Recruitment Of Endothelial Cells Research Articles

Peritruncal Coronary Endothelial Cells Contribute to Proximal Coronary Artery Stems and Their Aortic Orifices in the Mouse Heart

Avian embryo experiments proved an ingrowth model for the coronary artery connections with the aorta. However, whether a similar mechanism applies to the mammalian heart still remains unclear. Here we analyzed how the main coronary arteries and their orifices form during murine heart development. Apelin (Apln) is expressed in coronary vascular endothelial cells including peritruncal endothelial cells. By immunostaining, however, we did not find Apln expression in endothelial cells of the aorta during the period of coronary vessel development (E10.5 to E15.5). As a result of this unique expression difference, AplnCreERT2/+ genetically labels nascent coronary vessels forming on the heart, but not the aorta endothelium when pulse activated by tamoxifen injection at E10.5. This allowed us to define the temporal contribution of these distinct endothelial cell populations to formation of the murine coronary artery orifice. We found that the peritruncal endothelial cells were recruited to form the coronary artery orifices. These cells penetrate the wall of aorta and take up residence in the aortic sinus of valsalva. In conclusion, main coronary arteries and their orifices form through the recruitment and vascular remodeling of peritruncal endothelial cells in mammalian heart.

Vascular Endothelial Growth Factor-A and Islet Vascularization Are Necessary in Developing, but Not Adult, Pancreatic Islets

Pancreatic islets are highly vascularized mini-organs, and vascular endothelial growth factor (VEGF)-A is a critical factor in the development of islet vascularization. To investigate the role of VEGF-A and endothelial cells (ECs) in adult islets, we used complementary genetic approaches to temporally inactivate VEGF-A in developing mouse pancreatic and islet progenitor cells or in adult β-cells. Inactivation of VEGF-A early in development dramatically reduced pancreatic and islet vascularization, leading to reduced β-cell proliferation in both developing and adult islets and, ultimately, reduced β-cell mass and impaired glucose clearance. When VEGF-A was inactivated in adult β-cells, islet vascularization was reduced twofold. Surprisingly, even after 3 months of reduced islet vascularization, islet architecture and β-cell gene expression, mass, and function were preserved with only a minimal abnormality in glucose clearance. These data show that normal pancreatic VEGF-A expression is critical for the recruitment of ECs and the subsequent stimulation of endocrine cell proliferation during islet development. In contrast, although VEGF-A is required for maintaining the specialized vasculature observed in normal adult islets, adult β-cells can adapt and survive long-term reductions in islet vascularity. These results indicate that VEGF-A and islet vascularization have a lesser role in adult islet function and β-cell mass.

VEGFRS IN NEOPLASTIC ANGIOGENESIS AND PROSPECTS FOR THERAPY ОF BRAIN TUMORS

Glioblastoma (GBM) is the most common type of primary brain cancer that characterized by poor prognosis due to the rapid progression, active angiogenesis, enhanced tumor cell invasion and the emergence of resistance toward conventional therapy. In this connection, nowadays, new approaches for selective inhibition of crucial steps in tumor progression are actively developing. The key feature of tumor growth and development is angiogenesis. VEGF and its receptor VEGFR2 play the pivotal role in regulation of tumor vessel formation. Therefore, VEGFR2, as the main receptor of VEGF's pro-angiogenic signal transducer, is a promising molecular target for anti-angiogenic therapy. There is evidence that inhibitors of VEGF and VEGFR2 reduce endothelial cell proliferation, migration and survival that lead to regression of vessel density and decrease vascular permeability, thereby slowing tumor growth. Currently, a number of VEGFR2 inhibitors are under clinical trials (ramucirumab, cediranib) and several were approved (sunitinib, sorafenib). Despite the promising results of preclinical studies, the efficacy of antiangiogenic drugs in the clinical practice is significantly lower, mainly, due to rapid adaptation of malignant cells that consists of alternative pro-angiogenic pathways activation, recruitment of endothelial progenitor cells from bone marrow and increasing of the invasive growth. Given the diversity of pro-angiogenic mechanisms, enhancement of the efficacy of tumor therapy could be achieved by specific inhibition of VEGFR2 functions that will be supplemented by other antiangiogenic drugs (anti-VEGF,-PIGF,-HIF1alpha). In addition, multitargeting therapy should focus on the combined inhibition of angiogenesis, invasion, metastasis, proliferation and survival of tumor cells.

