Mesenchymal stem/stromal cells genetically engineered to produce vascular endothelial growth factor for revascularization in wound healing and ischemic conditions

Mesenchymal stem/stromal cells (MSCs) may be able to improve ischemic conditions as they can actively seek out areas of low oxygen and secrete proangiogenic factors. In more severe trauma and chronic cases, however, cells alone may not be enough. Therefore, we have combined the stem cell and angiogenic factor approaches to make a more potent therapy. We developed an engineered stem cell therapy product designed to treat critical limb ischemia that could also be used in trauma‐induced scarring and fibrosis where additional collateral blood flow is needed following damage to and blockage of the primary vessels. We used MSCs from normal human donor marrow and engineered them to produce high levels of the angiogenic factor vascular endothelial growth factor (VEGF). The MSC/VEGF product has been successfully developed and characterized using good manufacturing practice (GMP)‐compliant methods, and we have completed experiments showing that MSC/VEGF significantly increased blood flow in the ischemic limb of immune deficient mice, compared to the saline controls in each study. We also performed safety studies demonstrating that the injected product does not cause harm and that the cells remain around the injection site for more than 1 month after hypoxic preconditioning. An on‐demand formulation system for delivery of the product to clinical sites that lack cell processing facilities is in development.     

Vascular endothelial growth factor promotes physical wound repair and is anti-apoptotic in primary distal lung epithelial and A549 cells

OBJECTIVE: There is evidence to suggest a beneficial role for growth factors, including vascular endothelial growth factor (VEGF), in tissue repair and proliferation after injury within the lung. Whether this effect is mediated predominantly by actions on endothelial cells or epithelial cells is unknown. This study tested the hypothesis that VEGF acts as an autocrine trophic factor for human adult alveolar epithelial cells and that under situations of pro-apoptotic stress, VEGF reduces cell death. DESIGN: In vitro cell culture study looking at the effects of 0.03% H2O2 on both A549 and primary distal lung epithelial cells. MEASUREMENT AND MAIN RESULTS: Primary adult human distal lung epithelial cells express both the soluble and membrane-associated VEGF isoforms and VEGF receptors 1 and 2. At physiologically relevant doses, soluble VEGF isoforms stimulate wound repair and have a proliferative action. Specific receptor ligands confirmed that this effect was mediated by VEGF receptor 1. In addition to proliferation, we demonstrate that VEGF reduces A549 and distal lung epithelial cell apoptosis when administered after 0.03% H2O2 injury. This effect occurs due to reduced caspase-3 activation and is phosphatidylinositol 3'-kinase dependent. CONCLUSION: In addition to its known effects on endothelial cells, VEGF acts as a growth and anti-apoptotic factor on alveolar epithelial cells. VEGF treatment may have potential as a rescue therapy for diseases associated with alveolar epithelial damage such as acute respiratory distress syndrome.     

神经生长因子对骨折修复的作用

学术背景:近来研究发现,在正常骨组织和骨折骨痂中有神经生长因子及其受体的表达,局部给予外源性神经生长因子对骨折修复具有促进作用.目的:对神经生长因子在骨折修复中的表达、作用及可能的作用机制进行总结分析.检索策略:应用计算机检索PubMed 1951-01/2007-06期间的相关文章,检索词为"nerve growth factor,bone fracture,repair,osteogenesis".同时应用计算机检索中文CNKI全文数据库1990-01/2007-06期间的相关文章,检索词"神经生长因子,骨折,修复".对资料进行初审,纳入标准:①神经生长因子的生物学特性.②骨折修复的过程.③神经生长因子对骨折修复作用的实验或临床研究.排除标准:重复研究、Meta分析或综述类文章.文献评价:共收集到59篇相关文献,28篇符合纳入标准,排除的31篇为内容陈旧或重复文章.符合纳入标准的28篇文章中,分别涉及神经生长因子的发现发展、生物学特性9篇,神经生长因子的作用5篇,骨折修复过程中参与的因子及各方面因素的影响4篇,神经生长因子对骨折的修复作用10篇.资料综合:①正常骨组织和骨折骨痂中均有神经生长因子及其受体的表达.②神经生长因子主要由来源于神经嵴的神经元支配的靶组织产生,其被这些神经元轴突摄取后逆行运输至胞体,通过多种途径调节神经细胞的基因转录而发挥生物效应,维持神经元的存活、刺激轴突的生长,并对外周神经的发育、营养起重要的作用.神经生长因子主要是通过促进骨折部位神经的再生参与骨折修复.③骨折愈合的机制十分复杂,神经生长因子对骨组织的作用也是多方面、多层次和相互交叉的,其机制尚未完全探明.结论:虽然神经生长因子促进骨折修复作用的研究已经取得一些进展,但仍处于初级阶段,其作用机制尚不清楚.     

