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(Circulation. 2001;103:423.)
© 2001 American Heart Association, Inc.

Basic Science Reports

Estradiol Accelerates Reendothelialization in Mouse Carotid Artery Through Estrogen Receptor- but Not Estrogen Receptor-ß

L. Brouchet, MD; A. Krust, PhD; S. Dupont, PhD; P. Chambon, PhD; F. Bayard, MD, PhD; J. F. Arnal, MD, PhD

From INSERM U397, Institut L. Bugnard, CHU Rangueil, Toulouse (L.B., F.B., J.F.A.), and Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, Illkirch, CU de Strasbourg (A.K., S.D., P.C.), France.

Correspondence to J.F. Arnal, INSERM U397, Institut L. Bugnard, CHU Rangueil, 31403 Toulouse, France. E-mail arnal{at}rangueil.inserm.fr

	Abstract

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Background—The atheroprotective effect of 17ß-estradiol (E₂) has been suggested in women and clearly demonstrated in animals through both an effect on lipid metabolism and a direct effect on the cells of the arterial wall. It has been shown, for example, that E₂ promotes endothelium-dependent relaxation and accelerates reendothelialization in rats. Similar studies have been undertaken in mice to appreciate the molecular mechanism of this process.

Methods and Results—We report here a model of electric carotid injury adapted from that described by Carmeliet et al (1997) that allows us to precisely evaluate the reendothelialization process. We demonstrate that E₂ accelerates endothelial regeneration in castrated female wild-type mice. In ovariectomized transgenic mice in which either the estrogen receptor (ER)- or ERß gene has been disrupted, E₂ accelerated reendothelialization in female ERß knockout mice, whereas this effect was abolished in female ER knockout mice.

Conclusions—This study demonstrates that ER but not ERß mediates the beneficial effect of E₂ on reendothelialization and potentially the prevention of atherosclerosis.

Key Words: hormones • receptors • arteries • endothelium

	Introduction

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Epidemiological and observational studies^{1 2} support a vasculoprotective effect of estrogens. This is traditionally thought to be due to potentially favorable changes in blood lipids and lipoproteins,³ but a number of experimental studies^{4 5 6 7 8 9} strongly suggest a direct effect on the vascular system. Among the cell types present in the normal and atherosclerotic vessel wall, endothelium represents both a key actor in the pathophysiology of atherosclerosis and an important target for 17ß-estradiol (E₂).

Twenty years of intensive experimental work has confirmed the crucial role of endothelium in the physiology of circulation. The endothelium is uniquely positioned at the interface between the blood and the vessel wall. As such, it performs multiple functions: it is involved in the regulation of coagulation, leukocyte adhesion in inflammation, vessel tone, and vascular smooth muscle growth and also acts as a barrier to transvascular flux of liquids and solutes. In addition, endothelial abnormalities appear to be central to the pathogenesis of atherosclerosis.^{10 11} The importance of endothelial integrity was initially demonstrated by the facilitation of atherosclerotic lesion development in hypercholesterolemic animal models after removal of endothelium. Although subsequent studies demonstrated the presence of endothelium overlying the lesions, repeated mechanical, hemodynamic, and/or immunological injury probably contributes to morphological and functional alterations of the endothelium as well as its senescence. Telomere length is decreased in cells of the arterial tree subject to hemodynamic stress and prone to atherosclerosis, demonstrating an accelerated cell turnover at these sites.¹² Recent experimental work has demonstrated that low shear stress, which in some respects mimics turbulent blood flow, favors apoptosis of cultured endothelial cells.^{13 14} Altogether, these observations suggest that the capacity of endothelium to maintain a cell monolayer could be of crucial importance in the prevention of atherosclerosis and its complications.

