Mesenchymal stem cells enhance wound healing through differentiation and angiogenesis

Although chronic wounds are common, treatment for these disabling conditions remains limited and largely ineffective. In this study, we examined the benefit of bone marrow-derived mesenchymal stem cells (BM-MSCs) in wound healing. Using an excisional wound splinting model, we showed that injection around the wound and application to the wound bed of green fluorescence protein (GFP)(+) allogeneic BM-MSCs significantly enhanced wound healing in normal and diabetic mice compared with that of allogeneic neonatal dermal fibroblasts or vehicle control medium. Fluorescence-activated cell sorting analysis of cells derived from the wound for GFP-expressing BM-MSCs indicated engraftments of 27% at 7 days, 7.6% at 14 days, and 2.5% at 28 days of total BM-MSCs administered. BM-MSC-treated wounds exhibited significantly accelerated wound closure, with increased re-epithelialization, cellularity, and angiogenesis. Notably, BM-MSCs, but not CD34(+) bone marrow cells in the wound, expressed the keratinocyte-specific protein keratin and formed glandular structures, suggesting a direct contribution of BM-MSCs to cutaneous regeneration. Moreover, BM-MSC-conditioned medium promoted endothelial cell tube formation. Real-time polymerase chain reaction and Western blot analysis revealed high levels of vascular endothelial growth factor and angiopoietin-1 in BM-MSCs and significantly greater amounts of the proteins in BM-MSC-treated wounds. Thus, our data suggest that BM-MSCs promote wound healing through differentiation and release of proangiogenic factors. Disclosure of potential conflicts of interest is found at the end of this article.

Inhibition of tumor growth through suppression of angiogenesis by brain-specific angiogenesis inhibitor 1 gene transfer in murine renal cell carcinoma

This study was designed to elucidate the therapeutic effect of transfering the brain-specific angiogenesis inhibitor 1 (BAI1) gene to a mouse renal cell carcinoma cell line (Renca). Female BALB/c mice were inoculated subcutaneously with wild-type Renca (Renca/Wild) cells or Renca cells transfected with the BAI-1 (Renca/BAI-1) or LacZ (Renca/LacZ) gene. Tumor growth was observed every other day from 3 to 35 days after implantation. Moreover, the intratumoral injection of the adenovirus vector containing the gene encoding BAI1 was conducted at two-day intervals from 11 to 31 days after implantation of the Renca/Wild or Renca/BAI1 tumor. Tumor blood flow was measured by colorimetric angiogenesis assay (CAA). The concentration of the vascular endothelial growth factor (VEGF) in the cell culture supernatants was determined by enzyme-linked immunoassay. The size of the Renca/BAI1 tumor was significantly (p<0.01) suppressed compared to the Renca/Wild and Renca/LacZ tumors 21 days after tumor implantation. The injection of the BAI1 viral vector at 2-day intervals significantly inhibited the growth of both the Renca/Wild and Renca/BAI1 tumors. The blood volume measured by CAA and microvessel density was significantly lower in the Renca/BAI1 than in the Renca/Wild and Renca/LacZ tumors (p<0.01 and p<0.05, respectively). A significant (p<0.01) reduction in VEGF concentration in the supernatant was demonstrated in the Renca/BAI1 compared with the Renca/Wild and Renca/LacZ cell cultures. These observations suggest that the transfer of the BAI1 gene to Renca can suppress the tumor growth via the inhibition of angiogenesis. The down-regulation of VEGF production in tumor cells contributes to this anti-tumor effect.

