Efficacy and feasibility of cryoballoon ablation for atrial fibrillation in patients with heart failure: A large-scale multicenter study.

INTRODUCTION: Data are limited regarding outcomes of cryoballoon ablation for atrial fibrillation (AF) in patients with heart failure (HF). This large-scale multicenter study aimed to evaluate the prognosis of patients with HF after cryoballoon ablation for AF. METHODS: Among 3655 patients undergoing cryoballoon ablation at 17 institutions, 549 patients (15%) (391 with paroxysmal AF and 158 with persistent AF) diagnosed with HF preoperatively were analyzed. Clinical endpoints were recurrence, mortality, and HF hospitalization after ablation. RESULTS: Most patients had a preserved left ventricular ejection fraction (LVEF) ≥ 50%. During a mean follow-up period of 25.7 months, recurrence, all-cause death, and HF hospitalization occurred in 29%, 4.0%, and 4.8%, respectively. Cardiac function on echocardiography and B-type natriuretic peptide (BNP) levels significantly improved postoperatively, and the effect was more pronounced in the nonrecurrence group. Major complications occurred in 33 patients (6.0%), but most complications were phrenic nerve palsy (3.6%). Although death and HF hospitalization occurred more frequently in patients with LVEF ≤ 40% (n = 73) and New York Heart Association (NYHA) class III-IV (n = 19) than other subgroups, the BNP levels, and LVEF significantly improved after ablation in all LVEF and NYHA class subgroups. High BNP levels, NHYA class, CHADS2 score, and structural heart disease, but not postablation recurrence, independently predicted death, and HF hospitalization on multivariate analysis. The patients with tachycardia-induced cardiomyopathy had better recovery of BNP levels and LVEF after ablation than those with structural heart disease. CONCLUSIONS: Cryoballoon ablation for AF in HF patients is feasible and leads to significantly improved cardiac function.

Differences in prothrombotic response between the uninterrupted and interrupted apixaban therapies in patients undergoing cryoballoon ablation for paroxysmal atrial fibrillation: a randomized controlled study.

Periprocedural bleeding and thromboembolic events are worrisome complications of catheter ablation for atrial fibrillation (AF). Periprocedural anticoagulation management could decrease the risk of these complications. However, evaluation of the complications from pulmonary vein isolation using cryoballoon related to different anticoagulation strategies is limited. Therefore, we aimed to compare prothrombotic responses as assessed on the basis of D-dimer levels between the uninterrupted and interrupted apixaban therapies during cryoballoon ablation. Ninety-seven consecutive patients with paroxysmal AF scheduled to undergo cryoballoon ablation were randomly assigned in a 1:2 ratio to uninterrupted apixaban therapy (Group 1, n = 32) or interrupted apixaban therapy (Group 2, n = 65). D-Dimer levels were measured immediately before the ablation, at the end of the ablation, and 24 and 48 h after the procedure. No statistical difference was observed in the baseline characteristics between the two groups. The rates of hemorrhagic complications were similar in both groups (major bleeding: 3.1 vs. 1.5%; p = 0.61, and minor bleeding: 3.1 vs. 4.6%; p = 0.73, respectively). No thromboembolic events occurred in either group. However, D-dimer levels 48 h after the ablation increased more markedly following the procedure in Group 2 than in Group 1 (from 0.58 ± 0.16 to 1.01 ± 0.42 µg/mL vs. 0.58 ± 0.20 to 0.82 ± 0.25 µg/mL; p = 0.01). In conclusion, uninterrupted apixaban therapy during the periprocedural period of cryoballoon ablation for AF did not increase the risk of bleeding in this study and might reduce the periprocedural risk of subclinical hypercoagulable state.

Correction to: Differences in prothrombotic response between the uninterrupted and interrupted apixaban therapies in patients undergoing cryoballoon ablation for paroxysmal atrial fibrillation: a randomized controlled study.

In the original publication of the article, the table 2 was published incorrectly.

Head-to-head comparison of acute and chronic pulmonary vein stenosis for cryoballoon versus radiofrequency ablation.

