Macrophage (Drp1) Dynamin-Related Protein 1 Accelerates Intimal Thickening After Vascular Injury.

OBJECTIVE: Mitochondria consistently change their morphology in a process regulated by proteins, including Drp1 (dynamin-related protein 1), a protein promoting mitochondrial fission. Drp1 is involved in the mechanisms underlying various cardiovascular diseases, such as myocardial ischemia/reperfusion injury, heart failure, and pulmonary arterial hypertension. However, its role in macrophages, which promote various vascular diseases, is poorly understood. We therefore tested our hypothesis that macrophage Drp1 promotes vascular remodeling after injury. METHOD AND RESULTS: To explore the selective role of macrophage Drp1, we created macrophage-selective Drp1-deficient mice and performed femoral arterial wire injury. In these mice, intimal thickening and negative remodeling were attenuated at 4 weeks after injury when compared with control mice. Deletion of macrophage Drp1 also attenuated the macrophage accumulation and cell proliferation in the injured arteries. Gain- and loss-of-function experiments using cultured macrophages indicated that Drp1 induces the expression of molecules associated with inflammatory macrophages. Morphologically, mitochondrial fission was induced in inflammatory macrophages, whereas mitochondrial fusion was induced in less inflammatory/reparative macrophages. Pharmacological inhibition or knockdown of Drp1 decreased the mitochondrial reactive oxygen species and chemotactic activity in cultured macrophages. Co-culture experiments of macrophages with vascular smooth muscle cells indicated that deletion of macrophage Drp1 suppresses growth and migration of vascular smooth muscle cells induced by macrophage-derived soluble factors. CONCLUSIONS: Macrophage Drp1 accelerates intimal thickening after vascular injury by promoting macrophage-mediated inflammation. Macrophage Drp1 may be a potential therapeutic target of vascular diseases.

Lipid-Lowering Therapy With Ezetimibe Decreases Spontaneous Atherothrombotic Occlusions in a Rabbit Model of Plaque Erosion: A Role of Serum Oxysterols.

OBJECTIVE: Plaque erosion is increasing its importance as one of the mechanisms of acute coronary syndromes in this statin era. However, the clinical efficacy of currently used lipid-lowering agents in the prevention of thrombotic complications associated with plaque erosion has not been clarified. Therefore, we examined the therapeutic effects of ezetimibe or rosuvastatin monotherapy on spontaneous atherothrombotic occlusion. APPROACH AND RESULTS: Femoral arteries of Japanese white rabbits, fed a high-cholesterol diet, were injured by balloon catheter, and then angiotensin II was continuously administrated. In 94% of these arteries, spontaneous thrombotic occlusions were observed after 5 weeks (median) of balloon injury. Histochemical analyses indicated that the injured arteries had similar pathological features to human plaque erosions; (1) spontaneous thrombotic occlusion, (2) lack of endothelial cells, and (3) tissue factor expression in vascular smooth muscle cells. Ezetimibe (1.0 mg/kg per day), but not rosuvastatin (0.6 mg/kg per day), significantly decreased thrombotic occlusion of arteries accompanied with accelerated re-endothelialization and the decreases of serum oxysterols despite the comparable on-treatment serum cholesterol levels. The 7-ketocholesterol inhibited the migration of human umbilical vein endothelial cells. Both 7-ketocholesterol and 27-hydroxycholesterol increased tissue factor expression in cultured rat vascular smooth muscle cells. Tissue factor expression was also induced by serum from vehicle- or rosuvastatin-treated rabbits, but the induction was attenuated with serum from ezetimibe-treated rabbits. CONCLUSIONS: We have established a novel rabbit model of spontaneous atherothromobotic occlusion without plaque rupture that is feasible to test the therapeutic effects of various pharmacotherapies. Ezetimibe may decrease atherothrombotic complications after superficial plaque erosion by reducing serum oxysterols.

Nanoparticle-Mediated Targeting of Pitavastatin to Small Pulmonary Arteries and Leukocytes by Intravenous Administration Attenuates the Progression of Monocrotaline-Induced Established Pulmonary Arterial Hypertension in Rats.

