IntroductionThe urokinase-type plasminogen activator (u-PA) and its cellular receptor (u-PAR, CD87) are involved in cell migration such as occurs during tumor invasion and angiogenesis. 1 The u-PAR regulates the u-PA activity on the cell surface not only by mediating the localization of u-PA and the internalization of u-PA/inhibitor complexes but also by an increase in the efficiency of plasminogen activation by u-PAR-bound u-PA. 2 Pro-u-PA bound to the receptor can be converted into the protease u-PA and subsequently be inhibited by plasminogen activator inhibitor type 1 (PAI-1). The u-PA:PAI-1 complex is subsequently internalized and degraded in the lysosomes, while the u-PAR is recycled to the cell surface. Besides a role in controlling u-PA activity, u-PAR is involved in activating cell signaling pathways, including diacylglycerol formation, activation of a serine kinase, focal adhesion kinase, tyrosine kinase(s), and the activation of the Janus kinase/signal transducer and activator of transcription pathway. Furthermore, u-PAR enforces cellular interaction with the extracellular matrix, in particular by binding to the matrix protein vitronectin and to integrins. Recently, u-PAR has been shown to possess chemokine-like activity mediating chemotaxis of monocytes, neutrophils, and smooth muscle cells. 3,4 The u-PAR is a glycosyl phosphatidylinositol (GPI)-anchored receptor that contains 3 homologous domains. The amino-terminal domain (D1) is involved in both the binding of u-PA 5,6 and the interaction with vitronectin, 7,8 but the other 2 domains of u-PAR are also indispensable for high-affinity interactions. 9,10 The GPI anchor of u-PAR can be cleaved by GPI-specific phospholipases, resulting in a soluble form of u-PAR (su-PAR). Recently, Wilhelm et al showed that a cellular phospholipase D might be involved in the release of su-PAR. 11 In addition to the shedding of the full-size u-PAR, the finding of truncated D2D3 fragments of u-PAR on the cell membrane implies that D1 domains can also be cleaved directly from u-PAR. Cleavage of u-PAR between domains D1 and D2 can be mediated by proteolytic activity of u-PA, directly or indirectly via the plasminogen activation/plasmin 12,13 or by other proteases such as chymotrypsin and elastase. 5,14 A similar region has not been observed between domains D2 and D3. 15 The soluble form of u-PAR has been found in vitro in culture supernatants of tumor cell lines, 12,16 in vivo in plasma and serum, [17][18][19][20] in uterine tissue cultures from women with endometriosis, 21 and in ascitic and cystic fluid from ovarian cancer patients. 22,23 Recently, Chavakis et al 24 reported that normal human vascular cells (smooth muscle cells and endothelial cells) also release su-PAR in the medium, especially after stimulation with phorbol myristate acetate (PMA).Numerous studies have shown the involvement of u-PAR in the migration and tissue infiltration of cells. The u-PAR undoubtedly plays an important role in the migration and invasion of monocytes, 25 34 Previously we have provid...

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Abstract-Angiostatin, which consists of the kringle I-IV domains of plasminogen and which is secreted into urine, is an efficient inhibitor of angiogenesis and tumor growth. Because N-terminal apolipoprotein(a) [apo(a)] fragments, which also contain several types of kringle IV domains, are found in urine as well, we evaluated the potential angiostatic properties of these urinary apo(a) fragments and of a recombinant form of apo(a) [r-apo(a)]. We used human microvascular endothelial cell (hMVEC)-based in vitro assays of tube formation in 3-dimensional fibrin matrixes. Purified urinary apo(a) fragments or r-apo(a) inhibited the basic fibroblast growth factor/tumor necrosis factor-␣-induced formation of capillary-like structures. At concentrations varying from 0.2 to 10 g/mL, urinary apo(a) fragments inhibited tube formation by as much as 70%, whereas there was complete inhibition by r-apo(a). The highest concentrations of both inhibitors also reduced urokinase plasminogen activator production of basic fibroblast growth factor-induced hMVEC proliferation. The inhibitors had no effect on plasminogen activator inhibitor-1 expression. If our in vitro model for angiogenesis is valid for the in vivo situation as well, our data point toward the possibility that apo(a) may also be physiologically operative in modulating angiogenesis, as the concentration of free apo(a) found in humans exceeds that tested herein.