Effects of podocyte injury on glomerular development

To study the effects of podocyte injury on glomerular maturation and underlying mechanisms of such effects, puromycin aminonucleoside (PAN) was given to neonatal mice at 1 d post partum (1 dpp). Mice with PAN injection had smaller kidney weight (KW) and body weight (BW) at all times and smaller KW/BW at 4, 8, and 12 dpp versus normal saline (NS) controls. Electron microscopy (EM) revealed nearly complete podocyte foot process effacement and segmental microvillous transformation as early as 2 dpp, preceding proteinuria. PAN-injected kidneys showed significantly fewer glomerular capillary loops and decreased glomerular maturation index, as well as less CD31+ endothelium in cortical glomeruli at 12 dpp versus NS controls. Glomerular mesangial injury and glomerulosclerosis along with proteinuria were noted in PAN-injected kidneys starting from 30 dpp. Systolic blood pressure was increased significantly by 60 dpp in PAN mice. PAN mice also had significantly decreased Flk-1 and Tie2 mRNA expression and increased angiopoitein-1 (Ang-1) expression, without change in vascular endothelial growth factor (VEGF) at 2 dpp versus NS. Our study shows that podocyte injury in neonatal mice kidneys alters the expression of key capillary growth modulators in glomeruli, leading to abnormal development of glomerular capillaries, with subsequent development of proteinuria, hypertension, and glomerulosclerosis.

[Biology molecular of glioblastomas]

Glioblastomas, the most frequent and malignant human brain tumors, may develop de novo (primary glioblastoma) or by progression from low-grade or anapalsic astrocytoma (secondary glioblastoma). The molecular alteration most frequent in these tumor-like types is the loss of heterozygosity on chromosome 10, in which several genes have been identified as tumors suppressor. The TP53/MDM2/P14arf and CDK4/RB1/ P16ink4 genetic pathways involved in cycle control are deregulated in the majority of gliomas as well as genes that promote the cellular division, EGFR. Finally the increase of growth and angiogenics factors is also involved in the development of glioblastomas. One of the objectives of molecular biology in tumors of glial ancestry is to try to find the genetic alterations that allow to approach better the classification of glioblastomas, its evolution prediction and treatment. The new pathmolecular classification of gliomas should improve the old one, especially being concerned about the oncogenesis and heterogeneity of these tumors. It is desirable that this classification had clinical applicability and integrates new molecular findings with some known histological features with pronostic value. In this paper we review the most frequent molecular mechanisms involved in the patogenesis of glioblastomas.

Cytokine profile of human adipose-derived stem cells: expression of angiogenic, hematopoietic, and pro-inflammatory factors

Adipose tissue serves as a source of adipokines and cytokines with both local and systemic actions in health and disease. In this study, we examine the hypothesis that multipotent human adipose-derived stem cells (ASCs), capable of differentiating along the adipocyte, chondrocyte, and osteoblast pathways, contribute to adipose tissue-derived cytokine secretion. Following exposure to basic fibroblast growth factor (bFGF) or epidermal growth factor (EGF), the ASCs significantly increase their secretion of hepatocyte growth factor (HGF), a cytokine implicated in hematopoiesis, vasculogenesis, and mammary epithelial duct formation. Ascorbic acid synergizes with these inductive factors, further increasing HGF levels. Following exposure to lipopolysaccharide, ASCs increase their secretion of both hematopoietic (granulocyte/monocyte, granulocyte, and macrophage colony stimulating factors, interleukin 7) and proinflammatory (interleukins 6, 8, and 11, tumor necrosis factor alpha) cytokines based on ELISA and RT-PCR. In co-cultures established with umbilical cord blood-derived CD34(+) cells, the ASCs support long-term hematopoiesis in vitro. Furthermore, in short-term 12-day co-cultures, the ASC maintain and expand the numbers of both myeloid and lymphoid progenitors. These observations are consistent with the functionality of the secreted cytokines and confirm recent reports by other laboratories concerning the hematopoietic supportive capability of ASCs. We conclude that the ASCs display cytokine secretory properties similar to those reported for bone marrow-derived mesenchymal stem cells (MSCs).

Hypoxia-induced mediators of stem/progenitor cell trafficking are increased in children with hemangioma

OBJECTIVE

The mechanism of neovascularization during the proliferative phase of infantile hemangioma is poorly understood. It is known that circulating bone marrow-derived endothelial progenitor cells (EPCs) form new blood vessels in ischemic tissues using mediators regulated by the transcription factor, HIF-1alpha. Mobilization of EPCs is enhanced by VEGF-A, matrix metalloproteinase (MMP)-9, and estrogen, whereas homing is secondary to localized expression of stromal cell-derived factor-1alpha (SDF-1alpha). We examined whether these mediators of EPC trafficking are upregulated during the proliferation of infantile hemangioma.