BACKGROUND: Cryoballoon (CB) applications to pulmonary veins (PVs) can cause stenosis just as radiofrequency (RF) energy deliveries. The goal of the present study was to clarify whether or not there was any difference in the extent of acute or chronic PV narrowing after PV isolation between the two different energy sources. METHODS: Consecutive patients with paroxysmal atrial fibrillation who were scheduled to undergo a PV isolation were randomized 1:1 to receive CB or RF ablation. The endpoints were any acute PV narrowing assessed with the use of intracardiac ultrasound during the procedure and PV stenosis measured with cardiac computed tomography at the 3-month follow-up. RESULTS: An acute reduction in the luminal area of the left superior PV (mean ± standard deviation, -6.8 ± 8.7 vs -19.9 ± 14.7%; P < 0.001) and left inferior PV (-5.1 ± 20.2 vs -15.3 ± 11.6%; P = 0.03) was significantly smaller in the CB arm (N = 25) than the RF arm (N = 25). There was no difference in the extent of PV stenosis 3 months after the ablation between the arms (0-25% stenosis, 90% vs 88%, 25-50% stenosis, 10% vs 12%, >50% stenosis, both 0%; P = 0.82). A greater acute PV narrowing was likely to lead to chronic stenosis in the RF arm (P = 0.004). CONCLUSIONS: CB ablation may reduce the acute narrowing of the left-sided PVs as compared to RF ablation.

Therapeutic reendothelialization by induced pluripotent stem cells after vascular injury--brief report.

OBJECTIVE: Endothelial damage is an early requisite step for atherosclerosis after vascular injury. It has been reported that vascular wall cells can develop from induced pluripotent stem (iPS) cell-derived fetal liver kinase-1-positive (Flk-1(+)) cells. Here, we investigated the efficacies of intravenously administered iPS cell-derived Flk-1(+) cells on reendothelialization and neointimal hyperplasia in a mouse model of vascular injury. APPROACH AND RESULTS: Femoral arteries of KSN nude mice were injured using a steel wire. Mouse iPS cell-derived Flk-1(+) or Flk-1(-) cells were intravenously injected into those mice at 24 hours after vascular injury. Delivery of iPS cell-derived Flk-1(+) cells significantly attenuated neointimal hyperplasia compared with controls. Evans blue staining of the injured vessel revealed that administration of iPS cell-derived Flk-1(+) significantly enhanced reendothelialization compared with the Flk-1(-) cell control group. Recruitment of PKH26-labeled iPS cell-derived Flk-1(+) cells to the site of injury was also detectable. Expression level of CXCR4 in iPS cell-derived Flk-1(+) cells was 7.5-fold higher than that of iPS cell-derived Flk-1(-) cells. Stromal cell-derived factor-1α treatment significantly enhanced adhesion and migration of iPS cell-derived Flk-1(+) cells to the endothelia, but these were not observed in Flk-1(-) cells. CONCLUSIONS: Intravenously administered iPS cell-derived Flk-1(+) cells are recruited to the site of vascular injury, thereby enhancing reendothelialization followed by suppression of neointimal hyperplasia. Administration of iPS cell-derived Flk-1(+) cells is a potentially useful therapeutic means for vascular dysfunction and prevention of restenosis after angioplasty.

Clopidogrel Monotherapy After 1-Month Dual Antiplatelet Therapy in Patients With Diabetes Undergoing Percutaneous Coronary Intervention.

