γ-Hydroxybutyric acid and 5-fluorouracil, metabolites of UFT, inhibit the angiogenesis induced by vascular endothelial growth factor

UFT, a drug composed of uracil and tegafur at the molar ratio of 4:1, is an orally active agent for the treatment of a wide variety of malignant tumours. Using a murine dorsal air sac (DAS) assay, we have previously shown that UFT and its metabolites, γ-hydroxybutyric acid (GHB) and 5-fluorouracil (5-FU), inhibited the angiogenesis induced by murine renal cell carcinoma. Here we report that UFT was more effective than other fluorinated pyrimidines such as 5-FU and doxifluridine (5^′-DFUR) in blocking the angiogenic responses elicited by five human cancer cell lines which produced high levels of vascular endothelial growth factor (VEGF), but no detectable fibroblast growth factor-2 (FGF-2) in vitro. In contrast, UFT was unable to block the angiogenic response to one human gastric cancer cell line which produced both VEGF and FGF-2 in vitro. However, the production or secretion of VEGF by these cells was unaffected by GHB and 5-FU treatment. Interestingly, GHB suppressed the chemotactic migration and tube formation of human umbilical vein endothelial cells (HUVECs) stimulated by VEGF, without inhibiting their DNA synthesis. Since GHB did not affect the FGF-2-driven activities in HUVECs, its action appears to be VEGF-selective. On the other hand, 5-FU inhibited DNA synthesis and migration of HUVECs stimulated by both VEGF and FGF-2, and tube formation driven by VEGF, suggesting that 5-FU is cytotoxic to endothelial cells. The inhibitory effects of 5-FU, and especially those GHB, were reproduced under in vivo condition using the DAS assay. The VEGF-mediated angiogenesis was significantly inhibited by UFT, 5-FU, and especially by GHB. We propose that the selective inhibitory effects of GHB on VEGF-mediated responses of endothelial cells are involved in the anti-angiogenic activity of UFT. This revised version was published online in June 2006 with corrections to the Cover Date.     

Phosphoinositide 3 kinase is critical for survival, mitogenesis and migration but not for differentiation of endothelial cells

Angiogenesis involves endothelial cell invasion and migration into the surrounding tissue where cells differentiate, to form new lumen-containing vessels. We have investigated the role of phosphoinositide 3-kinase (PI3-kinase) in vascular endothelial growth factor (VEGF)- and fibroblast growth factor (FGF)-induced angiogenesis. Angiogenesis in vivo in chick embryos was inhibited by treatment with the PI3-kinase inhibitors wortmannin and LY294002. Stimulation of primary bovine capillary endothelial (BCE) cells with FGF-2, VEGF-A₁₆₅, or a combination of the two induced PI3-kinase activity in vitro and subsequent activation of the serine/threonine kinase Akt. The combination of FGF-2 and VEGF-A₁₆₅ led to an additive response. Activation of PI3-kinase was strictly required for FGF-2- and VEGF-A₁₆₅-induced migration and DNA synthesis of BCE cells. Tubular morphogenesis was unaffected by treatment with wortmannin or LY294002, but survival of the tubular structures was dependent on PI3-kinase activity. VEGF-A₁₆₅ and FGF-2 induced increased stability of the tubular structures in a synergistic manner. These data indicate that PI3-kinase activity is required for migration, mitogenicity and survival but not for differentiation of endothelial cells during angiogenesis. This revised version was published online in June 2006 with corrections to the Cover Date.     

Ectodomain shedding of VEGF183, a novel isoform of vascular endothelial growth factor, promotes its mitogenic activity in vitro