METHODS AND RESULTS

Surgical specimens and blood samples were obtained from children with proliferating hemangioma and age-matched controls (n=10, each group). VEGF-A and MMP-9 levels were measured in blood, and tissue sections were analyzed for SDF-1alpha, MMP-9, VEGF-A, and HIF-1alpha. The role of estrogen as a modulator of hemangioma endothelial cell growth was also investigated. We found that all these mediators of EPC trafficking are elevated in blood and specimens from children with proliferating infantile hemangioma. In vitro, the combination of hypoxia and estrogen demonstrated a synergistic effect on hemangioma endothelial cell proliferation.

CONCLUSIONS

These findings demonstrate that proliferating hemangiomas express known mediators of vasculogenesis and suggest that this process may play a role in the initiation or progression of this disease.

The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) regulates the production of proangiogenic molecules by myeloma cells and suppresses hypoxia-inducible factor-1 alpha (HIF-1alpha) activity: involvement in myeloma-induced angiogenesis

Angiogenesis has a critical role in the pathophysiology of multiple myeloma (MM); however, the molecular mechanisms underlying this process are not completely elucidated. The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) has been recently implicated in solid tumors as a repressor of angiogenesis. In this study, we found that ING4 expression in MM cells was correlated with the expression of the proangiogenic molecules interleukin-8 (IL-8) and osteopontin (OPN). Moreover, we demonstrate that ING4 suppression in MM cells up-regulated IL-8 and OPN, increasing the hypoxia inducible factor-1alpha (HIF-1alpha) activity and its target gene NIP-3 expression in hypoxic condition. In turn, we show that the inhibition of HIF-1alpha by siRNA suppressed IL-8 and OPN production by MM cells under hypoxia. A direct interaction between ING4 and the HIF prolyl hydroxylase 2 (HPH-2) was also demonstrated. Finally, we show that ING4 suppression in MM cells significantly increased vessel formation in vitro, blunted by blocking IL-8 or OPN. These in vitro observations were confirmed in vivo by finding that MM patients with high IL-8 production and microvascular density (MVD) have significantly lower ING4 levels compared with those with low IL-8 and MVD. Our data indicate that ING4 exerts an inhibitory effect on the production of proangiogenic molecules and consequently on MM-induced angiogenesis.

Disease susceptibility of the human macula: Differential gene transcription in the retinal pigmented epithelium/choroid

The discoveries of gene variants associated with macular diseases have provided valuable insight into their molecular mechanisms, but they have not clarified why the macula is particularly vulnerable to degenerative disease. Its predisposition may be attributable to specialized structural features and/or functional properties of the underlying macular RPE/choroid. To examine the molecular basis for the macula's disease susceptibility, we compared the gene expression profile of the human RPE/choroid in the macula with the profile in the extramacular region using DNA microarrays. Seventy-five candidate genes with differences in macular:extramacular expression levels were identified by microarray analysis, of which 29 were selected for further analysis. Quantitative PCR confirmed that 21 showed statistically significant differences in expression. Five genes were expressed at higher levels in the macula. Two showed significant changes in the macular:extramacular expression ratio; another two exhibited changes in absolute expression level, as a function of age or AMD. Several of the differentially expressed genes have potential relevance to AMD pathobiology. One is an RPE cell growth factor (TFPI2), five are extracellular matrix components (DCN, MYOC, OGN, SMOC2, TFPI2), and six are related to inflammation (CCL19, CCL26, CXCL14, SLIT2) and/or angiogenesis (CXCL14, SLIT2, TFPI2, WFDC1). The identification of regional differences in gene expression in the RPE/choroid is a first step in clarifying the macula's propensity for degeneration. These findings lay the groundwork for further studies into the roles of the corresponding gene products in the normal, aged, and diseased macula.