BACKGROUND: Diabetes was reported to be associated with an impaired response to clopidogrel. OBJECTIVES: The aim of this study was to evaluate the safety and efficacy of clopidogrel monotherapy after very short dual antiplatelet therapy (DAPT) in patients with diabetes undergoing percutaneous coronary intervention (PCI). METHODS: A subgroup analysis was conducted on the basis of diabetes in the STOPDAPT-2 (Short and Optimal Duration of Dual Antiplatelet Therapy After Everolimus-Eluting Cobalt-Chromium Stent-2) Total Cohort (N = 5,997) (STOPDAPT-2, n = 3,009; STOPDAPT-2 ACS [Short and Optimal Duration of Dual Antiplatelet Therapy After Everolimus-Eluting Cobalt-Chromium Stent-2 for the Patients With ACS], n = 2,988), which randomly compared 1-month DAPT followed by clopidogrel monotherapy with 12-month DAPT with aspirin and clopidogrel after cobalt-chromium everolimus-eluting stent implantation. The primary endpoint was a composite of cardiovascular (cardiovascular death, myocardial infarction, definite stent thrombosis, or stroke) or bleeding (TIMI [Thrombolysis In Myocardial Infarction] major or minor) endpoints at 1 year. RESULTS: There were 2,030 patients with diabetes (33.8%) and 3967 patients without diabetes (66.2%). Regardless of diabetes, the risk of 1-month DAPT relative to 12-month DAPT was not significant for the primary endpoint (diabetes, 3.58% vs 4.12% [HR: 0.87; 95% CI: 0.56-1.37; P = 0.55]; nondiabetes, 2.46% vs 2.49% [HR: 0.99; 95% CI: 0.67-1.48; P = 0.97]; Pinteraction = 0.67) and for the cardiovascular endpoint (diabetes, 3.28% vs 3.05% [HR: 1.10; 95% CI: 0.67-1.81; P = 0.70]; nondiabetes, 1.95% vs 1.43% [HR: 1.38; 95% CI: 0.85-2.25; P = 0.20]; Pinteraction = 0.52), while it was lower for the bleeding endpoint (diabetes, 0.30% vs 1.50% [HR: 0.20; 95% CI: 0.06-0.68; P = 0.01]; nondiabetes, 0.61% vs 1.21% [HR: 0.51; 95% CI: 0.25-1.01; P = 0.054]; Pinteraction = 0.19). CONCLUSIONS: Clopidogrel monotherapy after 1-month DAPT compared with 12-month DAPT reduced major bleeding events without an increase in cardiovascular events regardless of diabetes, although the findings should be considered as hypothesis generating, especially in patients with acute coronary syndrome, because of the inconclusive result in the STOPDAPT-2 ACS trial. (Short and Optimal Duration of Dual Antiplatelet Therapy After Everolimus-Eluting Cobalt-Chromium Stent-2 [STOPDAPT-2], NCT02619760; Short and Optimal Duration of Dual Antiplatelet Therapy After Everolimus-Eluting Cobalt-Chromium Stent-2 for the Patients With ACS [STOPDAPT-2 ACS], NCT03462498).

The potential of dynamic 99mTc-sestamibi cadmium zinc telluride-single-photon emission computed tomography camera assessing myocardial flow reserve in patients with heart failure with preserved ejection fraction.

Aims: Coronary microvascular dysfunction (CMD) is related to the pathophysiology, mortality, and morbidity of heart failure with preserved ejection fraction (HFpEF). A novel single-photon emission computed tomography (SPECT) camera with cadmium zinc telluride (CZT) detectors allows for the quantification of absolute myocardial blood flow and myocardial flow reserve (MFR) in patients with coronary artery disease. However, the potential of CZT-SPECT assessing for CMD has never been evaluated in patients with HFpEF. Methods and results: The clinical records of 127 consecutive patients who underwent dynamic CZT-SPECT were retrospectively reviewed. Rest and stress scanning were started simultaneously with 3 and 9 MBq/kg of 99mTc-sestamibi administration, respectively. Dynamic CZT-SPECT imaging data were analysed using a net-retention model with commercially available software. Transthoracic echocardiography was performed in all patients. The MFR value was significantly lower in the HFpEF group (mean ± SEM = 2.00 ± 0.097) than that in the non-HFpEF group (mean ± SEM = 2.74 ± 0.14, P = 0.0004). A receiver operating characteristic analysis indicated that if a cut-off value of 2.525 was applied, MFR could efficiently distinguish HFpEF from non-HFpEF. Heart failure with preserved ejection fraction had a consistently low MFR, regardless of the diastolic dysfunction score. Heart failure with preserved ejection fraction patients with MFR values lower than 2.075 had a significantly higher incidence of heart failure exacerbation. Conclusion: Myocardial flow reserve assessed by CZT-SPECT was significantly reduced in patients with HFpEF. A lower MFR was associated with a higher hospitalization rate in these patients. Myocardial flow reserve assessed by CZT-SPECT has the potential to predict future adverse events and stratify the severity of disease in patients with HFpEF.

Enhanced angiogenesis by transplantation of mesenchymal stem cell sheet created by a novel magnetic tissue engineering method.