Several models of arterial injury have been developed to study endothelial regrowth. Injury of an artery by passage of a balloon catheter causes endothelial denudation and medial damage and produces both an endothelial and a smooth muscle cell proliferative response in nonhuman primates, swine, dogs, rabbits, and rats.¹⁵ In such models, E₂ was reported to promote endothelial regrowth in castrated female rats.¹⁶ The effect of E₂ has long been thought to be mediated through activation of the estrogen receptor (ER)-. ER is a ligand-dependent transcriptional activator¹⁷ that modulates gene expression in target cells not only in reproductive tissues but also in bone and vessels.^{18 19} Moreover, ERß, recently discovered and cloned from rat prostate,²⁰ was found to be expressed in many other tissues, including injured arteries.^{21 22}

Evaluation of the respective roles of ER and ERß in the reendothelialization process requires a reliable model of mouse arterial injury in which the extent of endothelial regrowth can be quantified. Removal of the endothelium in the mouse carotid artery with a flexible wire was described in 1993²³ and allowed the arterial smooth muscle proliferation and/or neointima formation in various transgenic mice to be evaluated. This model of endovascular carotid injury suggested that ER was not involved in one aspect of the protective effect of E₂, ie, the prevention of medial smooth muscle proliferation.²⁴ However, the specific evaluation of arterial reendothelialization appears to be difficult with this technique.²³ Recently, Carmeliet et al²⁵ described a novel model of electric injury to the mouse femoral artery that consisted of destroying endothelial, smooth muscle, and adventitial cells and allowing subsequent quantification of both arterial neointima formation and reendothelialization.²⁵ We have adapted this model of electric arterial injury to allow the precise study of arterial reendothelialization and to determine which ER subtype was involved in this process. Our results indicate that the beneficial effect of estrogen on reendothelialization is mediated by ER in female mice.

	Methods

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Animals
All procedures involving experimental animals were performed in accordance with the recommendations of the French Accreditation of Laboratory Animal Care. They were housed in stainless steel cages in groups of 5, kept in a temperature-controlled facility on a 12-hour light-dark cycle, and fed normal laboratory mouse chow diet.

Targeted disruption (knockout) of mouse ER and ERß genes was generated by homologous recombination, resulting in ER- and ERß-null mice.^25A Six backcrosses with C57Bl/6 mice were performed.

For all surgical procedures, mice were anesthetized by injection of 150 mg/kg ketamine IP and allowed to recover on a 37°C heat pack. Mice were ovariectomized at 4 weeks of age and given either 60-day time-release E₂ pellets (0.1 mg E₂, Innovative Research of America, ie, releasing 80 µg · kg^-1 · d^-1) or placebo-containing pellets implanted subcutaneously into the backs of the animals with a sterile trochar. Electric carotid artery injury was performed 2 weeks later, ie, in 6-week-old mice. Three days after injury, the animals were killed and the vessels harvested.

Electric Injury Model
We adapted the electric injury model described by Carmeliet et al²⁵ on the femoral artery to the common carotid artery, the latter being easier to dissect. Surgery was carried out with a dissection microscope (Nikon SMZ-2B) in 6-week-old female mice weighing 20 g on average. Because the proximal part of the carotid artery is intrathoracic, the injury could not be applied to the whole common carotid artery. The left common carotid artery was exposed via an anterior incision of the neck. The electric injury (in fact primarily thermal) was applied to the distal part of the common carotid artery. The carotid artery was injured by electric current with a bipolar microregulator. To standardize the temperature increase in the vessel wall, we used forceps with large tips (1 mm) instead of microsurgical forceps (200 µm) and a bipolar microregulator Force FX (Valleylab). The "precise" mode of this apparatus allowed delivery of electric energy within a narrow range of resistance, because the generator microprocessor disrupted the electric current when the resistance increased as a consequence of temperature increase. This allowed the increase in tissue temperature to be controlled and avoided the risk of desiccation and coagulation of the arterial wall. The optimal conditions were determined as follows: electric current of 2 W applied for 2 seconds to each millimeter of carotid artery over a total length of 4 mm with the help of a size marker placed parallel to the long axis of the carotid. Despite optimization of the technique, coagulation and thrombosis of the carotid artery occurred in 10% of the cases, which were then excluded from the study.

