Sustained Placental Growth Factor-2 Treatment Does Not Aggravate Advanced Atherosclerosis in Ischemic Cardiomyopathy.

Angiogenic growth factor therapy for ischemic cardiovascular disease carries a risk of stimulating atherosclerotic plaque growth. We evaluated risk benefit ratio of sustained administration of recombinant human placental growth factor (rhPlGF)-2 in mice with advanced atherosclerosis and chronic ischemic cardiomyopathy. We maintained apolipoprotein E-deficient mice on a high cholesterol diet and induced myocardial infarction by transient ligation at 4 weeks. At 8 weeks, we assessed left ventricular (LV) function and randomized mice to receive rhPlGF-2 or vehicle (VEH) subcutaneously for 28 days. Administration of rhPlGF-2 significantly increased PlGF plasma levels without adverse hemodynamic or systemic inflammatory effects. RhPlGF-2 did not increase plaque area, composition, or vulnerability in the aortic arch. RhPlGF-2 significantly improved contractile function and reduced LV end-systolic and end-diastolic volume indices with a concomitant increase in capillary and arteriolar density in ischemic myocardium. RhPlGF-2 may represent a promising therapeutic strategy in chronic ischemic cardiomyopathy.

Placental growth factor 2--A potential therapeutic strategy for chronic myocardial ischemia.

OBJECTIVES: We investigated whether sustained infusion of recombinant human placental growth factor-2 (rhPlGF-2) improves myocardial perfusion and left ventricular (LV) function in a porcine model of ischemic cardiomyopathy (ICM). METHODS: We induced myocardial ischemia using a flow-limiting stent in the LAD. Four weeks later, we randomized pigs with confirmed myocardial dysfunction to blinded rhPlGF-2 administration (PlGF2, 15 µg/kg/day, 14 days) or PBS (CON). At 8 weeks, we measured hemodynamics, contractile function and regional perfusion at rest and during stress using MRI and microspheres. We evaluated neovascularization post mortem. RESULTS: RhPlGF-2 administration increased PlGF serum levels more than 63-fold (83 3 ± 361 versus 11 ± 5 pg/ml CON, P<0.05) without adverse effects. After 4weeks, rhPlGF-2 significantly enhanced perfusion in the ischemic region at rest (0.83 ± 0.32 versus 0.58 ± 0.21 ml/min/g CON, P<0.05) and during hyperemia (1.50 ± 0.50 versus 1.02 ± 0.46 ml/min/g CON, P<0.05). Consequently, regional contractile function in rhPlGF-2-treated pigs improved at rest (37 ± 15% versus 23 ± 9% CON, P<0.05) and during high dose dobutamine stress (53 ± 31% versus 27 ± 16% CON, P<0.05). Enhanced perfusion translated into a greater improvement in LV ejection fraction and in preload-recruitable stroke work in rhPlGF-2-treated animals than in CON (52 ± 11 versus 41 ± 9%, and 76 ± 24 versus 41 ± 21 mmHg, respectively, P<0.05 for both), which was associated with significantly greater vascular density in the ischemic region. CONCLUSIONS: In chronic ICM, systemic rhPlGF-2 administration significantly enhances regional myocardial perfusion, contractile function at rest and during stress, and induces a prominent recovery of global cardiac function. PlGF-2 protein infusion is safe and may represent a promising therapy in chronic ICM.