OBJECTIVE: Therapeutic angiogenesis with cell transplantation represents a novel strategy for severe ischemic diseases. However, some patients have poor response to such conventional injection-based angiogenic cell therapy. Here, we investigated a therapeutic potential of mesenchymal stem cell (MSC) sheet created by a novel magnetite tissue engineering technology for reparative angiogenesis. METHODS AND RESULTS: Human MSCs incubated with magnetic nanoparticle-containing liposomes were cultured, and a magnet was placed on the reverse side. Magnetized MSCs formed multilayered cell sheets according to magnetic force. Nude mice were subjected to unilateral hind limb ischemia and separated into 3 groups. For the control group, saline was injected into ischemic tissue. In the MSC-injected group, mice received magnetized MSCs by conventional needle injections without sheet formula as a control cell group. In the MSC-sheet group, MSC sheet was layered onto the ischemic tissues before skin closure. Blood flow recovery and the extent of angiogenesis were assessed by a laser Doppler blood flowmetry and histological capillary density, respectively. The MSC-sheet group had a greater angiogenesis in ischemic tissues compared to the control and MSC-injected groups. The angiogenic and tissue-preserving effects of MSC sheets were attributable to an increased expression of vascular endothelial growth factor and reduced apoptosis in ischemic tissues. In cultured MSCs, magnetic labeling itself inhibited apoptosis via a catalase-like antioxidative mechanism. CONCLUSIONS: MSC sheet created by the novel magnetic nanoparticle-based tissue engineering technology would represent a new modality for therapeutic angiogenesis and tissue regeneration.

Very Short Dual Antiplatelet Therapy After Drug-Eluting Stent Implantation in Patients Who Underwent Complex Percutaneous Coronary Intervention: Insight From the STOPDAPT-2 Trial.

BACKGROUND: Safety and efficacy of clopidogrel monotherapy after very short dual antiplatelet therapy (DAPT) is uncertain in patients undergoing complex percutaneous coronary intervention (PCI). METHODS: We conducted a post hoc subgroup analysis based on the complexity of PCI in the STOPDAPT-2 trial (Short and Optimal Duration of Dual Antiplatelet Therapy-2), which randomly compared 1-month DAPT followed by clopidogrel monotherapy with 12-month DAPT after cobalt-chromium everolimus-eluting stent implantation. Complex PCI was defined as any of the following: 3 vessels treated, ≥3 stents implanted, ≥3 lesions treated, bifurcation with 2 stents, >60 mm total stent lengths, and target of chronic total occlusion. The primary end point was the composite of cardiovascular (cardiovascular death/myocardial infarction/definite stent thrombosis/stroke) and bleeding (TIMI [Thrombolysis in Myocardial Infarction] major/minor) end points. The major secondary end points were the cardiovascular and bleeding end points. RESULTS: Among the 3009 study patients, there were 509 patients (16.9%) with complex PCI (1-month DAPT: N=245, and 12-month DAPT: N=264) and 2500 patients (83.1%) without complex PCI (1-month DAPT: N=1255, and 12-month DAPT: N=1245). There were no significant interactions between the complexity of PCI and the effects of 1-month DAPT versus 12-month DAPT on the primary end point (complex PCI: 1.67% versus 5.32%, hazard ratio, 0.30 [95% CI, 0.10­0.92], P=0.04, and noncomplex PCI: 2.50% versus 3.35%, hazard ratio, 0.75 [95% CI, 0.47­1.20], P=0.23; Pinteraction=0.14), and on the major secondary cardiovascular end point (complex PCI: 1.67% versus 3.04%, hazard ratio, 0.54 [95% CI, 0.16­1.79], P=0.31, and noncomplex PCI: 2.02% versus 2.39%, hazard ratio, 0.86 [95% CI, 0.50­1.47], P=0.58; Pinteraction=0.49). The cumulative 1-year incidence of the major secondary bleeding end point was significantly lower in the 1-month DAPT group than in the 12-month DAPT group regardless of the complexity of PCI (complex PCI: 0% versus 2.29%, log-rank P=0.02, and noncomplex PCI: 0.48% versus 1.38%, log-rank P=0.02). CONCLUSIONS: The effects of clopidogrel monotherapy after 1-month DAPT relative to 12-month DAPT for the primary and major secondary end points were comparable in complex PCI and noncomplex PCI without significant interactions. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02619760.

