Takanobu Imada

Improvement of Collateral Perfusion and Regional Function by Implantation of Peripheral Blood Mononuclear Cells Into Ischemic Hibernating Myocardium

Objective—This study was performed to evaluate the angiogenic effect of implantation of peripheral blood mononuclear cells (PB-MNCs) compared with bone marrow mononuclear cells (BM-MNCs) into ischemic hibernating myocardium. Methods and Results—A NOGA electromechanical system was used to map the hibernating region and to inject cells. PB-MNCs and BM-MNCs contained similar levels of vascular endothelial growth factor and basic fibroblast growth factor, whereas contents of angiogenic cytokines (interleukin-1&bgr; and tumor necrosis factor-&agr;) were larger in PB-MNCs. Numbers of endothelial progenitors were ≈500-fold higher in BM-MNCs. In BM-MNC–implanted myocardia of pigs, an increase in systolic function (ejection fraction from 33% to 52%) and regional blood flow (2.1-fold) and a reduction of the ischemic area (from 29% to 8%) were observed. PB-MNC implantation reduced the ischemic area (from 31% to 17%), the extent of which was less than that seen with BM-MNCs. In saline-implanted myocardium, the ischemic area expanded (from 28% to 38%), and systolic function deteriorated. Angiography revealed an increase in collateral vessel formation by PB-MNC or BM-MNC implantation. Capillary numbers were increased 2.6- and 1.7-fold by BM-MNC and PB-MNC implantation, respectively. BM-MNCs but not PB-MNCs were incorporated into neocapillaries. Conclusions—Catheter-based implantation of PB-MNCs can effectively improve collateral perfusion and regional function in hibernating ischemic myocardium by its ability to mainly supply angiogenic factors and cytokines.

Enhancement of ischemia-induced angiogenesis by eNOS overexpression

Abstract—It remains undetermined whether continuous endothelial nitric oxide (NO) overexpression exerts angiogenic action. We surgically induced hindlimb ischemia in transgenic mice overexpressing endothelial NO synthase in the endothelium (eNOS-Tg) and studied neocapillary formation, ischemia-induced vascular endothelial growth factor (VEGF) expression, cGMP accumulation, and Akt/PKB signaling. Laser Doppler imaging revealed a markedly increased recovery of blood perfusion in ischemic limbs of eNOS-Tg mice (44% increase) compared with that in wild-type mice. Angiography showed a marked increase in basal and ischemia-induced collateral vessel formation in eNOS-Tg mice. Basal capillary densities and tissue cGMP levels were increased in eNOS-Tg mice (1.8-fold and 1.6-fold versus wild-type mice, respectively). Ischemia-induced neocapillary formation and cGMP accumulation were markedly increased in eNOS-Tg mice (3.6-fold and 4.1-fold versus preischemia levels, respectively), whereas those in wild-type mice were much less (1.8-fold and 1.5-fold, respectively). Basal and time-dependent VEGF expression in ischemic muscles did not differ between eNOS-Tg and wild-type mice. Basal and VEGF-mediated Akt phosphorylation in aortas was similar between eNOS-Tg and wild-type mice. Aortic basal eNOS expression was increased 3.3-fold, and VEGF-mediated eNOS phosphorylation was markedly induced in aortas of eNOS-Tg compared with preischemia levels (4.2-fold), whereas much smaller changes were observed in wild-type mice (1.8-fold increase). Our study demonstrates that overexpression of eNOS protein causes a marked increase in neocapillary formation in response to tissue ischemia without affecting ischemia-induced VEGF expression or VEGF-mediated Akt phosphorylation.