Medical Therapy for Intermittent Claudication

Medical therapy to improve symptoms, stabilise the underlying vascular disease and improve lower limb outcomes is an important and effective adjunct to lifestyle modification and surgical or endovascular interventions in patients with IC. Randomised placebo controlled trials have shown that the phosphodiesterase III inhibitor cilostazol 100mg bid improves pain-free and maximum walking distance, as well as quality of life, in a range of patients with intermittent claudication in whom there is no evidence of tissue necrosis or rest pain. This review summarises the evidence from 8 pivotal trials of cilostazol involving over 2000 patients with intermittent claudication treated for up to 6 months. There is comparatively less evidence to support the use of other treatment modalities for relief of symptoms in intermittent claudication, but there is considerable interest in therapeutic angiogenesis to promote new vessel formation and enhance collateralisation of the lower limb using recombinant growth factor proteins or gene transfer strategies. The rationale for therapeutic angiogenesis is discussed, together with the most recent results from randomised trials in patients with peripheral arterial disease.

[Screening of AGGF1 interacting with inhibitor of differentiation-1]

OBJECTIVE

To screen the proteins interacting with inhibitor of differentiation 1(Id1) using yeast two-hybrid analysis in adult human lung cDNA libraries.

METHODS

The coding sequence of Id1 was amplified by PCR and cloned into the bait plasmid. The recombinant bait vector pHybLex/Zeo-Id1 was verified by restriction endonuclease digestion before transformation into the yeast strain EGY48/pSH18-34, which was tested subsequently for reporter genes Leu2 and LacZ activation. The pHybLex/Zeo-Id1 plasmid and the cDNA library plasmid were sequentially transformed into the yeast strains and screened to obtain Leu2(+) and Leu2(+)LacZ(+) clones, with the false positive clones excluded using positive and negative controls, and the plasmid of the true positive clone was sequenced and blasted for homological analysis.

RESULTS

Successful construction of pHybLex/Zeo-Id1 was confirmed by enzyme digestion. After transformation of pHybLex/Zeo-Id1 into EGY48/pSH18-34, no specific reporter genes Leu2 and LacZ activation was found. The pHybLex/Zeo-Id1 plasmid and the cDNA library plasmid were sequentially transformed into yeast strain, and 198 Leu(+) clones and 19 Leu(+)LacZ(+) double positive clones were obtained. After elimination of the false positive clones, one true positive clone was obtained, whose plasmid analysis by sequencing and blasting indicated high homology (99.5%, 556/559) to AGGF1 (an angiogenic factor with G-patch and FHA domains 1). AGGF1 expression was confirmed in the true positive yeast cells by Western blotting.

CONCLUSION

AGGF1 is confirmed to interact with Id1 by yeast two-hybrid analysis for screening adult human lung cDNA libraries.

Angiogenic growth factors in the treatment of peripheral arterial disease

Peripheral arterial disease (PAD) remains a major cause of morbidity. Despite advances in revascularisation procedures and medical treatment, limb salvage and relief of pain are still not satisfactory in patients with severe disease. This has prompted the exploration of alternative modes of treatment including enhancement of new vessel formation (angiogenesis). Angiogenic Growth Factors (AGF), mainly Vascular Endothelial Growth Factor (VEGF), basic Fibroblast Growth Factor (bFGF) and Hepatocyte Growth Factor (HGF) have emerged as exciting therapeutic modalities. Both experimental and clinical studies have demonstrated that topical (mainly intramuscular) AGF gene therapy results in improved peripheral vasculature and alleviation of symptoms. However, most clinical work is limited to small patient series and the long-term safety and efficacy are still unclear. Clinical benefit must be balanced against potential untoward effects, such as tumour growth and atherosclerotic plaque angiogenesis leading to plaque instability. VEGF is important in the pathogenesis of diabetic microvascular disease. Further studies are required before implementation of AGF therapy in clinical practice.

Effect of CDT6 on factors of angiogenic balance in tumour cell lines

BACKGROUND

Cornea-derived transcript 6 (CDT6, also known as AngX) is an angiopoietin-related factor resulting in anti-tumour effect in vivo. However, a recent abstract reported that CDT6 can also induce angiogenesis and promotes tumour growth. In our previous work, CDT6 had failed to show pro- or anti-angiogenic effects. It is unknown if CDT6 expression occurs in human cancer.

MATERIALS AND METHODS

An array of human tumour cell lines and tumour tissues was tested for CDT6-gene expression using RT-PCR. To address the controversial role of CDT6 on angiogenesis in different tumour models, the expression levels of four factors of the angiogenic balance (VEGF, endostatin, TIMP-1 and PAI-1) were determined in CDT6-transfected and control cells of the human and murine melanoma cell lines BLM and B16-F10. Endostatin was significantly up-regulated by CDT6 expression in the human model and significantly down-regulated in the mouse model. None of 18 cell lines or 23 tumours expressed CDT6.