Therapeutic angiogenesis by transplantation of induced pluripotent stem cell-derived Flk-1 positive cells.

BACKGROUND: Induced pluripotent stem (iPS) cells are the novel stem cell population induced from somatic cells. It is anticipated that iPS will be used in the expanding field of regenerative medicine. Here, we investigated whether implantation of fetal liver kinase-1 positive (Flk-1+) cells derived from iPS cells could improve angiogenesis in a mouse hind limb model of ischemia. RESULTS: Flk-1+ cells were induced from iPS cells after four to five days of culture. Hind limb ischemia was surgically induced and sorted Flk-1+ cells were directly injected into ischemic hind limbs of athymic nude mice. Revascularization of the ischemic hind limb was accelerated in mice that were transplanted with Flk-1+ cells compared with control mice, which were transplanted with vehicle, as evaluated by laser Doppler blood flowmetry. Transplantation of Flk-1+ cells also increased expression of VEGF mRNA in ischemic tissue compared to controls. CONCLUSIONS: Direct local implantation of iPS cell-derived Flk-1+ cells would salvage tissues from ischemia. These data indicate that iPS cells could be valuable in the therapeutic induction of angiogenesis.

Study design and protocol for evaluating the long-term prognosis of patients receiving his bundle pacing: A multicenter observational study.

BACKGROUND: His bundle pacing (HBP) is a recently developed pacing technique that can achieve an ideal physiological pattern of ventricular activation via stimulation of the native His-Purkinje system. Despite the widespread introduction of HBP in clinical practice, its appropriate indications are yet to be determined clearly. Moreover, the efficacy and safety of HBP and long-term prognosis of patients undergoing such are unknown. METHODS: We conducted a multicenter observational prospective study in patients undergoing HBP in Japan. Patients with atrioventricular block or conduction delay and estimated ventricular pacing of ≥ 40% scheduled for HBP implantation are included. All patients are followed up until 3 years after the implantation. The primary endpoints are all-cause death, heart failure-related hospitalization, and upgrade to cardiac resynchronization therapy. The secondary endpoint is changes in cardiac function based on echocardiographic findings and laboratory data after the implantation. RESULTS: The results are currently under investigation. CONCLUSIONS: This multicenter observational study evaluates the long-term prognosis and changes in cardiac function of patients undergoing HBP implantation in a clinical setting. Considering the large number of patients included, the cumulative results would be helpful in establishing evidence on HBP application in this area and consequently allow accurate management and treatment of patients undergoing HBP.

Angioblast Derived from ES Cells Construct Blood Vessels and Ameliorate Diabetic Polyneuropathy in Mice.

BACKGROUND: Although numerous reports addressing pathological involvements of diabetic polyneuropathy have been conducted, a universally effective treatment of diabetic polyneuropathy has not yet been established. Recently, regenerative medicine studies in diabetic polyneuropathy using somatic stem/progenitor cell have been reported. However, the effectiveness of these cell transplantations was restricted because of their functional and numerical impairment in diabetic objects. Here, we investigated the efficacy of treatment for diabetic polyneuropathy using angioblast-like cells derived from mouse embryonic stem cells. METHODS AND RESULTS: Angioblast-like cells were obtained from mouse embryonic stem cells and transplantation of these cells improved several physiological impairments in diabetic polyneuropathy: hypoalgesia, delayed nerve conduction velocities, and reduced blood flow in sciatic nerve and plantar skin. Furthermore, pathologically, the capillary number to muscle fiber ratios were increased in skeletal muscles of transplanted hindlimbs, and intraepidermal nerve fiber densities were ameliorated in transplanted plantar skin. Transplanted cells maintained their viabilities and differentiated to endothelial cells and smooth muscle cells around the injection sites. Moreover, several transplanted cells constructed chimeric blood vessels with recipient cells. CONCLUSIONS: These results suggest that transplantation of angioblast like cells induced from embryonic stem cells appears to be a novel therapeutic strategy for diabetic polyneuropathy.

[Clinical results of hemiarthroplasty for femoral neck fracture].