Notch3 Arg170Cys knock-in mice display pathologic and clinical features of the neurovascular disorder cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

OBJECTIVE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult-onset neurovascular disorder caused by stereotyped mutations in the NOTCH3 receptor. Elucidation of its pathobiology is still incomplete and remains a challenge, in part because the available preclinical mouse models to date do not reproduce the full spectrum of CADASIL pathology and clinical disease. METHODS AND RESULTS: Here, we report a novel knock-in mouse with Arg170Cys substitution in murine Notch3, corresponding to the prevalent Arg169Cys substitution in CADASIL. The Notch3(Arg170Cys) mice displayed late-onset, dominant CADASIL arteriopathy with typical granular osmiophilic material deposition and developed brain histopathology including thrombosis, microbleeds, gliosis, and microinfarction. Furthermore, Notch3(Arg170Cys) mice experienced neurological symptoms with motor defects such as staggering gait and limb paresis. CONCLUSIONS: This model, for the first time, phenocopies the arteriopathy and the histopathologic as well as clinical features of CADASIL and may offer novel opportunities to investigate disease pathogenesis.

Differential effects of progenitor cell populations on left ventricular remodeling and myocardial neovascularization after myocardial infarction.

OBJECTIVES: We compared biological repair after acute myocardial infarction (AMI) with selected porcine progenitor cell populations. BACKGROUND: Cell types and mechanisms responsible for myocardial repair after AMI remain uncertain. METHODS: In a blinded, randomized study, we infused autologous late-outgrowth endothelial progenitor cells (EPC) (n = 10, 34 +/- 22 x 10(6) CD29-31-positive, capable of tube formation), allogeneic green fluorescent peptide-labeled mesenchymal stem cells (MSC) (n = 11, 10 +/- 2 x 10(6) CD29-44-90-positive, capable of adipogenic and osteogenic differentiation), or vehicle (CON) (n = 12) in the circumflex artery 1 week after AMI. Systolic function (ejection fraction), left ventricular (LV) end-diastolic and end-systolic volumes, and infarct size were assessed with magnetic resonance imaging at 1 week and 7 weeks. Cell engraftment and vascular density were evaluated on postmortem sections. RESULTS: Recovery of LV ejection fraction from 1 to 7 weeks was similar between groups, but LV remodeling markedly differed with a greater increase of LV end-systolic volume in MSC and CON (+11 +/- 12 ml/m(2) and +7 +/- 8 ml/m(2) vs. -3 +/- 11 ml/m(2) in EPC, respectively, p = 0.04), and a similar trend was noted for LV end-diastolic volume (p = 0.09). After EPC, infarct size decreased more in segments with >50% infarct transmurality (p = 0.02 vs. MSC and CON) and was associated with a greater vascular density (p = 0.01). Late outgrowth EPCs secrete higher levels of the pro-angiogenic placental growth factor (733 [277 to 1,214] pg/10(6) vs. 59 [34 to 88] pg/10(6) cells in MSC, p = 0.03) and incorporate in neovessels in vivo. CONCLUSIONS: Infusion of late-outgrowth EPCs after AMI improves myocardial infarction remodeling via enhanced neovascularization but does not mediate cardiomyogenesis. Endothelial progenitor cell transfer might hold promise for heart failure prevention via pro-angiogenic or paracrine matrix-modulating effects.

Further pharmacological and genetic evidence for the efficacy of PlGF inhibition in cancer and eye disease.

Our findings that PlGF is a cancer target and anti-PlGF is useful for anticancer treatment have been challenged by Bais et al. Here we take advantage of carcinogen-induced and transgenic tumor models as well as ocular neovascularization to report further evidence in support of our original findings of PlGF as a promising target for anticancer therapies. We present evidence for the efficacy of additional anti-PlGF antibodies and their ability to phenocopy genetic deficiency or silencing of PlGF in cancer and ocular disease but also show that not all anti-PlGF antibodies are effective. We also provide additional evidence for the specificity of our anti-PlGF antibody and experiments to suggest that anti-PlGF treatment will not be effective for all tumors and why. Further, we show that PlGF blockage inhibits vessel abnormalization rather than density in certain tumors while enhancing VEGF-targeted inhibition in ocular disease. Our findings warrant further testing of anti-PlGF therapies.

Cardioselective nitric oxide synthase 3 gene transfer protects against myocardial reperfusion injury.