CONCLUSION

This contradictory effect on endostatin expression in human and mouse models may be an explanation for the conflicting results for the effect of CDT6 expression on angiogenesis.

Placental growth, angiogenic gene expression, and vascular development in undernourished adolescent sheep

Limiting maternal nutrient intake during ovine adolescent pregnancy progressively depleted maternal body reserves, impaired fetal nutrient supply, and slowed fetal soft tissue growth. The present study examined placental growth, angiogenic gene expression, and vascular development in this undernourished adolescent model at Days 90 and 130 of gestation. Singleton pregnancies were established, and ewes were offered an optimal control (C; n = 14) or low (L [0.7 x C]; n = 21) dietary intake. Seven ewes receiving L intakes were switched to C intakes on Day 90 of gestation (L-C). Fetal body weight (P < 0.01) and glucose concentrations (P < 0.03) were reduced in L versus C pregnancies by Day 130, whereas L-C group values were intermediate. Placental cellular proliferation, gross morphology, and mass were independent of maternal nutrition at both Day 90 and 130. In contrast, capillary area density in the maternal caruncular portion of the placentome was reduced by 20% (P < 0.001) at both stages of gestation in L compared with C groups. Caruncular capillary area density was equivalent in the L and L-C groups at Day 130. Placental mRNA expression of five key angiogenic ligands or receptors increased (P < 0.001) between Days 90 and 130 of gestation. VEGFA mRNA expression was higher (P < 0.04) in L compared with C and L-C pregnancies at Day 130, but otherwise gene expression of the remaining angiogenic factors and receptors analyzed was unaffected by maternal intake. Undernourishing the pregnant adolescent dam restricts fetal growth independently of changes in placental mass. Alterations in maternal placental vascular development may, however, play a role in mediating the previously reported reduction in maternal and hence fetal nutrient supply.

A role for the aryl hydrocarbon receptor in regulation of ischemia-induced angiogenesis

OBJECTIVE

The aryl hydrocarbon receptor (AHR) is a transcription factor that binds to DNA as a heterodimer with the AHR nuclear translocator (ARNT) after interaction with ligands such as polycyclic and halogenated aromatic hydrocarbons found in tobacco smoke and the environment. We have investigated the interaction between AHR and hypoxia signaling pathways in regulation of angiogenesis with the use of a surgical model of ischemia.

METHODS AND RESULTS

Ischemia was induced by femoral artery occlusion in wild-type and AHR-null mice. Ischemia-induced angiogenesis was markedly enhanced in AHR-null mice compared with that in wild-type animals. Ischemia-induced upregulation of the expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and ARNT as well as that of target genes for these transcription factors, such as that for vascular endothelial growth factor (VEGF), were also enhanced in AHR-null mice. Furthermore, the DNA binding activity of the HIF-1alpha-ARNT complex as well as the association of HIF-1alpha and ARNT with the VEGF gene promoter were increased by ischemia to a greater extent in AHR-null mice than in wild-type animals.

CONCLUSIONS

Ablation of AHR resulted in enhancement of ischemia-induced angiogenesis. This effect was likely attributable in part to the associated enhancement of ischemia-induced VEGF expression, which in turn may be caused by an increased abundance and activity of the HIF-1alpha-ARNT heterodimer.

Angiogenic Expression Profile of Normal and Neurofibromin-Deficient Human Schwann Cells

Peripheral nerve sheath tumors from individuals with Neurofibromatosis Type 1 (NF1) are highly vascular and contain Schwann cells which are deficient in neurofibromin. This study examines the angiogenic expression profile of neurofibromin-deficient human Schwann cells relative to normal human Schwann cells, characterizing both pro-angiogenic and anti-angiogenic factors. Conditioned media from neurofibromin-deficient Schwann cell lines was pro-angiogenic as evidenced by its ability to stimulate endothelial cell proliferation and migration. Using gene array and protein array analysis, we found increased expression of pro-angiogenic factors and decreased expression of anti-angiogenic factors in neurofibromin-deficient Schwann cells relative to normal human Schwann cells. Neurofibromin-deficient Schwann cells also showed increased expression of several growth factor receptors and decreased expression of an integrin. We conclude that neurofibromin-deficient Schwann cells have dysregulated expression of pro-angiogenic factors, anti-angiogenic factors, growth factor receptors, and an integrin. These dysregulated molecules may contribute to the growth and progression of NF1 peripheral nerve sheath tumors.

