Vascular respiratory uncoupling increases blood pressure and atherosclerosis

The observations that atherosclerosis often occurs in non-smokers without elevated levels of low-density lipoprotein cholesterol, and that most atherosclerosis loci so far identified in mice do not affect systemic risk factors associated with atherosclerosis, suggest that as-yet-unidentified mechanisms must contribute to vascular disease. Arterial walls undergo regional disturbances of metabolism that include the uncoupling of respiration and oxidative phosphorylation, a process that occurs to some extent in all cells and may be characteristic of blood vessels being predisposed to the development of atherosclerosis. To test the hypothesis that inefficient metabolism in blood vessels promotes vascular disease, we generated mice with doxycycline-inducible expression of uncoupling protein-1 (UCP1) in the artery wall. Here we show that UCP1 expression in aortic smooth muscle cells causes hypertension and increases dietary atherosclerosis without affecting cholesterol levels. UCP1 expression also increases superoxide production and decreases the availability of nitric oxide, evidence of oxidative stress. These results provide proof of principle that inefficient metabolism in blood vessels can cause vascular disease.     

利用成体干细胞体外小口径血管的构建

设计了一套血管生物反应器系统,采用有限元的方法对组织工程小血管托架材料进行了分析,从而开发完成了一套用于构建直径为2 mm的小血管托架;通过收集人的原代骨髓基质干细胞(hBMSCs)和脂肪基质干细胞(ADSCs)进行体外扩增和培养,并选用第3代细胞与聚羟基乙酸酯(PGA)复合后置于血管生物反应器中动态培养;在生物反应器中动态培养4周后,对材料复合物进行取材,分别进行大体观察、HE染色和扫描电镜等指标检测.结果表明:血管色泽明亮,有一定的弹性,细胞分泌的胶原基质排列较规则,免疫组化结果表明血管含有平滑肌弹性肌动蛋白的成分.说明改进的血管生物反应器能模拟血管的力学环境,并能利用人骨髓间充质干细胞扣脂肪基质干细胞成功构建组织工程小血管组织.     

Activated T lymphocytes produce a matrix-degrading heparan sulphate endoglycosidase

We have previously found that lines of activated T lymphocytes specifically autosensitized to the basic protein of myelin (BP), on intravenous inoculation into syngeneic rats, were able to penetrate blood vessels, accumulate in the nervous system and cause experimental autoimmune encephalomyelitis (EAE). An important question is how effector T cells reach such targets outside the walls of blood vessels. To investigate this we have studied in vitro the interaction of anti-BP effector T lymphocytes with the basement membrane-like extracellular matrix produced by vascular endothelial cells. We now report that activated but not resting T lymphocytes produce an endoglycosidase capable of degrading heparan sulphate side chains of the proteoglycan scaffold of the extracellular matrix. Moreover, the anti-BP T lymphocytes respond to BP presented by extracellular matrix by markedly enhanced elaboration of the endoglycosidase. These results suggest that tissue-specific antigens on blood vessel walls could direct lymphocyte homing by activating enzymes that facilitate penetration of the subendothelial basal lamina. They also suggest that effector T lymphocytes can recognize antigen which is not associated with a major histocompatibility complex signal.     

Single stretch-activated ion channels in vascular endothelial cells as mechanotransducers?

Endothelial cells line the inner surface of blood vessels and act as the main barrier to the passage of cells and large molecules from the blood stream to the tissues. Recent interest in the part played by the endothelium in regulating vascular tone has focused on the synthesis and secretion of prostacyclin and an endothelium-derived relaxing factor. Endothelial cells respond to blood-borne agonist, but how the endothelium senses and responds to mechanical forces generated by the flow of blood under pressure is not known. Here we report patch-clamp recordings of ion channel activity from cell-attached membrane patches on aortic endothelial cells. In most of the patches examined, we observed unitary inward currents associated with the opening of a cation-selective channel (approximately 40 pS in standard saline). The channel is permeable to Ca2+ and its opening frequency increases when the membrane is stretched by applying suction through the patch electrode. The presence of mechanotransducing ion channels in endothelial cells may help explain how the endothelium mediates vascular responses to haemodynamic stresses.     