Nitric oxide modulates the severity of myocardial ischemia-reperfusion (I/R) injury. We investigated whether cardioselective nitric oxide synthase 3 (NOS3) gene transfer could confer myocardial protection against I/R injury in pigs and examined potential molecular mechanisms. I/R injury was induced by balloon occlusion of the left anterior descending artery for 45 min followed by 4 or 72 h reperfusion. Hemodynamic and pathological changes were measured in pigs in the absence (n = 11) or presence of prior intracoronary retroinfusion of human NOS3 (AdNOS3, 5 x 10(10) PFU, n = 13) or control vector (AdRR5, 5 x 10(10) PFU, n = 11). Retrograde NOS3 gene transfer selectively increased NOS3 expression and NO bioavailability in the area at risk (AAR) without changing endogenous NOS isoform expression. At 4 h R, LV systolic (dP/dt(max)) and diastolic (dP/dt(min)) function was better preserved in AdNOS3- than in AdRR5-injected pigs (2,539 +/- 165 vs. 1,829 +/- 156 mmHg/s, and -2,781 +/- 340 vs. -2,062 +/- 292 mmHg/s, respectively, P < 0.05 for both). Myocardial infarct size (% AAR) was significantly smaller in AdNOS3 than in control and AdRR5 and associated with a significantly greater reduction in cardiac myeloperoxidase activity, a marker of neutrophil infiltration. The latter effects were sustained at 72 h R in a subset of pigs (n = 7). In the AAR, intercellular endothelial adhesion molecule-1 expression and cardiomyocyte apoptosis were significantly lower in AdNOS3. In conclusion, single myocardial NOS3 retroinfusion attenuates I/R injury, and causes a sustained reduction in myocardial infarct size and inflammatory cell infiltration. Gene-based strategies to increase NO bioavailability may have therapeutic potential in myocardial I/R.

Short-term delivery of anti-PlGF antibody delays progression of atherosclerotic plaques to vulnerable lesions.

AIMS: Placental growth factor (PlGF), a homologue of vascular endothelial growth factor, is a pleiotropic cytokine with a pro-inflammatory activity. Previous gene-inactivation studies revealed that the loss of PlGF delays atherosclerotic lesion development and inhibits macrophage infiltration, but the activity of an anti-PlGF antibody (alphaPlGF mAb) has not been evaluated yet. METHODS AND RESULTS: We characterized the potential of short-term delivery of alphaPlGF mAb in inhibiting lesion development in ApoE-deficient mice (apoE(-/-)) and in CD4:TGFbetaRII(DN) x apoE(-/-) mice, a more severe atherosclerosis model. Short-term treatment of alphaPlGF mAb reduces early atherosclerotic plaque size and inflammatory cell infiltration in the lesion. CONCLUSION: These pharmacological alphaPlGF mAb results confirm previous genetic evidence that inhibition of PlGF slows down early atherosclerotic lesion development. Furthermore, the phenocopy of genetic and pharmacological loss-of-function strategies underscores that alphaPlGF acts by selectively neutralizing PlGF.

Emerging treatments for thrombocytopenia: increasing platelet production.

Thrombocytopenia is a common medical problem. The first generation thrombopoietic agents, recombinant THPO and 'megakaryocyte growth and development factor' (PEG-rHuMGDF) entered clinical trials, but their development was discontinued owing to neutralizing auto-antibodies cross-reacting with endogenous THPO, causing thrombocytopenia in healthy volunteers. Although an approved drug for prevention of severe thrombocytopenia following myelosuppressive chemotherapy (human Interleukin-11) exists, the search for new thrombopoietic agents continued because its use is limited by side effects. Several second generation thrombopoietic factors have entered clinical trials and some new negative regulators of megakaryopoiesis have been found, such as platelet factor 4 (PF4) and the pituitary adenylate cyclase activating polypeptide (PACAP). Their inhibition may be useful in the treatment of thrombocytopenia. This article reviews second generation thrombopoietic factors and those recently discovered regulators of megakaryopoiesis.