神经生长因子对骨折修复的作用

学术背景：近来研究发现，在正常骨组织和骨折骨痂中有神经生长因子及其受体的表达，局部给予外源性神经生长因子对骨折修复具有促进作用。 目的：对神经生长因子在骨折修复中的表达、作用及可能的作用机制进行总结分析。 检索策略：应用计算机检索PubMed 1951-01／2007—06期间的相关文章，检索词为“nerve growth factor，bone fracture，repair，osteogenesis”。同时应用计算机检索中文CNKI全文数据库1990—01／2007—06期间的相关文章，检索词“神经生长因子，骨折，修复”。对资料进行初审，纳入标准：①神经生长因子的生物学特性。②骨折修复的过程。③神经生长因子对骨折修复作用的实验或临床研究。排除标准：重复研究、Meta分析或综述类文章。 文献评价：共收集到59篇相关文献，28篇符合纳入标准，排除的31篇为内容陈旧或重复文章。符合纳入标准的28篇文章中，分别涉及神经生长因子的发现发展、生物学特性9篇，神经生长因子的作用5篇，骨折修复过程中参与的因子及各方面因素的影响4篇，神经生长因子对骨折的修复作用10篇。 资料综合：①正常骨组织和骨折骨痂中均有神经生长因子及其受体的表达。②神经生长因子主要由来源于神经嵴的神经元支配的靶组织产生。其被这些神经元轴突摄取后逆行运输至胞体，通过多种途径调节神经细胞的基因转录而发挥生物效应，维持神经元的存活、刺激轴突的生长，并对外周神经的发育、营养起重要的作用。神经生长因子主要是通过促进骨折部位神经的再生参与骨折修复。③骨折愈合的机制十分复杂，神经生长因子对骨组织的作用也是多方面、多层次和相互交叉的，其机制尚未完全探明。 结论：虽然神经生长因子促进骨折修复作用的研究已经取得一些进展，但仍处于初级阶段，其作     

超声微血管成像联合血管内皮生长因子诊断胎儿生长受限

目的 观察超声微血管成像(MV-Flow)联合孕妇血清血管内皮生长因子(VEGF)表达水平诊断胎儿生长受限(FGR)的价值。方法 前瞻性纳入87例胎儿生长受限[FGR组,包括43例孕周<28周(<28周亚组)及44例孕周≥28周(≥28周亚组)]孕妇及112名正常孕妇[对照组,55名孕周<28周(对照组1)、57名孕周≥28周(对照组1)],以MV-Flow技术测量胎盘微血管指数(MVI),于同期检测孕妇血清VEGF表达水平,于分娩后即刻检测胎盘母体面VEGF表达水平;绘制受试者工作特征曲线,评价胎盘MVI、母体血清VEGF及二者联合诊断FGR的价值。结果 FGR组2亚组胎盘MVI、孕妇血清VEGF表达水平及胎盘组织VEGF表达水平均明显低于对照组(P<0.01)。胎盘MVI、母体血清VEGF及二者联合诊断<28周FGR的曲线下面积(AUC)分别为0.981、0.870和0.997,诊断≥28周FGR的AUC分别为0.991、0.867和0.993。以单一孕妇血清VEGF诊断2亚组FGR的AUC均低于胎盘MVI及其联合孕妇血清VEGF(P均<0.05...     

Modulation of platelet-derived growth factor receptor expression in microvascular endothelial cells during in vitro angiogenesis.