hCG in the Regulation of Placental Angiogenesis. Results of an In Vitro Study

Placental vascular development is essential for fetal growth and development. Inadequate placental vascular development is associated with early pregnancy losses and other pregnancy related pathologies. In addition to the ubiquitous, well-characterized angiogenic factors like vascular endothelial growth factor (VEGF) or basic fibroblast growth factor (bFGF), some pregnancy-specific factors (e.g. human chorionic gonadotropin (hCG), insulin-like growth factor-II (IGF-II) or alpha fetoprotein (AFP) were recently described to play a possible regulatory role in this process. In the present study we described an improved separation method for human placental microvascular endothelial cells (HPMVEC) and their functional characterization. Using the combination of enzymatic digestion and multistep immunomagnetic sorting with CD31 antibodies a model for villous vascularization was established. Isolated cells took up ac-dil-LDL, spontaneously formed capillary-like structures, and expressed common endothelial markers such as vascular endothelial growth factor receptor-2 (VEGFR-2), angiopoetin-1 and -2, Tie-2, CD144, thrombomodulin, and von Willebrand factor (vWF) as shown by RT-PCR, flow cytometry and Western blot analysis. The expression of the hCG/LH receptor in the placental vascular tree was verified both in vitro and in vivo. hCG stimulated proliferation of HPMVEC in a dose specific manner. While hCG alone had no significant effect on endothelial cell apoptosis, the combination of VEGF-A and hCG protected HPMVEC from staurosporine-induced apoptosis. hCG significantly stimulated sprout formation when compared to controls in a spheroid angiogenesis assay. Our results demonstrate a modified and reproducible method allowing studies of placental vascular development and provide new insights into the possible role of trophoblastic factors in this process.

Hypoxia affects mesenchymal stromal cell osteogenic differentiation and angiogenic factor expression

Mesenchymal stromal cells (MSCs) seeded onto biocompatible scaffolds have been proposed for repairing bone defects. When transplanted in vivo, MSCs (expanded in vitro in 21% O(2)) undergo temporary oxygen deprivation due to the lack of pre-existing blood vessels within these scaffolds. In the present study, the effects of temporary (48 h) exposure to hypoxia (<or=1% O(2)) on primary human MSC survival and osteogenic potential were investigated. Temporary exposure of MSCs to hypoxia had no effect on MSC survival, but resulted in (i) persistent (up to 14 days post exposure) down-regulation of cbfa-1/Runx2, osteocalcin and type I collagen and (ii) permanent (up to 28 days post exposure) up-regulation of osteopontin mRNA expressions. Since angiogenesis is known to contribute crucially to alleviating hypoxia, the effects of temporary hypoxia on angiogenic factor expression by MSCs were also assessed. Temporary hypoxia led to a 2-fold increase in VEGF expression at both the mRNA and protein levels. Other growth factors and cytokines secreted by MSCs under control conditions (namely bFGF, TGFbeta1 and IL-8) were not affected by temporary exposure to hypoxia. All in all, these results indicate that temporary exposure of MSCs to hypoxia leads to limited stimulation of angiogenic factor secretion but to persistent down-regulation of several osteoblastic markers, which suggests that exposure of MSCs transplanted in vivo to hypoxia may affect their bone forming potential. These findings prompt for the development of appropriate cell culture or in vivo transplantation conditions preserving the full osteogenic potential of MSCs.