Tumour vascularization via endothelial differentiation of glioblastoma stem-like cells

Glioblastoma is a highly angiogenetic malignancy, the neoformed vessels of which are thought to arise by sprouting of pre-existing brain capillaries. The recent demonstration that a population of glioblastoma stem-like cells (GSCs) maintains glioblastomas indicates that the progeny of these cells may not be confined to the neural lineage. Normal neural stem cells are able to differentiate into functional endothelial cells. The connection between neural stem cells and the endothelial compartment seems to be critical in glioblastoma, where cancer stem cells closely interact with the vascular niche and promote angiogenesis through the release of vascular endothelial growth factor (VEGF) and stromal-derived factor 1 (refs 5-9). Here we show that a variable number (range 20-90%, mean 60.7%) of endothelial cells in glioblastoma carry the same genomic alteration as tumour cells, indicating that a significant portion of the vascular endothelium has a neoplastic origin. The vascular endothelium contained a subset of tumorigenic cells that produced highly vascularized anaplastic tumours with areas of vasculogenic mimicry in immunocompromised mice. In vitro culture of GSCs in endothelial conditions generated progeny with phenotypic and functional features of endothelial cells. Likewise, orthotopic or subcutaneous injection of GSCs in immunocompromised mice produced tumour xenografts, the vessels of which were primarily composed of human endothelial cells. Selective targeting of endothelial cells generated by GSCs in mouse xenografts resulted in tumour reduction and degeneration, indicating the functional relevance of the GSC-derived endothelial vessels. These findings describe a new mechanism for tumour vasculogenesis and may explain the presence of cancer-derived endothelial-like cells in several malignancies.     

Flk1-positive cells derived from embryonic stem cells serve as vascular progenitors

Interaction between endothelial cells and mural cells (pericytes and vascular smooth muscle) is essential for vascular development and maintenance. Endothelial cells arise from Flk1-expressing (Flk1+) mesoderm cells, whereas mural cells are believed to derive from mesoderm, neural crest or epicardial cells and migrate to form the vessel wall. Difficulty in preparing pure populations of these lineages has hampered dissection of the mechanisms underlying vascular formation. Here we show that Flk1+ cells derived from embryonic stem cells can differentiate into both endothelial and mural cells and can reproduce the vascular organization process. Vascular endothelial growth factor promotes endothelial cell differentiation, whereas mural cells are induced by platelet-derived growth factor-BB. Vascular cells derived from Flk1+ cells can organize into vessel-like structures consisting of endothelial tubes supported by mural cells in three-dimensional culture. Injection of Flk1+ cells into chick embryos showed that they can incorporate as endothelial and mural cells and contribute to the developing vasculature in vivo. Our findings indicate that Flk1+ cells can act as 'vascular progenitor cells' to form mature vessels and thus offer potential for tissue engineering of the vascular system.     

磁热疗预防和治疗再狭窄研究进展

 冠心病是一种严重危害人类健康的心脏病,在中国的发病率和死亡率都呈上升趋势。经皮冠状动脉腔内成形术（PTCA）是治疗冠心病的常用方法,但PTCA术后6个月内血管再狭窄的发生率仍有30%～50%,严重影响了介入治疗的效果。目前,再狭窄的发生机制尚未完全明了。研究表明,再狭窄的机制之一是血管平滑肌细胞的过度增殖。已有研究证明热疗可以抑制血管平滑肌细胞的增殖,从而抑制血管再狭窄。利用外加磁场诱导支架升温抑制再狭窄发生是一种全新的治疗方法。磁热疗可使受热的细胞发生凋亡或细胞凝固性坏死,从而达到抑制组织过度增生的目的。该方法可重复治疗,无须再次手术,可显著减轻患者的痛苦,且对机体无其他不良刺激,是一种比较理想的治疗方法。本文综述了磁热疗对血管平滑肌细胞和内皮细胞的影响及其应用前景。     