Sustained endothelial progenitor cell dysfunction after chronic hypoxia-induced pulmonary hypertension.

Circulating endothelial progenitor cells (EPCs) contribute to neovascularization of ischemic tissues and repair of injured endothelium. The role of bone marrow-derived progenitor cells in hypoxia-induced pulmonary vascular remodeling and their tissue-engineering potential in pulmonary hypertension (PH) remain largely unknown. We studied endogenous mobilization and homing of EPCs in green fluorescent protein bone marrow chimeric mice exposed to chronic hypoxia, a common hallmark of PH. Despite increased peripheral mobilization, as shown by flow cytometry and EPC culture, bone marrow-derived endothelial cell recruitment in remodeling lung vessels was limited. Moreover, transfer of vascular endothelial growth factor receptor-2+/Sca-1+/CXCR-4+-cultured early-outgrowth EPCs failed to reverse PH, suggesting hypoxia-induced functional impairment of transferred EPCs. Chronic hypoxia decreased migration to stromal cell-derived factor-1alpha, adhesion to fibronectin, incorporation into a vascular network, and nitric oxide production (-41%, -29%, -30%, and -32%, respectively, vs. normoxic EPCs; p < .05 for all). The dysfunctional phenotype of hypoxic EPCs significantly impaired their neovascularization capacity in chronic hind limb ischemia, contrary to normoxic EPCs cultured in identical conditions. Mechanisms contributing to EPC dysfunction include reduced integrin alphav and beta1 expression, decreased mitochondrial membrane potential, and enhanced senescence. Novel insights from chronic hypoxia-induced EPC dysfunction may provide important cues for improved future cell repair strategies.

Role of Gas6 in erythropoiesis and anemia in mice.

Many patients with anemia fail to respond to treatment with erythropoietin (Epo), a commonly used hormone that stimulates erythroid progenitor production and maturation by human BM or by murine spleen. The protein product of growth arrest-specific gene 6 (Gas6) is important for cell survival across several cell types, but its precise physiological role remains largely enigmatic. Here, we report that murine erythroblasts released Gas6 in response to Epo and that Gas6 enhanced Epo receptor signaling by activating the serine-threonine kinase Akt in these cells. In the absence of Gas6, erythroid progenitors and erythroblasts were hyporesponsive to the survival activity of Epo and failed to restore hematocrit levels in response to anemia. In addition, Gas6 may influence erythropoiesis via paracrine erythroblast-independent mechanisms involving macrophages. When mice with acute anemia were treated with Gas6, the protein normalized hematocrit levels without causing undesired erythrocytosis. In a transgenic mouse model of chronic anemia caused by insufficient Epo production, Gas6 synergized with Epo in restoring hematocrit levels. These findings may have implications for the treatment of patients with anemia who fail to adequately respond to Epo.

Urokinase-type plasminogen activator receptor (uPAR) augments brain damage in a murine model of ischemic stroke.

Urokinase-type plasminogen activator receptor (uPAR) is a key component of the plasminogen activation system at the cell surface. Recent studies showed that uPAR is expressed in the ischemic damaged brain, suggesting its involvement in brain damage. In this study, we evaluated the role of uPAR in ischemic brain damage induced by permanent middle cerebral artery (MCA) occlusion in mice with genetic deficiency of uPAR (uPAR(-/-)) or of uPA (uPA(-/-)). Brain damage at 3 days was smaller in uPAR(-/-) mice (4.5+/-1.0mm(3)) than in littermate wild-type mice (uPAR(+/+)) (9.1+/-1.8mm(3), p<0.05), whereas it was comparable in uPA(-/-) (8.0+/-4.1mm(3)) and uPA(+/+) (6.9+/-2.6mm(3)) mice. uPAR expression was upregulated in the ipsilateral cerebral cortex within 12h, and remained elevated for up to 3 days. At 1 or 2 days after MCA occlusion, uPAR expression was selectively localized in vessels at the border of the damaged area. These findings suggest that uPAR expressed by endothelial cells augments the ischemic brain damage via a uPA-independent mechanism.