Differential expression of angiogenesis-related genes in human gastric cancers with and those without high-frequency microsatellite instability

Gastric cancers with and those without high-frequency microsatellite instability (MSI-H) represent distinctive pathways of carcinogenesis. The aim of this study was to clarify if expression of p53 related genes involved in angiogenesis is differentially regulated between these cancers. We systematically analyzed the expression of vascular endothelial growth factor A (VEGFA), fibroblast growth factor 2 (FGF2), thrombospondin 1 (THBS1), and brain-specific angiogenesis inhibitor 1 (BAI1), and we correlated the results with microvessel count (MVC), MSI status, p53 mutations, and prostaglandin-endoperoxide synthase 2 (PTGS2) expression in gastric cancers. Expression of VEGFA in carcinoma cells was immunohistochemically seen in 46% of 200 cases. VEGFA positivity was significantly associated with higher MVC, vascular invasion, lymph node and distant metastasis, and advanced tumor stage. FGF2 positivity was significantly associated with poor differentiation, depth of invasion, and higher MVC. VEGFA and FGF2 positivities and MVC were lower in MSI-H cancers than in MSI-L or MSS cancers. VEGFA expression was associated with both p53 mutations and PTGS2 expression. Methylation of the THBS1 gene was detected in 6 of 11 cancer cell lines and in 44% of 200 cases. THBS1 methylation was significantly associated with distal location, vascular invasion, distant metastasis, MSI-H, wild-type p53, and higher MVC. The prognosis was worst in patients with cancers that were VEGFA-positive and THBS1 methylation-positive. Gastric cancers with MSI-H were characterized by lower MVC, low frequency of VEGFA, FGF2, and PTGS2 overexpression, and high frequency of THBS1 methylation. Our results suggest that gastric cancers with and those without MSI-H represent distinctive pathways of carcinogenesis, including aberrant expression of factors regulating angiogenesis. The difference may be associated with less aggressive phenotype of these cancers with MSI-H and affect future molecular targeted therapeutics.

Angiogenic factors stimulate tubular branching morphogenesis of sonic hedgehog-deficient lungs

Sonic Hedgehog (Shh)-deficient mice have a severe lung branching defect. Recent studies have shown that hedgehog signaling is involved in vascular development and it is possible that the diminished airway branching in Shh-deficient mice is due to abnormal pulmonary vasculature formation. Therefore, we investigated the role of Shh in pulmonary vascular development using Shh/Tie2lacZ compound mice, which exhibit endothelial cell-specific LacZ expression, and Pecam-1 immunohistochemistry. In E11.5-13.5 Shh-deficient mice, the pulmonary vascular bed is decreased, but appropriate to the decrease in airway branching. However, when E12.5 Shh-deficient lungs were cultured for 4-6 days, the vascular network deteriorated compared to wild-type lungs. The expression of vascular endothelial growth factor (Vegf) or its receptor Vegfr2 (KDR/Flk-1) was not different between E12.5-13.5 Shh-deficient and wild-type lungs. In contrast, angiopoietin-1 (Ang1), but not Ang2 or the angiopoietin receptor Tie2, mRNA expression was downregulated in E12.5-E13.5 lungs of Shh null mutants. Recombinant Ang1 alone was unable to restore in vitro branching morphogenesis in Shh-deficient lungs. Conversely, the angiogenic factor fibroblast growth factor (Fgf)-2 alone or in combination with Ang1, increased vascularization and tubular growth and branching of Shh-deficient lungs in vitro. The angiogenic factors did not overcome the reduced smooth muscle cell differentiation in the Shh null lungs. These data indicate that early vascular development, mediated by Vegf/Vegfr2 signaling proceeds normally in Shh-deficient mice, while later vascular development and stabilization of the primitive network mediated by the Ang/Tie2 signaling pathway are defective, resulting in an abnormal vascular network. Stimulation of vascularization with angiogenic factors such as Fgf2 and Ang1 partially restored tubular growth and branching in Shh-deficient lungs, suggesting that vascularization is required for branching morphogenesis.