Bidirectional control of CNS capillary diameter by pericytes

Neural activity increases local blood flow in the central nervous system (CNS), which is the basis of BOLD (blood oxygen level dependent) and PET (positron emission tomography) functional imaging techniques. Blood flow is assumed to be regulated by precapillary arterioles, because capillaries lack smooth muscle. However, most (65%) noradrenergic innervation of CNS blood vessels terminates near capillaries rather than arterioles, and in muscle and brain a dilatory signal propagates from vessels near metabolically active cells to precapillary arterioles, suggesting that blood flow control is initiated in capillaries. Pericytes, which are apposed to CNS capillaries and contain contractile proteins, could initiate such signalling. Here we show that pericytes can control capillary diameter in whole retina and cerebellar slices. Electrical stimulation of retinal pericytes evoked a localized capillary constriction, which propagated at approximately 2 microm s(-1) to constrict distant pericytes. Superfused ATP in retina or noradrenaline in cerebellum resulted in constriction of capillaries by pericytes, and glutamate reversed the constriction produced by noradrenaline. Electrical stimulation or puffing GABA (gamma-amino butyric acid) receptor blockers in the inner retina also evoked pericyte constriction. In simulated ischaemia, some pericytes constricted capillaries. Pericytes are probably modulators of blood flow in response to changes in neural activity, which may contribute to functional imaging signals and to CNS vascular disease.     

Vascular-specific growth factors and blood vessel formation

A recent explosion in newly discovered vascular growth factors has coincided with exploitation of powerful new genetic approaches for studying vascular development. An emerging rule is that all of these factors must be used in perfect harmony to form functional vessels. These new findings also demand re-evaluation of therapeutic efforts aimed at regulating blood vessel growth in ischaemia, cancer and other pathological settings.     

Expression and function of a new angiogenic factor AA98 target molecule at the maternal-embryonic boundary of rhesus monkey

The target molecule of monoclonal antibody AA98 (AA for short) is a new vascular endothelial cell related factor and plays a role in angiogenesis as indicated by the previous data. To investigate its role in angiogenesis and placentation in primate, we examined its expression in the implantation sites on D17, 19, 28 and 34 of gestation in rhesus monkey by immunohistochemistry and Western immunoblot. Western blot analysis showed that the primary antibody used in this study was specific for its epitope. AA protein was mainly expressed in small blood vessels and in some cytotrophoblast cells. The AA staining was found mainly in the endothelial cells and vascular small muscle. This observation supported the AA‘s role in angiogenesis. AA was spatio-temporarily expressed in cytotrophoblasts: weak in proliferating trophoblast within cell column and endovascular trophoblast, strong in trophoblastic subpopulation within the basal plate and vascular trophoblast; AA staining within the basal plate was down-regulated during early placentation. The shift of AA98 expression in extravillous trophoblasts suggestes a role of this new factor during the course of cytotrophoblast metastasis and spiral artery remodeling. The spatio-temporarily expression indicats that AA98 could be also used as a trophoblast cellular marker to characterize the acquisition of a vascular endothelial and invasive phenotype.     

关于血管分支的数学模型

通过对血管分支建立数学模型，从优化角度进行分析得出每个血管分支夹角相等的结论，该模型为求出血管的条数和分支数，讨论血管的总长度提供了理论依据．     

基于萤火虫算法的三维Renyi熵眼底图像血管分割

对于眼底血管网络分割精度低的问题,提出了基于萤火虫算法的三维最大Renyi熵眼底血管分割方法。该方法先提取出眼底G通道图像;然后用多尺度线性滤波器对眼底血管增强;接着引入萤火虫算法,将基于三维共生矩阵的最大熵求解问题转化为寻找最亮萤火虫的问题;最后,将最亮萤火虫所处的三维空间位置作为Renyi熵函数的阈值对眼底图像分割。实验结果表明,方法的真阳性率和ROC曲线下方区域面积都有所提高,能准确分割出眼底血管。     

