Molecular Tissue Engineering: Applications for Modulation of Mesenchymal Stem Cells Proliferation by Transforming Growth Factor β_1 Gene Transfer

The effect of transforming growth factor β 1 (TGF β 1 ) gene transfection on the proliferation of bone marrow derived mesenchymal stem cells (MSC S ) and the mechanism was investigated to provide basis for accelerating articular cartilage repairing using molecular tissue engineering technology. TGF β 1 gene at different doses was transduced into the rat bone marrow derived MSCs to examine the effects of TGF β 1 gene transfection on MSCs DNA synthesis, cell cycle kinetics and the expression of proliferating cell nuclear antigen (PCNA). The results showed that 3 μl lipofectamine mediated 1 μg TGF β 1 gene transfection could effectively promote the proliferation of MSCs best; Under this condition (DNA/Lipofectamine=1μg/3μl), flow cytometry and immunohistochemical analyses revealed a significant increase in the 3 H incorporation, DNA content in S phase and the expression of PCNA. Transfection of gene encoding TGF β 1 could induce the cells at G0/G1 phase to S1 phase, modulate the replication of DNA through the enhancement of the PCNA expression, increase the content of DNA at S1 phase and promote the proliferation of MSCs. This new molecular tissue engineering approach could be of potential benefit to enhance the repair of damaged articular cartilage, especially those caused by degenerative joint diseases.

Monthly composites from Sentinel-1 and Sentinel-2 images for regional major crop mapping with Google Earth Engine

Rapid and accurate access to large-scale,high-resolution crop-type distribution maps is important for agricultural management and sustainable agricultural development.Due to the limitations of remote sensing image quality and data processing capabilities,large-scale crop classification is still challenging.This study aimed to map the distribution of crops in Heilongjiang Province using Google Earth Engine(GEE)and Sentinel-1 and Sentinel-2 images.We obtained Sentinel-1 and Sentinel-2 images from all the covered study areas in the critical period for crop growth in 2018(May to September),combined monthly composite images of reflectance bands,vegetation indices and polarization bands as input features,and then performed crop classification using a Random Forest(RF)classifier.The results show that the Sentinel-1 and Sentinel-2 monthly composite images combined with the RF classifier can accurately generate the crop distribution map of the study area,and the overall accuracy(OA)reached 89.75%.Through experiments,we also found that the classification performance using time-series images is significantly better than that using single-period images.Compared with the use of traditional bands only(i.e.,the visible and near-infrared bands),the addition of shortwave infrared bands can improve the accuracy of crop classification most significantly,followed by the addition of red-edge bands.Adding common vegetation indices and Sentinel-1 data to the crop classification improved the overall classification accuracy and the OA by 0.2 and 0.6%,respectively,compared to using only the Sentinel-2 reflectance bands.The analysis of timeliness revealed that when the July image is available,the increase in the accuracy of crop classification is the highest.When the Sentinel-1 and Sentinel-2 images for May,June,and July are available,an OA greater than 80%can be achieved.The results of this study are applicable to large-scale,high-resolution crop classification and provide key technologies for remote sensing-based crop classification in small-scale agricultural areas.

Engineered targeting tLyp-1 exosomes as gene therapy vectors for efficient delivery of siRNA into lung cancer cells

Natural exosomes can express specific proteins and carbohydratemolecules on the surface and hence have demonstrated the great potentials for gene therapy of cancer.However,the use of natural exosomes is restricted by their low transfection efficiency.Here,we report a novel targeting tLyp-1 exosome by gene recombinant engineering for delivery of siRNA to cancer and cancer stem cells.To reach such a purpose,the engineered tLyp-1-lamp2b plasmids were constructed and amplified in Escherichia coli.The tLyp-1-lamp2b plasmids were further used to transfect HEK293T tool cells and the targeting tLyp-1 exosomes were isolated from secretion of the transfected HEK293T cells.Afterwards,the artificially synthesized siRNA was encapsulated into targeting tLyp-1 exosomes by electroporation technology.Finally,the targeting siRNA tLyp-1 exosomes were used to transfect cancer or cancer stem cells.Results showed that the engineered targeting tLyp-1 exosomes had a nanosized structure(approximately 100 nm)and high transfection efficiency into lung cancer and cancer stem cells.The function verifications demonstrated that the targeting siRNA tLyp-1 exosomes were able to knock-down the target gene of cancer cells and to reduce the stemness of cancer stem cells.In conclusion,the targeting tLyp-1 exosomes are successfully engineered,and can be used for gene therapy with a high transfection efficiency.Therefore,the engineered targeting tLyp-1 exosomes offer a promising gene delivery platform for future cancer therapy.