Microvascular endothelial cells in vivo exhibit a plastic phenotype, forming a nonproliferative, differentiated capillary network, while retaining their ability to respond to injury by proliferation, migration and neovascularization. The presence of PDGF receptors and PDGF responsiveness in microvascular endothelial cells and the significance of PDGF isoforms in the control of endothelial cell growth and differentiation remain controversial. Since culture of microvascular endothelial cells in a three-dimensional (3D) system induced cell differentiation and angiogenesis and inhibited proliferation, the present study investigates the role of different extracellular matrix environments in inducing different microvascular endothelial cell phenotypes on microvascular endothelial cell PDGF receptor expression and PDGF responsiveness. In conventional two-dimensional (2D) culture, microvascular endothelial cells expressed both PDGF receptor alpha and beta chains. Suramin treatment demonstrated continuous downregulation of the alpha receptor surface expression. PDGF BB and, to a lesser extent, PDGF AB were mitogenic in 2D-culture, PDGF AA failed to induce any proliferative response despite inducing receptor autophosphorylation. During in vitro angiogenesis induced by 3D-culture, both PDGF receptors were rapidly downregulated. Assessment of cell proliferation showed quiescent cells and PDGF unresponsiveness. We conclude that the induction of a differentiated phenotype during in vitro angiogenesis (tube formation) driven in part by the spatial organization of the surrounding matrix is associated with a downregulation of PDGF receptors. Identification of the molecular cell-matrix interactions involved in this receptor regulation may allow for targeted manipulation of cell growth in vivo and lead to novel therapeutic applications for PDGF.     

难愈性创面修复局部人血管内皮生长因子165真核表达载体的构建与评价

目的:克隆人血管内皮生长因子165cDNA并构建其真核表达载体,为放创复合伤的难愈性创面的促愈修复提供实验基础。方法:实验于2001-09/2003-05在第三军医大学创伤、烧伤与复合伤国家重点实验室完成。从白血病HL-60细胞提取总RNA,经过反转录-聚合酶链反应扩增编码人血管内皮生长因子165的cDNA序列,将其克隆至pMD18-T载体后进行测序鉴定,然后将该序列插入双顺反子的真核表达载体pIRES2-EGFP的多克隆位点中。观察以下指标①反转录-聚合酶链反应扩增人血管内皮生长因子165cDNA。②阳性重组质粒pMD18-T-hVEGF165的筛选。③DNA测序鉴定。④阳性重组质粒pIRES2-EGFP-VEGF165的筛选。结果:反转录-聚合酶链反应扩增得到约600bp的目的DNA片段,酶切pMD18-T-hVEGF165得一与目的片段大小一致的条带,且测序分析其与GeneBank中报道的编码人血管内皮生长因子165cDNA序列完全一致。pIRES2-EGFP-hVEGF165的酶切电泳显示目的条带成功插入真核表达载体pIRES2-EGFP中。结论:成功构建了含有人血管内皮生长因子165cDNA的真核表达载体,如果通过转基因技术可提高血管内皮生长因子165在放创复合伤难愈性创面的局部的表达,有望为修复难愈创面开辟一条新的途径。     

肝细胞生长因子基因转染骨髓间充质干细胞异体移植修复烧伤创面

背景：经携带人肝细胞生长因子的重组腺病毒（adenoviral vector mediated human hepatocyte growth factor，Ad—HGF）修饰的骨髓间充质干细胞创面移植后，可分化为“修复细胞”，并能够在创面持续释放肝细胞生长因子。目的：观察Ad—HGF基因转染的骨髓间充质干细胞异体移植对大鼠烧伤创面愈合的影响。设计、时间及地点：随机对照动物观察，于2006—02／2007—03在解放军兰州军区兰州总医院临床实验科和烧伤整形科实验室完成，材料：Wistar大鼠40只，由解放军兰州军区兰州总医院动物实验科提供。Ad—HGF与携带绿色荧光蛋白的重组腺病毒（adenoviral vector mediated human hepatocyte growth factor，Ad-GFP）颗粒均由哈小琴博士惠赠。方法：取雄鼠10只，Percoll密度梯度离心法体外分离培养骨髓间充质干细胞，并行Ad—HGF转染。取雌鼠30只，随机分为未转染细胞组、Ad-HGF转染细胞组、Ad-GFP转染绌胞组、Ad-HGF对照组、假伤组，6只／组。前4组大鼠复制背部深Ⅱ度烧伤模型，并分别于创面真皮层下方多点注射对应的细胞悬液或病毒悬液1mL；假伤组大鼠背部剃毛后浸入37℃温水12S模拟烧伤，同法注射等量生理盐水。主要观察指标：对采集的创面标本行组织学观察和羟脯氨酸含量测定，采用免疫组化分析创面肝细胞生长因子的表达。结果：苏木精-伊红染色结果显示，Ad—HGF转染细胞组移植后7d创面表皮化优于其他组，至21d再生表皮明显厚于其他组，并可见真皮钉脚下伸。胶原特殊染色结果显示，Ad—HGF转染细胞组移植后7，21d创面中的胶原排列较其他组整齐。移植后7d，Ad—HGF转染细胞组羟脯氨酸含量显著低于其他组（F=3．216，P〈0．01）。移植后21d，Ad—HGF转染细胞组愈合创面中肝细胞生长因子的阳性表达位于真皮层，表达强度明显强于其他组。结论：Ad-HGF基因修饰的大鼠骨髓间充质干细胞异体移植后，对烧伤创而愈合存在一定的促进作用。     