The effects of indomethacin on angiogenic factors mRNA expression in renal cortex of healthy rats

Indomethacin is a nonsteroidal anti-inflammatory drug used frequently to control chronic or temporary pain. In the kidney, indomethacin decreases medullary and cortical perfusion, resulting in hypoxia. Kidney hypoxia has many effects, including changes in gene expression, and is a strong stimulus for angiogenesis. Other angiogenic factors include vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2), transforming growth factor beta 1 (TGFbeta1), and platelet-derived growth factor (PDGF). Our goal was to examine the influence of indomethacin on mRNA expression of these factors and their selected receptors in the renal cortex of healthy rats. Groups of 8 healthy, male, six-week-old Wistar rats received either indomethacin (5 mg/kg/day) or placebo orally for three months. RNA from renal cortex biopsies was analyzed by real-time polymerase chain reaction to quantify the mRNA levels of each cytokine. We observed significantly higher mRNA levels for VEGF (1.73-fold), FGF-2 (5.6-fold) and TGFbeta receptor III (2.93-fold), PDGF receptor alpha (2.93-fold) and receptor beta (2.91-fold) in rats receiving indomethacin compared to rats given placebo (p < 0.05). Amounts of mRNA for TGFbeta1, PDGF, FGF receptors 1 and 2 and TGFbeta receptor I did not differ between analysed groups. Our data indicates that indomethacin may regulate the expression of potent angiogenic factors VEGF and FGF-2.

Angiogenic proteins are expressed by brain blood vessels in Alzheimer's disease

Data are emerging to support the idea that mediators of angiogenesis are found in the Alzheimer's disease (AD) brain. The objective of this study is to compare the expression of the angiogenic mediators vascular endothelial growth factor (VEGF), angiopoietin, and matrix metalloproteinases (MMPs) in the microcirculation of AD patients and age-matched controls. Our results indicate that angiopoietin-2 and VEGF are expressed by AD- but not control-derived microvessels. AD-derived microvessels also release higher levels of MMP-2 and MMP-9 compared to controls. The data show that despite high levels of MMP-9, assessed by western blot, MMP-9 activity is not detectable in AD microvessels. In this regard we find high levels of the tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in AD, but not control vessels. Furthermore, we explore the ability of thrombin, previously shown to be present in AD microvessels, to affect TIMP expression in cultured brain endothelial cells and find that thrombin causes up regulation of TIMP-1. These data show that angiogenic changes occur in the microcirculation of the AD brain and suggest that if these changes are contributory to disease pathogenesis, targeting the abnormal brain endothelial cell would provide a novel therapeutic approach for the treatment of this disease.

Klippel-Trenaunay syndrome: a multisystem disorder possibly resulting from a pathogenic gene for vascular and tissue overgrowth

Klippel-Trenaunay syndrome is characterized by a triad of varicose veins, cutaneous capillary malformation, and hypertrophy of bone and soft tissue. Appropriate evaluation and treatment of children displaying features of the disease may minimize morbidity. The clinical appearance, etiology, genetics, diagnostics, and treatment of Klippel-Trenaunay syndrome are herein explored.

Evidence for the involvement of p38 MAP kinase in the action of the vascular disrupting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA)

AIMS

DMXAA (AS1404), a small-molecule vascular disrupting agent that has now completed Phase II clinical trial, induces endothelial cell apoptosis, increased vascular permeability and decreased tumour blood flow in vivo. Its action is incompletely understood and we wished to develop an in vitro system to study its effects.

METHODS

Human tumour cell lines developed from aggressive tumours were grown on Matrigel to simulate a tumour microenvironment. Cells were analysed by light microscopy and by gene expression profiling.

RESULTS

Several cell lines formed networks when grown on Matrigel and the NZM7 melanoma cell line was chosen for further study. Addition of DMXAA at a clinically achievable concentration (30 microg/mL) prevented network formation, but co-addition of SB203580 (10 microM), a selective inhibitor of p38 MAP kinase, reversed the effect of DMXAA and restored network formation. Analysis of expression genes for endothelial and related functions showed that cells growing on Matrigel expressed a pattern similar to that of NZM7 cells growing as xenografts in vivo but different from that of cells grown on standard tissue culture plates. Addition of DMXAA resulted in the inhibition of expression of several genes including the transcriptional activator Ets1 and matrix metalloproteinase-2 (MMP2), but co-addition of SB203580 did not reverse these effects of DMXAA on gene expression.

CONCLUSION

The results suggest that p38 MAP kinase plays an important role in the action of DMXAA and that growth of tumour cells on Matrigel provides a promising model for further studies on the action of this drug.