Expression of Transforming Growth Factor β_(1) in Mesenchymal Stem Cells: Potential Utility in Molecular Tissue Engineering for Osteochondral Repair

The feasibility of using gene therapy to treat full-thickness articular cartilage defects was investigated with respect to the transfection and expression of exogenous transforming growth factor(TGF)-β_(1)genes in bone marrow-derived mesenchymal stem cells(MSCs)in vitro.The full-length rat TGF-β_(1)cDNA was transfected to MSCs mediated by lipofectamine and then selected with G418,a synthetic neomycin analog.The transient and stable expression of TGF-β_(1)by MSCs was detected by using immunohistochemical staining.The lipofectamine-mediated gene therapy efficiently transfected MSCs in vitro with the TGF-β_(1)gene causing a marked up-regulation in TGF-β_(1)expression as compared with the vector-transfected control groups,and the increased expression persisted for at least 4 weeks after selected with G418.It was suggested that bone marrow-derived MSCs were susceptible to in vitro lipofectamine mediated TGF-β_(1)gene transfer and that transgene expression persisted for at least 4 weeks.Having successfully combined the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology,an innovative concept,i.e.molecular tissue engineering,are put forward for the first time.As a new branch of tissue engineering,it represents both a new area and an important trend in research.Using this technique,we have a new powerful tool with which:(1)to modify the functional biology of articular tissue repair along defined pathways of growth and differentiation and(2)to affect a better repair of full-thickness articular cartilage defects that occur as a result of injury and osteoarthritis.

Cell cycle exit and neuronal differentiation 1-engineered embryonic neural stem cells enhance neuronal differentiation and neurobehavioral recovery after experimental traumatic brain injury

Our previous study showed that cell cycle exit and neuronal differentiation 1(CEND1)may participate in neural stem cell cycle exit and oriented differentiation.However,whether CEND1-transfected neural stem cells can improve the prognosis of traumatic brain injury remained unclear.In this study,we performed quantitative proteomic analysis and found that after traumatic brain injury,CEND1 expression was downregulated in mouse brain tissue.Three days after traumatic brain injury,we transplanted CEND1-transfected neural stem cells into the area surrounding the injury site.We found that at 5 weeks after traumatic brain injury,transplantation of CEND1-transfected neural stem cells markedly alleviated brain atrophy and greatly improved neurological function.In vivo and in vitro results indicate that CEND1 overexpression inhibited the proliferation of neural stem cells,but significantly promoted their neuronal differentiation.Additionally,CEND1 overexpression reduced protein levels of Notch1 and cyclin D1,but increased levels of p21 in CEND1-transfected neural stem cells.Treatment with CEND1-transfected neural stem cells was superior to similar treatment without CEND1 transfection.These findings suggest that transplantation of CEND1-transfected neural stem cells is a promising cell therapy for traumatic brain injury.This study was approved by the Animal Ethics Committee of the School of Biomedical Engineering of Shanghai Jiao Tong University,China(approval No.2016034)on November 25,2016.

LEAP-1A型发动机防冰活门故障分析

LEAP-1A型发动机利用两级串联的防冰活门,调节高压防冰引气,用于发动机进气道和前缘防冰,以保证飞机在结冰气象条件下安全飞行。分析级联式防冰活门的工作原理,结合LEAP-1A型机队防冰活门的故障模式和维护数据,给出排故方法和维护建议。

对LEAP-1A型发动机部件更换周期优化与全寿命成本控制的探析

本文针对LEAP-1A型航空发动机,深入探讨其主要部件的更换周期优化策略以及全寿命成本的有效控制方法。首先,通过对LEAP-1A型发动机运行数据、故障统计和维护记录的详尽分析,研究各关键部件的实际磨损规律与使用寿命特征,为更换周期的合理设定提供科学依据。其次,借助可靠性工程理论和优化算法,构建了部件更换周期优化模型,旨在在确保飞行安全的前提下,最大限度地延长部件使用时间,降低维护频率和成本。再次,系统性地探究全寿命成本构成要素,包括购置费、维护费、运营成本等,并通过引入精益管理和全寿命管理理念,提出一套全面的成本控制方案。最后,结合实例验证上述策略的有效性,并对未来LEAP-1A型发动机的全寿命成本管理和维修策略提出了具有前瞻性和实践性的建议。