Abstract A084: TGFβ induces Chordin-like 1 (Chrdl1) expression in ErbB2 expressing breast cancer cells with attenuated ShcA signaling

Abstract Background: In 25 to 30% of human primary breast cancer, the ErbB2 receptor is overexpressed and is associated with poor prognosis. Transgenic mouse models have demonstrated that ErbB2 co-operates with TGFβ signaling pathway to promote the invasive and metastatic behavior of breast cancer cells. By transient knockdown approaches, a role for ShcA in mediating cooperation between the ErbB2 and TGFβ pathways has been established. Furthermore, a stable knockdown of ShcA in NMuMG cells overexpressing oncogenic ErbB2 significantly reduced tumor growth, which was found to be the consequence of reduced proliferation and endothelial cell recruitment coupled with increased apoptosis. Many of the migratory and invasive effects induced by TGFβ are secondary to the induction of a transcriptional program and TGFβ is known to uniquely induce the expression of specific genes in cells overexpressing ErbB2. Given that ShcA is required for TGFβ induced migration and invasion of ErbB2 expressing cells, we hypothesize that the signaling molecules engaged downstream of ShcA will ultimately modulate gene expression induced by TGFβ stimulation. Experimental Approach: To characterize ShcA dependent gene expression changes induced by TGFβ in ErbB2-expressing cells, we generated NMuMG-ErbB2 cells harboring dox-inducible ShcA shRNAs. These cell populations were divided into two groups treated with (ShcAlow) or without (ShcAhigh) Doxycycline, and each group was subjected to three conditions: one was left untreated and the others stimulated for 3 and 24 hours with TGFβ. Using gene expression profiling, we have identified a list of differentially expressed genes that are regulated by TGFβ signaling in the context of acute ShcA loss. Subsequently, we identified genes that have functions associated with migratory and invasive phenotypes. Results: Among the candidates identified by these approaches, Chrdl1, which has been demonstrated to interact with and neutralize several different members of the TGFβ family including BMP4, BMP5, BMP6, TGFβ1 and TGFβ2, displayed elevated transcript levels in ShcAlow cells following TGFβ treatment. ELISA assays reveal that reduced ShcA signaling results in the up-regulation of secreted Chrdl1 protein in ErbB2-expressing cells following TGFβ stimulation. Similar results were also obtained using additional human and mouse breast cancer cell lines. We next determined whether Chrdl1 found in the conditioned media of our NMuMG-ErbB2 ShcAlow cells, is functional. We observed that conditioned media from ShcAlow cells, which was harvested from cells stimulated with TGFβ (high Chrdl1), was able to decrease the activation of Smad1/5/8 following BMP4 stimulation, as measured by immunblot analysis for phospho-Smad1/5/8. Furthermore, immunohistochemical analysis confirmed that Chrdl1 induction, in response to reduced ShcA expression, is also observed in mammary tumors in vivo. Moreover, high levels of Chrdl1 correlated with diminished pSmad2 and pSmad1/5/8 in these tumor lysates. Conclusion: We have identified Chrdl1, a BMP inhibitor, as an interesting candidate that may account for the reduced growth and metastasis that accompany ShcA loss in ErbB2-expressing breast cancer cells. Citation Format: Chanèle Cyr-Depauw, Jason Northey, Zhifeng Dong, Sean Cory, Michael Hallett, Peter M. Siegel. TGFβ induces Chordin-like 1 (Chrdl1) expression in ErbB2 expressing breast cancer cells with attenuated ShcA signaling. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A084.

Dynamic responses of endothelial cells to changes in blood flow during vascular remodeling of the mouse yolk sac

Despite extensive work showing the importance of blood flow in angiogenesis and vessel remodeling, very little is known about how changes in vessel diameter are orchestrated at the cellular level in response to mechanical forces. To define the cellular changes necessary for remodeling, we performed live confocal imaging of cultured mouse embryos during vessel remodeling. Our data revealed that vessel diameter increase occurs via two distinct processes that are dependent on normal blood flow: vessel fusions and directed endothelial cell migrations. Vessel fusions resulted in a rapid change in vessel diameter and were restricted to regions that experience the highest flow near the vitelline artery and vein. Directed cell migrations induced by blood flow resulted in the recruitment of endothelial cells to larger vessels from smaller capillaries and were observed in larger artery segments as they expanded. The dynamic and specific endothelial cell behaviors captured in this study reveal how sensitive endothelial cells are to changes in blood flow and how such responses drive vascular remodeling.