Statins are known to improve pulmonary arterial hypertension (PAH) by their anti-inflammatory and anti-proliferative effects in animal models. However, recent clinical studies have reported that clinically approved statin doses failed to improve clinical outcomes in patients with PAH. We therefore hypothesized that nanoparticle (NP) -mediated targeting of pitavastatin could attenuate the progression of established PAH.We induced PAH by subcutaneously injecting monocrotaline (MCT) in Sprague-Dawley rats. On day 14 after the MCT injection, animals that displayed established PAH on echocardiography were included. On day 17, they were randomly assigned to the following 5 groups: daily intravenous administration of (1) vehicle, (2) fluorescein-isothiocyanate-NP, (3) pitavastatin, (4) pitavastatin-NP, or (5) oral sildenafil. Intravenous NP was selectively delivered to small pulmonary arteries and circulating CD11b-positive leukocytes. On day 21, pitavastatin-NP attenuated the progression of PAH at lower doses than pitavastatin alone. This was associated with the inhibition of monocyte-mediated inflammation, proliferation, and remodeling of the pulmonary arteries. Interestingly, sildenafil attenuated the development of PAH, but had no effects on inflammation or remodeling of the pulmonary arteries. In separate experiments, only treatment with pitavastatin-NP reduced the mortality rate at day 35.NP-mediated targeting of pitavastatin to small pulmonary arteries and leukocytes attenuated the progression of established MCT-induced PAH and improved survival. Therapeutically, pitavastatin-NP was associated with anti-inflammatory and anti-proliferative effects on small pulmonary arteries, which was completely distinct from the vasodilatory effect of sildenafil. Pitavastatin-NP can be a novel therapeutic modality for PAH.

Safety, Tolerability, and Pharmacokinetics of NK-104-NP.

Pulmonary hypertension (PH) is a disease with poor prognosis, caused by the obstruction/stenosis of small pulmonary arteries. Statin is known to have vasodilating and anti-inflammatory property and is considered to be a candidate of therapeutic agents for the treatment of PH, but its efficacy has not been verified in clinical trials. We have formulated pitavastatin incorporating nanoparticles composed of poly (lactic-co-glycolic acid) (NK-104-NP) to improve drug delivery to the pulmonary arteries and evaluated their safety and pharmacokinetics in healthy volunteers. To accomplish this purpose, phase I clinical trials were conducted. In the single intravenous administration regimen, 40 healthy subjects were enrolled and PK (pharmacokinetic) parameters in 4 groups (1, 2, 4, and 8 mg as pitavastatin calcium) were as follows: 1.00 hour after the administration, the plasma concentration of pitavastatin reached Cmax (the maximum drug concentration) in all groups. Cmax, AUC0-t (area under the curve from time 0 to the last measurable concentration) and AUC0-∞ (area under the curve from time 0 extrapolated to infinite time) were increased in a dose-dependent manner. Population pharmacokinetic analysis based on these results indicated no accumulation of pitavastatin after repeated administration of NK-104-NP for 7 days. In this 7-day administration trial, the mean Cmax and AUC0-∞ of pitavastatin were not significantly different between days 1 and 7, suggesting that pitavastatin is unlikely to accumulate after repeated administration. In these trials, three adverse events (AEs) were reported, but they were resolved without any complications and judged to have no causal relationships with NK-104-NP. These results indicate that the innovative nanotechnology-based medicine NK-104-NP exhibited dose-dependent pharmacokinetics and was well tolerated with no significant AEs in healthy volunteers.

Delta-Like Ligand 4-Notch Signaling in Macrophage Activation.