LEAP-1A发动机燃油喷嘴设计缺陷及在翼管理

LEAP-1A发动机作为一种新型的航空发动机,在商业航空领域得到了广泛应用。燃油喷嘴是发动机燃烧系统中至关重要的组件,直接影响着燃料供给的均匀性和效率。因此,深入分析LEAP-1A发动机燃油喷嘴设计缺陷及其在翼管理中的影响具有重要意义。本文以LEAP-1A发动机燃油喷嘴设计缺陷为切入点,通过对相关故障和堵塞原因进行分析,提出了解决措施,以期帮助帮助生产厂家和维修人员更好地理解问题根源,并采取有效措施来提高发动机的可靠性、安全性和经济性,促进航空发动机技术的进一步发展。

程序性细胞死亡受体1影响高糖条件下成骨细胞分化的机制

背景:程序性细胞死亡受体1属于免疫球蛋白基因超家族,可以调控成骨细胞分化、影响骨稳态,然而其在糖尿病性骨质疏松中的调控作用及机制尚不明确。目的:探讨程序性细胞死亡受体1对高糖环境下大鼠骨髓间充质干细胞成骨分化的调控作用及机制。方法:①动物实验:采用随机数字法将12只SD大鼠随机分为对照组(n=6)与模型组(n=6),对照组常规喂养,模型组腹腔注射链脲佐菌素建立1型糖尿病模型,高脂饲料喂养8周建立1型糖尿病性骨质疏松模型。喂养8周后,取2组大鼠股骨,分别进行苏木精-伊红染色、micro-CT检测与程序性细胞死亡受体1、程序性细胞死亡配体1 mNRA表达。②细胞实验:将第3代大鼠骨髓间充质干细胞随机分4组处理:正常对照组、高糖模型组加入低糖培养基,PD-1沉默组转染程序性细胞死亡受体1 siRNA,PD-1沉默空载组转染siRNA-NC。转染48 h后,正常对照组更换为新的低糖培养基,高糖模型组、PD-1沉默组、PD-1沉默空载组更换为高糖培养基,培养48 h后进行成骨诱导培养。成骨诱导21 d后,分别进行茜素红染色、qRT-PCR(程序性细胞死亡受体1、RUNX2 mRNA表达)与Western blot(β-catenin、GSK-3β、p-GSK-3β与Axin2蛋白表达)检测。结果与结论:①动物实验:苏木精-伊红染色与micro-CT检测结果显示,模型组大鼠1型糖尿病骨质疏松造模成功。qRT-PCR检测结果显示,模型组程序性细胞死亡受体1、程序性细胞死亡配体1 mRNA表达均高于对照组(P<0.05)。②细胞实验:茜素红染色结果显示,高糖模型组、PD-1沉默空载组矿化结节形成能力低于对照组、PD-1沉默组。与正常对照组比较,高糖模型组、PD-1沉默空载组程序性细胞死亡受体1 mRNA表达及GSK3β、Axin2蛋白表达均升高(P<0.05),RUNX2 mRNA表达及p-GSK3β、β-catenin蛋白表达均降低(P<0.05);与高糖模型组、PD-1沉默空载组比较,PD-1沉默组程序性细胞死亡受体1 mRNA表达及GSK3β、Axin2蛋白表达均降低(P<0.05),RUNX2 mRNA表达及p-GSK3β、β-catenin蛋白表达均升高(P<0.05)。③结果表明:沉默程序性细胞死亡受体1表达可通过激活Wnt/β-catenin信号通路促进高糖条件下大鼠骨髓间充质干细胞的成骨分化。

P144 Increases Adipose Tissue Volume by Inhibiting TGF-<i>β</i>1-Mediated Fibrous Capsule Formation in a Tissue Engineering Chamber

Tissue engineering chambers (TECs) represent a new and attractive in vivo tissue engineering model that can successfully generate mature adipose tissue. However, the newly formed adipose tissue is not able to fill the volume of the chamber as expected. To investigate whether the capsule surrounding the newly formed adipose tissue limits the adipose tissue volume in the chamber, we detected fibrotic parameters two months after these chambers were implanted into rats. The results showed that the newly formed adipose tissue was surrounded by a thick layer of capsule, and the protein levels of transforming growth factor-β1 (TGF-β1), phosphorylated Smad2 (p-Smad2), connective tissue growth factor (CTGF), collagen type I (COL-I) and α-smooth muscle actin (α-SMA) in the capsule were increased. The levels of these proteins decreased following systemic administration of P144 (a peptide inhibitor of TGF-β1). Furthermore, the capsule thickness was significantly reduced, and the adipose tissue volume was markedly greater when using P144. These findings indicate that capsule formation, which is mediated through a TGF-β1 signaling pathway, restricted the volume of the engineered adipose tissue that was formed. This study may provide a new approach to regenerate amounts of adipose tissue for the reconstruction of large soft tissue defects.