Modulation of transforming growth factor beta receptor levels on microvascular endothelial cells during in vitro angiogenesis.

Microvascular endothelial cells (RFCs) cultured in two-dimensional (2D) cultures proliferate rapidly and exhibit an undifferentiated phenotype. Addition of transforming growth factor beta1 (TGFbeta1) increases fibronectin expression and inhibits proliferation. RFCs cultured in three-dimensional (3D) type I collagen gels proliferate slowly and are refractory to the anti-proliferative effects of TGF beta1. TGF beta1 promotes tube formation in 3D cultures. TGF beta1 increases fibronectin expression and urokinase plasminogen activator (uPA) activity and plasminogen activator inhibitor-1 (PAI-1) levels in 3D cultures. Since the TGF beta type I and II receptors have been reported to regulate different activities induced by TGF beta1, we compared the TGF beta receptor profiles on cells in 2D and 3D cultures. RFCs in 3D cultures exhibited a significant loss of cell surface type II receptor compared with cells in 2D cultures. The inhibitory effect of TGF beta1 on proliferation is suppressed in transfected 2D cultures expressing a truncated form of the type II receptor, while its stimulatory effect on fibronectin production is reduced in both 2D and 3D transfected cultures expressing a truncated form of the type I receptor. These data suggest that the type II receptor mediates the antiproliferative effect of TGF beta1 while the type I receptor mediates the matrix response of RFCs to TGF beta1 and demonstrate that changes in the matrix environment can modulate the surface expression of TGF beta receptors, altering the responsiveness of RFCs to TGF beta1.     

Human wound assessment: status report and implications for clinicians

Wound care has long been carried out by professional nurses. Yet, as a result of their increasing qualifications and changes in health care practices, the nurse's role in and responsibility for wound care has expanded. Despite this, there is a paucity of valid and reliable methods by which nurses and physicians alike can evaluate healing status. This chapter provides an overview of the instruments designed to evaluate healing in humans, focusing particular attention on those intended to measure healing noninvasively. Implications for clinical practice and suggestions for research also are offered. Additionally, this article is written to raise clinicians' awareness to the need for concentrated efforts in devising clinically usable, valid, and reliable instruments to evaluate human tissue repair.     

Solid emulsion gel as a vehicle for delivery of polyunsaturated fatty acids: implications for tissue repair, dermal angiogenesis and wound healing

The paper describes preparation and biological characterization of the solid hybrid biomaterial that was designed for cell-targeted lipid delivery in healing tissues. The material referred to as 'solid emulsion gel' combines a protein-stabilized lipid emulsion and a hydrogel structure in a single compartment. The potential of the omega-3 (n-3)-fatty acids rich solid emulsion gel for tissue repair applications was investigated at the macro-, micro-, molecular and gene expression levels, using human fibroblasts and endothelial cells and a porcine model of full-thickness wounds. Being non-cytotoxic in vitro and in vivo, the biomaterial was found to affect cell metabolism, modulate expression of certain genes, stimulate early angiogenesis and promote wound repair in vivo. The neovascular response in vivo was correlated with upregulated expression of the genes involved in lipid transport (e.g. adipophilin), anti-apoptosis (e.g. heat shock proteins, haem oxygenase 1) and angiogenesis (vascular endothelial growth factor, placental growth factor). Collectively, the results of this study provide first evidence that the angiogenic response provided by solid emulsion gel-mediated delivery of n-3 fatty acids is an alternative to the topical administration of exogenous growth factors or gene therapy, and can be advantageously used for the stimulation of tissue repair in complex wounds.     