The Notch signaling pathway regulates the development of various cell types and organs, and also contributes to disease mechanisms in adults. Accumulating evidence suggests its role in cardiovascular and metabolic diseases. Notch signaling components also control the phenotype of immune cells. Delta-like ligand 4 (Dll4) of the Notch pathway promotes proinflammatory activation of macrophages in vitro and in vivo. Dll4 blockade attenuates chronic atherosclerosis, vein graft disease, vascular calcification, insulin resistance, and fatty liver in mice. The Dll4-Notch axis may, thus, participate in the shared mechanisms for cardiometabolic disorders, serving as a potential therapeutic target for ameliorating these global health problems.

Pioglitazone-Incorporated Nanoparticles Prevent Plaque Destabilization and Rupture by Regulating Monocyte/Macrophage Differentiation in ApoE-/- Mice.

OBJECTIVE: Inflammatory monocytes/macrophages produce various proteinases, including matrix metalloproteinases, and degradation of the extracellular matrix by these activated proteinases weakens the mechanical strength of atherosclerotic plaques, which results in a rupture of the plaque. Peroxisome proliferator-activated receptor-γ induces a polarity shift of monocytes/macrophages toward less inflammatory phenotypes and has the potential to prevent atherosclerotic plaque ruptures. Therefore, we hypothesized that nanoparticle-mediated targeted delivery of the peroxisome proliferator-activated receptor-γ agonist pioglitazone into circulating monocytes could effectively inhibit plaque ruptures in a mouse model. APPROACH AND RESULTS: We prepared bioabsorbable poly(lactic-co-glycolic-acid) nanoparticles containing pioglitazone (pioglitazone-NPs). Intravenously administered poly(lactic-co-glycolic-acid) nanoparticles incorporated with fluorescein isothiocyanate were found in circulating monocytes and aortic macrophages by flow cytometric analysis. Weekly intravenous administration of pioglitazone-NPs (7 mg/kg per week) for 4 weeks decreased buried fibrous caps, a surrogate marker of plaque rupture, in the brachiocephalic arteries of ApoE(-/-) mice fed a high-fat diet and infused with angiotensin II. In contrast, administration of control-NPs or an equivalent dose of oral pioglitazone treatment produced no effects. Pioglitazone-NPs inhibited the activity of matrix metalloproteinases and cathepsins in the brachiocephalic arteries. Pioglitazone-NPs regulated inflammatory cytokine expression and also suppressed the expression of extracellular matrix metalloproteinase inducer in bone marrow-derived macrophages. CONCLUSIONS: Nanoparticle-mediated delivery of pioglitazone inhibited macrophage activation and atherosclerotic plaque ruptures in hyperlipidemic ApoE(-/-) mice. These results demonstrate a promising strategy with a favorable safety profile to prevent atherosclerotic plaque ruptures.

Nanoparticle-Mediated Delivery of Pitavastatin to Monocytes/Macrophages Inhibits Left Ventricular Remodeling After Acute Myocardial Infarction by Inhibiting Monocyte-Mediated Inflammation.

Left ventricular (LV) remodeling after myocardial infarction (MI) causes heart failure. Although medical therapies including angiotensin converting enzyme inhibitors show inhibitory effects on post-infarct LV remodeling, the prognosis of patients with post-infarct heart failure is still poor. Accumulating evidence suggests that an inflammatory response is implicated in the process of post-infarct LV remodeling. Therefore, we hypothesized that anti-inflammatory therapy by nanoparticle-mediated monocyte/macrophage-targeting delivery of pitavastatin may protect the heart from post-infarct LV remodeling.Male C57BL/6 mice were subjected to permanent coronary ligation and pitavastatin-incorporating nanoparticles (Pitavastatin-NPs) were intravenously injected for 3 to 5 consecutive days. Pitavastatin-NPs were delivered to CD11b+ monocytes/macrophages, but not to cardiomyocytes. Treatment with Pitavastatin-NPs after establishment of MI attenuated post-infarct LV remodeling accompanied by a reduction of monocytes/macrophages in the heart, whereas pitavastatin solution treatment did not. Pitavastatin-NPs inhibited mobilization of monocytes from the spleen after MI. In mice after splenectomy, Pitavastatin-NPs still decreased the number of monocytes/macrophages in the infarcted heart and inhibited post-infarct LV remodeling.Nanoparticle-mediated delivery of pitavastatin to monocytes/macrophages may be a novel therapeutic strategy to protect the heart from post-infarct LV remodeling. Inhibition of monocyte mobilization from the bone marrow is one of the major mechanisms by which Pitavastatin-NPs attenuated post-infarct LV remodeling.