Contents and Abstracts of Journal of Mechanical Engineering ISSN 0577-6686, CN 11-2187/TH

Through the development in the past 20 years, the compliant mechanism has become an important branch of modern mechanisms and is widely applied in such fields as precision engineering and robotics. Although a series of design methods and theories of compliant mechanism have emerged, its design problem is still facing challenge. A comprehensive overview of design methods is provided for compliant mechanisms used for precision applications, usually called flexure mechanisms. Several main approaches to analysis and design of flexure mechanisms, including pseudo-rigid-body model, structural matrix model,

Contents and Abstracts of Chinese Journal of Mechanical Engineering (Chinese Edition),Vol.43,No.1～2,2007

SEVERAL ISSUES OF SCIENTIFIC DEVELOPMENT OF SAFETY PRODUCTION (INCLUDING SAFETY MANUFACTURING) IN CHINA ZHONG Qunpeng ZHANG Zheng YOU Yiliang (School of Materials Science and Engineering, Beihang University, Beijing 100083, China) Abstract: Taking the viewpoint of scientific development on safety produc-

Reform and Practice of the Core Curriculum of Civil Engineering and Architecture Based on the “1+X” System

The“1+X”system has a great impact on the development of vocational education.Based on this system,it is imperative to carry out the reform and practice of the core curriculum of Civil Engineering and Architecture.Several vocational colleges have made attempts in the reform and practice of the curriculum,but the effect is not ideal.Under the influence of various factors,such as the lack of experience,there are also several problems in the reform and practice of the curriculum.Among them,the most apparent problems are as follows:the curriculum reform is not synchronized with the development of teaching materials,the pertinence of practical teaching is lacking,and the guidance provided for professional certificate examinations is not well-established.This paper specifically analyzes the problems existing in the reform and practice of the core curriculum of Civil Engineering and Architecture under the“1+X”system,and then puts forward effective strategies for these problems.

干扰和过表达端粒酶卡哈尔体蛋白1小鼠骨髓间充质干细胞的生物学特性对比

背景:随着年龄的增长,骨髓间充质干细胞的功能逐渐降低,延缓骨髓间充质干细胞自身衰老成为一项重要课题。目的:通过改变端粒酶卡哈尔体蛋白1(telomerase cajal body protein 1,TCAB1)基因的表达,探讨延缓骨髓间充质干细胞衰老的途径。方法:细胞贴壁法培养小鼠骨髓间充质干细胞,应用重组慢病毒技术过表达或干扰骨髓间充质干细胞中的TCAB1基因,采用qPCR检测衰老相关基因P16、P21、P53、P27的表达,qPCR检测Telomere的表达判断端粒的相对长度;Western blot检测衰老蛋白P16、P21、P53、P27的表达;CCK-8法检测细胞增殖情况;Annexin V-PE/7-AAD细胞凋亡试剂盒检测细胞凋亡情况。结果与结论:过表达TCAB1基因骨髓间充质干细胞中衰老相关基因及蛋白的表达量下降,端粒相对长度增加,细胞增殖能力较强,细胞凋亡数量较少,细胞呈现年轻状态;干扰TCAB1基因骨髓间充质干细胞中衰老相关基因及蛋白的表达量上升,端粒相对长度缩短,细胞增殖能力较弱,细胞凋亡数量较多,细胞呈现衰老状态。以上结果表明,在适当范围内增加TCAB1的表达量,可以延缓细胞衰老的速度。