UNLABELLED: Subsequent clinical results of hemiarthroplasty for the femoral neck fracture over 80 years old was examined. SUBJECTS AND METHODS: One hundred and sixteen post-op. femoral neck fractures (22 males and 94 females, mean age 86 y.o.) were included in this series. Investigation in each case was done about 10 factors (see the article) which might deteriorate post-op. mobility and mortality. RESULTS: In 74.2% of all cases in which 45.5% with senile dementia and 86.7% without senile dementia were included, ability to walk was maintained after the operation with variable degree. In 65 cases without senile dementia, ability to walk after operation was doomed by low degree of ability to walk before the injury, comparable long waiting periods till the operation and consumed condition against some post-op. inflammated complications. The post-op. mortality within 3 months was 3.5% of all cases and 1.5% without senile dementia. DISCUSSION: Since approximately half of the patients with senile dementia completely lost their gait after the operation, even if they could before the injury, an alternative approach which is not aimed to achieve the impractical gait might be needed for such patients. To achieve of better functional and vital prognosis, patients without senile dementia should be operated as soon as possible and organized their pos-op. general conditions intensively.

Comparison of the change in the dimension of the pulmonary vein ostia immediately after pulmonary vein isolation for atrial fibrillation-open irrigated-tip catheters versus non-irrigated conventional 4 mm-tip catheters.

INTRODUCTION: A difference in the lesion formation between open irrigated-tip (OITC) and non-irrigated 4-mm-tip catheters (NITC) may result in a difference in the dimension of the pulmonary vein (PV) ostia after PV isolation of atrial fibrillation (AF). This study evaluated the difference using intracardiac echocardiography (ICE) before and immediately after an extensive encircling PV isolation (EPVI) with an OITC and with an NITC. METHODS AND RESULTS: We studied 100 consecutive patients (OITC group, 54; NITC group, 46) who received EPVI. Changes in the vessel, lumen, and wall thickness areas of the PVs were evaluated at the PV ostia by ICE. There were no significant differences in the baseline characteristics and acute success rate of the EPVI between the OITC and NITC groups. The energy delivered to achieve EPVI was higher in the OITC group than that in the NITC group (34,967 ± 13,222 J vs. 28,300 ± 10,614 J; p=0.01). After the ablation, the reduction in the vessel and lumen cross-sectional areas was significantly smaller in the OITC group than that in the NITC group (-9.05 ± 28.4 % vs. -21.2 ± 28.8 %, p<0.001; -8.76 % vs. -17.7 ± 26.9 %, p=0.003). The wall thickness area slightly decreased in the OITC group, but increased in the NITC group (-2.96 ± 38.4 % vs. 10.5 ± 76.6 %, p=0.591). During a median follow-up of 234 days, there was no significant difference in the AF recurrence after the initial ablation procedure between the two groups. CONCLUSION: Greater PV ostial narrowing occurred with the NITC than OITC immediately after the EPVI. PV ostial wall edema was noted with only the NITC. These findings suggested that an OITC might reduce any acute PV narrowing and wall edema as compared with an NITC.

Mesenchymal stem cell-like cells derived from mouse induced pluripotent stem cells ameliorate diabetic polyneuropathy in mice.

BACKGROUND: Although pathological involvements of diabetic polyneuropathy (DPN) have been reported, no dependable treatment of DPN has been achieved. Recent studies have shown that mesenchymal stem cells (MSCs) ameliorate DPN. Here we demonstrate a differentiation of induced pluripotent stem cells (iPSCs) into MSC-like cells and investigate the therapeutic potential of the MSC-like cell transplantation on DPN. RESEARCH DESIGN AND METHODS: For induction into MSC-like cells, GFP-expressing iPSCs were cultured with retinoic acid, followed by adherent culture for 4 months. The MSC-like cells, characterized with flow cytometry and RT-PCR analyses, were transplanted into muscles of streptozotocin-diabetic mice. Three weeks after the transplantation, neurophysiological functions were evaluated. RESULTS: The MSC-like cells expressed MSC markers and angiogenic/neurotrophic factors. The transplanted cells resided in hindlimb muscles and peripheral nerves, and some transplanted cells expressed S100 ß in the nerves. Impairments of current perception thresholds, nerve conduction velocities, and plantar skin blood flow in the diabetic mice were ameliorated in limbs with the transplanted cells. The capillary number-to-muscle fiber ratios were increased in transplanted hindlimbs of diabetic mice. CONCLUSIONS: These results suggest that MSC-like cell transplantation might have therapeutic effects on DPN through secreting angiogenic/neurotrophic factors and differentiation to Schwann cell-like cells.

iPS cell sheets created by a novel magnetite tissue engineering method for reparative angiogenesis.