One to 7 days later, the endothelial regeneration process was evaluated by staining the denuded areas with Evans blue dye as previously described.²³ Briefly, 50 µL of solution containing 5% Evans blue diluted in saline was injected into the tail vein with a 30-gauge needle 10 minutes before euthanization, followed by fixation with a perfusion of 4% phosphate-buffered formalin (pH 7.0) for 5 minutes. Blood, saline, and fixative were removed through an incision in the right atrium. The left common carotid artery was dissected with an adjacent portion of the aortic arch and carotid bifurcation. The artery was then opened longitudinally and placed between slides with Fluoprep. After transparency scanning and numeration, the total and stained carotid artery areas were planimetered with an image analyzer (VISIOL@b2000). The ratio between the area stained in blue and the total carotid artery area was calculated. The surface of the area that remained deendothelialized was indexed to the total carotid artery area to take into account the changes in vessel area due to both the elasticity of the carotid artery and the flattening of the vessel between slides. The coefficients of variation of the endothelial regrowth were 2.6%, 4.5%, and 13.5% at days 1, 3, and 5, respectively (Figure 1C).

View larger version (21K): [in this window] [in a new window]   Figure 1. A, Drawing representing left common carotid artery of C57Bl/6 mouse 3 days after electric injury, with aortic arch (bottom) and bifurcation (top). Blue area corresponds to deendothelialized area (DA), and orange rectangle corresponds to total area (TA) of common carotid artery. B, Time course of endothelial regeneration. Representative photograph showing carotid area remaining deendothelialized (area stained in blue) at days 1, 3, 5, and 7 after electric injury. Complete reendothelialization was observed on day 7. C, Ratio of remaining DA to TA of carotid artery was calculated for each day. Data are mean±SEM from n=4 mice for each point.

Histology and Scanning Electron Microscopy
Arteries were also embedded in paraffin, and sections perpendicular to the long axis of the carotid were cut from the proximal, middle, and distal thirds of the injured carotid artery. Sections were subjected to standard hematoxylin and eosin staining.

To verify that the area stained with Evans blue corresponded to the deendothelialized area and that the unstained area corresponded to the reendothelialized area, 3 animals were killed 3 days after the electric injury procedure. Perfusion fixation was carried out as described above with phosphate-buffered 4% paraformaldehyde in vivo. The vessels were cut open longitudinally, pinned flat on a silicone-coated dish, and photographed. The vessels were then further fixed with 2% glutaraldehyde for 24 hours, rinsed with PBS, incubated with 2% osmium tetroxide, and then dehydrated through a series of ethanol dilutions. The tissue was dried to critical point and mounted on scanning electron microscopy stubs with colloidal silver paste. After having been sputter-coated with gold/palladium, the specimens were examined with a scanning electron microscope.

Serum Hormone Concentrations
Radioimmunoassay kits for E₂ were used according to the manufacturer’s instructions (Sorin Biomedica). Hormone levels could not be measured in the same mice that were injected with Evans blue because it interfered with the assay. Thus, additional groups of mice were ovariectomized at 4 weeks of age, given either E₂- or placebo-containing pellets as described above, and killed 17 days later. Hormone levels were assayed for each individual mouse in a similar series of assays. The intra-assay coefficient of variability was 4.5%. The assay sensitivity, defined as 15% displacement of labeled tracer, was 0.5 pg E₂.

Statistics
Results are expressed as mean±SEM. To test the respective roles of E₂ treatment and of genotype on reendothelialization, a 2-factor ANOVA was performed (comparison of the 6 groups) in ER and in ERß mice. When an interaction was observed between the 2 factors, the effect of E₂ treatment was studied in each genotype with a t test. A value of P<0.05 was considered statistically significant.

	Results

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Generation of the ER and ERß Mutant Mice
Heterozygous ER- and ERß-null mice, originally generated as C57Bl/6Jx129 hybrids, were crossbred into the C57Bl/6 background to generate the heterozygous ER^+/- and ERß^+/- lines, which constituted the population that served as the parental genotypes for all animals in the studies. The offspring of the parental ER^+/- strain were ER^+/+, ER^+/-, and ER^-/-, and those of the parental ERß^+/- strain were ERß^+/+, ERß^+/-, and ERß^-/- littermates, respectively, which served as the subjects of our studies.

Description of the Model of Carotid Artery Injury
We first determined the time course of endothelial regeneration (days 1, 3, 5, and 7 after injury) in 6-week-old female C57Bl/6 mice. As shown in Figure 1, 50% of the endothelial regeneration was observed on days 3 and 4, and complete reendothelialization was observed on day 7. We chose to study reendothelialization on day 3 to evaluate the effect of E₂. To further ensure that the area stained with Evans blue dye corresponded to a deendothelialized area, electron scanning microscopy studies were performed. These confirmed that the area stained colocalized with an area of endothelial cell denudation and a monolayer of aggregated platelets. A front of migrating endothelial cells was observed at the edges of the lesion (Figure 2A, 2B, and 2C).