Macrophage Migration Inhibitory Factor (MIF) is associated with higher collateralization grade in patients with coronary chronic total occlusions

Purpose: Chronically total occluded coronary artery (CTO) is often associated with collateral circulation that is only partially supplying to the lack of antegrade blood flow. Therefore, variable degree of residual myocardial ischemia might still be present. The macrophage migration inhibitory factor (MIF), secreted by endothelial cells, has been showed to promote in vitro the recruitment of the endothelial progenitor cells to the ischemic tissues. It is still unknown whether MIF is involved in collateral formation of patients (pts) with CTO. We evaluated the possible correlation of MIF levels with the extent of collateral circulation in pts with CTO. Methods and results: Blood collection for MIF evaluation was performed in 32 consecutive patients (n=32) undergoing to percutaneous coronary intervention (PCI) of CTO at three different sites: a) Femoral arterial sheath (ART); 2) Tip of the guiding catheter proximal to CTO (PROX); 3) Tip of the microcatheter distal to CTO (DIST) after the occlusion was crossed, but not yet dilated. MIF was also assessed at ART and PROX level in 10 patients with normal coronary arteries, class ≤ 2 identified pts with Low Collateralization Grade (LCG; n=19), Rentrop class 3 identified pts with High Collateralization Grade (HCG; n=13). MIF was analyzed with a commercially available ELISA kit. Within CTO pts, a significant MIF increase was found across the 3 sampling sites (ART: 20.9±7.4 vs. PROX: 28.0±18.8 vs. DIST 39.4±20.6 ng/ml, p<0.01). MIF was significantly higher at DIST level in HCG as compared with LCG pts (45.2±23.9 vs. 35.5±17.6 ng/ml, p=0.05), while no difference was found at PROX (26.5±9.1 vs. 28.9±21.7 ng/ml, p=0.41) or ART level (18.7±5.2 vs. 22.3±8.4 ng/ml, p=0.42). Within CTRL pts, MIF was not significantly increased at the 2 sampling sites (ART: 18.7±7.4 vs. PROX: 15.6±5.3, p=0.10). Compared with CTRL pts, MIF was found significantly elevated in CTO pts at PROX (p=0.05), but not at ART (p<0.55) level. Conclusions: Higher MIF levels are found downstream to the arterial occlusion. This along with lower levels found proximal to the occlusion and at peripheral level suggest a loco-regional MIF production. In addition, the higher the MIF levels the higher the collateralization grade.

Lung Macrophages Contribute to House Dust Mite Driven Airway Remodeling via HIF-1α

HIF-1α is a transcription factor that is activated during hypoxia and inflammation and is a key regulator of angiogenesis in vivo. During the development of asthma, peribronchial angiogenesis is induced in response to aeroallergens and is thought to be an important feature of sustained chronic allergic inflammation. Recently, elevated HIF-1α levels have been demonstrated in both the lung tissue and bronchoalveolar lavage of allergic patients, respectively. Therefore, we investigated the role of HIF-1α on the development of angiogenesis and inflammation following acute and chronic allergen exposure. Our data shows that intranasal exposure to house dust mite (HDM) increases the expression of HIF-1α in the lung, whilst reducing the expression of the HIF-1α negative regulators, PHD1 and PHD3. Blockade of HIF-1α in vivo, significantly decreased allergic inflammation and eosinophilia induced by allergen, due to a reduction in the levels of IL-5 and Eotaxin-2. Importantly, HIF-1α blockade significantly decreased levels of VEGF-A and CXCL1 in the lungs, which in turn led to a profound decrease in the recruitment of endothelial progenitor cells and a reduction of peribronchial angiogenesis. Furthermore, HDM or IL-4 treatment of primary lung macrophages resulted in significant production of both VEGF-A and CXCL1; inhibition of HIF-1α activity abrogated the production of these factors via an up-regulation of PHD1 and PHD3. These findings suggest that novel strategies to reduce the expression and activation of HIF-1α in lung macrophages may be used to attenuate allergen-induced airway inflammation and angiogenesis through the modulation of VEGF-A and CXCL1 expression.Clinical RelevanceThis study provides new insights into the role of HIF-1α in the development of peribronchial angiogenesis and inflammation in a murine model of allergic airway disease. These findings indicate that strategies to reduce activation of macrophage derived HIF-1α may be used as a target to improve asthma pathology.