Angiogenic cell therapy represents a novel strategy for ischemic diseases, but some patients show poor responses. We investigated the therapeutic potential of an induced pluripotent stem (iPS) cell sheet created by a novel magnetite tissue engineering technology (Mag-TE) for reparative angiogenesis. Mouse iPS cell-derived Flk-1(+) cells were incubated with magnetic nanoparticle-containing liposomes (MCLs). MCL-labeled Flk-1(+) cells were mixed with diluted extracellular matrix (ECM) precursor and a magnet was placed on the reverse side. Magnetized Flk-1(+) cells formed multi-layered cell sheets according to magnetic force. Implantation of the Flk-1(+) cell sheet accelerated revascularization of ischemic hindlimbs relative to the contralateral limbs in nude mice as measured by laser Doppler blood flow and capillary density analyses. The Flk-1(+) cell sheet also increased the expressions of VEGF and bFGF in ischemic tissue. iPS cell-derived Flk-1(+) cell sheets created by this novel Mag-TE method represent a promising new modality for therapeutic angiogenesis.

Transplantation of neural crest-like cells derived from induced pluripotent stem cells improves diabetic polyneuropathy in mice.

Impaired vascularity and nerve degeneration are the most important pathophysiological abnormalities of diabetic polyneuropathy (DPN). Therefore, regeneration of both the vascular and nervous systems is required for the treatment of DPN. The neural crest (NC) is a transient embryonic structure in vertebrates that differentiates into a vast range of cells, including peripheral neurons, Schwann cells, and vascular smooth muscle cells. In this study, we investigated the ability of transplantation of NC-like (NCL) cells derived from aged mouse induced pluripotent stem (iPS) cells in the treatment of DPN. iPS cells were induced to differentiate into neural cells by stromal cell-derived inducing activity (SDIA) and subsequently supplemented with bone morphogenetic protein 4 to promote differentiation of NC lineage. After the induction, p75 neurotrophin receptor-positive NCL cells were purified using magnetic-activated cell sorting. Sorted NCL cells differentiated to peripheral neurons, glial cells, and smooth muscle cells by additional SDIA. NCL cells were transplanted into hind limb skeletal muscles of 16-week streptozotocin-diabetic mice. Nerve conduction velocity, current perception threshold, intraepidermal nerve fiber density, sensitivity to thermal stimuli, sciatic nerve blood flow, plantar skin blood flow, and capillary number-to-muscle fiber ratio were evaluated. Four weeks after transplantation, the engrafted cells produced growth factors: nerve growth factor, neurotrophin 3, vascular endothelial growth factor, and basic fibroblast growth factor. It was also confirmed that some engrafted cells differentiated into vascular smooth muscle cells or Schwann cell-like cells at each intrinsic site. The transplantation improved the impaired nerve and vascular functions. These results suggest that transplantation of NCL cells derived from iPS cells could have therapeutic effects on DPN through paracrine actions of growth factors and differentiation into Schwann cell-like cells and vascular smooth muscle cells.

Nifedipine ameliorates ischemia-induced revascularization in diet-induced obese mice.