View larger version (78K): [in this window] [in a new window]   Figure 2. A, Common carotid artery opened longitudinally after blue staining 3 days after electric injury. Electron scanning microscopy of same vessel at a low (B, x74) or a high (C, x860) magnification. Note that deendothelialized area (C, left) is covered with a monolayer of aggregated platelets.

Paraffin sections (day 2) with standard staining (hematoxylin/eosin and Masson’s trichrome) also demonstrated the absence of endothelial cells (or rare pyknotic nuclei), the absence of smooth muscle cells in the media (or only necrotic fragments), and infiltration of the adventitia by inflammatory cells (Figure 3a and 3b). Verhoeff staining for elastic lamina revealed that only the most internal lamina was in some cases ruptured (not shown). At day 15, ad integrum restoration of the intima and of the media was observed (Figure 3c and 3d). However, no neointimal hyperplasia was observed after electric injury of the carotid, even on day 30 (Figure 3e and 3ff). Adventitia was still infiltrated by inflammatory cells, which persisted at day 15 (Figure 3c and 3d) and at day 30 (Figure 3e and 3f).

View larger version (106K): [in this window] [in a new window]   Figure 3. Paraffin sections with hematoxylin and eosin staining at days 2 and 15 after injury and with Masson’s trichrome at day 30 (magnification: a, c, and e, x10; b and d, x100; f, x40). At day 2, sections show absence of both endothelial cells and smooth muscle cells in media. At day 15, intima and media are restored, but an intense inflammatory infiltrate is present in adventitia. At day 30, adventitia was still infiltrated by inflammatory cells. No neointimal hyperplasia was observed after electric injury of carotid artery.

Effect of Estradiol on Endothelial Regeneration
Ovariectomized mice with an implanted placebo pellet showed nondetectable (<5 pg/mL ie, 20x10^-12 mol/L) circulating levels of E₂, whereas those implanted with a pellet releasing 0.1 mg E₂ for 60 days (ie, 80 µg · kg^-1 · d^-1) showed serum E₂ concentrations averaging 0.5x10^-9 mol/L, irrespective of genotype (Tables 1 and 2). Ovariectomized, placebo-treated mice showed atrophied uteri (<20 mg); E₂-treated mice showed a significant increase in uterine weight, except ER^-/- mice, which had atrophied uteri even when treated with E₂ (Tables 1 and 2).

View this table: [in this window] [in a new window]   Table 1. Effect of Estradiol Treatment on Body and Uterine Weights, Serum Estradiol, and Reendothelialization Process in Ovariectomized ER-Deficient Mice

View this table: [in this window] [in a new window]   Table 2. Effect of Estradiol Treatment on Body and Uterine Weights, Serum Estradiol, and Reendothelialization Process in Ovariectomized ERß-Deficient Mice

Endothelial regeneration was similar in all categories of mice with an implanted placebo pellet, irrespective of genotype (Tables 1 and 2, Figure 4). In ER-deficient mice, an interaction (P=0.004) between E₂ treatment and genotype on reendothelialization was revealed by the 2-factor ANOVA. In these animals, E₂ treatment significantly accelerated reendothelialization in ER^+/+ mice (P<0.0001), tended to accelerate the reendothelialization in ER^+/- mice (P=0.14), but had no effect in ER^-/- mice (P=0.95) (Figure 4 and Table 1). In contrast, in ERß-deficient animals, E₂ treatment significantly accelerated the reendothelialization process in ERß^+/+, ERß^+/-, and ERß^-/- mice in a similar fashion (P<0.0001), without influence of genotype (P=0.27, NS). Although the acceleration of the reendothelialization tended to be greater in E₂-treated ERß^-/- mice treated with E₂ than in ERß^+/+ mice, the difference was not statistically significant, because no interaction between E₂ treatment and the genotype was observed (P=0.73, NS) (Figure 4 and Table 2).