We have previously reported the discovery of VEGF183, a novel isoform of vascular endothelial growth factor (VEGF), whose nucleotide sequence revealed an 18-bp deletion in the exon 6A-encoded region of VEGF. The following study was done to characterize VEGF183 and to determine its biological activity in vitro and in vivo. Recombinant human VEGF183 was expressed in Escherichia coli (rhVEGF183) or in human 293 embryonic kidney cells (293-VEGF183) and tested for stimulation of permeability of dermal vessels in normal rats as well as for mitogenic activity and phosphorylation of mitogen-activated protein kinases (MAPK) in cultured human umbilical vein endothelial cells (HUVECs). While small amounts of VEGF183 were secreted into the conditioned media (CM) of 293 cells expressing VEGF183 (293-VEGF183 cells), most of the VEGF183 remained cell surface-bound and could be released into the CM following treatment with plasmin or heparin. CM from 293-VEGF183 cells treated with heparin or plasmin induced about a twofold increase in cell numbers and stimulated MAPK phosphorylation in HUVECs as compared with CM from untreated 293-VEGF183 cells or from heparin- or plasmin-treated 293 cells containing the vector alone. Intradermal injections of rhVEGF183 promoted increased permeability of dermal vessels to Evan's blue dye. Our study shows that VEGF183 is predominantly a cell-anchored protein that promotes increased vascular permeability in vivo but requires extracellular cleavage or release by heparin or plasmin to promote its mitogenic activity in vitro. This revised version was published online in June 2006 with corrections to the Cover Date.     

VEGF function for upregulation of endogenous PlGF expression during FGF-2-mediated therapeutic angiogenesis

Vascular endothelial growth factor (VEGF) is a major positive angiogenic factor. Using a murine hindlimb ischemia model, we previously showed that fibroblast growth factor-2 (FGF-2) enhances the expression of endogenous VEGF which highly contribute to the therapeutic effect of FGF-2 gene transfer. Recently, placental growth factor (PlGF) has been shown to play an important role in angiogenesis. However, the molecular mechanism of endogenous PlGF during FGF-2-mediated angiogenesis has not been elucidated. Severe hindlimb ischemia stimulated PlGF expression that was more strongly enhanced by FGF-2 gene transfer, and a blockade of PlGF activity diminished the recovery of blood flow by FGF-2-mediated angiogenesis. The PlGF expression in cultured endothelial cells was significantly enhanced by VEGF stimulation, but not by FGF-2. The upregulation of endogenous PlGF expression was significantly decreased by the inhibition of endogenous VEGF activity in vivo. Subsequent signal inhibition experiments revealed that the PKC, MEK, and possibly NF-κB-related pathways were essential in stimulating PlGF expression with VEGF, while p70S6K is the regulator for VEGF expression. These results indicate that the FGF-2-mediated enhancement of PlGF expression was dependent on VEGF function, and the FGF-2/VEGF axis participates in FGF-2-mediated angiogenesis indirectly via PlGF as well as directly.     

cDNA microarray analysis of the gene expression profile of VEGF-activated human umbilical vein endothelial cells

Vascular endothelial growth factor (VEGF) is one of the most important factors that stimulate angiogenesis and vascular permeability. To clarify the role of VEGF, we analysed a human cDNA chip containing 7267 human genes to identify genes induced by VEGF in human umbilical vein endothelial cells (HUVECs). One hundred thirty-nine cDNAs, including ninety-nine previously known and forty poorly characterized or novel sequences, were increased more than two-fold by VEGF within twenty-four hours of stimulation. Among them, only five are known to regulate angiogenesis: cyclooxygenase 2 (COX2), heparin-binding epidermal growth factor-like growth factor, early growth response 1 (EGR 1), CYR61, and angiopoietin 2. Fifty-three genes induced within the first two hours were thought to be directly induced by VEGF. Of these, Down syndrome candidate region 1 (maximum induction = 6.1-fold) was the most profoundly induced, followed by Mif1 (KIAA0025; 5.5-fold), COX2 (4.7-fold), EGR 3 (3.7-fold), EGR 2 (3.2-fold), bactericidal/permeability-increasing protein (3.1-fold), and CD1B antigen, b polypeptide (3.1-fold). In addition to the genes mentioned above, there were many poorly characterized or novel genes induced by VEGF. Further analysis of these genes may aid in the elucidation of the molecular mechanisms of angiogenesis or vascular permeability stimulated by VEGF. This revised version was published online in June 2006 with corrections to the Cover Date.     

