Endothelial progenitor cells (EPCs) seem to be a promising option to treat patients with ischemic diseases. Here, we investigated the effects of late outgrowth EPCs, or endothelial colony-forming cells (ECFCs), a recently defined homogeneous subtype of EPCs, in a rat model of transient middle cerebral artery occlusion (MCAO). Either vehicle or 4.10(6) ECFCs, isolated from human cord blood, were intravenously injected 24 h after 1 h MCAO in rats assigned to control and transplanted groups respectively. (111)In-oxine-labeled ECFCs specifically homed to ischemic hemisphere and CM-Dil prelabeled ECFCs preferentially settled in the inner boundary of the core area of transplanted animals. Although incorporation of cells into neovessels was hardly detectable, ECFCs transplantation was associated with a reduction in apoptotic cell number, an increase in capillary density and a stimulation of neurogenesis at the site of injury. These effects were associated with an increase in growth factors expression in homogenates from ischemic area and may be related to the secretion by ECFCs of soluble factors that could affect apoptosis, vascular growth and neurogenesis. Microscopic examination of the ischemic hemisphere showed that ECFCs transplantation was also associated with a reduction in reactive astrogliosis. In conclusion, we demonstrated that ECFCs injected 24 h after MCAO settled in the injured area and improved functional recovery. The neurological benefits may be linked to a reduction in ischemia-induced apoptosis and a stimulation of ischemia-induced angiogenesis and neurogenesis. These findings raise perspectives for the use of ECFCs as a well-characterized cell therapy product for optimal therapeutic outcome after stroke.

Fucoidans are sulfated fucosylated polymers from brown algae cell wall that exhibit some heparin/heparan sulfate properties. We previously demonstrated that these polysaccharides were able in vitro to stimulate dermal fibroblast proliferation and extracellular matrix deposition. Here, we investigated the action of a 16kDa fucoidan fraction on parameters involved in connective tissue breakdown. This fucoidan is able to inhibit gelatinase A secretion and stromelysin 1 induction by interleukin-1beta on dermal fibroblasts in culture. Furthermore, we observed that fucoidan increases the rate of association of MMPs with their specific inhibitors namely TIMPs. Using tissue sections of human skin in ex vivo experiments, we evidenced that this polysaccharide was able to minimize human leukocyte elastase activity resulting in the protection of human skin elastic fiber network against the enzymatic proteolysis due to this serine proteinase. These results suggested that fucoidan could be used for treating some inflammatory pathologies in which uncontrolled extracellular matrix degradation takes place.

CD146, an endothelial molecule involved in permeability and monocyte transmigration, has recently been reported to promote vessel growth. As CD146 is also detectable as a soluble form (sCD146), we hypothesized that sCD146 could stimulate angiogenesis. Experiments of Matrigel plugs in vivo showed that sCD146 displayed chemotactic activity on endogenous endothelial cells, and exogenously injected late endothelial progenitor cells (EPCs) . IntroductionCD146 is a component of the endothelial junction primarily expressed in endothelial cells. It is involved in the control of cell and tissue architecture, as demonstrated by the regulation of its expression during endothelium monolayer formation, its involvement in the control of paracellular permeability, and its colocalization with the actin cytoskeleton. 1 Besides its structural role, CD146 is also involved in cell signaling. 2,3 We have recently demonstrated that CD146 is involved in the regulation of monocyte transendothelial migration. 4 Recent findings indicate that CD146 displays angiogenic properties. In one study, the authors showed that an anti-CD146 antibody, mAb AA98, displayed antiangiogenic properties in chicken chorioallantoic membrane assays and inhibited tumor growth in different xenografted human tumor models in mice. In a model of human umbilical vein endothelial cells (HUVECs), it was also shown that silencing CD146 with specific siRNA inhibited the proliferation and migration of the cells. [5][6][7] Of interest, we have established that CD146 also exists in a soluble form (sCD146) as the result of metalloprotease-dependent shedding of membrane CD146. 4,8 sCD146 is detectable in the human serum, and its level is modulated in different pathologies, such as inflammatory bowel diseases, 9 pathologic pregnancies, 10 and chronic renal failure. 11 However, its exact role is still largely unknown.Postischemic neovascularization occurs as a result of 2 mechanisms: angiogenesis, which relies on mature endothelial cells already present at the ischemic site; and vasculogenesis, which involves the homing and endothelial differentiation of endothelial progenitor cells (EPCs) mobilized from the bone marrow. 12,13 Different angiogenic factors have been shown to trigger angiogenesis and/or vasculogenesis by directly or indirectly stimulating proliferation, differentiation, and migration of mature or precursor cells. Among these factors, the more effective are fibroblast growth factors (FGFs), vascular endothelial growth factor (VEGF), and angiopoietins (Ang). FGF-1 has been shown to stimulate the proliferation and differentiation of all cell types necessary for the constitution of an arterial vessel, including endothelial cells and smooth muscle cells. FGF-2 also promotes endothelial cell proliferation and organization of endothelial cells into capillary-like structures. 14 In vitro studies have clearly demonstrated that VEGF is a potent stimulator of angiogenesis, stimulating endothelial cell mitogenesis and migration, 15 and numerous clinical trials have been co...