View larger version (17K): [in this window] [in a new window]   Figure 4. Effect of E2 on reendothelialization process in ER mice (A) and in ERß mice (B). Genotype for each ER subtype is indicated as +/+ (control), +/- (heterozygous), and -/- (homozygous-deficient). Percentage of deendothelialization (estimated as ratio of remaining deendothelialized area on total carotid area) at day 3 in ovariectomized mice given placebo (solid bars) or estradiol (open bars). *P<0.05 vs respective placebo-treated group.

	Discussion

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Endothelium is both a key actor in the pathophysiology of atherosclerosis and an important target of E₂ in the vessel wall. Indeed, the modulation of several properties of endothelium in response to E₂ could account for the vasculoprotective effect of the hormone. One major function of endothelium is the release of the vasorelaxant and antiaggregant messenger nitric oxide, which is enhanced in oophorectomized females treated with estrogens^{26 27 28} either directly by upregulation of the endothelial NO synthase gene expression²⁹ or indirectly by a receptor-mediated antioxidant effect.³⁰ E₂ was also reported to promote reendothelialization in castrated female rats,¹⁶ but to the best of our knowledge, this effect has not been reported in mice. Moreover, the availability of genetically modified mice with ER or ERß gene disruption offers the possibility of studying the role of each of these ER subtypes in the effect of E₂ on endothelial regeneration.

Preliminary experiments led us to modify the model of electric injury initially described by Carmeliet et al²⁵ to study the reendothelialization process. For technical reasons, we elected to perform the electric injury in the carotid instead of the femoral artery. As reported for the femoral site,²⁵ we found that the reendothelialization process started immediately after injury and proceeded very actively during the first week after injury. The 4 mm of injured carotid artery was completely reendothelialized within 7 days, ie, 300 µm/d for each edge. Taking into account that the average length of an endothelial cell is 50 µm (see previous reports^{31 32} and Figure 2) and that the doubling time of this cell population is in the range of 24 hours, proliferation would contribute to 50 µm/d from each edge over the 7-day period. It would appear from these calculations that reendothelialization relies essentially on local cell migration or circulating endothelial progenitor cells, which have been shown to be incorporated into foci of neovascularization.^{33 34}

We observed that E₂ accelerated endothelial regrowth in wild-type mice by 25%, a value close to what had been measured in the rat species.¹⁶ We then sought to determine which ER gene promoted the reendothelialization process. ER has long been considered to be the unique target of E₂, because it has been characterized in reproductive tissues, in bone, and in vessels, particularly in the endothelial cells.^{35 36 37} Iafrati et al²⁴ reported that the prevention of medial enlargement (ie, smooth muscle cell proliferation) by E₂ is preserved in ER-deficient mice in a model of endovascular carotid injury. Very recently, the same group reported that E₂ also inhibits medial enlargement in the injured carotid of ERß-deficient mice.³⁸ It should be underlined that in these studies, vascular smooth muscle cell proliferation was evaluated, whereas in our studies, the effect of E₂ on endothelial regeneration was appreciated. Altogether, these series of data led to the intriguing possibility that reendothelialization could be mediated specifically by the ER gene, whereas arterial smooth muscle cell proliferation could be mediated by a third, as yet unidentified ER gene. Further work should clarify this situation, but taking into account the crucial role of endothelium in the maintenance of vascular integrity, ER should be considered a prime target of pharmacological studies in the area of cardiovascular diseases.

	Acknowledgments

 
The work at INSERM U397 was supported in part by INSERM, the Ministère de la Recherche et de la Technologie, the Fondation de France, the Fondation de l’Avenir, and the Conseil Régional Midi-Pyrénées. The work at the Institut de Génétique et de Biologie Moléculaire et Cellulaire was supported by a grant from the CNRS, INSERM, the Collège de France, the Hôpital Universitaire de Strasbourg, the Association pour la Recherche Médicale, the Fondation pour la Recherche Médicale, and by GIP/HMR. Dr Dupont was supported by a fellowship from Hoechst Marion Roussel. We thank J.-L. Fontanilles, G.B.M., Hôpital Rangueil, for his valuable technical assistance.

Received May 22, 2000; revision received July 11, 2000; accepted August 1, 2000.