Regulation of VEGF and bFGF mRNA expression and other proliferative compounds in skeletal muscle cells

The role of muscle contraction, prostanoids, nitric oxide and adenosine in the regulation of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and endothelial cell proliferative compounds in skeletal muscle cell cultures was examined. VEGF and bFGF mRNA, protein release as well as the proliferative effect of extracellular medium was determined in non-stimulated and electro-stimulated rat and human skeletal muscle cells. In rat skeletal muscle cells these aspects were also determined after treatment with inhibitors and/or donors of nitric oxide (NO), prostanoids and adenosine. Electro-stimulation caused an elevation in the VEGF and bFGF mRNA levels of rat muscle cells by 33% and 43% (P < 0.05), respectively, and in human muscle cells VEGF mRNA was elevated by 24%. Medium from electro-stimulated human, but not rat muscle cells induced a 126% higher (P < 0.05) endothelial cell proliferation than medium from non-stimulated cells. Cyclooxygenase inhibition of rat muscle cells induced a 172% increase (P < 0.05) in VEGF mRNA and a 104% increase in the basal VEGF release. Treatment with the NO donor SNAP (0.5 M) decreased (P < 0.05) VEGF and bFGF mRNA by 42 and 38%, respectively. Medium from SNAP treated muscle cells induced a 45% lower (P < 0.05) proliferation of endothelial cells than control medium. Adenosine enhanced the basal VEGF release from muscle cells by 75% compared to control. The present data demonstrate that contractile activity, NO, adenosine and products of cyclooxygenase regulate the expression of VEGF and bFGF mRNA in skeletal muscle cells and that contractile activity and NO regulate endothelial cell proliferative compounds in muscle extracellular fluid.     

The mechanisms of hepatic sinusoidal endothelial cell regeneration: A possible communication system associated with vascular endothelial growth factor in liver cells

Vascular endothelial growth factor (VEGF) has been shown to induce proliferation of sinusoidal endothelial cells in primary culture. To elucidate the mechanisms of sinusoidal endothelial cell regeneration in vivo, mRNA expression of VEGF and its receptors, flt-1 and KDR/flk-1, were studied in rat livers. Northern blot analysis revealed that VEGF-mRNA was expressed in hepatocytes immediately after isolation from normal rats. In contrast, non-parenchymal cells, including sinusoidal endothelial cells, expressed VEGF receptor-mRNA. Vascular endothelial growth factor-mRNA expression in hepatocytes was decreased during primary culture, but increased following a peak of DNA synthesis, induced by addition of epidermal growth factor or hepatocyte growth factor to the culture medium at 24 h of plating. In a 70% resected rat liver, VEGF-mRNA expression increased with a peak at 72 h after the operation, and mRNA expression of VEGF receptors between 72 and 168 h. In such a liver, mitosis was maximal in hepatocytes at 36 h and in sinusoidal endothelial cells at 96 h. Also, mRNA expression of both VEGF and its receptors was significantly increased in carbon tetrachloride-intoxicated rat liver compared with normal rat liver. Vascular endothelial growth factor expression was minimal in Kupffer cells isolated from normal rats, but marked in activated Kupffer cells and hepatic macrophages from the intoxicated rats. Vascular endothelial growth factor-mRNA expression was also increased in activated stellate cells from these rats and in the cells activated during primary culture compared with quiescent cells. We conclude that increased levels of VEGF expression in regenerating hepatocytes may contribute to the proliferation of sinusoidal endothelial cells in partially resected rat liver, probably through VEGF receptors up-regulated on the cells. Also, VEGF derived from activated Kupffer cells, hepatic macrophages and stellate cells may be involved in this proliferation in injured rat liver.     

