Objective. Defective angiogenesis, resulting in tissue ischemia, is particularly prominent in the diffuse form of systemic sclerosis (SSc). The present study was undertaken to identify possible differences between normal and SSc microvascular endothelial cells (MVECs) in the expression of the cell-associated urokinase-type plasminogen activator (uPA)/uPA receptor (uPAR) system, which is critical in the angiogenic process.Methods. MVECs were isolated from the dermis of healthy individuals and from the dermis of patients with diffuse SSc. The uPA/uPAR system was examined at the protein and messenger RNA levels. Angiogenesis was assayed on Matrigel-coated porous filters and plates to evaluate cell proliferation, invasion, and capillary morphogenesis. Cleavage of uPAR and the activity of matrix metalloproteinase 12 (MMP-12) were evaluated by Western blotting.Results

Objective. Systemic sclerosis (SSc) is a disorder characterized by vascular damage and fibrosis of the skin and internal organs. Despite marked tissue hypoxia, there is no evidence of compensatory angiogenesis. The ability of mesenchymal stem cells (MSCs) to differentiate into endothelial cells was recently demonstrated. The aim of this study was to determine whether impaired differentiation of MSCs into endothelial cells in SSc might contribute to disease pathogenesis by decreasing endothelial repair.Methods. MSCs obtained from 7 SSc patients and 15 healthy controls were characterized. The number of colony-forming unit-fibroblastoid colonies was determined. After culture in endothelial-specific medium, the endothelial-like MSC (EL-MSC) phenotype was assessed according to the surface expression of vascular endothelial growth factor receptors (VEGFRs). Senescence, chemoinvasion, and capillary morphogenesis studies were also performed.Results. MSCs from SSc patients displayed the same phenotype and clonogenic activity as those from controls. In SSc MSCs, a decreased percentage of VEGFR-2؉, CXCR4؉, VEGFR-2؉/CXCR4؉ cells and early senescence was detected. After culturing, SSc EL-MSCs showed increased expression of VEGFR-1, VEGFR-2, and CXCR4, did not express CD31 or annexin V, and showed significantly decreased migration after specific stimuli. Moreover, the addition of VEGF and stromal cell-derived factor 1 to cultured SSc ELMSCs increased their angiogenic potential less than that in controls.Conclusion. Our data strongly suggest that endothelial repair may be affected in SSc. The possibility that endothelial progenitor cells could be used to increase vessel growth in chronic ischemic tissues may open up new avenues in the treatment of vascular damage caused by SSc.

These results indicate that HSCT with a high dose CYC regimen may foster vascular remodelling, while CYC at lower doses and with a chronic regimen does not influence the microvasculature.

Objective. Postnatal angiogenesis relies on a proper response of endothelial cells to angiogenic stimuli. In systemic sclerosis (SSc), endothelial cells are unresponsive to angiogenic factors. Since circumstantial and experimental evidence points to tissue kallikreins as powerful effectors of the angiogenic response, we undertook this study to investigate the kallikrein pattern of normal and SSc endothelial cells in order to identify differences that can account for defective angiogenesis.Methods. Expression of 14 tissue kallikreins was studied by a microarray approach, by reverse transcription-polymerase chain reaction, and by Western blotting in endothelial cells isolated from the skin of clinically healthy subjects and SSc patients. Cell proliferation was quantified by direct cell counting. Invasion and capillary morphogenesis were evaluated in a Boyden chamber and in culture flasks layered with Matrigel. Cyclic nucleotide production was measured by enzyme immunoassay. MAP kinase and ERK activation were measured by Western blotting.Results. Endothelial cells from SSc patients showed poor expression of kallikreins 9, 11, and 12 compared with endothelial cells from normal subjects. Antibodies against the relevant kallikreins on normal endothelial cells revealed that while kallikreins 9, 11, and 12 induced cell growth, only kallikrein 12 regulated invasion and capillary morphogenesis. Buffering of kallikrein 12 with antibodies resulted in the acquisition of an SSc-like pattern by normal cells in in vitro angiogenesis. Reduction of cAMP and cGMP production and of ERK phosphorylation upon administration of antikallikrein antibodies revealed that the activity of kallikreins 9, 11, and 12 was mediated by kinins.Conclusion. Reduction of tissue kallikreins 9, 11, and 12 may be relevant to reduced angiogenesis in SSc patients.

Objectives:To study the expression of adhesion molecules in patients with systemic sclerosis (SSc) with and without pulmonary arterial hypertension (PAH) and the effects of therapy with the endothelin-1 (ET-1) receptor antagonist, bosentan.Methods:In all, 35 patients with SSc and 25 healthy donors (HD) were selected for this study. Of 35 patients, 10 had isolated PAH assessed by Doppler echocardiography and treated with bosentan. Peripheral blood (PB) lymphocytes were isolated by density gradient centrifugation, and the expression of lymphocyte function-associated antigen-1 (LFA-1), very late antigen-4 (VLA-4) and L-selectin on CD3 T cells was assessed by double immunofluorescence and flow-cytometry. As endothelial activation markers, serum soluble P-selectin, platelet/endothelial cell adhesion molecule (PECAM)-1, vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1 and von Willebrand factor (vWF) antigen were assessed by ELISA. In patients with SSc-PAH, T cell subsets and soluble endothelial markers were assessed at baseline and after 6 and 12 months of bosentan therapy.Results:In patients with SSc-PAH, serum soluble ICAM-1, VCAM-1, P-selectin and PECAM-1 levels were higher than in HD at baseline and fell to normal values after 12 months of bosentan therapy. CD3–LFA1 T cells were significantly higher in PAH-SSc at baseline than in HD or SSc and significantly decreased after therapy. CD3–L-selectin T cells were significantly lower in SSc-PAH at baseline than in HD or SSc and rose to normal levels after bosentan therapy.Conclusions:This study confirms that endothelial activation occurs in SSc, and suggests that changes in the T cell/endothelium interplay take place in SSc-associated PAH. Bosentan seems to be able to hamper these changes and restore T cell functions in these patients.