈合,骨膜细胞。最终选择48篇重要文献进行综述。结果与结论:①骨膜的完整性对于骨折愈合和骨组织的修复极其重要,因其较好的成骨性能、优质的材料学特性和屏障作用等特点被广泛应用于骨组织工程;②骨膜在牵拉成骨过程中的作用机制目前尚且存在争议,研究证实骨膜缺如并不会影响下颌骨缺损牵拉成骨的效果,但在四肢骨缺损牵拉成骨中的作用仍有待进一步研究。     

胃癌干细胞表面标记物的研究与最新进展

背景:最近人们研究发现,肿瘤的复发与肿瘤干细胞密切相关。肿瘤干细胞理论为研究胃癌的发病机制以及诊治开辟了新的途径,确定的表型有利于锁定胃癌干细胞,这有助于探讨胃癌干细胞在自我更新和分化过程中的作用,并为治疗胃癌提供新思路,但其表型仍存在争议。目的:综述胃癌干细胞表面标志物的研究进展。方法:由第一作者分别以"Gastric Cancer Stem Cells"为英文关键词检索PubM ed英文数据库(http://www.ncbi.nlm.nih.gov/pubmed)中1965年1月至2015年10月的文献,共保留68篇文献进行综述。结果与结论:通过分析整理,传统上的肿瘤干细胞表型不适合于标记胃癌干细胞。研究发现CD90在胃癌原发性肿瘤中有表达,分离后经无血清肿瘤球培养法培养可获得肿瘤球。CD24的表达有助于提高胃癌细胞的黏附、侵袭、迁移能力。此外研究证实CD44及CD54共表达的细胞会大量出现在胃癌复发早期患者的体内而不是晚期,表达CD44及CD54的肿瘤细胞很可能是导致胃癌发生以及复发的重要原因。综上所述,CD44^+CD24^+CD90^+CD54^+很可能是胃癌干细胞的表型。     

仿生骨基质材料的研究进展

骨缺损修复是临床中所面临的难题之一,为了解决这个难题,人们研制了不同的仿生骨基质材料。本文对仿生骨基质材料的研究进展进行综述。     

糖尿病大鼠骨折愈合早期局部骨痂组织中Ⅰ型胶原纤维表达和骨密度的变化

背景：糖尿病患者骨折愈合过程中局部骨痂形成较差,成骨细胞增殖能力下降,骨折延迟愈合或者不愈合,而Ⅰ型胶原纤维和钙质成分是骨痂的主要成分。 目的：观察糖尿病大鼠骨折愈合早期过程中骨痂组织中Ⅰ型胶原纤维含量和骨密度的变化,分析糖尿病大鼠骨折愈合过程中骨折延迟愈合,或者不愈合的原因。 方法：10只腹腔内注射链脲佐菌素破坏胰岛细胞诱导为糖尿病大鼠,10只为正常对照大鼠,腹腔内注射等容量生理盐水。2组大鼠均造成右胫骨斜形骨折,于伤后第1,2,4,6周取骨痂组织进行检测。 结果与结论：正常对照组X射线片显示骨痂生成量多,骨折愈合程度明显优于模型对照组(P < 0.01),各组Ⅰ型胶原纤维表达均呈上升趋势,在第2周达到峰值,第4周下降,至第6周进一步下降。模型对照组骨痂中Ⅰ型胶原纤维表达和骨密度升高幅度明显低于正常对照组(P < 0.01)。提示糖尿病大鼠骨折愈合过程中较正常大鼠骨痂生成下降,骨痂中Ⅰ型胶原纤维表达和骨密度升高幅度同步下降。     

Recent advances in the development of adenovirus- and poxvirus-vectored tuberculosis vaccines

Tuberculosis vaccine research began with the search for a vaccine that might be better than, and thus could replace, the current Bacillus Calmette Guérin (BCG) vaccine. Over the last fifteen years or so, intense research effort has led to the identification of a number of novel tuberculosis (TB) vaccines which can be divided into 4 categories: genetically modified mycobacteria, protein, plasmid DNA and viral. However, it is increasingly believed that the current BCG vaccine will continue to be used as a childhood vaccine and that more effort should be directed to developing appropriate boosting vaccines. Mounting evidence suggests that recombinant genetic vaccines, particularly recombinant viral vaccines, are effective in boosting immune activation and protection by BCG vaccination. Since modified vaccinia virus Ankara (MVA)- and adenovirus-vectored TB vaccines have been most extensively studied, this review will focus on recent advances in the development and applications of these two viral TB vaccines.     

Recent advances in the development of an inhaled insulin product

Inhaled insulin first entered clinical human testing in the mid 1990s. Since then, the commercial potential and technical challenges of an inhaled insulin product have grown increasingly clear, with several pharmaceutical partnerships now targeting treatment of diabetes mellitus through inhalation products in clinical development. While clinical results to date show the therapy to be generally promising, recent data have raised questions related to human safety and slowed progress toward a commercial product. Answering these questions positively in the coming years will be critical to making inhalation therapy a practical diabetes-care reality.     