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				C. D. DuSell, M. Umetani, P. W. Shaul, D. J. Mangelsdorf, and D. P. McDonnell 27-Hydroxycholesterol Is an Endogenous Selective Estrogen Receptor Modulator Mol. Endocrinol., January 1, 2008; 22(1): 65 - 77. [Abstract] [Full Text] [PDF]

				G. Douglas, M. Natalia Cruz, L. Poston, J.-A. Gustafsson, and K. Kublickiene Functional characterization and sex differences in small mesenteric arteries of the estrogen receptor- knockout mouse Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2008; 294(1): R112 - R120. [Abstract] [Full Text] [PDF]

				S. A. Sorrentino, F. H. Bahlmann, C. Besler, M. Muller, S. Schulz, N. Kirchhoff, C. Doerries, T. Horvath, A. Limbourg, F. Limbourg, et al. Oxidant Stress Impairs In Vivo Reendothelialization Capacity of Endothelial Progenitor Cells From Patients With Type 2 Diabetes Mellitus: Restoration by the Peroxisome Proliferator-Activated Receptor-{gamma} Agonist Rosiglitazone Circulation, July 10, 2007; 116(2): 163 - 173. [Abstract] [Full Text] [PDF]

				J.-B. Michel, O. Thaunat, X. Houard, O. Meilhac, G. Caligiuri, and A. Nicoletti Topological Determinants and Consequences of Adventitial Responses to Arterial Wall Injury Arterioscler. Thromb. Vasc. Biol., June 1, 2007; 27(6): 1259 - 1268. [Abstract] [Full Text] [PDF]

				D. Xing, W. Feng, A. P. Miller, N. M. Weathington, Y.-F. Chen, L. Novak, J. E. Blalock, and S. Oparil Estrogen modulates TNF-{alpha}-induced inflammatory responses in rat aortic smooth muscle cells through estrogen receptor-beta activation Am J Physiol Heart Circ Physiol, June 1, 2007; 292(6): H2607 - H2612. [Abstract] [Full Text] [PDF]

				M. E. Wierman and W. M. Kohrt Review Article: Vascular and Metabolic Effects of Sex Steroids: New Insights Into Clinical Trials Reproductive Sciences, May 1, 2007; 14(4): 300 - 314. [Abstract] [PDF]

				T. Adriaenssens, J. Mehilli, R. Wessely, G. Ndrepepa, M. Seyfarth, A. Wieczorek, B. Blaich, R. Iijima, J. Pache, A. Kastrati, et al. Does Addition of Estradiol Improve the Efficacy of a Rapamycin-Eluting Stent?: Results of the ISAR-PEACE Randomized Trial J. Am. Coll. Cardiol., March 27, 2007; 49(12): 1265 - 1271. [Abstract] [Full Text] [PDF]

				Y. D. Krom, N. M.M. Pires, J. W. Jukema, M. R. de Vries, R. R. Frants, L. M. Havekes, K. W. van Dijk, and P. H.A. Quax Inhibition of neointima formation by local delivery of estrogen receptor alpha and beta specific agonists Cardiovasc Res, January 1, 2007; 73(1): 217 - 226. [Abstract] [Full Text] [PDF]

				B. Dawn and R. Bolli Increasing Evidence That Estrogen Is an Important Modulator of Bone Marrow-Mediated Cardiac Repair After Acute Infarction Circulation, November 21, 2006; 114(21): 2203 - 2205. [Full Text] [PDF]

				H. Hamada, M. K. Kim, A. Iwakura, M. Ii, T. Thorne, G. Qin, J. Asai, Y. Tsutsumi, H. Sekiguchi, M. Silver, et al. Estrogen Receptors {alpha} and {beta} Mediate Contribution of Bone Marrow-Derived Endothelial Progenitor Cells to Functional Recovery After Myocardial Infarction Circulation, November 21, 2006; 114(21): 2261 - 2270. [Abstract] [Full Text] [PDF]

				V. Fontaine, C. Filipe, N. Werner, P. Gourdy, A. Billon, B. Garmy-Susini, L. Brouchet, F. Bayard, H. Prats, T. Doetschman, et al. Essential Role of Bone Marrow Fibroblast Growth Factor-2 in the Effect of Estradiol on Reendothelialization and Endothelial Progenitor Cell Mobilization Am. J. Pathol., November 1, 2006; 169(5): 1855 - 1862. [Abstract] [Full Text] [PDF]