Targeted Delivery of Bone Marrow Mononuclear Cells by Ultrasound Destruction of Microbubbles Induces Both Angiogenesis and Arteriogenesis Response

Objective—Ultrasound (US)-mediated destruction of contrast microbubbles causes capillary rupturing that stimulates arteriogenesis, whereas intramuscular implantation (im) of bone marrow mononuclear cells (BM-MNCs) induces angiogenesis. We therefore studied whether US-targeted microbubble destruction combined with transplantation of BM-MNCs can enhance blood flow restoration by stimulating both angiogenesis and arteriogenesis. Methods and Results—US-mediated destruction of phospholipid-coated microbubbles was applied onto ischemic hindlimb muscle and subsequently BM-MNCs were transfused. A significant enhancement in blood flow recovery after Bubble+US+BM-MNC infusion (34% increase, P<0.05) was observed compared with Bubble+US (25%). The ratio of capillary/muscle fiber increased by Bubble+US+BM-MNC-i.v (260%, P<0.01) than that in the Bubble+US group (172%), into which BM-MNCs were incorporated (angiogenesis). Smooth muscle &agr;-actin–positive arterioles were also increased, and angiography showed augmented collateral vessel formation (arteriogenesis). Platelet-derived proinflammatory factors activated by Bubble+US induces the expression of adhesion molecules (P-selectin and ICAM-1), leading to the attachment of transplanted BM-MNCs on the endothelium. Flow assay confirmed that the platelet-derived factors cause the adhesion of BM-MNCs onto endothelium under laminar flow. Conclusions—This study demonstrates that the targeted delivery of BM-MNCs by US destruction of microbubbles enhances regional angiogenesis and arteriogenesis response, in which the release of platelet-derived proinflammatory factors activated by Bubble+US play a key role in the attachment of transplanted BM-MNCs onto the endothelial layer.

'Takotsubo' cardiomyopathy in a maintenance hemodialysis patient.

Abstract:  An 84‐year‐old woman undergoing maintenance hemodialysis presented with chest discomfort lasting several days and electrocardiographic abnormalities. She had stopped smoking 2 weeks earlier and was experiencing irritability. Upon admission, electrocardiography showed ST‐segment elevation in leads I, II, aVF, and V2‐6 and an abnormal Q wave in leads II, III, and aVF. Ultrasound cardiography showed left ventricular anteroapical akinesia and basal hyperkinesia. The chest discomfort disappeared without specific therapy. During hospital days 1–5, the ST‐segment elevation gradually improved. Giant negative T waves then developed. The left ventricular asynergy resolved by day 8. Radionuclide imaging with iodine‐123‐beta‐methyl‐p‐iodophenyl pentadecanoic acid, but not with technetium‐99 m‐sestamibi, showed an apical defect. Elective coronary angiography showed no stenosis. ‘Takotsubo’ cardiomyopathy was diagnosed. After discharge, the patient continued regular dialysis without cardiac symptoms. We concluded that endogenously activated sympathetic nerve action in hemodialysis patients, especially those under emotional or physical stress, might be a causative factor for Takotsubo cardiomyopathy.

Olmesartan Induces Renoprotective Effects by Stimulating Angiotensin Type 2 Receptors and Reducing Oxidative Stress in Diabetic Nephropathy

Background: Angiotensin receptor blockers reduce the progression of diabetic nephropathy primarily by inhibiting angiotensin type 1 (AT1) receptors. In the present study, we investigated the role of angiotensin type 2 (AT2) receptors on the renoprotective effects of olmesartan in diabetic nephropathy. Methods: Six-week-old mice were treated with streptozotocin and divided into four groups: the OLM group (mice treated with olmesartan), the OLM+Ang II group (mice treated with olmesartan and angiotensin II), the OLM+PD group (mice treated with olmesartan and the AT2 antagonist PD 123319), and the vehicle group. Nondiabetic mice were used as controls. We measured blood glucose levels and urinary excretions of albumin and 8-hydroxy-2’-deoxyguanosine (8-OHdG), which is a marker for oxidative stress. Results: Although urinary albumin excretion in the OLM and OLM+Ang II groups showed a tendency to be reduced compared to the vehicle group, it was significantly lower compared to the OLM+PD group. Urinary excretion of 8-OHdG was also significantly lower in the OLM and OLM+Ang II groups compared to the OLM+PD group. Conclusions: In diabetic nephropathy, the renoprotective effects of olmesartan are due not only to the blockade of AT1 receptors, but also to a reduction in oxidative stress via stimulation of AT2 receptors.