Biomechanical model to simulate tissue differentiation and bone regeneration: Application to fracture healing

Bone regeneration is a common biological process occurring, for example, during fracture healing or osseo-integration of prostheses. Computer simulation of bone regeneration is difficult to carry out because it is a complex sequence of cell-mediated processes regulated by mechanobiological stimuli. An algorithm to predict the time-course of intramembranous and endochondral ossification has been developed. The algorithm assumes that there are precursor cells in the undifferentiated tissue and that these cells differentiate into either fibroblasts (to form fibrous connective tissue), chondrocytes (to form cartilaginous tissue) or osteoblasts (to form bone), based on a combination of biophysical stimuli derived from strain in the collagenous matrix and flow of the interstitial fluid. Both these stimuli are known to deform the precursor cells, and the authors hypothesise that this causes activation of cell differentiation pathways. The observation that precursor cells take time to spread throughout the fracture callus has been included in the algorithm. The algorithm was tested in an investigation of the fracture healing of a long bone using an axisymmetric finite element model. The spatio-temporal sequence of tissue phenotypes that appear in the course of fracture healing was successfully simulated. Furthermore, the origin of the precursor cells (either surrounding muscle, bone marrow or periosteum) was predicted to have a fundamental effect on the healing pattern and on the rate of reduction of the interfragmentary strain (IFS). The initial IFS=0.15 drops to 0.01 within seven iterations if cells originated from the surrounding soft tissue, but took more than 50% longer if cells originated in the inner cambium layer of the periosteum, and four times longer if precursor cells originated from the bone marrow only.     

Osteocyte: the impresario in the electrical stimulation for bone fracture healing

Delayed healing and nonunions of bone fracture are critical problems in orthopedic surgery. Electrical stimulation has been used as a therapeutic method for enhancing bone healing for a long time. Despite unanimous clinical success, the underlying mechanism concerning bone tissue in response to electrical stimulation remains poorly understood. In the meantime, emerging evidences suggest that osteocytes, with their unique location and morphologies, play an important role in regulating the behaviors of other bone cells, including osteoblasts, osteoclasts and their progenitor cells. In this paper, we hypothesize that osteocytes are the sensory cells for the electrical stimulation, and they orchestrate the whole process of new bone formation and remodeling in the electrotherapy for bone fracture. The postulated electrosensory transduction pathway might be a coupling effect of osteoblasts and osteoclasts, which is regulated by the biochemical signals expressed from osteocytes after sensing the membrane potential changes. It is believed that better understanding of this mechanism would facilitate optimizing the electrotherapy for bone disorders and assist in solving these clinical problems.     

骨质疏松性骨折愈合中骨改建的动态参数及骨密度变化

背景：当骨质疏松骨强度下降时,遭受轻微创伤或其他各种风险因素均易发生骨折。 目的：观察骨质疏松性骨折愈合过程中骨小梁组织学变化,骨密度及骨矿化沉积率的改变。 方法：SD大鼠随机分为骨质疏松组与对照组,骨质疏松组大鼠切除双侧卵巢,术后3个月,建立骨折模型。骨折后4,8,12,16 周,荧光显微镜下观察骨改建的动态参数,双能X线骨密度仪下测定骨痂组织的骨密度;骨折后1,2,4,6,8,12,16 周,应用自动图像系统测量骨组织形态。 结果与结论：骨质疏松组大鼠成熟小梁骨占骨痂面积比对照组小,且小梁骨厚度变薄、小梁骨间距较宽,骨质疏松组骨小梁表面荧光标记百分比及骨痂组织骨密度低于对照组;而骨矿化沉积率高于后者对照组。说明在骨质疏松性骨折愈合过程中,骨痂组织的组织学的异常改变导致骨折愈合质量的降低。     

羟基磷灰石/聚乳酸复合人工骨修复材料的研究进展

近年来,羟基磷灰石/聚乳酸复合生物材料用做人工骨修复材料得到了广泛的研究。本文综述了近年来羟基磷灰石/聚乳酸(HA/PLA)复合人工骨修复材料的各种制备方法及其性能影响因素的研究进展。     

Recent advances in the use of genetically engineered negative signaling molecules to treat allergic diseases

PURPOSE OF REVIEW: This review summarizes current knowledge regarding the control of human mast cell and basophil signaling and recent developments using a new therapeutic platform consisting of a human bifunctional gamma and epsilon heavy chain (Fcgamma-Fcepsilon) protein to inhibit allergic reactivity. RECENT FINDINGS: Crosslinking of FcgammaRIIb to FcepsilonRI on human mast cells and basophils by a genetically engineered Fcgamma-Fcepsilon protein (GE2) leads to the inhibition of mediator release upon FcepsilonRI challenge. GE2 protein was shown to inhibit cord blood-derived mast cell and peripheral blood basophil mediator release in vitro in a dose dependent fashion including inhibition of human IgE reactivity to cat. In addition, IgE-mediated release from lung tissue was inhibited through GE2. The mechanism of inhibition in mast cells included alterations in IgE-mediated Ca2+ mobilization, Syk phosphorylation and the formation of Dok-Grb2-SHIP complex. Proallergic effects of Langerhans-like dendritic cells and B cell IgE switching were also inhibited by GE2. In vivo, GE2 was shown to block passive cutaneous anaphylaxis (PCA) driven by human IgE in mice expressing the human FcepsilonRI and inhibit skin test reactivity to dust mite antigen in a dose dependent manner in rhesus monkeys. The balance between positive and negative signaling controls mast cell and basophil reactivity that is critical in the expression of human allergic diseases. This approach using a human Fcgamma-Fcepsilon fusion protein to co-aggregate FcepsilonRI with the FcgammaRII holds promise as a new therapeutic platform for the immunomodulation of allergic diseases and potentially other mast cell/basophil-dependent disease states.