Background: Sarcopenia contributes to the decreased quality of life in the older person.While resistance exercise is an effective measure to increase muscle mass and strength, the hypertrophic response may be blunted in old age.Objectives: To determine 1) whether hypertrophy in the m. plantaris of old mice was blunted compared to adult and 2) whether this was related to a reduced satellite cell (SC) density and 3) how resveratrol affects hypertrophy in old mice. Methods:In adult (7.5 months, n=11), old (23.5 months, n=10) and old-resveratrol-treated (n=10) male C57BL/6j mice, hypertrophy of the left m. plantaris was induced by denervation of its synergists. The contralateral leg served as control.Results: After six weeks, overload-induced myofiber hypertrophy and IIB-IIA shift in myofiber type composition were less pronounced in old than adult mice (P=0.03), irrespective of resveratrol treatment. Muscles from old mice had a lower SC density than adult muscles (P=0.002). Overload-induced SC proliferation (P<0.05) resulted in an increased SC density in old, but not adult muscles (P=0.02), while a decrease occurred after resveratrol supplementation (P=0.044). Id2 and myogenin protein expression levels were higher in old than adult muscles (P<0.05). Caspase-3 was expressed more in hypertrophied than control muscles and was reduced with resveratrol (P<0.05). Conclusion:The blunted hypertrophic response in old mice was associated with a lower SC density, but there was no evidence for a lower capacity for proliferation. Resveratrol did not rescue the hypertrophic response and even reduced, rather than increased, the number of SCs in hypertrophied muscles.

Objective-Emerging evidence suggests that human blood contains bone marrow (BM)-derived endothelial progenitor cells that contribute to postnatal neovascularization. Clinical trials demonstrated that administration of BM-cells can enhance neovascularization. Most studies, however, used crude cell populations. Identifying the role of different cell populations is important for developing improved cellular therapies. Methods and Results-Effects of the hematopoietic stem cell-containing CD34ϩ cell population on migration, proliferation, differentiation, stimulation of, and participation in capillary-like tubule formation were assessed in an in vitro 3-dimensional matrix model using human microvascular endothelial cells. During movement over the endothelial monolayer, CD34ϩ cells remained stuck at sites of capillary tube formation and time-and dose-dependently formed cell clusters. Immunohistochemistry confirmed homing and proliferation of CD34 ϩ cells in and around capillary sprouts. CD34 ϩ cells were transduced with the LNGFR marker gene to allow tracing. LNGFR gene-transduced CD34 ϩ cells integrated in the tubular structures and stained positive for CD31 and UEA-1. CD34ϩ cells alone stimulated neovascularization by 17%. Coculture with CD34Ϫ cells led to 68% enhancement of neovascularization, whereas CD34 Key Words: angiogenesis Ⅲ nitric oxide, endothelium, vascular type Ⅲ gene therapy Ⅲ peripheral vascular disease T he formation of new capillaries plays a critical role in physiological and pathological processes such as wound healing, ischemia, and tumor growth. It has long been thought that postnatal neovascularization occurred exclusively by migration and proliferation of preexisting endothelial cells (angiogenesis). Increasing evidence indicates that bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs) are also involved in postnatal new vessel formation, 1 a process that, reminiscent of embryonic vessel formation, is termed adult vasculogenesis. 2 The concept of "therapeutic vasculogenesis," administration of adult progenitor cells or progenitor-containing cell populations to stimulate neovascularization, and the potential of progenitor cells to serve as new vehicles for gene therapy have received a lot of scientific attention. Several small clinical trials aimed at therapeutic vasculogenesis by autologous transplantation of BM cells have been performed and improved clinical outcomes in patients with severe chronic limb ischemia or myocardial ischemia have been reported. [3][4][5][6] An important question concerning therapeutic vasculogenesis is, which cell population should be administered? Thus far, most clinical studies have used nonselected BM mononuclear cells; however, administration of such crude cell populations may have unwanted side effects. Recent data suggest that beside EPCs, BM contains other progenitor cells that may contribute to atherosclerosis, 7 whereas hematopoietic cells were reported to have the capacity to produce profibrotic and angiogenic factors. 8,9 Better charact...