Renal cell carcinoma-adjacent tissues enhance mobilization and recruitment of endothelial progenitor cells to promote the invasion of the neoplasm

AimsThe aim of this study was to detect the levels of CD34+/Flk-1+ endothelial progenitor cells (EPCs) in renal cell carcinoma (RCC)-adjacent tissues and explore the correlation of RCC-adjacent tissues EPCs and tumor invasion. MethodsAn orthotopic renal tumor model was successfully established. At days 7, 12, 17 and 21, eight mice were put to death respectively. Tumor diameters were measured and RCC-adjacent tissues were collected. The percentage of EPCs within the kidney mononuclear cell population was detected. The expression levels of Stromal cell-derived factor-1 (SDF-1), vascular endothelial growth factor (VEGF) and their receptors CXCR4, Flk-1 mRNA and protein were probed respectively. And then, mean microvascular density (MVD) was examined. ResultsEPC numbers in RCC-adjacent tissues were significantly higher than those in control groups. The ratios of EPCs were increased gradually, and so were tumor diameters. The levels of SDF-1 and VEGF were also increased gradually, but significantly reduced compared with control group at each time point. In addition, CXCR4 and Flk-1 expression were decreased gradually. ConclusionsOur investigation suggested that EPCs in RCC-adjacent tissues play an important role in early stage RCC invasion, involving the promotion on angiogenesis through releasing several angiogenic factors.

Evidence That CXCL16 Is a Potent Mediator of Angiogenesis and Is Involved in Endothelial Progenitor Cell Chemotaxis: Studies in Mice With K/BxN Serum–Induced Arthritis

To examine the possibility that CXCL16 recruits endothelial cells (ECs) to developing neovasculature in rheumatoid arthritis (RA) synovium. We utilized the RA synovial tissue SCID mouse chimera system to examine human microvascular EC (HMVEC) and human endothelial progenitor cell (EPC) recruitment into engrafted human synovium that was injected intragraft with CXCL16-immunodepleted RA synovial fluid (SF). CXCR6-deficient and wild-type (WT) C57BL/6 mice were primed to develop K/BxN serum-induced arthritis and evaluated for angiogenesis. HMVECs and EPCs from human cord blood were also examined for CXCR6 expression, by immunofluorescence and assessment of CXCL16 signaling activity. CXCR6 was prominently expressed on human EPCs and HMVECs, and its expression on HMVECs could be up-regulated by interleukin-1β. SCID mice injected with CXCL16-depleted RA SF exhibited a significant reduction in EPC recruitment. In experiments using the K/BxN serum-induced inflammatory arthritis model, CXCR6(-/-) mice showed profound reductions in hemoglobin levels, which correlated with reductions in monocyte and T cell recruitment to arthritic joint tissue compared to that observed in WT mice. Additionally, HMVECs and EPCs responded to CXCL16 stimulation, but exhibited unique signal transduction pathways and homing properties. These results indicate that CXCL16 and its receptor CXCR6 may be a central ligand/receptor pair that is closely associated with EPC recruitment and blood vessel formation in the RA joint.

AB0147 Oxidative stress and flogosis: The role of endothelial progenitor cells in rheumathoid arthtritis

BackgroundPatients affected by Rheumathoid arthtritis (RA) present accelerated atherosclerosis and increased cardiovascular morbidity and mortality, with respect to the general population. In RA an impairment of the number and the...