Ttrap is an essential modulator of Smad3-dependent Nodal signaling during zebrafish gastrulation and left-right axis determination.

During vertebrate development, signaling by the TGFbeta ligand Nodal is critical for mesoderm formation, correct positioning of the anterior-posterior axis, normal anterior and midline patterning, and left-right asymmetric development of the heart and viscera. Stimulation of Alk4/EGF-CFC receptor complexes by Nodal activates Smad2/3, leading to left-sided expression of target genes that promote asymmetric placement of certain internal organs. We identified Ttrap as a novel Alk4- and Smad3-interacting protein that controls gastrulation movements and left-right axis determination in zebrafish. Morpholino-mediated Ttrap knockdown increases Smad3 activity, leading to ectopic expression of snail1a and apparent repression of e-cadherin, thereby perturbing cell movements during convergent extension, epiboly and node formation. Thus, although the role of Smad proteins in mediating Nodal signaling is well-documented, the functional characterization of Ttrap provides insight into a novel Smad partner that plays an essential role in the fine-tuning of this signal transduction cascade.

Anti-PlGF inhibits growth of VEGF(R)-inhibitor-resistant tumors without affecting healthy vessels.

Novel antiangiogenic strategies with complementary mechanisms are needed to maximize efficacy and minimize resistance to current angiogenesis inhibitors. We explored the therapeutic potential and mechanisms of alphaPlGF, an antibody against placental growth factor (PlGF), a VEGF homolog, which regulates the angiogenic switch in disease, but not in health. alphaPlGF inhibited growth and metastasis of various tumors, including those resistant to VEGF(R) inhibitors (VEGF(R)Is), and enhanced the efficacy of chemotherapy and VEGF(R)Is. alphaPlGF inhibited angiogenesis, lymphangiogenesis, and tumor cell motility. Distinct from VEGF(R)Is, alphaPlGF prevented infiltration of angiogenic macrophages and severe tumor hypoxia, and thus, did not switch on the angiogenic rescue program responsible for resistance to VEGF(R)Is. Moreover, it did not cause or enhance VEGF(R)I-related side effects. The efficacy and safety of alphaPlGF, its pleiotropic and complementary mechanism to VEGF(R)Is, and the negligible induction of an angiogenic rescue program suggest that alphaPlGF may constitute a novel approach for cancer treatment.

Soluble guanylate cyclase-alpha1 deficiency selectively inhibits the pulmonary vasodilator response to nitric oxide and increases the pulmonary vascular remodeling response to chronic hypoxia.

BACKGROUND: Nitric oxide (NO) activates soluble guanylate cyclase (sGC), a heterodimer composed of alpha- and beta-subunits, to produce cGMP. NO reduces pulmonary vascular remodeling, but the role of sGC in vascular responses to acute and chronic hypoxia remains incompletely elucidated. We therefore studied pulmonary vascular responses to acute and chronic hypoxia in wild-type (WT) mice and mice with a nonfunctional alpha1-subunit (sGCalpha1-/-). METHODS AND RESULTS: sGCalpha1-/- mice had significantly reduced lung sGC activity and vasodilator-stimulated phosphoprotein phosphorylation. Right ventricular systolic pressure did not differ between genotypes at baseline and increased similarly in WT (22+/-2 to 34+/-2 mm Hg) and sGCalpha1-/- (23+/-2 to 34+/-1 mm Hg) mice in response to acute hypoxia. Inhaled NO (40 ppm) blunted the increase in right ventricular systolic pressure in WT mice (22+/-2 to 24+/-2 mm Hg, P<0.01 versus hypoxia without NO) but not in sGCalpha1-/- mice (22+/-1 to 33+/-1 mm Hg) and was accompanied by a significant rise in lung cGMP content only in WT mice. In contrast, the NO-donor sodium nitroprusside (1.5 mg/kg) decreased systemic blood pressure similarly in awake WT and sGCalpha1-/- mice as measured by telemetry (-37+/-2 versus -42+/-4 mm Hg). After 3 weeks of hypoxia, the increases in right ventricular systolic pressure, right ventricular hypertrophy, and muscularization of intra-acinar pulmonary vessels were 43%, 135%, and 46% greater, respectively, in sGCalpha1-/- than in WT mice (P<0.01). Increased remodeling in sGCalpha1-/- mice was associated with an increased frequency of 5'-bromo-deoxyuridine-positive vessels after 1 and 3 weeks (P<0.01 versus WT). CONCLUSIONS: Deficiency of sGCalpha1 does not alter hypoxic pulmonary vasoconstriction. sGCalpha1 is essential for NO-mediated pulmonary vasodilation and limits chronic hypoxia-induced pulmonary vascular remodeling.