Macrophage Notch Ligand Delta-Like 4 Promotes Vein Graft Lesion Development: Implications for the Treatment of Vein Graft Failure.

OBJECTIVE: Despite its large clinical impact, the underlying mechanisms for vein graft failure remain obscure and no effective therapeutic solutions are available. We tested the hypothesis that Notch signaling promotes vein graft disease. APPROACH AND RESULTS: We used 2 biotherapeutics for Delta-like ligand 4 (Dll4), a Notch ligand: (1) blocking antibody and (2) macrophage- or endothelial cell (EC)-targeted small-interfering RNA. Dll4 antibody administration for 28 days inhibited vein graft lesion development in low-density lipoprotein (LDL) receptor-deficient (Ldlr(-/-)) mice, and suppressed macrophage accumulation and macrophage expression of proinflammatory M1 genes. Dll4 antibody treatment for 7 days after grafting also reduced macrophage burden at day 28. Dll4 silencing via macrophage-targeted lipid nanoparticles reduced lesion development and macrophage accumulation, whereas EC-targeted Dll4 small-interfering RNA produced no effects. Gain-of-function and loss-of-function studies suggested in vitro that Dll4 induces proinflammatory molecules in macrophages. Macrophage Dll4 also stimulated smooth muscle cell proliferation and migration and suppressed their differentiation. CONCLUSIONS: These results suggest that macrophage Dll4 promotes lesion development in vein grafts via macrophage activation and crosstalk between macrophages and smooth muscle cells, supporting the Dll4-Notch axis as a novel therapeutic target.

Nanoparticle-mediated delivery of pitavastatin inhibits atherosclerotic plaque destabilization/rupture in mice by regulating the recruitment of inflammatory monocytes.

BACKGROUND: Preventing atherosclerotic plaque destabilization and rupture is the most reasonable therapeutic strategy for acute myocardial infarction. Therefore, we tested the hypotheses that (1) inflammatory monocytes play a causative role in plaque destabilization and rupture and (2) the nanoparticle-mediated delivery of pitavastatin into circulating inflammatory monocytes inhibits plaque destabilization and rupture. METHODS AND RESULTS: We used a model of plaque destabilization and rupture in the brachiocephalic arteries of apolipoprotein E-deficient (ApoE(-/-)) mice fed a high-fat diet and infused with angiotensin II. The adoptive transfer of CCR2(+/+)Ly-6C(high) inflammatory macrophages, but not CCR2(-/-) leukocytes, accelerated plaque destabilization associated with increased serum monocyte chemoattractant protein-1 (MCP-1), monocyte-colony stimulating factor, and matrix metalloproteinase-9. We prepared poly(lactic-co-glycolic) acid nanoparticles that were incorporated by Ly-6G(-)CD11b(+) monocytes and delivered into atherosclerotic plaques after intravenous administration. Intravenous treatment with pitavastatin-incorporated nanoparticles, but not with control nanoparticles or pitavastatin alone, inhibited plaque destabilization and rupture associated with decreased monocyte infiltration and gelatinase activity in the plaque. Pitavastatin-incorporated nanoparticles inhibited MCP-1-induced monocyte chemotaxis and the secretion of MCP-1 and matrix metalloproteinase-9 from cultured macrophages. Furthermore, the nanoparticle-mediated anti-MCP-1 gene therapy reduced the incidence of plaque destabilization and rupture. CONCLUSIONS: The recruitment of inflammatory monocytes is critical in the pathogenesis of plaque destabilization and rupture, and nanoparticle-mediated pitavastatin delivery is a promising therapeutic strategy to inhibit plaque destabilization and rupture by regulating MCP-1/CCR2-dependent monocyte recruitment in this model.

descSPIM: an affordable and easy-to-build light-sheet microscope optimized for tissue clearing techniques.