BACKGROUND: Obesity is a risk factor for the development of cardiovascular diseases that are associated with impaired angiogenesis. Nifedipine, a calcium-channel blocker, has a number of blood pressure (BP)-independent effects as well, such as improving endothelial function and decreasing oxidative stress. Here, we investigated whether nifedipine could improve the angiogenic responses in a diet-induced obese (DIO) model. METHODS: DIO was induced by allowing 8-week-old C57BL/6J mice ad libitum access to a high-fat/high-sucrose (HF/HS) diet. Mice were randomly divided into two groups that were fed either the HF/HS or normal chow. At the age of 12 weeks, the animals were treated/not treated with nifedipine admixed with food at a concentration of 0.001%. Then, 1 week later, the mice were subjected to unilateral hind limb surgery. RESULTS: Angiogenic repair of the ischemic hind limb was impaired in the DIO mice as compared with that in the control mice as evaluated by laser Doppler blood flowmetry (LDBF) and capillary density analysis. Treatment with nifedipine accelerated angiogenic repair in the DIO mice to a level equal to that seen in the control mice. DIO mice showed increased reactive oxygen species (ROS) production after hind limb ischemia. The number of endothelial progenitor cells (EPCs), which contribute to blood vessel formation, was also significantly lower in these mice. Nifedipine treatment ameliorated the oxidative status and increased the number of EPCs in the DIO mice. CONCLUSIONS: Our observations demonstrated that DIO impaired revascularization in response to tissue ischemia. Nifedipine ameliorated obesity-impaired revascularization through suppressing oxidative stress and enhancing the number of EPCs.

Comparative angiogenic activities of induced pluripotent stem cells derived from young and old mice.

Advanced age is associated with decreased stem cell activity. However, the effect of aging on the differentiation capacity of induced pluripotent stem (iPS) cells into cardiovascular cells has not been fully clarified. We investigated whether iPS cells derived from young and old mice are equally capable of differentiating into vascular progenitor cells, and whether these cells regulate vascular responses in vivo. iPS cells from mouse embryonic fibroblasts (young) or 21 month-old mouse bone marrow (old) were used. Fetal liver kinase-1 positive (Flk-1(+)) cells, as a vascular progenitor marker, were induced after 3 to 4 days of culture from iPS cells derived from young and old mice. These Flk-1(+) cells were sorted and shown to differentiate into VE-cadherin(+) endothelial cells and α-SMA(+) smooth muscle cells. Tube-like formation was also successfully induced in both young and old murine Flk-1(+) cells. Next, hindlimb ischemia was surgically induced, and purified Flk-1(+) cells were directly injected into ischemic hindlimbs of nude mice. Revascularization of the ischemic hindlimb was significantly accelerated in mice transplanted with Flk-1(+) cells derived from iPS cells from either young or old mice, as compared to control mice as evaluated by laser Doppler blood flowmetry. The degree of revascularization was similar in the two groups of ischemic mice injected with iPS cell-derived Flk-1(+) cells from young or old mice. Transplantation of Flk-1(+) cells from both young and old murine iPS cells also increased the expression of VEGF, HGF and IGF mRNA in ischemic tissue as compared to controls. iPS cell-derived Flk-1(+) cells differentiated into vascular progenitor cells, and regulated angiogenic vascular responses both in vitro and in vivo. These properties of iPS cells derived from old mice are essentially the same as those of iPS cells from young mice, suggesting the functionality of generated iPS cells themselves to be unaffected by aging.

Maximum derivative of left ventricular pressure predicts cardiac mortality after cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been reported to improve cardiac performance. However, CRT in patients with advanced heart failure is not always accompanied by an improvement in survival rates. We investigated the association between hemodynamic studies and long-term prognosis after CRT. METHODS: A total of 68 consecutive patients receiving CRT devices due to advanced heart failure were assessed by hemodynamic study and long-term outcome after implantation of the device. Hemodynamic parameters were measured both with the CRT on and off. RESULTS: Patients demonstrated significant improvement in the maximum first derivative of left ventricular (LV) pressure (LV dP/dt(max) ) and QRS duration after periods with the CRT on. During the follow-up period of 34.9 ± 17.6 months, basal LV dP/dt(max) and isovolemic LV pressure half-time (T½), but not percent change in LV dP/dt(max) , were independent predictors of cardiac mortality or hospitalization due to heart failure after multivariate Cox regression analysis. The Kaplan-Meier survival analysis revealed that patients in the lowest basal LV dP/dt(max) tertile or the longest basal T½ tertile exhibited a significantly higher cardiac-caused mortality or heart failure hospitalization. CONCLUSIONS: Lower LV dP/dt(max) or longer T½ independently predicts cardiac mortality or heart failure hospitalization in patients receiving CRT. The assessment of the basal LV dP/dt(max) and T½ could provide useful information in long-term prognosis after CRT.