神经生长因子对大鼠坐骨神经损伤修复的影响

以坐骨神经损伤的大鼠为动物模型，采用形态学方法，研究了外源性短暂给予较大剂量神经生长因子后，对大鼠周围神经损伤修复的影响。结果表明，神经生长因子可促进周围神经损伤的修复，该促进作用在早期较为明显，晚期则不明显，可能与神经生长因子进入体内的途径、方式、活性持续时间有关；损伤神经近侧端的再生修复好于远侧端，可能与其有利于接受胞体对再生修复的调节有关。     

Dog mastocytoma cells produce transforming growth factor beta 1.

Transforming growth factor-beta (TGF beta) promotes deposition of extracellular matrix and is associated with fibrotic conditions both in experimental animals and in humans. Although a role for mast cells has been suspected in the pathogenesis of fibrosis, no potent mediator capable of stimulating fibroblast growth or extracellular matrix deposition has been identified in mast cell supernatants. We report here the constitutive production of TGF beta 1 by four dog mastocytoma cell lines. TGF beta 1 was identified by characteristic biologic activity, blockade of biologic effect by specific neutralizing antibody, and by recognition of a band with the appropriate migration by western blot. TGF beta 1 mRNA, but not TGF beta 2 or TGF beta 3 mRNA, was also produced constitutively by all four cell lines. Quantitation by bioassay revealed baseline TGF beta secretion of approximately 1 ng/10(6) cells over 48 h. Stimulation of mastocytoma cells with phorbol ester increased the rate of release of TGF beta 1, most markedly in the first 30 min after stimulation, without increasing TGF beta 1 mRNA. Dog mastocytoma cells produced TGF beta 1 primarily in a latent form, inactive until treated with acid. Both pure TGF beta 1 and TGF beta-containing mastocytoma cell-conditioned media inhibited mitogenesis and proliferation in dog mastocytoma cell lines, suggesting that mast cell tumor lines would not grow preferentially based on their ability to produce TGF beta. These studies may make possible further investigation of the mechanism by which mast cells contribute to the induction of fibrosis.     

Human endothelial cells bioactivate organic nitrates to nitric oxide: implications for the reinforcement of endothelial defence mechanisms

Abstract. Although in therapeutic use for more than a century, the mode of cellular action of organic nitrates remains incompletely understood. Despite ample experimental evidence from animal studies to show that nitrates are metabolized to NO in the vascular smooth muscle, direct demonstration of such an activity in human vascular cells is still lacking. Moreover, the role of the endothelium in modulating the pharmacodynamic action of nitrates is far from clear. We therefore aimed to investigate whether or not human endothelial cells are capable of bioactivating these drugs to NO and whether the amounts generated are sufficient to elicit any biological effects. Using cultured human umbilical vein endothelial cells (HUVECs) as an established model system a combination of three different methods was used to address this issue: (1) quantification of NO formation upon endothelial nitrate metabolism using the oxyhaemo-globin technique; (2) evaluation of the second messenger response using radioimmunoassay for cGMP; and (3) assessment of mechanism and extent of potentiation of the anti-aggregatory effect of nitrates in the presence of endothelial cells as a relevant bioassay. We now show that superfusion of cultured human endothelial cells on microcarrier beads with either glyceryl trinitrate (GTN) or isosorbide dinitrate (ISDN; both at 01.100 μmol L^-1) results in a concentration-dependent formation of NO. NO generation from isosorbide 5-mononitrate (IS-5-N) was below the detection limit. The amounts of NO produced (maximally 2–97 ± 0.98 pmoles NO min^-1 x mg protein with 100μmol L^-1 GTN; n= 8) were similar to those elicited upon challenge of the cells with 100nM bradykinin. NO formation from either organic nitrate was accompanied, in a concentration-dependent and methylene blue-inhibitable manner, by stimulation of endothelial soluble guany-lyl cyclase with consequent increases in the intracel-lular level of cGMP (maximally 32-fold over basal levels with ISDN), a significant portion of which was released into the extracellular space. Upon continuous 30 min superfusion or repeated application of high concentrations of GTN (100μmol L^-1) nitrate bioac-tivation to NO was subject to partial tachyphylaxis. Co-incubation of washed human platelets with HUVECs potentiated the anti-aggregatory action of nitrates in a cell number dependent and oxyhaemo-globin-sensitive manner and this effect, too, was accompanied by increases in intraplatelet cGMP levels. The potentiating effect was largely inhibited after blockade of sulfhydryl groups by pre-incubadon of HUVECs with N-ethylmaleimide and completely abrogated after pretreatment of cells with the tissue fixative glutaraldehyde. These results demonstrate that human endothelial cells are capable of bioactivating organic nitrates to NO by an enzymatic, apparently thiol-sensitive pathway, in quantities sufficient to influence endothelial and platelet function. Besides the well known vasorelaxant action of organic nitrates, which is mainly due to their metabolism in the smooth muscle compartment, these drugs may therefore be endowed with a hitherto underestimated potential to directly influence endothelial functions via the NO/ cGMP pathway. Through specific bioactivation in the endothelium itself organic nitrates can thus mimic and reinforce protective functions normally served by a functional endothelium such as the modulation of blood cell/vessel wall interactions and inhibition of cell proliferation.     

