Background-Transplantation of endothelial progenitor cells has been proposed as a potential strategy for therapeutic revascularization. However, the limited endogenous cell pool and the related technical difficulties constitute clinically important disadvantages to autologous transplantation. In this study we investigated whether fully differentiated endothelial cells (ECs) modified with gene transfer of Id1, a helix-loop-helix transcription factor involved in angiogenesis, have the potential to contribute to therapeutic angiogenesis. Methods and Results-The

oth coronary artery bypass grafting and percutaneous coronary intervention ameliorate angina pectoris, prevent myocardial infarction and improve the long-term survival of patients with atherosclerotic coronary artery disease. However, the nature of coronary arteries significantly impacts the quality of life. Standard therapies for myocardial revascularization are often limited because of diffuse lesions or small-caliber vessels. Angiogenic therapy to induce myocardial neovascularization is not dependent on vessel caliber and provides an alternative treatment alone or in combination with standard revascularization. Basic fibroblast growth factor (bFGF) is a potent angiogenic protein that induces endothelial and smooth muscle cell proliferation in vivo and elicits angiogenesis that includes the migration and proliferation of endothelial cells, vascular tube formation and linkage to the extant vascular network. 1 Intracoronary injections of bFGF reduce infarct size in a canine model of myocardial infarction and improve myocardial function in chronically ischemic porcine hearts. 2,3 We have previously shown that the intramyocardial administration of bFGF increased the number of capillaries and arterioles in the peri-infarct region, increased regional myocardial blood flow and consequently improved ven- Circulation Journal Vol.70, April 2006tricular function in a canine infarction model. 4 However, angiogenesis induced by growth factors has not been always successful. Despite high binding affinity for acidic polysaccharides such as heparin and heparan sulfate in the extracellular matrix, bFGF has a short biological half-life in tissues. 5 The sustained release of bFGF might help to enhance its angiogenic activity in vivo. 6,7 Gelatin is a nontoxic, biodegradable, natural polymer with low antigenicity and gelatin hydrogel is considered to be a preferable matrix for the sustained release of protein drugs, such as growth factors. 8,9 However, the effects of intramyocardial injections of slow-release bFGF on vascular growth, cardiomyocyte apoptosis and cardiac function have not been investigated in detail. The present study evaluates the ability of gelatin hydrogels to enhance the benefits of bFGF on neoangiogenesis, cardiomyocyte apoptosis, myocardial fibrosis, ventricular remodeling and cardiac function in a rat infarction model. Methods Preparation of bFGFHuman recombinant bFGF and gelatin hydrogels were provided by Kaken Pharmaceutical, Tokyo, Japan. Gelatin with an isoelectric point of 4.9 was prepared using alkaline treatment of bovine collagen with Ca(OH)2. To obtain gelatin hydrogels that incorporated bFGF, 0.7 ml of saline containing 350 g of bFGF was impregnated into freezedried hydrogels. The release of biologically active bFGF is sustained as a result of hydrogel degradation in vivo. Empty gelatin hydrogels free of bFGF were similarly prepared. Background Basic fibroblast growth factor (bFGF) stimulates neoangiogenesis. Incorporation into biodegradable gelatin hydrogels provides the sustained release of bFGF....

Id1, an inhibitory partner of basic-helix-loop-helix transcriptional factors, has recently been recognized as a potent contributor to angiogenesis. However, the molecular mechanism underlying its role in angiogenesis remains essentially unknown. Herein we demonstrate the subcellular localization of Id1 to be altered depending on the cellular context of vascular endothelial cells. Id1 was localized in the nuclei of human umbilical vein endothelial cells (HUVECs) cultured on uncoated plates, whereas it was translocated to the cytoplasm in HUVECs on Matrigel along with the formation of capillary-like structures. Treatment with the nuclear export inhibitor leptomycin B and mutagenesis analysis using green fluorescent protein-fused Id1 revealed CRM1/exportin-dependent nuclear export of Id1 in HUVECs on Matrigel. This nuclear export of Id1 was inhibited by protein kinase A (PKA) activation by dibutyryl cyclic AMP and forskolin but was promoted by PKA inactivation by H-89 and MDL-12,330A. Mutagenesis analysis of Id1 showed the phosphorylation of Ser-5 to possibly mediate the effect of PKA. These results suggest the function of Id1 as a transcriptional factor to be controlled by nucleocytoplasmic shuttling during angiogenesis and that PKA might be involved in this process. This may serve as a novel mechanism regulating angiogenesis and as a possible target for therapeutic vascular regeneration.

We retrospectively searched for factors that can predict the circulating platelet count after cardiopulmonary bypass (CPB) and postoperative blood loss. Correlations between the circulating platelet count after CPB and several other perioperative variables were investigated in 42 patients who underwent cardiac surgery using the same type of oxygenator. Correlations between perioperative variables and 24 hour postoperative blood loss were also investigated. A multiple stepwise regression analysis showed that the preoperative platelet count, age, and intraoperative blood transfusion values were independent predictors of the circulating platelet count after CPB (R2 = 0.661, p < 0.0001). Gender, operation type, and priority (elective or urgent) were not associated with the platelet count after CPB or postoperative blood loss. Independent predictive factors for postoperative blood loss consisted of age and intraoperative blood loss (R2 = 0.231, p = 0.006). In addition to preoperative platelet count, age and amount of intraoperative blood transfusion are predictive factors for circulating platelet count after CPB. The association of postoperative blood loss with age and intraoperative blood loss may suggest friability of the tissues, including blood vessels, in elderly patients.