A dose-finding clinical trial of staphylokinase SY162 in patients with long-term venous access catheter thrombotic occlusion.

BACKGROUND: We investigated the safety and efficacy of several dosing regimens of catheter-directed staphylokinase (SY162) bolus administration for the treatment of long-term venous access catheter occlusion. METHODS: This open-label, ascending dose study enrolled 24 subjects. Three doses of SY162 were evaluated in three cohorts (0.15 mg, 0.3 mg and 0.45 mg) with eight subjects each. Catheter function was evaluated 30 min after the first bolus administration. In case of incomplete catheter function restoration, a second bolus was administered with reassessment of catheter function 30 min thereafter. Cathetergram was repeated to assess thrombus resolution. RESULTS: Complete restoration of catheter withdrawal function was observed in 2 (25%), 1 (13%) and 7 (88%) subjects after the first bolus in the first, second and third cohort respectively and in 4 (50%), 7 (88%) and 7 (88%) patients after the second administration of SY162. There were no bleeding complications nor other adverse events related to SY162. CONCLUSIONS: The doses tested in this trial were well tolerated and safe. A dose-response effect within the dose range tested was observed. A 2 ml bolus injection of 0.45 mg SY162 resulted in optimal efficacy after 30 min.

Lack of endothelial cell survivin causes embryonic defects in angiogenesis, cardiogenesis, and neural tube closure.

We explored the physiologic role of endothelial cell apoptosis during development by generating mouse embryos lacking the inhibitor of apoptosis protein (IAP) survivin in endothelium. This was accomplished by intercrossing survivin(lox/lox) mice with mice expressing cre recombinase under the control of the endothelial cell specific tie1 promoter (tie1-cre mice). Lack of endothelial cell survivin resulted in embryonic lethality. Mutant embryos had prominent and diffuse hemorrhages from embryonic day 9.5 (E9.5) and died before E13.5. Heart development was strikingly abnormal. Survivin-null endocardial lineage cells could not support normal epithelial-mesenchymal transformation (EMT), resulting in hypoplastic endocardial cushions and in utero heart failure. In addition, 30% of mutant embryos had neural tube closure defects (NTDs) that were not caused by bleeding or growth retardation, but were likely due to alterations in the release of soluble factors from endothelial cells that otherwise support neural stem cell proliferation and neurulation. Thus, regulation of endothelial cell survival, and maintenance of vascular integrity by survivin are crucial for normal embryonic angiogenesis, cardiogenesis, and neurogenesis.

Tiplaxtinin impairs nutritionally induced obesity in mice.

