Antagonism of the renin-angiotensin system can counteract cardiac angiogenic vascular endothelial growth factor gene therapy and myocardial angiogenesis in the normal heart.

BACKGROUND: The aim of this study was to test the hypothesis that angiotensin converting enzyme inhibition or angiotensin II antagonism can counteract cardiac human vascular endothelial growth factor-A165 (phVEGF-A165) induced angiogenesis. METHODS: Mice were given a single intramyocardial injection of phVEGF-A165. Either enalapril or candesartan was given subcutaneously for 10 consecutive days. Hearts were harvested and capillary count was performed by immunohistochemistry. With similar design, groups of mice were sacrificed after 24 h for the determination of tissue expression of phVEGF-A protein, mRNA expression of mouse VEGF-A, and VEGF receptors 1 and 2, after pEGFP-Luc transfection for luciferase expression. RESULTS: Increased myocardial capillary density (P < .02) induced by phVEGF-A165 was counteracted by both enalapril (P < .07) and candesartan (P < .02) and then did not differ from control values. We found that phVEGF-A165 induced myocardial hVEGF-A expression (110 +/- 15 pg/heart, P < .0001). Both enalapril and candesartan decreased (P < .01) expression of hVEGF-A to a level not different from control values. Although phVEGF-A165 upregulated (P < .0001) mVEGFR-2, addition of candesartan downregulated endogenous mVEGF-A (P < .0001) and mVEGFR-2 (P < .0001) below the level in normal myocardium. Enalapril or candesartan did not effect luciferase expression. CONCLUSIONS: Enalapril and candesartan both specifically inhibit phVEGF-A165 induced myocardial angiogenesis in the normal heart. The mechanism of inhibition is a combination of inhibition of cardiac hVEGF-A expression and of decreased endogenous expression of the mVEGF ligand and receptor system.

Simvastatin enhances myocardial angiogenesis induced by vascular endothelial growth factor gene transfer.

Statins have cardioprotective roles. We explored the cardiac angiogenic effects of simvastatin in combination with transient overexpression of vascular endothelial growth factor (VEGF). Compared with normal mice, 1-year-old ApoE(-/-) mice fed on a high-fat diet (HFD) had about 30% less myocardial capillary (P < 0.001) and arteriolar (P < 0.03) densities, associated with decreased VEGF (55%), VEGFR-1 (56%) and VEGFR-2 (78%) mRNA expressions and myocardial endothelial nitric oxide synthase (eNOS) production (58%). By contrast, angiopoietin-1 and angiopoietin-2 mRNA expressions were increased (500% P < 0.02, and 400% P < 0.01, respectively) in the ApoE(-/-) hearts. No change was observed in Tie-2 gene expression. Phosphorylation of antiapoptotic Akt was lower and proapoptotic p38 mitogen-activated protein kinase (MAPK) was higher in the ApoE(-/-) mice compared with controls. Intramyocardial VEGF gene transfer increased capillary and arteriolar densities in the ApoE(-/-) mice, and simvastatin treatment further enhanced capillary density (P < 0.03) to a level similar to that of normal mice. Simvastatin did not change the lipid profile but blocked p38 MAPK phosphorylation in the ApoE(-/-) myocardium. Concurrent with these changes, there were increased levels of expression of mVEGF (P < 0.04) and VEGFR-2 (P < 0.03) mRNAs and increased production of eNOS (P < 0.05) in the ApoE(-/-) mice, while no changes were detected in the angiopoietin system. Thus, increased myocardial angiogenesis in the ApoE(-/-) mice following transient overexpression of VEGF is further increased by additional simvastatin treatment. These effects occurred concurrently with simvastatin-induced stimulation of the VEGF system, increased eNOS production and reduction in p38 MAPK phosphorylation.

Xenoreactivity and engraftment of human mesenchymal stem cells transplanted into infarcted rat myocardium.