TFR和VEGF基因双顺反子慢病毒感染骨髓内皮祖细胞的研究

目的:研究转铁蛋白受体 (transferrin receptor,TFR)和血管内皮生长因子(vascular endothelial growth factor,VEGF)的双基因共表达慢病毒载体是否能介导目的基因在中华小型猪骨髓内皮祖细胞（endothelial progenitor cells,EPCs）中的有效表达。方法:通过分子克隆技术构建双顺反子慢病毒表达载体pLenti-GFP-TIR;分离培养中华小型猪骨髓EPCs,用流式细胞仪(FCM)检测细胞表面抗原CD31和Flk-1的表达;并利用Lipofectin 2000将含目的基因的转移质粒与pRsv-REV、pMDlg-pRRE及pMD2G共转染293T细胞并进行慢病毒包装。72 h后,收集病毒上清,感染中华小型猪骨髓EPCs,并通过RT-PCR法检测TFR和VEGF基因的表达。结果:①成功地构建了双顺反子慢病毒表达载体pLenti-GFP-TIR;②FCM检测证实,分离的细胞为骨髓EPCs;包装好的慢病毒颗粒可成功地感染中华小型猪骨髓EPCs;③RT-PCR法检测表明,TFR和VEGF呈高水平的表达。结论:TFR和VEGF基因双顺反子慢病毒载体Lenti-GFP-TIR可有效地转移目的基因至中华小型猪骨髓EPCs中,并成功地表达目的基因,为进一步探讨移植细胞分子成像奠定了基础。     

Soluble VEGFR-1 secreted by endothelial cells and monocytes is present in human serum and plasma from healthy donors

It was shown before that the soluble form of VEGFR-1 (sVEGFR-1) is present in serum of pregnant women. The aim of the present study was to investigate the presence of this endogenous vascular endothelial growth factor-A (VEGF-A) antagonist in human serum in more detail. sVEGFR-1 was detected in human serum and plasma from normal healthy male and female donors by ELISA. sVEGFR-1 levels ranged from non-detectable up to 440 pg/ml, with no significant difference between male and female donors. In addition, vein endothelial cells (ECs) from an intact vascular bed, the umbilical cord, were shown to secrete sVEGFR-1. Furthermore, human peripheral blood monocytes, a non-EC type expressing VEGFR-1, were shown to contribute to the sVEGFR-1 detectable in human serum and plasma for the first time. EC- and monocyte-derived sVEGFR-1 proved capable of inhibiting the VEGF-induced proliferation and migration of ECs in vitro. Finally, secretion of sVEGFR-1 was increased by the angiogenic factor basic fibroblast growth factor (bFGF) in human ECs and was also enhanced in lipopolysaccharide-activated human monocytes. In human umbilical vein endothelial cells, both the membrane-bound and the sVEGFR-1 seem to be equally regulated on the mRNA as well as the protein level. The presence of an sVEGFR-1 in human serum and plasma of normal male and female donors strongly suggests that it plays an important role as a naturally occurring VEGF antagonist in the regulation and availability of VEGF-mediated biological activities in vivo. This revised version was published online in June 2006 with corrections to the Cover Date.     

Soluble neuropilin targeted to the skin inhibits vascular permeability

Neuropilin 1 (NRP1) is a co-receptor for vascular endothelial growth factor (VEGF₁₆₅), an inducer of vascular permeability and angiogenesis. Numerous physiological factors enhance VEGF expression and function but only a few have been shown to be negative regulators. Previously, we have shown that the naturally occurring soluble form of NRP1 (sNRP1) inhibits binding of VEGF₁₆₅ to endothelial cells in vitro and impairs tumor growth in vivo. To investigate the role of sNRP1 in the regulation of vascular development and function, sNRP1 expression was targeted to the skin, where it is not normally expressed, using a keratin 14 (K14) promoter expression construct. K14-sNRP1 transgenic mice displayed normal skin architecture with a subtle abnormal vascular phenotype. While the overall number of skin blood vessels remained unchanged, the lumen size of smooth muscle-associated dermal vessels was reduced. K14-sNRP1 mice had reduced vascular permeability in response to VEGF₁₆₅, but also to VEGF₁₂₁ and platelet activating factor, suggesting that the lack of permeability was not solely due to the sequestration of VEGF. sNRP1 also reversed the increase in inflammation and edema induced by transgenic VEGF overexpression in cutaneous delayed-type hypersensitivity reactions. In summary, sNRP1 appears to primarily regulate vessel permeability while its effect on physiological angiogenesis is less evident in this model.     