Despite widespread adoption of tissue clearing techniques in recent years, poor access to suitable light-sheet fluorescence microscopes remains a major obstacle for biomedical end-users. Here, we present descSPIM (desktop-equipped SPIM for cleared specimens), a low-cost ($20,000-50,000), low-expertise (one-day installation by a non-expert), yet practical do-it-yourself light-sheet microscope as a solution for this bottleneck. Even the most fundamental configuration of descSPIM enables multi-color imaging of whole mouse brains and a cancer cell line-derived xenograft tumor mass for the visualization of neurocircuitry, assessment of drug distribution, and pathological examination by false-colored hematoxylin and eosin staining in a three-dimensional manner. Academically open-sourced ( https://github.com/dbsb-juntendo/descSPIM ), descSPIM allows routine three-dimensional imaging of cleared samples in minutes. Thus, the dissemination of descSPIM will accelerate biomedical discoveries driven by tissue clearing technologies.

Regulation of NETosis and Inflammation by Cyclophilin D in Myeloperoxidase-Positive Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

OBJECTIVE: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is pathologically characterized by focal fibrinoid necrosis, in which ANCA-mediated neutrophil extracellular trap (NET) formation and subsequent endothelial cell necrosis occur. Cyclophilin D (CypD) plays an important role in mediation of cell necrosis and inflammation via the opening of mitochondrial permeability transition pores. This study was undertaken to examine the role of CypD in AAV pathogenesis. METHODS: We assessed the role and mechanism of CypD in ANCA-stimulated neutrophils in vitro by immunostaining and electron microscopy observation. We performed a comprehensive RNA-sequencing analysis on ANCA-treated murine neutrophils. To investigate the role of CypD in vivo, we assessed disease features in CypD-knockout mice and wild-type mice using 2 different murine AAV models: anti-myeloperoxidase IgG transfer-induced AAV and spontaneous AAV. RESULTS: In vitro experiments showed that pharmacologic and genetic inhibition of CypD suppressed ANCA-induced NET formation via the suppression of reactive oxygen species and cytochrome c release from the mitochondria. RNA-sequencing analyses in ANCA-treated murine neutrophils revealed the involvement of inflammatory responses, with CypD deficiency reducing ANCA-induced alterations in gene expression. Furthermore, analyses of upstream regulators revealed the relevance of intracellular calcium (CypD activator) and cyclosporin (CypD inhibitor) in ANCA stimulation, indicating that the CypD-dependent opening of mitochondrial permeability transition pores is associated with ANCA-induced neutrophil activation and NETosis. In both AAV mouse models, the genetic deletion of CypD ameliorated crescentic glomerulonephritis via the inhibition of CypD-dependent neutrophil and endothelial necrosis. CONCLUSION: CypD targeting is a novel and specific therapeutic strategy for AAV via the resolution of necrotizing vasculitis.

Nanoparticle-Mediated Delivery of Pitavastatin to Monocytes/Macrophages Inhibits Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in Apoe-/- Mice.

AIM: Abdominal aortic aneurysm (AAA) is a lethal and multifactorial disease. To prevent a rupture and dissection of enlarged AAA, prophylactic surgery and stenting are currently available. There are, however, no medical therapies preventing these complications of AAA. Statin is one of the candidates, but its efficacy on AAA formation/progression remains controversial. We have previously demonstrated that nanoparticles (NPs) incorporating pitavastatin (Pitava-NPs)-clinical trials using these nanoparticles have been already conducted-suppressed progression of atherosclerosis in apolipoprotein E-deficient ( Apoe-/-) mice. Therefore, we have tested a hypothesis that monocytes/macrophages-targeting delivery of pitavastatin prevents the progression of AAA. METHODS: Angiotensin II was intraperitoneally injected by osmotic mini-pumps to induce AAA formation in Apoe-/- mice. NPs consisting of poly(lactic-co-glycolic acid) were used for in vivo delivery of pitavastatin to monocytes/macrophages. RESULTS: Intravenously administered Pitava-NPs (containing 0.012 mg/kg/week pitavastatin) inhibited AAA formation accompanied with reduction of macrophage accumulation and monocyte chemoattractant protein-1 (MCP-1) expression. Ex vivo molecular imaging revealed that Pitava-NPs not only reduced macrophage accumulation but also attenuated matrix metalloproteinase activity in the abdominal aorta, which was underpinned by attenuated elastin degradation. CONCLUSION: These results suggest that Pitava-NPs inhibit AAA formation associated with reduced macrophage accumulation and MCP-1 expression. This clinically feasible nanomedicine could be an innovative therapeutic strategy that prevents devastating complications of AAA.

