SUMMARY:A subset of human peripheral blood mononuclear cells (PB-MNCs) differentiate into endothelial progenitor cells (EPCs) that participate in postnatal neovascularization. Although tissue ischemia can mobilize EPCs from bone marrow, the effects of hypoxia on differentiation and angiogenic function of EPCs are little known. We examined whether hypoxic conditioning would modulate differentiation and function of human PB-MNC-derived EPCs. A subset of PB-MNCs gave rise to EPC-like attaching (AT) cells under either normoxic or hypoxic conditions. However, hypoxia much enhanced the differentiation of AT cells from PB-MNCs compared with normoxia. AT cells released vascular endothelial growth factor (VEGF) protein and expressed CD31 and kinase insert domain receptor/VEGFR-2, endothelial lineage markers, on their surface, which were also enhanced by hypoxia. Both a neutralizing anti-VEGF mAb and a KDR-specific receptor tyrosine kinase inhibitor, SU1498, suppressed PB-MNC differentiation into EPC-like AT cells in a dose-dependent manner. Migration of AT cells in response to VEGF as examined by a modified Boyden chamber apparatus was also enhanced by hypoxia. Finally, in vivo neovascularization efficacy was significantly enhanced by in vitro hypoxic conditioning of AT cells when cells were transplanted into the ischemic hindlimb of immunodeficient nude rats. In conclusion, hypoxia directly stimulated differentiation of EPC-like AT cells from human PB-MNC culture. Moreover, hypoxic preconditioning of AT cells before in vivo transplantation is a useful means to enhance therapeutic vasculogenesis. (Lab Invest 2003, 83:65-73).

Abstract-Hyperhomocysteinemia (HH) is an independent risk factor for atherosclerosis, including peripheral arterial occlusive disease (PAOD). Because angiogenesis and collateral vessel formation are important self-salvage mechanisms for ischemic PAOD, we examined whether HH modulates angiogenesis in vivo in a rat model of hindlimb ischemia. Rats were divided into 3 groups: the control group was given tap water, the HH group was given water containing, and the HHϩL-arg group was given water containing methionine (1 g ⅐ kg [1][2][3][4][5] Moreover, it has been established that modest HH occurs in up to 40% of patients with stroke, myocardial infarction, and/or peripheral arterial obstructive disease (PAOD). 1,6 HH may exert multiple adverse effects on cells composing the vascular wall. In particular, homocysteine induces endothelial dysfunction and thereby accelerates atherosclerosis. 7,8 Light-and electron-microscopic studies of arteries and arterioles from humans and animals have revealed that HH alters endothelial morphology. 5,7,9 HH has also been shown to attenuate endothelium-dependent vasodilatation, 8,10,11 presumably because of the inactivation of endothelium-derived NO (EDNO). 8 In addition, HH has been shown to produce oxygenderived free radicals that further inactivate EDNO. 12,13 We and others have recently reported that EDNO is an important endogenous modulator of angiogenesis. 14 -17 For example, angiogenesis induced by substance P, an endothelium-dependent vasodilator, 14 or vascular endothelial growth factor, 15,16 a potent angiogenic cytokine, was significantly attenuated by inhibitors of NO synthase (NOS). More recently, we showed that angiogenesis occurring after surgically induced hindlimb ischemia was severely impaired in mice lacking the gene for the endothelial constitutive NOS. 17 Although such adverse effects of HH on endothelial cells (ECs) have been documented in numerous studies, the effects of HH on angiogenesis and collateral vessel formation in response to tissue ischemia have not been examined as yet. This issue is clinically relevant inasmuch as HH is an independent risk factor for PAOD. In patients with PAOD, regional angiogenesis and collateral vessel formation from surrounding tissues are critical self-defense mechanisms for tissue survival. 18 Accordingly, we investigated the effects of HH on angiogenesis, collateral vessel formation, and regional blood flow in a rat model of surgically induced hindlimb ischemia. We also investigated whether oral supplementation of L-arginine, a substrate for NOS, had favorable effects on a potential HH-mediated impairment of angiogenesis.

Ischemia-induced angiogenesis was inhibited by HC, which was rescued by oral folate supplementation, at least in part, via an NO-dependent manner.

Transthoracic echocardiography or transesophageal echocardiography is sometimes useful in intracardiac tumor biopsy. Intracardiac echocardiography was used as an alternative to either of these for performing a biopsy of a right cardiac tumor in a 79-year-old woman. The procedure was well tolerated and no complications occurred. Histopathological findings and immunohistological staining were compatible with the diagnosis of neurogenic sarcoma.

Thirty-one-year-old woman with Kawasaki disease wanted a child. She had a large coronary aneurysm on the left main coronary artery and complete obstruction of the right coronary artery, but there was no sign of ischemia. Heparin anticoagulant therapy was begun 8 weeks after the onset of pregnancy. The activated partial thromboplastin time (APTT) was successfully maintained at 1.5 to 2.0 times normal value during pregnancy and puerperium. There were no thromboembolic complications during pregnancy or after an uneventful cesarean delivery. The neonate was healthy.