An Engineered Heparin-Binding Form of VEGF-E (hbVEGF-E). Biological effects in vitro and mobilizatiion of precursor cells

Vascular endothelial growth factor (VEGF-A) is the founding member of a family of angiogenic proteins with various binding abilities to three cognate VEGF receptors. Previously, a gene encoding from the genome of parapox orf virus (OV) with about 25% amino acid identity to mammalian VEGF-A was named VEGF-E and shown to bind and specifically activate the vascular endothelial growth factor receptor VEGFR-2 (KDR/flk-1). Here, we have generated a novel heparin-binding form of VEGF-E by introducing the heparin-domain of the human VEGF-A(165) splice variant into the viral VEGF-E protein. Recombinant heparin-binding VEGF-E (hbVEGF-E) is shown to stimulate proliferation and sprout formation of macro- and microvascular endothelial cells to a similar extent as the parental OV-VEGF-E but fails to activate peripheral mononuclear cells. However, hbVEGF-E is more potent in binding competition assays with primary human endothelial cells when compared to the OV-VEGF-E. This can be explained by our finding that binding of hbVEGF-E but not of parental OV-VEGF-E to the VEGFR-2 is strongly increased by the addition of neuropilin-1 (NP-1), a cognate co-receptor for VEGF-A. The engineered hbVEGF-E was compared with the VEGFR-1 selective and also heparin-binding form of placenta growth factor (PlGF-2) in vivo. Both heparin-binding homologues induced mobilization of endothelial progenitor cells from the bone marrow and gave rise to similar colony numbers of myeloic cells in a colony-forming assay. These findings suggest that both VEGFR-1 and VEGFR-2 are involved in stem cell mobilization.     

Berberine inhibits angiogenic potential of Hep G2 cell line through VEGF down-regulation in vitro

Background and Aim: Berberine, an herbal alkaloid, has been reported to have promotion potential of apoptosis and anticancer effect on a variety of human tumor cells. To obtain more specific understanding of those consequences of berberine on hepatocellular carcinoma (HCC) and the tumor microenvironment, we conducted in vitro experiments to investigate the inhibitory effect of berberine on tumor‐induced angiogenesis using HCC cells and human umbilical vein endothelial cells (HUVECs). Methods: Human umbilical vein endothelial cell growth was quantified with the CCK‐8 cell proliferation assay; cell migration was observed with a Boyden chamber (Transwell, Corning, Lowell, MA, USA), and angiogenesis was assessed by endothelial tube formation in Matrigel in vitro. In addition, VEGF level was determined by ELISA and VEGF mRNA expression by RT‐PCR. Results: Berberine inhibited the capacity of HCC to stimulate HUVEC's proliferation, migration and endothelial tube formation, suggesting that berberine could influence the cross‐talk between the HCC cell and vascular endothelial cells. These results demonstrate berberine's antiangiogenesis property and its clinical potential as an inhibitor of tumor angiogenesis. Subsequently analyses reveal that berberine prevents secretion of VEGF from HCC and down‐regulates VEGF mRNA expression. Conclusion: These findings strongly suggest that berberine is a potential antiangiogenic agent and a promising antitumor drug for HCC.     

Thrombospondin 1 as a scavenger for matrix-associated fibroblast growth factor 2

The antiangiogenic factor thrombospondin 1 (TSP-1) binds with high affinity to several heparin-binding angiogenic factors, including fibroblast growth factor 2 (FGF-2), vascular endothelial growth factor (VEGF), and hepatocyte growth factor/scatter factor (HGF/SF). The aim of this study was to investigate whether TSP-1 affects FGF-2 association with the extracellular matrix (ECM) and its bioavailability. TSP-1 prevented the binding of free FGF-2 to endothelial cell ECM. It also promoted the mobilization of matrix-bound FGF-2, generating a TSP-1/FGF-2 complex. The region of TSP-1 responsible for these activities was located within the 140-kDa antiangiogenic and FGF-2 binding fragment, whereas the 25-kDa heparin-binding fragment was inactive. Matrix-released FGF-2/TSP-1 complex had a reduced ability to bind to and induce proliferation of endothelial cells. TSP-1 depleted the ECM laid by FGF-2-overproducing tumor cells of its FGF-2-dependent mitogenic activity for endothelial cells. Besides FGF-2, TSP-1 also inhibited VEGF and HGF/SF binding to the ECM and mobilized them from the ECM. Our study shows that TSP-1 acts as a scavenger for matrix-associated angiogenic factors, affecting their location, bioavailability, and function.     