Pitavastatin-Incorporated Nanoparticles for Chronic Limb Threatening Ischemia: A Phase I/IIa Clinical Trial.

AIM: To assess the results of a phase I/IIa open-label dose-escalation clinical trial of 5-day repeated intramuscular administration of pitavastatin-incorporated poly (lactic-co-glycolic acid) nanoparticles (NK-104-NP) in patients with chronic limb threatening ischemia (CLTI). METHODS: NK-104-NP was formulated using an emulsion solvent diffusion method. NK-104-NP at four doses (nanoparticles containing 0.5, 1, 2, and 4 mg of pitavastatin calcium, n=4 patients per dose) was investigated in a dose-escalation manner and administered intramuscularly into the ischemic limbs of 16 patients with CLTI. The safety and therapeutic efficacy of treatment were investigated over a 26-week follow-up period. RESULTS: No cardiovascular or other serious adverse events caused by NK-104-NP were detected during the follow-up period. Improvements in Fontaine and Rutherford classifications were noted in five patients (one, three, and one in the 1-, 2-, and 4-mg dose groups, respectively). Pharmacokinetic parameters including the maximum serum concentration and the area under the blood concentration-time curve increased with pitavastatin treatment in a dose-dependent manner. The area under the curve was slightly increased at day 5 compared with that at day 1 of treatment, although the difference was not statistically significant. CONCLUSIONS: This is the first clinical trial of pitavastatin-incorporated nanoparticles in patients with CLTI. Intramuscular administration of NK-104-NP to the ischemic limbs of patients with CLTI was safe and well tolerated and resulted in improvements in limb function.

Dietary 7-ketocholesterol exacerbates myocardial ischemia-reperfusion injury in mice through monocyte/macrophage-mediated inflammation.

Emerging evidence suggests that 7-ketocholesterol (7-KC), one of the most abundant dietary oxysterols, causes inflammation and cardiovascular diseases. Here we show the deteriorating effects of dietary 7-KC on myocardial ischemia-reperfusion (IR) injury and detailed the molecular mechanisms. A high-fat high-cholesterol diet containing 7-KC (7KWD) for 3 weeks increased the plasma 7-KC level compared with high-fat high-cholesterol diet in mice. In wild-type mice but not in CCR2-/- mice, dietary 7-KC increased the myocardial infarct size after IR. Flow cytometry revealed that the ratio of Ly-6Chigh inflammatory monocytes to total monocytes was increased in the 7KWD group. Unbiased RNA sequencing using murine primary macrophages revealed that 7-KC regulated the expression of transcripts related to inflammation and cholesterol biosynthesis. We further validated that in vitro, 7-KC induced endoplasmic reticulum stress, mitochondrial reactive oxygen species production, and nuclear factor-kappa B activation, which are associated with increased mRNA levels of proinflammatory cytokines. Administration of N-acetyl-L-cysteine or siRNA-mediated knockdown of PKR-like endoplasmic reticulum kinase or endoplasmic reticulum oxidase 1α suppressed the levels of 7-KC-induced inflammation. Dietary 7-KC exacerbates myocardial IR injury through monocyte/macrophage-mediated inflammation. Endoplasmic reticulum stress and oxidative stress are involved in the 7-KC-induced proinflammatory response in macrophages.

