R-Smad signaling-mediated VEGF expression coordinately regulates endothelial cell differentiation of rat mesenchymal stem cells.

A low-efficiency yield hinders the use of stem cells as a source of endothelial cells (ECs) for therapeutic vascularization, and the diversity of the transforming growth factor-ß (TGF-ß) superfamily has undermined understanding the effects of its potent vascularization-inducing. Herein, we studied the role of the TGF-ß superfamily in EC differentiation of rat bone marrow mesenchymal stem cells (MSCs) induced by Smad2/3 and Smad1/5/8 signaling. MSCs that had been sorted by flow cytometry as CD31-negative were cultured for 14 days in medium supplemented with vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) as the control. The Smad2/3 pathway was activated by TGF-ß1 and Smad1/5/8 by bone morphogenetic proteins (BMPs). In the early phase in the Smad2/3-activated group, there were 10% CD31-positive cells, which was significantly higher than in the control group. A low Smad1/5/8 phosphorylation level after BMP4 activation doubled the number of CD31-positive cells, while a higher phosphorylation level after BMP9 activation showed no effect. A Smad2/3 inhibitor initially blocked differentiation but later promoted it, while a Smad1/5/8 inhibitor reversed the induction observed with BMPs. Moreover, the positive effects of R-Smad on differentiation were weakened by the VEGF neutralizing antibody, and a Smad3 inhibitor decreased VEGF expression and blocked differentiation in both the early and late phases. In conclusion, differentiation of ECs from MSCs via Smad2/3 signaling is stage dependent. Activation, particularly by Smad3, significantly promotes differentiation at an early phase but later is suppressive. A low Smad1/5/8 phosphorylation level has a positive effect, and R-Smad effects are partly mediated by VEGF.

MCP-1 stimulates MMP-9 expression via ERK 1/2 and p38 MAPK signaling pathways in human aortic smooth muscle cells.

OBJECTIVE: We investigated the molecular mechanism underlying the role of monocyte chemoattractant protein-1 (MCP-1) in the formation and development of human abdominal aortic aneurysm (AAA). METHODS: We examined protein expression profiles using a protein array and found that MCP-1 was the most highly expressed protein in AAA tissues compared with normal aortas. To investigate the potential mechanism of MCP-1 involvement in the pathogenesis of AAA, we treated human aortic smooth muscle cells (HASMCs) with human recombinant MCP-1. RESULTS: MCP-1 was the most highly expressed protein in AAA tissues compared with normal aorta; matrix metalloproteinase-9 (MMP-9) expression was also significantly increased. Treatment with MCP-1 significantly increased the expression and activation of MMP-9 and activated the three major mitogen activated protein kinases (MAPKs) extracellular signal regulated kinase (ERK), c-Jun amino terminal kinase (JNK1/2) and p38 MAPK. Furthermore, MCP-1-induced secretion of MMP-9 was inhibited by U0126 (inhibitor of the ERK 1/2 pathway) and SB203580 (inhibitor of the p38 MAPK pathway), but not SP600125 (inhibitor of the JNK1/2 pathway). CONCLUSION: These data demonstrate that MCP-1 stimulates secretion of MMP-9 directly through the ERK1/2 and p38 MAPK mediated pathways in HASMCs. Thus, inhibition of this molecular mechanism might be a potential therapeutic target in the non-surgical treatment of AAA.

Combination of stromal-derived factor-1alpha and vascular endothelial growth factor gene-modified endothelial progenitor cells is more effective for ischemic neovascularization.

BACKGROUND: Recruitment and entrapment of bone marrow-derived endothelial progenitor cells (EPCs) is important in vascular endothelial growth factor (VEGF)-induced angiogenesis. EPC mobilization and differentiation are modulated by stromal-derived factor-1alpha (SDF-1alpha/CXCL12), another important chemokine. In this study, we investigated the hypothesis that SDF-1alpha and VEGF might act synergistically on EPC-mediated vasculogenesis. METHODS: EPCs were isolated and cultured from human peripheral blood, then transduced with retroviral vectors pBabe containing human VEGF(165) complimentary DNA (Td/V-EPCs) and pBabe wild-type (Td/p-EPCs). EPC migration activity was investigated with a modified Boyden chamber assay. EPC apoptosis induced by serum starvation was studied by annexin V assays. The combined effect of local administration of SDF-1alpha and Td/V-EPC transplantation on neovascularization was investigated in a murine model of hind limb ischemia. RESULTS: Over-expression of hVEGF(165) increased SDF-1alpha-mediated EPC migration. SDF-1alpha-mediated migration was significantly increased when EPCs were modified with VEGF (Td/V-EPCs) vs when VEGF was not present (Td/p-EPCs) or when VEGF alone was present (Td/V-EPCs; 196.8 +/- 15.2, 81.2 +/- 9.8, and 67.4 +/- 7.4/mm(2), respectively P < .001). SDF-1alpha combined with VEGF reduced serum starvation-induced apoptosis of EPCs more than SDF-1alpha or VEGF alone (P < .001). To determine the effect of this combination in vivo, SDF-1alpha was locally injected alone into the ischemic hind limb muscle of nude mice or combined with systemically injected Td/V-EPCs. The SDF-1alpha plus VEGF group showed significantly increased local accumulation of EPCs, blood-flow recovery, and capillary density compared with the other groups. The ratio of ischemic/normal blood flow in Td/V-EPCs plus SDF-1alpha group was significantly higher (P < .01), as was capillary density (capillaries/mm(2)), an index of neovascularization (Td/V-EPCs plus SDF-1alpha group, 863 +/- 31; no treatment, 395 +/-13; SDF-1alpha, 520 +/- 29; Td/p-EPCs, 448 +/- 28; Td/p-EPCs plus SDF-1alpha, 620 +/- 29; Td/V-EPCs, 570 +/- 30; P < .01). To investigate a possible mechanistic basis, we showed that VEGF up-regulated the receptor for SDF-1alpha, CXCR4, on EPCs in vitro. CONCLUSION: The combination of SDF-1alpha and VEGF greatly increases EPC-mediated angiogenesis. The use VEGF and SDF-1alpha together, rather than alone, will be a novel and efficient angiogenesis strategy to provide therapeutic neovascularization.

[Clinical analysis of mesenteric venous thrombosis:a report of 23 cases].

OBJECTIVE: To assess the early clinical diagnosis and treatment of mesenteric venous thrombosis (MVT). METHODS: Clinical data of 23 cases with MVT from January 1994 to December 2003 were analyzed retrospectively. RESULTS: There were 17 males and 6 females, the age ranged from 19 to 74 years old with a mean age of 42 years. Of them, 20 patients presented acute MVT. The main symptoms included abdominal pain and distention, nausea, vomiting, and bloody stool. The detect able rates of transabdominal color Doppler ultrasonography and CT for MVT were 94.1% and 100% respectively. Nine of 11 (81.8%) patients were cured with non-surgical management. Twelve patients underwent surgical treatments including resection of the infarcted bowel and open mesenteric venous thrombectomy with Fogarty catheter via a branch of mesenteric vein. The in-hospital mortality rate was 8.7%, and the postoperative morbidity rate was 33.3%, including ascites in 2 patients and postprandial abdominal pain in other 2 patients. After follow-up from 2 months to nine years, 3 patients had MVT recurrence because of ceasing anti-coagulation treatment and 3 died of myocardial infarction, liver cancer and hepatic cirrhosis. CONCLUSION: Color Doppler ultrasonography and CT scanning are valuable diagnostic methods for MVT, and anticoagulation treatment and operation are effective managements.