Biological activity of bevacizumab,a humanized anti-VEGF antibody <Emphasis Type="Italic">in vitro</Emphasis>

Bevacizumab (Avastin, Genentech) is a humanized monoclonal antibody targeting vascular endothelial growth factor (VEGF), a critical angiogenic factor involved in both physiological and pathological conditions. It has been recently approved by the US FDA as a first-line therapy for widespread metastatic colorectal cancer. This report is a detailed biological characterization of bevacizumab in a variety of in vitro models. It is shown that bevacizumab potently neutralizes VEGF and blocks its signal transduction through both the VEGFR-1 and VEGFR-2 receptors, as demonstrated by the inhibition of VEGF-induced cell proliferation, survival, permeability, nitric oxide production, as well as migration and tissue factor production. Although bevacizumab retains the ability to bind to human Fc receptors and complement protein C1q, it does not demonstrate cell or complement-mediated cytotoxicity in either VEGF producing or targeting cells. Thus the mechanism of anti-tumor activity of bevacizumab is most likely due to its anti-angiogenesis effect through binding and neutralization of secreted VEGF.     

Involvement of VEGFR-2 (kdr/flk-1) but not VEGFR-1 (flt-1) in VEGF-A and VEGF-C-induced tube formation by human microvascular endothelial cells in fibrin matrices in vitro

Different forms of vascular endothelial growth factor (VEGF) and their cellular receptors (VEGFR) are associated with angiogenesis, as demonstrated by the lethality of VEGF-A, VEGFR-1 or VEGFR-2 knockout mice. Here we have used an in vitro angiogenesis model, consisting of human microvascular endothelial cells (hMVEC) cultured on three-dimensional (3D) fibrin matrices to investigate the roles of VEGFR-1 and VEGFR-2 in the process of VEGF-A and VEGF-C-induced tube formation. Soluble VEGFR-1 completely inhibited the tube formation induced by the combination of VEGF-A and TNFα (VEGF-A/TNFα). This inhibition was not observed when tube formation was induced by VEGF-C/TNFα or bFGF/TNFα. Blocking monoclonal antibodies specific for VEGFR-2, but not antibodies specifically blocking VEGFR-1, were able to inhibit the VEGF-A/TNFα-induced as well as the VEGF-C/TNFα-induced tube formation in vitro. PlGF-2, which interacts only with VEGFR-1, neither induced tube formation in combination with TNFα, nor inhibited or stimulated by itself the VEGF-A/TNFα-induced tube formation in vitro. These data indicate that VEGF-A or VEGF-C activation of the VEGFR-2, and not of VEGFR-1, is involved in the formation of capillary-like tubular structures of hMVEC in 3D fibrin matrices used as a model of repair-associated or pathological angiogenesis in vitro. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enhanced angiogenesis following allogeneic blood transfusion1

Blood transfusions are associated with recurrence of solid cancers. Angiogenesis is essential for cancer growth. Our aim was to determine for the first time in a prospective cohort study the effect of prestorage allogeneic leucodepleted SAGM (saline, adenine, glucose, mannitol) red cell transfusion on angiogenic factor levels and in vitro angiogenesis. Forty pretransfusion adult hospital inpatients were selected consecutively. Serum vascular endothelial growth factor (VEGF) and endostatin were measured in each patient before and after prestorage allogeneic leucodepleted SAGM red cell transfusion. All samples were exposed to an in vitro endothelial cell proliferation assay and 10 sample groups were also exposed to an in vitro whole angiogenesis assay. The median number of units transfused was 2 (minimum–maximum, 2–4). Twenty‐nine (73%) patients had a rise in VEGF, with an overall increase of 118 pg/ml (quartiles ?5, 306; P < 0.01). Twenty‐eight (70%) patients had a decrease in endostatin, with an overall reduction of 1.2 ng/ml (quartiles 4.0, 0.0; P = 0.017). There was an overall 33% increase in endothelial cell proliferation (P < 0.01) and a 9.4% increase in in vitro whole assay angiogenesis (P < 0.01). Prestorage allogeneic leucodepleted SAGM red cell transfusions are associated with a favourable angiogenic factor imbalance and an elevation in in vitro angiogenesis.     