Nanoparticle-Mediated Simultaneous Targeting of Mitochondrial Injury and Inflammation Attenuates Myocardial Ischemia-Reperfusion Injury.

Background The opening of mitochondrial permeability transition pore and inflammation cooperatively progress myocardial ischemia-reperfusion (IR) injury, which hampers therapeutic effects of primary reperfusion therapy for acute myocardial infarction. We examined the therapeutic effects of nanoparticle-mediated medicine that simultaneously targets mitochondrial permeability transition pore and inflammation during IR injury. Methods and Results We used mice lacking cyclophilin D (CypD, a key molecule for mitochondrial permeability transition pore opening) and C-C chemokine receptor 2 and found that CypD contributes to the progression of myocardial IR injury at early time point (30-45 minutes) after reperfusion, whereas C-C chemokine receptor 2 contributes to IR injury at later time point (45-60 minutes) after reperfusion. Double deficiency of CypD and C-C chemokine receptor 2 enhanced cardioprotection compared with single deficiency regardless of the durations of ischemia. Deletion of C-C chemokine receptor 2, but not deletion of CypD, decreased the recruitment of Ly-6Chigh monocytes after myocardial IR injury. In CypD-knockout mice, administration of interleukin-1ß blocking antibody reduced the recruitment of these monocytes. Combined administration of polymeric nanoparticles composed of poly-lactic/glycolic acid and encapsulating nanoparticles containing cyclosporine A or pitavastatin, which inhibit mitochondrial permeability transition pore opening and monocyte-mediated inflammation, respectively, augmented the cardioprotection as compared with single administration of nanoparticles containing cyclosporine A or pitavastatin after myocardial IR injury. Conclusions Nanoparticle-mediated simultaneous targeting of mitochondrial injury and inflammation could be a novel therapeutic strategy for the treatment of myocardial IR injury.

Soluble Flt-1 gene transfer ameliorates neointima formation after wire injury in flt-1 tyrosine kinase-deficient mice.

OBJECTIVE: We have demonstrated that vascular endothelial growth factor (VEGF) expression is upregulated in injured vascular wall, and blockade of VEGF inhibited monocyte infiltration and neointima formation in several animal models. In the present study, we aimed to clarify relative role of two VEGF receptors, flt-1 versus flk-1/KDR, in neointima formation after injury using flt-1 tyrosine kinase-deficient (Flt-1 TK(-/-)) mice and soluble Flt-1(sFlt-1) gene transfer. METHODS AND RESULTS: Neointima formation was comparable between wild-type and Flt-1 TK(-/-) mice 28 days after intraluminal wire injury in femoral arteries. By contrast, neointima formation was significantly suppressed by sFlt-1 gene transfer into Flt-1 TK(-/-) mice that blocks VEGF action on flk-1 (intima/media ratio: 2.8+/-0.4 versus 1.4+/-0.4, P<0.05). The inhibition of neointima formation was preceded by significant reduction of monocyte chemoattractant protein (MCP-1) expression in vascular smooth muscle cells (VSMCs) and monocyte infiltration 7 days after injury. Gene transfer of sFlt-1 or treatment of flk-1-specific antibody significantly inhibited VEGF-induced MCP-1 expression determined by RT-PCR in cultured aortic tissue and VSMCs. MCP-1-induced chemotaxis was equivalent between wild-type and Flt-1 TK(-/-) mice. CONCLUSIONS: These results suggest that endogenous VEGF accelerates neointima formation through flk-1 by regulating MCP-1 expression in VSMCs and macrophage-mediated inflammation in injured vascular wall in murine model of wire injury.

Therapeutic neovascularization by nanotechnology-mediated cell-selective delivery of pitavastatin into the vascular endothelium.

