Inhibitory effects of mesenchymal stem cells in intimal hyperplasia after balloon angioplasty.

OBJECTIVE: Intimal hyperplasia is a major cause of restenosis after arterial bypass and balloon angioplasty. Induction of rapid re-endothelialization has been proposed to reduce intimal hyperplasia. The aim of this study was to evaluate the inhibitory effect of mesenchymal stem cells on intimal hyperplasia. METHODS: Male New Zealand white rabbits were fed 1% cholesterol diets from 1 week before balloon angioplasty to the day of harvest. After dissection of rabbit carotid arteries, balloon angioplasty was performed with a 2F Fogarty embolectomy catheter. The injured carotid artery was coated with a mixture of 7 × 10(6) human umbilical cord mesenchymal stem cells (HUC-MSCs) and fibrin matrix. The carotid arteries were harvested 2, 4, and 8 weeks thereafter, and immunofluorescent staining and quantitative real-time polymerase chain reaction analysis were performed. RESULTS: The intima/media ratio was significantly reduced in the group treated with HUC-MSCs compared with the nontreated group (Student t-tests, *P < .05). The area of re-endothelialization was significantly higher (Student t-tests, *P < .05) in the group treated with HUC-MSCs than in the nontreated group. Expression of angiogenic genes such as vascular endothelial growth factor, platelet-derived growth factor, kinase insert domain receptor 1, angiopoietin 1, and angio-associated migratory cell protein was increased (analysis of variance, P < .05) in the group treated with HUC-MSCs relative to the nontreated group. CONCLUSIONS: Our study showed that HUC-MSCs reduce the formation of intimal hyperplasia through rapid re-endothelialization. This result might be applied to development of stem cell-coated stents as well as to development of a stem cell-containing sheet coat for inhibition of intimal hyperplasia after angioplasty or surgery.

Enhancement of angiogenic effects by hypoxia-preconditioned human umbilical cord-derived mesenchymal stem cells in a mouse model of hindlimb ischemia.

It has been studied that mesenchymal stem cells (MSCs) have the capability to promote angiogenesis. Furthermore, there is strong evidence that hypoxic conditions can enhance angiogenesis and immune modulation mediated by MSCs, a notion that has been applied in many fields of clinical application. In the present study, we compared the efficacy of hypoxia preconditioned human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) and normoxia conditioned hUC-MSCs for the treatment of ischemic injury in hindlimbs of an immunodeficient mouse model. Expression of negative markers for MSC such as CD31, CD34, and CD45 or positive markers such as CD44, CD73, CD90, and CD105 was not significantly changed in hypoxia preconditioned hUC-MSCs compared with hUC-MSCs cultured in normoxic condition. Expression of angiogenesis-related genes such as COX-2, VEGF, Tie-2, and TGF-ß1 was increased compared with hUC-MSCs cultured in normoxic conditions. In the in vivo model, CD31 expression as a marker of angiogenesis was significantly increased in the ischemic limbs at 1 month after injection with hypoxic hUC-MSCs. Angiogenesis-related genes such as Ang-1, COX-1, PIGF, and MCP-1 were significantly upregulated in the muscle of ischemic hindlimbs treated with hypoxic hUC-MSCs than normoxic hUC-MSCs. Expression of proinflammatory genes such as IL-1, and IL-20 was reduced, whereas TGF-ß1, which has an anti-inflammatory effect, was strongly increased. In conclusion, hypoxic culture conditions could induce expression of angiogenesis related genes in hUC-MSCs, and hypoxia preconditioned hUC-MSCs showed enhancing effects by inducing angiogenesis and low inflammatory immune response compared with normoxic hUC-MSCs in the ischemia injured hindlimb of immunodeficient mice.

Protein profiling and angiogenic effect of hypoxia-cultured human umbilical cord blood-derived mesenchymal stem cells in hindlimb ischemia.

The aim of the present study was to investigate protein profiles of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) cultured in normoxic (21% O2) and hypoxic (1% O2) conditions, and evaluate oxygenation effects on angiogenesis in an ischemic hindlimb mouse model using a modified ischemic scoring system. Hypoxic conditions did not change the expression of phenotypic markers and increased adipogenesis and chondrogenesis. Epidermal growth factor (EGF), transforming growth factor alpha (TGF-α), TGF-ß RII, and vascular endothelial growth factor (VEGF) were upregulated in the conditioned medium of hypoxic hUCB-MSCs, which are commonly related to angiogenesis and proliferation of biological processes by Gene Ontology. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, significant enrichment of the phosphorylation of abelson murine leukemia viral oncogene homolog 1 (ABL1) (Phospho-Tyr204) and B-cell lymphoma-extra large (BCL-XL) (Phospho-Thr47) as anti-apoptotic pathways was observed in hypoxic hUCB-MSCs. Furthermore, hypoxic conditions induced proliferation and migration, and reduced apoptosis of hUCB-MSCs in vitro. Based on the results of protein antibody array, we evaluated the angiogenic effects of injecting normoxic or hypoxic hUCB-MSCs (1×106) into the ischemic hindlimb muscles of mice. Ischemic scores and capillary generation were significantly greater in the hypoxic hUCB-MSC injection group than in the normoxic hUCB-MSC group. Our findings demonstrate that culturing hUCB-MSCs in hypoxic conditions not only significantly enriches phosphorylation in the anti-apoptosis pathway and enhances the secretion of several angiogenic proteins from cells, but also alleviates ischemic injury of hindlimb of mice.