骨髓间充质干细胞体外定向诱导内皮祖细胞的实验研究

目的:研究兔骨髓间充质干细胞(mensenchymal stem cell,MSC)在体外定向诱导分化为内皮祖细胞(endothelial progenitor cell,EPC)的状况。方法:取兔髂骨骨髓,经密度梯度离心法分离并培养骨髓间充质干细胞,实验组细胞在内皮细胞生长添加剂、血管内皮生长因子、成纤维细胞生长因子等诱导条件下定向分化为内皮祖细胞。对照组不干预,继续培养。结果:实验组细胞集落接近融合时形态呈现“鹅卵石”样或“铺路石”样外观,流式细胞仪检测发现实验组细胞较对照组高度表达CD133、CD34(P<0．05)。结论:体外诱导可使骨髓间充质干细胞分化为内皮祖细胞,并有效扩增。     

Platelets from glioblastoma patients promote angiogenesis of tumor endothelial cells and exhibit increased VEGF content and release

Glioblastoma multiforme (GBM) is the most common and fatal intracranial cancer in humans and exhibits intense and aberrant angiogenesis that sustains its malignancy and involves several angiogenic signals. Among them, vascular endothelial growth factor (VEGF) plays a key role and is overexpressed in GBM. Different cells appear to act as triggers of the aberrant angiogenesis, and, among them, platelets act as key participants. In order to provide further insights into the platelet features and angiogenic role in GBM, this study investigated the effects of platelet releasate on GBM-derived endothelial cells (GECs) and the levels of VEGF and endostatin, as pro- and anti-angiogenic components of platelet releasate from GBM patients. We demonstrate for the first time that: 1) platelet releasate exerts powerful pro-angiogenic effect on GECs, suggesting it might exert a role in the aberrant angiogenesis of GBM; 2) ADP and thrombin stimulation leads to significantly higher level of VEGF, but not of endostatin, in the releasate of platelets from GBM patients than those from healthy subjects; and 3) the intraplatelet concentrations of VEGF were significantly elevated in GBM patients as compared to controls. Moreover, we found a direct correlation between platelet-released VEGF and overall survival in our patient cohort. Although preliminary, these findings prompt further investigations to clarify the biologic relevance of platelet VEGF in GBM and prospective studies for screening GBM patients for anti-VEGF therapy and/or to optimize this treatment.     

犬骨髓成年多能祖细胞诱导分化血管内皮细胞的实验研究

目的内皮细胞移植对损伤组织的修复治疗至关重要,本研究旨在探讨骨髓成年多能干细胞(MAPCs)体内外诱导分化血管内皮细胞的可行性.方法采用Percoll密度梯度法分离培养MAPCs.应用10 ng/ml血管内皮细胞生长因子(VEGF)对骨髓MAPCs进行体外诱导分化2～3周,使其定向分化成为血管内皮细胞.采用细胞形态学、细胞免疫组化以确定诱导分化的效果.将标记BrdU的MAPCs自体移植于犬心肌内,观察局部微环境对于骨髓MAPCs的分化能力.结果应用10 ng/ml VEGF孵育骨髓MAPCs 2～3周,可见MAPCs分化为血管内皮细胞:细胞形态呈鹅卵石样;形成血管样结构;细胞vWF免疫染色阳性.移植于心肌内的MAPCs在体内形成新生血管,血管内皮BrdU染色与vWF染色均阳性.结论骨髓MAPCs可在体外VEGF诱导下或在体内微环境作用下分化为成熟血管内皮细胞.骨髓MAPCs可为损伤组织的移植修复治疗提供内皮细胞资源.