Neutrophil adherence to bladder microvascular endothelial cells following platelet-activating factor acetylhydrolase inhibition

Interstitial cystitis (IC) is an inflammatory bladder condition of unknown etiology. Tryptase released from elevated numbers of activated mast cells is a proposed mediator of the inflammatory process in IC. We have previously shown that tryptase increases human bladder microvascular endothelial cell (HBMEC) calcium-independent phospholipase A(2) (iPLA(2)) activity, resulting in the production of multiple biologically active phospholipid metabolites, including platelet-activating factor (PAF), that can mediate inflammation. Because the design of selective PLA(2) inhibitors may provide a useful therapeutic strategy to reduce the inflammatory process in IC, we tested several frequently used PLA(2) inhibitors on PAF production in tryptase-stimulated HBMEC. Among the inhibitors tested, methyl arachidonyl fluorophosphonate (MAFP) was found to be a potent inhibitor of PAF-acetylhydrolase activity. Pretreatment of HBMEC with MAFP significantly increased PAF production in both unstimulated and tryptase-stimulated cells. In addition, MAFP pretreatment of tryptase-stimulated HBMEC increased both surface expression of P-selectin and polymorphonuclear leukocyte adherence to the HBMEC monolayer. These effects suggest that MAFP has a proinflammatory effect, irrespective of its ability to inhibit PLA(2).     

脑源性神经营养因子与心脏微血管内皮细胞的管状形成

背景：研究发现脑源性神经营养因子可促进内皮细胞的存活,诱导血管新生,但其促进血管新生的细胞与分子机制尚不清楚。目的：观察脑源性神经营养因子在3D体外管状形成模型中对心脏微血管内皮细胞管状结构形成的影响。方法：分离提取大鼠心脏微血管内皮细胞并培养使之形成细胞小球,将心脏微血管内皮细胞小球接种于Ⅰ型胶原-甲基纤维素的3D环境中培养,然后分别加入50,70,100μg/L的脑源性神经营养因子继续培养,于培养24,48h观察并测量心脏微血管内皮细胞的分枝长度和分枝条数。结果与结论：经分离的大鼠心脏微血管内皮细胞小球在Ⅰ型胶原-甲基纤维素3D环境中培养24h,均可见管状分枝,且脑源性神经营养因子可促进管状分枝生长,以100μg/L的脑源性神经营养因子的促生长效果最明显,分枝也最多。培养至48h,心脏微血管内皮细胞小球的分枝更长。说明脑源性神经营养因子在3D体外管状形成模型中可促进大鼠心脏微血管内皮细胞发芽及管状结构的形成,且具有剂量依赖性。     