Reciprocal epithelial:endothelial paracrine interactions during thyroid development govern follicular organization and C-cells differentiation

The thyroid is a highly vascularized endocrine gland, displaying a characteristic epithelial organization in closed spheres, called follicles. Here we investigate how endothelial cells are recruited into the developing thyroid and if they control glandular organization as well as thyrocytes and C-cells differentiation. We show that endothelial cells closely surround, and then invade the expanding thyroid epithelial cell mass to become closely associated with nascent polarized follicles. This close and sustained endothelial:epithelial interaction depends on epithelial production of the angiogenic factor, Vascular Endothelial Growth Factor-A (VEGF-A), as its thyroid-specific genetic inactivation reduced the endothelial cell pool of the thyroid by >90%. Vegfa KO also displayed decreased C-cells differentiation and impaired organization of the epithelial cell mass into follicles. We developed an ex vivo model of thyroid explants that faithfully mimicks bilobation of the thyroid anlagen, endothelial and C-cells invasion, folliculogenesis and differentiation. Treatment of thyroid explants at e12.5 with a VEGFR2 inhibitor ablated the endothelial pool and reproduced ex vivo folliculogenesis defects observed in conditional Vegfa KO. In the absence of any blood supply, rescue by embryonic endothelial progenitor cells restored folliculogenesis, accelerated lumen expansion and stimulated calcitonin expression by C-cells. In conclusion, our data demonstrate that, in developing mouse thyroid, epithelial production of VEGF-A is necessary for endothelial cells recruitment and expansion. In turn, endothelial cells control epithelial reorganization in follicles and C-cells differentiation.

VEGF in Tumor Progression and Targeted Therapy

Progression of solid tumors depends on vascularization and angiogenesis in a malignant tissue. Among a whole range of proangiogenic factors, a vascular endothelial growth factor A (VEGF-A) plays a key role. Blockade of VEGF may lead to regression of vascular network and inhibition of a tumor growth. In the present time, bevacizumab has been introduced into wide clinical practice in therapy of breast cancer, colorectal cancer and recurrent high-grade gliomas (HGGs). Coadministration of antiangiogenic therapy with irinotecan may increase probability of the response to the treatment and prolong progression-free survival rate (PFS). Moreover, bevacizumab is well tolerated and significantly improves patient's quality of life. However, in the case of brain tumors, the efficiency of such an approach is controversial. The antiangiogenic therapy can slightly delay tumor growth and does not lead to complete recovery. In addition, it contributes to enhanced tumor cell invasion into the normal brain. The mechanisms of resistance include activation of alternative proangiogenic signaling pathways, of an invasive population of tumor cells, metabolic change toward glycolysis and recruitment of myeloid bone marrow-derived cells to tumors. Obviously, that anti-VEGF therapy as monotherapy was not effective against HGGs. To enhance the antitumor treatment efficacy, it is necessary to develop a multi-target strategy to inhibit critical processes in malignancy progression such as angiogenesis, invasion, autophagy, metastatic spread, recruitment of bone marrow-derived endothelial cells and tumor stem-like cells. In addition, anti-VEGF antibodies have shown a promising result as a tumor-targeting vector for delivery therapeutic and diagnostic drugs in brain tumors.

Activation of plasma kallikrein‐kinin system mediates synovial recruitment of endothelial progenitor cells in arthritis

OBJECTIVEThis study aimed at determining whether activation of the plasma kallikrein‐kinin system (KKS) mediates synovial recruitment of endothelial progenitor cells (EPCs) in arthritis.METHODSEPCs were isolated from Lewis rat bone marrow, and expression of progenitor cell‐lineage markers and functional properties were characterized. EPCs were injected intravenously into Lewis rats with arthritis, and their recruitment and formation of de novo blood vessels in inflamed synovium were evaluated. The role of plasma KKS was examined using plasma kallikrein inhibitors. A transendothelial migration assay was used to determine the role of bradykinin and its receptor in EPC mobilization.RESULTSEPCs from Lewis rats exhibited a strong capacity to form tubes and vacuoles and expressed increased levels of bradykinin type 2 receptor (B2R) and progenitor cell markers CD34 and Sca‐1. In Lewis rats with arthritis, EPCs were recruited into inflamed synovium at the acute phase of disease and formed de novo blood vessels. Inhibition of plasma kallikrein significantly suppressed synovial recruitment of EPCs and hyperproliferation of synovial cells. Bradykinin stimulated transendothelial migration of EPCs in a concentration‐dependent manner. This was mediated by B2R, as demonstrated by the finding that knockdown of B2R with silencing RNA completely blocked bradykinin‐stimulated transendothelial migration. Moreover, bradykinin selectively up‐regulated expression of the homing receptor CXCR4 in EPCs.CONCLUSIONThese observations demonstrate a novel role of plasma KKS activation in the synovial recruitment of EPCs in arthritis, acting via kallikrein activation and B2R‐dependent mechanisms. B2R might be involved in the mobilization of EPCs via up‐regulation of CXCR4.