Rationale: CD146, a transmembrane immunoglobulin mainly expressed at the intercellular junction of endothelial cells, is involved in cell-cell cohesion, paracellular permeability, monocyte transmigration and angiogenesis. CD146 exists as 2 isoforms, short (sh) and long (lg), but which isoform is involved remains undefined. Objective: The recently described role of CD146 in angiogenesis prompted us to investigate which isoform was involved in this process in human late endothelial progenitors (EPCs), with the objective of increasing their proangiogenic potential. Methods and Results: Immunofluorescence experiments showed that, in subconfluent EPCs, shCD146 was localized in the nucleus and at the migrating edges of the membrane, whereas lgCD146 was intracellular. In confluent cells, shCD146 was redistributed at the apical membrane and lgCD146 was directed toward the junction. In contrast to lgCD146, shCD146 was overexpressed in EPCs as compared to mature endothelial cells and upregulated by vascular endothelial growth factor and SDF-1 (stromal cell-derived factor 1). Study of the properties of both isoforms in vitro provided evidence that shCD146 was involved in EPC adhesion to activated endothelium, migration, and proliferation, with a paracrine secretion of interleukin-8 or angiopoietin 2, whereas lgCD146 was implicated in stabilization of capillary-like structures in Matrigel and transendothelial permeability. In an animal model of hindlimb ischemia, transplantation of shCD146-modified EPCs selectively promoted both EPC engraftment and blood flow. Conclusions: Altogether, these findings establish that CD146 isoforms display distinct functions in vessels regeneration.Selective improvement of therapeutic angiogenesis by shCD146 overexpression suggests a potential interest of shCD146-transduced EPCs for the treatment of peripheral ischemic disease. (Circ Res. 2010;107:66-75.)Key Words: CD146 Ⅲ endothelial progenitor Ⅲ angiogenesis Ⅲ ischemia Ⅲ peripheral artery disease C D146 is a cell adhesion molecule belonging to the immunoglobulin superfamily. It has been described as a component of the endothelial junction involved in the control of cell cohesion, permeability, and monocyte transmigration. 1,2 Initially described as a marker of tumor growth and metastasis in human melanoma, 3 CD146 has recently been shown to be involved in angiogenesis. Thus, it was reported that anti-CD146 antibodies inhibited proliferation and migration of HUVECs, 4 and also inhibited angiogenesis in chicken chorioallantoic membrane assays and tumor growth in mice. 5 Two different isoforms of gicerin, the chicken homolog of CD146, have been described by Dunon and colleagues.These 2 isoforms are generated by alternative splicing and differ at the end of their cytoplasmic region. 6 -8 The short isoform of gicerin exhibits a putative PDZ binding domain, which could mediate its anchoring to the cytoskeleton, whereas the long isoform contains a putative endocytosis motif. 6 Recently it was shown that, under shear stress conditions, transfection...

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