人参皂苷粉、银杏叶提取物对鸡胚绒毛尿囊膜血管新生的作用

为探讨人参皂苷粉和银杏叶提取物对鸡胚绒毛尿囊膜血管新生的影响,取孵育9天的种蛋,通过暴露鸡胚绒毛尿囊膜来建立模型,28只存活的鸡胚随机分为4组,包含两组空白载体的对照,一组加人参皂苷粉水溶液,一组加含银杏叶提取物药膜,作用3天后,观察分析鸡胚绒毛尿囊膜上血管生长的变化.结果显示:人参皂苷粉组,血管数量明显增多,但血管直径变细,颜色变淡;银杏叶提取物组,血管数量显著增多,血管颜色加深.研究发现:人参皂苷粉既能促进血管生成,又能抑制血管生成,总体表现为抑制;银杏叶提取物能够明显的促进血管的新生.     

Vascular endothelial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis.

Inefficient vascular supply and the resultant reduction in tissue oxygen tension often lead to neovascularization in order to satisfy the needs of the tissue. Examples include the compensatory development of collateral blood vessels in ischaemic tissues that are otherwise quiescent for angiogenesis and angiogenesis associated with the healing of hypoxic wounds. But the presumptive hypoxia-induced angiogenic factors that mediate this feedback response have not been identified. Here we show that vascular endothelial growth factor (VEGF; also known as vascular permeability factor) probably functions as a hypoxia-inducible angiogenic factor. VEGF messenger RNA levels are dramatically increased within a few hours of exposing different cell cultures to hypoxia and return to background when normal oxygen supply is resumed. In situ analysis of tumour specimens undergoing neovascularization show that the production of VEGF is specifically induced in a subset of glioblastoma cells distinguished by their immediate proximity to necrotic foci (presumably hypoxic regions) and the clustering of capillaries alongside VEGF-producing cells.     

Haemodynamic shear stress activates a K+ current in vascular endothelial cells

The endothelial lining of blood vessels is subjected to a wide range of haemodynamically-generated shear-stress forces throughout the vascular system. In vivo and in vitro, endothelial cells change their morphology and biochemistry in response to shear stress in a force- and time-dependent way, or when a critical threshold is exceeded. The initial stimulus-response coupling mechanisms have not been identified, however. Recently, Lansman et al. described stretch-activated ion channels in endothelial cells and suggested that they could be involved in the response to mechanical forces generated by blood flow. The channels were relatively nonselective and were opened by membrane stretching induced by suction. Here we report whole-cell patch-clamp recordings of single arterial endothelial cells exposed to controlled levels of laminar shear stress in capillary flow tubes. A K+ selective, shear-stress-activated ionic current (designated Ik.s) was identified which is unlike previously described stretch-activated currents. Ik.s varies in magnitude and duration as a function of shear stress (half-maximal effect at 0.70 dyn cm-2), desensitizes slowly and recovers rapidly and fully on cessation of flow. Ik.s activity represents the earliest and fastest stimulus-response coupling of haemodynamic forces to endothelial cells yet found. We suggest that localized flow-activated hyperpolarization of endothelium involving Ik.s may participate in the regulation of vascular tone.     

The netrin receptor UNC5B mediates guidance events controlling morphogenesis of the vascular system

Blood vessels and nerves are complex, branched structures that share a high degree of anatomical similarity. Guidance of vessels and nerves has to be exquisitely regulated to ensure proper wiring of both systems. Several regulators of axon guidance have been identified and some of these are also expressed in endothelial cells; however, the extent to which their guidance functions are conserved in the vascular system is still incompletely understood. We show here that the repulsive netrin receptor UNC5B is expressed by endothelial tip cells of the vascular system. Disruption of the Unc5b gene in mice, or of Unc5b or netrin-1a in zebrafish, leads to aberrant extension of endothelial tip cell filopodia, excessive vessel branching and abnormal navigation. Netrin-1 causes endothelial filopodial retraction, but only when UNC5B is present. Thus, UNC5B functions as a repulsive netrin receptor in endothelial cells controlling morphogenesis of the vascular system.     