1137 FGF2-MEDIATED RECIPROCAL TUMOR CELL-ENDOTHELIAL CELL INTERPLAY CONTRIBUTES TO THE GROWTH OF CHEMO-RESISTANT BLADDER CANCER CELLS

You have accessJournal of UrologyBladder Cancer: Basic Research (III)1 Apr 20131137 FGF2-MEDIATED RECIPROCAL TUMOR CELL-ENDOTHELIAL CELL INTERPLAY CONTRIBUTES TO THE GROWTH OF CHEMO-RESISTANT BLADDER CANCER CELLS Yule Chen, Kaijie Wu, Jin Zeng, Lei Li, and Dalin He Yule ChenYule Chen Xi'an, China, People's Republic of More articles by this author , Kaijie WuKaijie Wu Xi'an, China, People's Republic of More articles by this author , Jin ZengJin Zeng Xi'an, China, People's Republic of More articles by this author , Lei LiLei Li Xi'an, China, People's Republic of More articles by this author , and Dalin HeDalin He Xi'an, China, People's Republic of More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.752AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Chemo-resistance is of outstanding importance for the limited results of chemotherapy in bladder cancer, because chemo-resistant cancer cells probably provide the main sources of recurrent tumors. However, the mechanisms by which these chemo-resistant cells develop into recurrent tumors remain unclear. It has been recently reported that the proangiogenic factor FGF2, a molecule associated with the recruitment of endothelial cells, was identified as an independent prognostic factor for bladder cancer recurrence after chemotherapy. Here, we explored the mechanisms of chemo-resistant cells mediated bladder cancer recurrence, focusing on FGF2-associated endothelial cell recruitment mediated by drug-resistant bladder cancer cells as well as the possible effect of tumor cell-endothelial cell interaction on chemo-resistant cancer cell growth. METHODS A novel multidrug resistant subline (253J/DOX) of human bladder cancer 253J cell line was generated by culturing these cells in gradually increasing doses of doxorubicin (DOX) for 12 months. The chemo-resistant phenotype was identified. The expression levels of P-glycoprotein and FGF2 and the interaction between chemo-resistant tumor cells and endothelial cells was assessed. RESULTS As compared with parental 253J cells, 253J/DOX cells expressed higher level of the drug transporter P-glycoprotein, accompanied with significant resistance to doxorubicin, pirarubicin and vincristine. Downregulation of P-glycoprotein expression by specific siRNA reversed this multidrug resistant phenotype. In 253J/DOX cells, the expression and secretion levels of FGF2 were both markedly increased. The conditioned medium of 253J/DOX cells recruited abundant endothelial cells and promoted endothelial cell proliferation and tube formation potential, which was blocked by FGF2 neutralizing antibody. Furthermore, co-culture with endothelial cells or conditioned medium of endothelial cells significantly enhanced the proliferative capacity of 253J/DOX cells. CONCLUSIONS Our findings provided the first evidences that FGF2-mediated tumor cell-endothelial cell interplay facilitated the growth of chemo-resistant bladder cancer, which may possibly contribute to bladder cancer recurrence after chemotherapy. On one hand, the residual chemo-resistant cells after chemotherapy can recruit endothelial cells by secreting proangiogenic factors, while on the other hand the recruited endothelial cells may promote residual cancer cell growth. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e464 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Yule Chen Xi'an, China, People's Republic of More articles by this author Kaijie Wu Xi'an, China, People's Republic of More articles by this author Jin Zeng Xi'an, China, People's Republic of More articles by this author Lei Li Xi'an, China, People's Republic of More articles by this author Dalin He Xi'an, China, People's Republic of More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Recruitment of human cord blood-derived endothelial colony-forming cells to sites of tumor angiogenesis