To investigate the effect of tiplaxtinin, designed as a synthetic inhibitor of plasminogen activator inhibitor-1 (PAI-1), on obesity, male C57Bl/6 mice (13-14 weeks old) were kept on a high-fat diet (20.1 kJ/g) for four weeks without or with addition of tiplaxtinin (PAI-039) at a dose of 2 mg/g food. At the time of sacrifice, body weights were significantly lower in the inhibitor-treated mice (p < 0.0005). The weights of the isolated subcutaneous and gonadal fat deposits were also significantly lower (both p < 0.0005), associated with adipocyte hypotrophy. Inhibitor-treated adipose tissues displayed similar blood vessel size, but a higher blood vessel density. Fasting glucose and insulin levels, as well as glucose-tolerance tests were not significantly affected by the inhibitor treatment, whereas plasma triglyceride levels were significantly reduced (p = 0.02) and LDL-cholesterol levels significantly enhanced (p = 0.0002). Insulin-tolerance tests revealed significantly lower glucose levels at the end of the test in the inhibitor treated mice (p = 0.03). Thus, in this model of diet-induced obesity in mice administration of tiplaxtinin resulted in impaired adipose tissue development.

Expression of aggrecan(ases) during murine preadipocyte differentiation and adipose tissue development.

The expression and potential functional role of aggrecan in adipogenesis and adipose tissue development was investigated in murine models of obesity. Aggrecan, as well as the two aggrecanases ADAMTS-4 and ADAMTS-5 (A Disintegrin And Metalloproteinase with Thrombospondin motif) mRNAs, are expressed in subcutaneous (SC) and gonadal (GON) adipose tissues of mice. Their presence was confirmed by western blotting using adipose tissue extracts. In mice with nutritionally induced obesity (high fat diet) as well as in lean controls, aggrecan mRNA expression was downregulated whereas ADAMTS-4 and ADAMTS-5 were upregulated with time. In mice with genetically determined obesity (ob/ob), ADAMTS-5 mRNA was upregulated in both SC and GON adipose tissues, as compared to wild-type (WT) mice (p<0.001). Enhanced aggrecanase expression levels in these tissues were associated with significantly elevated levels of G1-NITEGE, a degradation product of aggrecan. Thus, aggrecan levels were high at the early stages of adipose tissue development in mice, whereas its production decreased and its degradation increased during development of obesity. A functional role of aggrecan in promoting early stages of adipogenesis is supported by the findings that it stimulated the in vitro differentiation of 3T3-F442A preadipocytes and the de novo in vivo accumulation of fat in Matrigel plaques injected into WT mice. Proteoglycans in the extracellular matrix of adipose tissue, such as aggrecan, may contribute to the regulation of lipid uptake and obesity in mice.

Impaired adipose tissue development in mice with inactivation of placental growth factor function.

Placental growth factor (PlGF)-deficient (PlGF-/-) and wild-type mice were kept on a standard-fat or high-fat diet for 15 weeks. With the standard-fat diet, the body weights of PlGF-/- and wild-type mice were comparable, whereas the combined weight of subcutaneous and gonadal adipose tissues was lower in PlGF-/- mice (P = 0.02). With the high-fat diet, PlGF-/- mice had a lower body weight (P < 0.05) and less total subcutaneous plus gonadal adipose tissue (P < 0.0001). Blood vessel size was lower in gonadal adipose tissue of PlGF-/- mice with both the standard-fat and high-fat diet (P < 0.05). Blood vessel density, normalized to adipocyte number, was significantly lower in subcutaneous adipose tissue of PlGF-/- mice fed the high-fat diet (P < 0.01). De novo adipose tissue development in nude mice injected with 3T3-F442A preadipocytes was reduced (P < 0.005) by administration of a PlGF-neutralizing antibody. Bone marrow transplantation from wild-type or PlGF-/- mice to wild-type or PlGF-/- recipient mice revealed significantly lower blood vessel density in PlGF-/- recipient mice without an effect on adipose tissue growth. Thus, in murine models of diet-induced obesity, inactivation of PlGF impairs adipose tissue development, at least in part as a result of reduced angiogenesis.