OBJECTIVE: It is thought that adult human mesenchymal stem cells do not induce immunoreactivity even to xenografts. We wanted to study whether adult human mesenchymal stem cells survive and engraft in experimentally induced ischemic rat myocardium. METHODS: Bone marrow-derived adult human mesenchymal stem cells (2.5 x 10(6)) were injected into the myocardium of 4 Sprague-Dawley rats. One week after injection, peripheral blood rat lymphocytes were added to adult human mesenchymal stem cells in a mixed lymphocyte reaction. Furthermore, an infarction was created by left anterior descending artery ligation of 8 Sprague-Dawley rats, 4 of which were immunosuppressed with tacrolimus (0.1 mg/kg/d) and 4 RNU athymic rats. One week after left anterior descending artery ligation, 2.5 to 3.5 x 10(6) adult human mesenchymal stem cells were injected around the infarcted area. The adult human mesenchymal stem cells were identified with fluorescence in situ hybridization technique and myocardial antigens by immunohistochemistry. The immune response was studied by hematoxylin and eosin staining and by antibodies directed toward macrophages. RESULTS: Significant rat lymphocyte proliferation was observed when adult human mesenchymal stem cells were added to peripheral blood from Sprague-Dawley rats previously exposed to adult human mesenchymal stem cells. No reactivity was seen in lymphocytes from untreated Sprague-Dawley rats and athymic rats. Adult human mesenchymal stem cells could only be identified in the myocardium of athymic rats. Further, in normal Sprague-Dawley rats, there was a significant myocardial infiltration of round cells, mostly macrophages, in the area of injection of adult human mesenchymal stem cells. In RNU rats, this reaction was less intense. CONCLUSION: Adult human mesenchymal stem cells did not induce xenoreactivity in vitro in previously unexposed immunocompetent Sprague-Dawley rats. However, although mesenchymal stem cells are transplantable across allogeneic barriers, transplant rejection can occur in a xenogenic model. When transplanted into an immunoincompetent host, adult human mesenchymal stem cells showed persistent engraftment.

Angiogenic effects of dual gene transfer of bFGF and PDGF-BB after myocardial infarction.

Therapeutic effects of combination of angiogenic growth factors for the treatment of ischemia after myocardial infarction are largely unknown. Plasmids expressing basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF-BB) or their combination with a 1:1 mass ratio were injected into hearts with 7-day-old myocardial infarction. Hearts were harvested after 1 and 4 weeks after gene transfer. The major findings in this chronic myocardial infarction model were that bFGF, PDGF-BB and their combination all had a more pronounced angiogenic effect on the arteriolar than the capillary level. bFGF stimulated both capillary and arteriolar growth while PDGF-BB preferentially stimulated arterioles. The combination increased the amount of both capillaries and arterioles and in addition gave rise to stable capillaries compared to single factor transfer but did not further enhance angiogenesis. No cardiovascular side effects were observed after gene transfer.

Surgical closure of patent foramen ovale in patients with suspected paradoxical embolism: long-term results.

OBJECTIVE: It is thought that a patent foramen ovale (PFO) is the crucial mechanism in patients with suspected paradoxical embolism and cryptogenic stroke. It has been hypothesized that closure of the PFO would prevent further cerebrovascular incidents. We describe our early and late experience with surgical closure of the PFO in patients with paradoxical embolism. PATIENTS AND METHODS: Between May 1994 and December 2001, 33 patients (26 men, 7 women; mean age, 55.2 +/- 8.7 years; range, 37-74) underwent surgical closure of a PFO at our institution. All patients had preoperatively suffered from a stroke and/or a transient ischemic attack, after which echocardiography showed a PFO. Mean follow-up at 99 +/- 30 months (range, 10-111 months) was 100% complete. RESULTS: All patients survived the operative procedure. Early complications occurred in four patients (12%). Actuarial survival at 1, 5 and 8 years was 97 +/- 3%, 97 +/- 5% and 94 +/- 8%, respectively. At long-term follow-up all but two patients were alive. The deaths of these two patients were related to malignancy and ischemic heart disease, respectively. Two patients (6%) had suffered a residual cerebrovascular event after successful surgery. CONCLUSION: Surgical closure of PFO in patients with paradoxical embolism can safely be performed with a low risk of early mortality. Residual thromboembolic events were rare and in those few it occurred it did so with the interatrial septum being closed, indicating that in those patients the PFO was not the mechanism of the thromboembolic event in the first place.