脑源性神经营养因子与心脏微血管内皮细胞的管状形成

背景:研究发现脑源性神经营养因子可促进内皮细胞的存活,诱导血管新生,但其促进血管新生的细胞与分子机制尚不清楚.目的:观察脑源性神经营养因子在3D体外管状形成模型中对心脏微血管内皮细胞管状结构形成的影响.方法:分离提取大鼠心脏微血管内皮细胞并培养使之形成细胞小球,将心脏微血管内皮细胞小球接种于Ⅰ型胶原-甲基纤维素的3D环境中培养,然后分别加入50,70,100 μg/L的脑源性神经营养因子继续培养,于培养24,48 h观察并测量心脏微血管内皮细胞的分枝长度和分枝条数.结果与结论:经分离的大鼠心脏微血管内皮细胞小球在Ⅰ型胶原-甲基纤维素3D环境中培养24 h,均可见管状分枝,且脑源性神经营养因子可促进管状分枝生长,以100 μg/L的脑源性神经营养因子的促生长效果最明显,分枝也最多.培养至 48 h,心脏微血管内皮细胞小球的分枝更长.说明脑源性神经营养因子在3D体外管状形成模型中可促进大鼠心脏微血管内皮细胞发芽及管状结构的形成,且具有剂量依赖性.     

Tissue localization of beta receptors for platelet-derived growth factor and platelet-derived growth factor B chain during wound repair in humans.

The expression and localization of PDGF beta receptors and PDGF-AB/BB in human healing wounds was evaluated by immunohistochemical techniques and in situ hybridization. Expression of PDGF beta receptor protein and PDGF-AB/BB were analyzed in wound margin biopsies using the PDGFR-B2 and PDGF 007 antibodies. PDGF beta receptor expression was minor in normal skin. An increased expression of PDGF beta receptor protein was prominent in vessels in the proliferating tissue zone in wounds as early as 1 d after surgery and was apparent < or = 4 wk after surgery. There was also a concordant increase in PDGF beta receptor mRNA detected by in situ hybridization. PDGF-AB/BB was present in healing wounds as well as in normal skin. In normal skin, expression of PDGF-AB/BB was confined to peripheral nerve fibers and to solitary cells of the epidermis and of the superficial dermis. In wounds, infiltrating mononuclear cells also stained for PDGF-AB/BB. To identify cell types expressing PDGF AB/BB and PDGF beta receptors, respectively, we performed double immunofluorescence stainings. PDGF beta receptors were expressed by vascular smooth muscle cells and cells in capillary walls; the receptor protein could not be detected in neurofilament containing structures, T lymphocytes, or CD68 expressing macrophages. PDGF-AB/BB colocalized with neurofilaments, it was present in Langerhans cells of the epidermis and in HLA-DR positive cells located in the epidermal/dermal junction area. Of the macrophages infiltrating the wound, 43 +/- 18% stained positively for PDGF AB/BB. Since PDGF-AB/BB and PDGF beta receptors are expressed in the healing wound, two essential prerequisites for a role of PDGF in wound healing are fulfilled.     

许旺细胞及小肠黏膜下层复合生长因子缓释微球修复周围神经缺损

背景:前期实验已初步证实许旺细胞复合小肠黏膜下层及碱性成纤维细胞生长因子构建的人工神经具有体外神经活性、趋化性。目的:观察许旺细胞及小肠黏膜下层复合碱性成纤维细胞生长因子缓释微球修复周围神经缺损后神经传导的再通情况。方法:制作SD大鼠坐骨神经缺损模型,随机分组:实验组以许旺细胞及小肠黏膜下层复合碱性成纤维细胞生长因子缓释微球修复,阳性对照组以许旺细胞及小肠黏膜下层复合游离碱性成纤维细胞生长因子修复,阴性对照组以许旺细胞及小肠黏膜下层修复,空白对照组以自体神经修复。结果与结论:术后16周实验组再生神经纤维数目,DiI示踪标记的阳性神经元数量、S-100及神经细丝蛋白的阳性表达率、髓鞘及再生轴突的超微结构恢复、神经传导速度及复合动作电位的改善均优于阳性对照组与阴性对照组(P<0.05)。表明许旺细胞复合小肠黏膜下层及碱性成纤维细胞生长因子缓释微球构建的人工神经可重建坐骨神经缺损后的神经传导通路。