《ENGINE》引擎 2007F1暗战

从比利时的斯帕赛道到上海的上赛道,从迈凯伦到法拉利,F1的世界里,风驰电掣的速度背后,涌动着名利场上少不了的尔虞我诈……82是战场,Fl是商场,F1是名利场。

基质细胞衍生因子1修饰左旋聚乳酸多孔微球促进软骨细胞增殖和组织形成

背景:二维培养条件下的软骨细胞增殖及表型维持受限,多孔微球作为支架材料可提供三维培养环境,以更好地模拟体内生长条件。基质细胞衍生因子1是有强趋化效力的稳态细胞因子,能够促进细胞的黏附与增殖。目的:明确接枝基质细胞衍生因子1左旋聚乳酸多孔微球对软骨细胞生物学特性及软骨组织形成的影响。方法:(1)体外验证不同质量浓度基质细胞衍生因子1对兔软骨细胞增殖、迁移、表型维持的影响。(2)采用复乳法制备左旋聚乳酸多孔微球,利用碳二亚胺法将基质细胞衍生因子1接枝于左旋聚乳酸多孔微球上,通过酶联免疫吸附实验及孵育基质细胞衍生因子1特异荧光抗体验证接枝情况。(3)将兔软骨细胞分别接种于左旋聚乳酸多孔微球、接枝基质细胞衍生因子1左旋聚乳酸多孔微球上,检测细胞增殖与黏附。(4)在裸鼠背部皮下分别植入甲基丙烯酰胺基明胶-软骨细胞复合体(对照组)、左旋聚乳酸多孔微球-甲基丙烯酰胺基明胶-软骨细胞复合体(多孔微球组)、接枝基质细胞衍生因子1左旋聚乳酸多孔微球-甲基丙烯酰胺基明胶-软骨细胞复合体(多孔微球修饰组),8周后取材,分别进行组织学染色与成软骨相关基因qRT-PCR检测。结果与结论:(1)相较于0,1 000 ng/mL基质细胞衍生因子1,500 ng/mL基质细胞衍生因子1可促进软骨细胞的增殖与迁移,提升软骨细胞内Ⅱ型胶原、弹性蛋白、增殖细胞核抗原、Bcl-2 mRNA表达;(2)基质细胞衍生因子1成功接枝于左旋聚乳酸多孔微球上,接枝率为93.75%;(3)相较于左旋聚乳酸多孔微球,接枝基质细胞衍生因子1左旋聚乳酸多孔微球可促进软骨细胞的增殖、黏附;(4)裸鼠皮下植入8周后,相较于对照组、多孔微球组,多孔微球修饰组具有更明显的软骨陷窝结构、更丰富的软骨特异性基质和Ⅱ型胶原沉积,弹性蛋白、Ⅱ型胶原、增殖细胞核抗原、Bcl-2 mRNA表达升高。结果表明:接枝基质细胞衍生因子1左旋聚乳酸多孔微球有利于软骨细胞的黏附、增殖、表型维持以及体内软骨组织形成。

新工科背景下“1+X”教学方法研究——以智能机器人技术课程为例

在新工科背景下,高等教育需要不断创新教学方法,以适应时代的发展和人才培养的需求。通过对智能机器人技术课程教学现状的分析,详细阐述基于“1+X”教学方法的具体实施步骤和对学生的影响,研究和探索该方法在课程教学实践中对学生的理论知识、实践能力、工程意识的成效。同时探讨该方法对高等教育教学改革和创新的启示,对于在新工科背景下开展高质量教学具有一定的参考价值。

基于Sentinel-1/2数据的洪水淹没范围提取模型

遥感是监测洪水淹没范围、掌握洪涝灾情演变的重要手段,而光学影像在洪水发生时往往有较多缺失,全天候的SAR影像在提取水体时精度略低。为快速、精准提取洪水淹没范围,构建了一种综合利用Sentinel-2光学影像和Sentinel-1雷达影像数据的洪水淹没范围提取模型,采用一种自适应阈值分割算法即大津算法(OTSU)分别对两种数据以及该模型进行了水体范围提取试验,并以河北省保定市为例进行了应用分析。结果显示:云量较少的Sentinel-2影像水体提取效果最好,总体精度(OA)达到95.6%;所构建的模型在引入部分可用Sentinel-2数据后,OA达到95%,相比单独使用Sentinel-1数据OA和Kappa系数分别提升1.2%和2.4%。该模型搭载于Google Earth Engine平台,能实现快速、准确、低成本的地表水体空间范围连续输出,不受限于云雾且比单独使用Sentinel-1影像的提取精度更高,在云覆盖严重导致Sentinel-2数据缺少的情况下,该模型可作为洪水淹没范围提取方法的一种选择。

基于1+X证书制度的“岗课赛证”融通路径研究

在教育部大力推进1+X证书制度背景下,“岗课赛证”融通成为高职教育领域的重要研究课题。针对工程造价专业“岗课赛证”融通存在的问题,结合河南建筑职业技术学院“岗课赛证”融通的工作经验,提出校企双元育人共同制订人才培养方案、构建基于1+X证书制度的“岗课赛证”融通课程体系、推进“三教”改革等解决路径,以期为高职工程造价专业“岗课赛证”融通提供参考。

Interactive Training Model of TRIZ for Mechanical Engineers in China

Abstract： Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows： selecting engineers, training stage-l, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.