Determinants of the Change in Arterial Stiffness in Peritoneal Dialysis Patients: A Cross-Sectional and Longitudinal Study after Initiation of Therapy

Arterial stiffness is an important risk factor for cardiovascular disease (CVD) in patients with end-stage renal failure. However, little is known about the factors that contribute to arterial rigidity in peritoneal dialysis (PD) patients. The aim of this study was to define the pattern and determinants of the longitudinal change in arterial stiffness after PD initiation.Arterial stiffening was estimated for 46 PD patients by using brachial-ankle pulse wave velocity (baPWV) and carotid intima-media thickness (cIMT). The cross-sectional relationship between the arterial markers and their clinical determinants was studied. The longitudinal effects of blood pressure (BP), body fluid status, and glucose were studied over the two years after initiating PD.Multivariate analysis showed that higher baPWV was associated positively with urinary protein excretion (P < 0.001), systolic BP (P = 0.001), and hemoglobin A1c (P = 0.003). In contrast, increased cIMT correlated with smoking (P = 0.004) and hypoalbuminemia (P = 0.04), suggesting that endothelial dysfunction is implicated in the atherogenic process. Neither cIMT nor baPWV correlated significantly with other PD-related covariates of volume overload, peritoneal solute transport, kidney function, and C-reactive protein. Longitudinal observation demonstrated that BP had a greater influence on baPWV changes than hyperglycemia or fluid status.Our study indicates that 1) baPWV represent an arterial marker that integrates multifactorial interaction between modifiable variables including BP and plasma glucose; and 2) intervention aimed at controlling BP as well as nutritional conditions (glucose and albumin) may reduce CVD risk in PD patients.

Czech Society News

Nephrology has a long tradition in the Czech Republic. The first acute dialysis was performed in 1955, a chronic dialysis programme started in the early 60ies, and a transplantation programme in 1966. This was reflected by many important international meetings held in Prague: The 2nd Congress of the International Society of Nephrology (1963), 17th Congress of the European Dialysis and Transplantation Association (1980) and the 15th Congress of the European Society of Artificial Organs (1988). More recently, the 17th and 25th meetings of the International Society of Blood Purification (1999 and 2007), 11th ANCA and Vasculitis Workshop (2003), 7th European Peritoneal Dialysis Meeting (2005), 13th Congress of the European Society of Organ Transplantation (2007) and finally, this year, the 48th Congress of ERA-EDTA.

Targeted Delivery of Bone Marrow Mononuclear Cells by Ultrasound Destruction of Microbubbles Induces both Angiogenesis and Arteriogenesis Response

OBJECTIVE Ultrasound (US)-mediated destruction of contrast microbubbles causes capillary rupturing that stimulates arteriogenesis, whereas intramuscular implantation (im) of bone marrow mononuclear cells (BM-MNCs) induces angiogenesis. We therefore studied whether US-targeted microbubble destruction combined with transplantation of BM-MNCs can enhance blood flow restoration by stimulating both angiogenesis and arteriogenesis. METHODS AND RESULTS US-mediated destruction of phospholipid-coated microbubbles was applied onto ischemic hindlimb muscle and subsequently BM-MNCs were transfused. A significant enhancement in blood flow recovery after Bubble+US+BM-MNC infusion (34% increase, P<0.05) was observed compared with Bubble+US (25%). The ratio of capillary/muscle fiber increased by Bubble+US+BM-MNC-i.v (260%, P<0.01) than that in the Bubble+US group (172%), into which BM-MNCs were incorporated (angiogenesis). Smooth muscle alpha-actin-positive arterioles were also increased, and angiography showed augmented collateral vessel formation (arteriogenesis). Platelet-derived proinflammatory factors activated by Bubble+US induces the expression of adhesion molecules (P-selectin and ICAM-1), leading to the attachment of transplanted BM-MNCs on the endothelium. Flow assay confirmed that the platelet-derived factors cause the adhesion of BM-MNCs onto endothelium under laminar flow. CONCLUSIONS This study demonstrates that the targeted delivery of BM-MNCs by US destruction of microbubbles enhances regional angiogenesis and arteriogenesis response, in which the release of platelet-derived proinflammatory factors activated by Bubble+US play a key role in the attachment of transplanted BM-MNCs onto the endothelial layer.