				C. Bolego, E. Vegeto, C. Pinna, A. Maggi, and A. Cignarella Selective Agonists of Estrogen Receptor Isoforms: New Perspectives for Cardiovascular Disease Arterioscler. Thromb. Vasc. Biol., October 1, 2006; 26(10): 2192 - 2199. [Abstract] [Full Text] [PDF]

				T. Simoncini, C. Scorticati, P. Mannella, A. Fadiel, M. S. Giretti, X.-D. Fu, C. Baldacci, S. Garibaldi, A. Caruso, L. Fornari, et al. Estrogen Receptor {alpha} Interacts with G{alpha}13 to Drive Actin Remodeling and Endothelial Cell Migration via the RhoA/Rho Kinase/Moesin Pathway Mol. Endocrinol., August 1, 2006; 20(8): 1756 - 1771. [Abstract] [Full Text] [PDF]

				R. C. Christian, P. Y. Liu, S. Harrington, M. Ruan, V. M. Miller, and L. A. Fitzpatrick Intimal Estrogen Receptor (ER){beta}, But Not ER{alpha} Expression, Is Correlated with Coronary Calcification and Atherosclerosis in Pre- and Postmenopausal Women J. Clin. Endocrinol. Metab., July 1, 2006; 91(7): 2713 - 2720. [Abstract] [Full Text] [PDF]

				D. Seetharam, C. Mineo, A. K. Gormley, L. L. Gibson, W. Vongpatanasin, K. L. Chambliss, L. D. Hahner, M. L. Cummings, R. L. Kitchens, Y. L. Marcel, et al. High-Density Lipoprotein Promotes Endothelial Cell Migration and Reendothelialization via Scavenger Receptor-B Type I Circ. Res., January 6, 2006; 98(1): 63 - 72. [Abstract] [Full Text] [PDF]

				R. G. Mishra, F. Z. Stanczyk, K. A. Burry, S. Oparil, B. S. Katzenellenbogen, M. L. Nealen, J. A. Katzenellenbogen, and R. K. Hermsmeyer Metabolite ligands of estrogen receptor-{beta} reduce primate coronary hyperreactivity Am J Physiol Heart Circ Physiol, January 1, 2006; 290(1): H295 - H303. [Abstract] [Full Text] [PDF]

				H. Tan, X. Jiang, F. Yang, Z. Li, D. Liao, J. Trial, M. J. Magera, W. Durante, X. Yang, and H. Wang Hyperhomocysteinemia inhibits post-injury reendothelialization in mice Cardiovasc Res, January 1, 2006; 69(1): 253 - 262. [Abstract] [Full Text] [PDF]

				K. Wassmann, S. Wassmann, and G. Nickenig Progesterone Antagonizes the Vasoprotective Effect of Estrogen on Antioxidant Enzyme Expression and Function Circ. Res., November 11, 2005; 97(10): 1046 - 1054. [Abstract] [Full Text] [PDF]

				K. Kublickiene, E. Svedas, B.-M. Landgren, M. Crisby, N. Nahar, H. Nisell, and L. Poston Small Artery Endothelial Dysfunction in Postmenopausal Women: In Vitro Function, Morphology, and Modification by Estrogen and Selective Estrogen Receptor Modulators J. Clin. Endocrinol. Metab., November 1, 2005; 90(11): 6113 - 6122. [Abstract] [Full Text] [PDF]

				W. Koch, P. Hoppmann, A. Pfeufer, J. C. Mueller, A. Schomig, and A. Kastrati No Replication of Association Between Estrogen Receptor {alpha} Gene Polymorphisms and Susceptibility to Myocardial Infarction in a Large Sample of Patients of European Descent Circulation, October 4, 2005; 112(14): 2138 - 2142. [Abstract] [Full Text] [PDF]

				K. H. Kim and J. R. Bender Rapid, Estrogen Receptor-Mediated Signaling: Why Is the Endothelium So Special? Sci. Signal., June 14, 2005; 2005(288): pe28 - pe28. [Abstract] [Full Text] [PDF]

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