[show abstract][hide abstract] ABSTRACT: Poor homing efficiency is one of the major limitations of current stem cell therapy. Magnetic bionanoparticles (MPs) obtained from Magnetospirillum sp. AMB-1 have a lipid bilayer membrane and ferromagnetic properties. We evaluated a novel priming strategy using MPs to enhance the homing of transplanted progenitor cells to target tissue.
Effects of MP on proliferation, viability, and migration of late human endothelial progenitor cells (EPCs) were examined in vitro. Additionally, effects of MP on gene and protein expression related to survival and adhesion were evaluated. Homing and angiogenic efficiency of MP transferred late EPCs was evaluated in nude mouse hindlimb ischemia model.
Below threshold concentration, MP transfer did not influence proliferation or survival of late EPCs, but enhanced migration and trans-endothelial migration of late EPCs toward magnet. Below threshold concentration, MP transfer did not influence gene and protein expression related to survival. In the mouse hindlimb ischemia model, late EPCs treated with high dose MP (5 ug/mL) showed enhanced homing of injected late EPCs in the ischemic limb by magnet, compared to low dose MP (1 ug/mL) treated late EPCs. In addition, high dose MP transferred EPC showed significantly better improvement of perfusion in ischemic limb compared to untreated EPC.
MP transfer with magnet application can be a promising novel strategy to enhance homing efficacy and outcomes of current stem cell therapy.
[show abstract][hide abstract] ABSTRACT: The role and underlying mechanisms of rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist, on myocardial infarction are poorly understood. We investigated the effects of this PPAR-γ agonist on the expression of tissue factor (TF), a primary molecule for thrombosis, and elucidated its underlying mechanisms. The PPAR-γ agonist inhibited TF expression in response to TNF-α in human umbilical vein endothelial cells, human monocytic leukemia cell line, and human umbilical arterial smooth muscle cells. The overexpression of TF was mediated by increased phosphorylation of mitogen-activated protein kinase (MAPK), which was blocked by the PPAR-γ agonist. The effective MAPK differed depending on each cell type. Luciferase and ChIP assays showed that transcription factor, activator protein-1 (AP-1), was a pivotal target of the PPAR-γ agonist to lower TF transcription. Intriguingly, two main drugs for drug-eluting stent, paclitaxel or rapamycin, significantly exaggerated thrombin-induced TF expression, which was also effectively blocked by the PPAR-γ agonist in all cell types. This PPAR-γ agonist did not impair TF pathway inhibitor (TFPI) in three cell types. In rat balloon injury model (Sprague-Dawley rats, n = 10/group) with continuous paclitaxel infusion, the PPAR-γ agonist attenuated TF expression by 70±5% (n = 4; P<0.0001) in injured vasculature. Taken together, rosiglitazone reduced TF expression in three critical cell types involved in vascular thrombus formation via MAPK and AP-1 inhibitions. Also, this PPAR-γ agonist reversed the paclitaxel-induced aggravation of TF expression, which suggests a possibility that the benefits might outweigh its risks in a group of patients with paclitaxel-eluting stent implanted.
PLoS ONE 01/2011; 6(11):e28327. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: We investigated the effects of human resistin on atherosclerotic progression and clarified its underlying mechanisms.
Resistin is an adipokine first identified as a mediator of insulin resistance in murine obesity models. But, its role in human pathology is under debate. Although a few recent studies suggested the relationship between resistin and atherosclerosis in humans, the causal relationship and underlying mechanism have not been clarified.
We cloned rabbit resistin, which showed 78% identity to human resistin at the complementary deoxyribonucleic acid level, and its expression was examined in 3 different atherosclerotic rabbit models. To evaluate direct role of resistin on atherosclerosis, collared rabbit carotid arteries were used. Histological and cell biologic analyses were performed.