Background aimsEndothelial progenitor cells (EPCs) specifically home to sites of malignant growth, rendering them attractive for anti-cancer therapies. Data are conflicting on the phenotype and quantitative contribution toward tumor angiogenesis based on differing culture assays to outgrow EPCs. To evaluate the origin and early phenotype of EPCs and to define a population with enhanced tumor-targeting capacity, we evaluated a hierarchy of cord blood-derived EPCs modeling the multi-step nature of tumor homing. MethodsCD34+ mononuclear cells were isolated from fresh cord blood and cultured to derive endothelial colony-forming cells (ECFCs). Human umbilical vein endothelial cells (HUVECs) served as control. Using intra-vital microscopy, the recruitment was analyzed in mice bearing C6 xenografts. Adhesion, migration, transmigration and differentiation were further addressed. ResultsWithin the primary passage, ECFCs underwent a rapid maturation from a CD45+ and CD31+ phenotype to a CD45− and endothelial marker positive phenotype. Assessing in vivo tumor recruitment, ECFCs had the highest activity in all steps analyzed. In vitro, ECFCs demonstrated significantly higher adhesion under static and flow conditions. Similarly, ECFCs exhibited highest migratory and trans-migratory activity toward tumor-conditioned medium. On subcutaneous implantation, only ECFCs formed blood vessels covered with perivascular cells, similar to HUVECs. ConclusionsOur study indicates that ECFCs emerge from a CD45+ and CD31+ progenitor and rapidly mature in culture. ECFCs have a significantly higher potential for tumor targeting than non-cultured CD34+ cells and HUVECs. They are ideal candidates for future cell-based anti-cancer therapies.

Effects of Ischemic Preconditioning in the Late Phase on Homing of Endothelial Progenitor Cells in Renal Ischemia/Reperfusion Injury

ObjectiveThe aim of this study was to determine whether the mobilization and recruitment of endothelial progenitor cells (EPCs) contribute to the protection of kidneys from ischemia/reperfusion (I/R) injury after ischemic preconditioning (IPC) during the late phase. MethodsSeventy-five male Sprague-Dawley rats were divided into the following groups: sham-operated (group A; n = 25), ischemia/reperfusion hosts that underwent 45 minutes of left renal artery ischemia (group B; n = 25), and ischemic preconditioning-treated group (group C; n = 25). Group C underwent 3 cycles of 5 minutes of occlusion and 5 minutes of reperfusion followed by 24 hours of reperfusion before the following 45 minutes of occlusion. Serum samples were collected and renal tissues harvested for histological examination terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, immunohistochemical staining, and Western blot analysis to determine the expression levels of CD34, VEGFR-2 (Vascular Endothelial Growth Factor Receptor 2)/flk-1, vascular endothelial growth factor (VEGF), and stromal cell–derived factor-1α (SDF-1α). ResultsCompared with group B, the levels of blood urea nitrogen (BUN), serum creatinine (Scr) and acute tubulointerstitial injury at 24 hours after operation were significantly reduced in group C. At 72 hours, tubular epithelial cell apoptosis was also decreased (17.6 ± 4.45 vs 63.8 ± 6.10; P < .01). CD34+ and flk-1+ cells that mostly accumulated in the medullopapillary parenchyma were significantly increased at 72 hours (P < .05). Expression levels of VEGF and SDF-1α were also significantly higher in group C (P < .05). ConclusionThe present work suggested that IPC protected kidneys from IR injury in the later phase through enhanced mobilization and recruitment of EPCs. VEGF and SDF-1α may play important roles in this protective effect.

Animal models for anti-angiogenic therapy in endometriosis

Endometriosis is a gynecological disease characterized by the growth of endometrium outside of the uterine cavity. It is often associated with dysmenorrhea, dyspareunia, pelvic pain and infertility. One of the key requirements for endometriotic lesions to survive is development of a blood supply to support their growth. Indeed, dense vascularization is characteristic feature of endometriotic lesions. This has led to the idea that suppression of blood vessel growth (anti-angiogenic therapy) may be a successful therapeutic approach for endometriosis. Potential effectiveness of anti-angiogenic therapies has been assessed in some animal models but there are no reports of human clinical trials. Without understanding the specific mechanism by which endometriosis lesions establish a new blood supply, short-term animal experiments will have limited value for translation into human medicine. Further, it is crucial to use appropriate animal models to assess efficacy of anti-angiogenic compounds. Syngeneic and autologous rodent models, where endometrial fragments are auto-transplanted into the peritoneal cavity are commonly used in anti-angiogenic therapy studies. Another approach is xenograft models where human endometrium is engrafted into immunodeficient mice. Here we review the animal models and experimental techniques used to evaluate anti-angiogenic therapies for endometriosis. We also review our own work on the role of stromal cell derived factor-1 in the recruitment of endothelial progenitor cells in endometriotic lesion angiogenesis, and the effects of the anti-angiogenic peptide ABT-898, a thrombospondin-1 mimetic, on endometriotic lesion growth and vascular development.