基于人工微台阶分选与捕获肿瘤细胞的微流控芯片

开发具有契合肿瘤细胞尺寸的微台阶结构的微流控芯片以将肿瘤细胞从正常人血细胞中分选并捕获出来．结合微加工技术,先后两次对同一块玻璃基底进行刻蚀,改变两次刻蚀的图样与时间最终与盖板间形成高度为10μm的微台阶结构,通过玻璃基底与有机高聚物PDMS（Polydimethylsiloxane）盖板的键合制作出微流控芯片．利用具有微台阶结构的芯片,悬浮于磷酸盐缓冲盐溶液中的肿瘤细胞（MCF-7）被全部捕获在微台阶结构内,尺寸小于台阶的正常人血细胞（红细胞）流过台阶未被捕获,实现了将肿瘤细胞从正常血细胞中分选并捕获．捕获在芯片中的肿瘤细胞都具有活性．芯片整体透明,肿瘤细胞捕获过程不需要进行化学修饰等预处理．     

In vitro differentiation of human adipose-derived mesenchymal stem cells into endothelial-like cells

The neovascularization of ischemic tissue is a crucial initial step for the functional rehabilitation and wound healing. However, there is lack of a potential source of cells for the foundation of a vascular network. The re- cent studies indicate that hum…     

In vivo imaging of specialized bone marrow endothelial microdomains for tumour engraftment

The organization of cellular niches is known to have a key role in regulating normal stem cell differentiation and regeneration, but relatively little is known about the architecture of microenvironments that support malignant metastasis. Using dynamic in vivo confocal imaging, here we show that murine bone marrow contains unique anatomic regions defined by specialized endothelium. This vasculature expresses the adhesion molecule E-selectin and the chemoattractant stromal-cell-derived factor 1 (SDF-1) in discrete, discontinuous areas that influence the homing of a variety of tumour cell lines. Disruption of the interactions between SDF-1 and its receptor CXCR4 inhibits the homing of Nalm-6 cells (an acute lymphoblastic leukaemia cell line) to these vessels. Further studies revealed that circulating leukaemic cells can engraft around these vessels, suggesting that this molecularly distinct vasculature demarcates a microenvironment for early metastatic tumour spread in bone marrow. Finally, purified haematopoietic stem/progenitor cells and lymphocytes also localize to the same microdomains, indicating that this vasculature might also function in benign states to demarcate specific portals for the entry of cells into the marrow space. Specialized vascular structures therefore appear to delineate a microenvironment with unique physiology that can be exploited by circulating malignant cells.     

血管内皮生长因子在大鼠乳腺炎中的作用

应用组织化学方法及免疫组化技术对正常组和急性攻毒组大鼠乳腺组织血管内皮生长因子（Vascular Endothelial Growth Factor,VEGF）的表达水平、肥大细胞的活力和炎性细胞的动态变化进行了研究.结果表明,急性攻毒后6 h乳腺组织VEGF在腺泡间、小叶间质、血管周围及部分肥大细胞内的表达出现一个峰值,而后表达开始减弱,攻毒48 h后表达又迅速增强;攻毒组大鼠的肥大细胞及其脱颗粒和炎性细胞随着攻毒时间的延长急剧增多,均极显著高于正常组（P〈0.01）,且其变化趋势均与VEGF表达趋势相吻合;同时,小叶间质内的小血管内皮细胞开始出现裂隙、脱落损伤.由此表明,VEGF和肥大细胞参与大鼠乳腺炎的发病过程.