Rabbit resistin was expressed by macrophages of the plaque in the 3 different atherosclerotic models. Peri-adventitial resistin gene transfer induced macrophage infiltration and expression of various inflammatory cytokines, resulting in the acceleration of plaque growth and destabilization. In vitro experiments elucidated that resistin increased monocyte-endothelial cell adhesion by upregulating very late antigen-4 on monocytes and their counterpart vascular cell adhesion molecule-1 on endothelial cells. Resistin augmented monocyte infiltration in collagen by direct chemoattractive effect as well as by enhancing migration toward monocyte chemotactic protein-1. Administration of connecting segment-1 peptide, which blocks very late antigen-4 × vascular cell adhesion molecule-1 interaction, ameliorated neointimal growth induced by resistin in vivo.
Our results indicate that resistin aggravates atherosclerosis by stimulating monocytes, endothelial cells, and vascular smooth muscle cells to induce vascular inflammation. These findings provide the first insight on the causal relationship between resistin and atherosclerosis.
Journal of the American College of Cardiology 12/2010; 57(1):99-109. · 14.09 Impact Factor
[show abstract][hide abstract] ABSTRACT: Transplantation of autologous skeletal myoblasts (SMBs) is a potential therapeutic approach for myocardial infarction. However, their clinical efficacy and safety is still controversial. Electrical coupling through gap junction between SMBs and host myocardium is essential for synchronized contraction and electrical stability. Here, we investigated the effect of heart beat-simulating environment, oscillating pressure, on the expression of connexin43 in two types of SMBs from rat and mouse. We found that connexin43 is markedly decreased under ischemia-mimicking conditions such as serum starvation and hypoxia (1% O(2)) in rat primary cultured SMBs and mouse C2C12 SMB cell line. Interestingly, the decrease of connexin43 expression under serum starvation was attenuated by oscillating pressure. Oscillating pressure treatment increased the expression of connexin43 twofold through AP-1 stimulation, which was blocked by PD98059, ERK inhibitor. In coculture of cardiomyocytes and C2C12, pressure-treated C2C12 and cardiomyocytes were able to form functional gap junction, which was demonstrated by both calcein-AM dye transfer assay and measurement of simultaneous contraction. In rat myocardial infarction model, transplantation of SMBs pretreated with oscillating pressure resulted in lesser ventricular dilatation and better systolic function than transplantation of untreated SMBs and control group. These results suggested that application of oscillating pressure on SMBs before transplantation may be useful to promote therapeutic efficacy for myocardial infarction by enhancing gap junction formation between transplanted and host cells.
[show abstract][hide abstract] ABSTRACT: Granulocyte-colony stimulating factor (G-CSF) has been shown to have protective effects in the heart and brain. However, it may also be involved in the acute inflammatory response which may be harmful. The effects of G-CSF on endothelial cells (ECs) and the vasculature are mostly unknown. To study the possible dual effects of G-CSF on ECs, we investigated whether G-CSF induces release of C-reactive protein (CRP) by hepatocytes and whether the direct beneficial effects of G-CSF could protect ECs from the detrimental effects of CRP. G-CSF treatment significantly induced monocytes to produce IL-6, and culture supernatants of G-CSF-stimulated monocytes induced CRP production in hepatocytes. On the other hand, G-CSF directly promoted EC proliferation and migration and reversed the deleterious effects of CRP. In mechanistic analyses, G-CSF increased not only the protein expression of endothelial nitric oxide synthase (eNOS), but also its transcription. Furthermore, it enhanced eNOS phosphorylation and activation, leading to increased production of NO. Thus, G-CSF reversed the attenuated production of NO by CRP. These effects of G-CSF on eNOS transcription, translation, and activation were blunted by the PI3K inhibitor, suggesting that EC protective effects of G-CSF were associated with the activation of the Akt/eNOS pathway. In conclusion, although G-CSF induces an inflammatory reaction leading to CRP production, it has direct beneficial effects protecting ECs from the deleterious effects of CRP through activation of Akt/eNOS pathway, leading to an increase in NO production. Our data suggests that G-CSF may exert dual opposing effects on endothelial cells.
Journal of Molecular and Cellular Cardiology 08/2008; 45(5):670-8. · 5.15 Impact Factor