Strategies and Techniques to Enhance theIn SituEndothelialization of Small-Diameter Biodegradable Polymeric Vascular Grafts

Due to the lack of success in small-diameter (<6 mm) prosthetic vascular grafts, a variety of strategies have evolved utilizing a tissue-engineering approach. Much of this work has focused on enhancing the endothelialization of these grafts. A healthy, confluent endothelial layer provides dynamic control over homeo-stasis, influencing and preventing thrombosis and smooth muscle cell proliferation that can lead to intimal hyperplasia. Strategies to improve endothelialization of biodegradable polymeric grafts have encompassed both chemical and physical modifications to graft surfaces, many focusing on the recruitment of endothelial and endothelial progenitor cells. This review aims to provide a compilation of current and developing strategies that utilize in situ endothelialization to improve vascular graft outcomes, providing a context for the future directions of vascular tissue-engineering strategies that do not require preprocedural cell seeding.

Distinct Phosphotyrosine-dependent Functions of the ShcA Adaptor Protein Are Required for Transforming Growth Factor β (TGFβ)-induced Breast Cancer Cell Migration, Invasion, and Metastasis

The ErbB2 and TGFβ signaling pathways cooperate to promote the migratory, invasive, and metastatic behavior of breast cancer cells. We previously demonstrated that ShcA is necessary for these synergistic interactions. Through a structure/function approach, we now show that the phosphotyrosine-binding, but not the Src homology 2, domain of ShcA is required for TGFβ-induced migration and invasion of ErbB2-expressing breast cancer cells. We further demonstrate that the tyrosine phosphorylation sites within ShcA (Tyr(239)/Tyr(240) and Tyr(313)) transduce distinct and non-redundant signals that promote these TGFβ-mediated effects. We demonstrate that Grb2 is required specifically downstream of Tyr(313), whereas the Tyr(239)/Tyr(240) phosphorylation sites require the Crk adaptor proteins to augment TGFβ-induced migration and invasion. Furthermore, ShcA Tyr(313) phosphorylation enhances tumor cell survival, and ShcA Tyr(239)/Tyr(240) signaling promotes endothelial cell recruitment into ErbB2-expressing breast tumors in vivo, whereas all three ShcA tyrosine residues are required for efficient breast cancer metastasis to the lungs. Our data uncover a novel ShcA-dependent signaling axis downstream of TGFβ and ErbB2 that requires both the Grb2 and Crk adaptor proteins to increase the migratory and invasive properties of breast cancer cells. In addition, signaling downstream of specific ShcA tyrosine residues facilitates the survival, vascularization, and metastatic spread of breast tumors.

Topically Delivered Adipose Derived Stem Cells Show an Activated-Fibroblast Phenotype and Enhance Granulation Tissue Formation in Skin Wounds

Multipotent mesenchymal stem cells (MSCs) are found in various tissues and can proliferate extensively in vitro. MSCs have been used in preclinical animal studies and clinical trials in many fields. Adipose derived stem cells (ASCs) have several advantages compared to other MSCs for use in cell-based treatments because they are easy to isolate with relative abundance. However, quantitative approaches for wound repair using ASCs have been limited because of lack of animal models which allow for quantification. Here, we addressed the effect of topically delivered ASCs in wound repair by quantitative analysis using the rabbit ear model. We characterized rabbit ASCs, and analyzed their multipotency in comparison to bone marrow derived-MSCs (BM-MSCs) and dermal fibroblasts (DFs) in vitro. Topically delivered ASCs increased granulation tissue formation in wounds when compared to saline controls, whereas BM-MSCs or DFs did not. These studies suggest that ASCs and BM-MSCs are not identical, though they have similar surface markers. We found that topically delivered ASCs are engrafted and proliferate in the wounds. We showed that transplanted ASCs exhibited activated fibroblast phenotype, increased endothelial cell recruitment, and enhanced macrophage recruitment in vivo.