OBJECTIVE: Recent clinical studies of therapeutic neovascularization using angiogenic growth factors demonstrated smaller therapeutic effects than those reported in animal experiments. We hypothesized that nanoparticle (NP)-mediated cell-selective delivery of statins to vascular endothelium would more effectively and integratively induce therapeutic neovascularization. METHODS AND RESULTS: In a murine hindlimb ischemia model, intramuscular injection of biodegradable polymeric NP resulted in cell-selective delivery of NP into the capillary and arteriolar endothelium of ischemic muscles for up to 2 weeks postinjection. NP-mediated statin delivery significantly enhanced recovery of blood perfusion to the ischemic limb, increased angiogenesis and arteriogenesis, and promoted expression of the protein kinase Akt, endothelial nitric oxide synthase (eNOS), and angiogenic growth factors. These effects were blocked in mice administered a nitric oxide synthase inhibitor, or in eNOS-deficient mice. CONCLUSIONS: NP-mediated cell-selective statin delivery may be a more effective and integrative strategy for therapeutic neovascularization in patients with severe organ ischemia.

Therapeutic Arteriogenesis/Angiogenesis for Peripheral Arterial Disease by Nanoparticle-Mediated Delivery of Pitavastatin into Vascular Endothelial Cells.

Two decades have passed since therapeutic angiogenesis was proposed to promote reparative collateral growth as an alternative therapy for ischemic diseases in patients for whom neither surgical revascularization nor endovascular therapy was suitable. When therapeutic angiogenesis first began, local administration was conducted using recombinant growth factor proteins or gene-encoding growth factors for endothelial cells. Since then, autologous stem cells and endothelial progenitor cell transplantation therapy have been developed. Although many clinical trials have been performed on patients, most therapies have not yet become standard treatments. We have developed a nanoparticle (NP)-mediated, drug-targeting delivery system using bioabsorbable poly-lactic/glycolic acid (PLGA) NPs. In several animal models, pitavastatin-incorporated (Pitava)-NPs showed significant therapeutic effects on critical limb ischemia. Because PLGA NPs are delivered selectively to vascular endothelial cells after intramuscular administration, it is suggested that therapeutic angiogenesis/arteriogenesis plays an important role in the mechanism by which Pitava-NPs exert beneficial therapeutic effects. To translate this to clinical medicine, we have performed studies and produced Pitava-NPs in compliance with good laboratory practice/good manufacturing practice regulations, and completed a phase I/II clinical trial, reporting the safety and efficacy of Pitava-NP intramuscular injection for patients with critical limb ischemia. This review will focus on therapeutic angiogenesis/arteriogenesis for peripheral arterial disease induced by Pitava-NPs.

Simultaneous targeting of mitochondria and monocytes enhances neuroprotection against ischemia-reperfusion injury.

Ischemia-reperfusion injury impairs the efficacy of reperfusion therapy after ischemic stroke. Cyclophilin D (CypD)-mediated openings of mitochondrial permeability transition pore (mPTP) and subsequent monocyte-mediated inflammation are considered as major mechanisms of reperfusion injury. However, no medical therapies are currently available. Therefore, we have tested a hypothesis that simultaneous targeting of mPTP and inflammation confers substantial neuroprotection after cerebral ischemia-reperfusion. To address this point, we prepared CypD knockout mice, C-C chemokine receptor 2 (CCR2) knockout mice and CypD/CCR2 double knockout mice. These mice were subjected to 60 min transient cerebral ischemia by occluding middle cerebral arteries. Neurological deficits evaluated 3 days after reperfusion were significantly attenuated in CypD/CCR2 double knockout mice as compared to wild-type mice and other single knockout mice. Then, we have prepared polymeric nanoparticles containing cyclosporine A (CsA-NPs) and pitavastatin (Pitava-NPs), targeting mPTP opening and inflammation, respectively. Simultaneous administration of CsA-NP and Pitava-NP at the time of reperfusion also decreased infarct size and attenuated neurological deficits as compared to control nanoparticles and single administration of CsA-NPs or Pitava-NPs. These results indicate that simultaneous targeting of the mPTP opening and monocyte-mediated inflammation could be a novel strategy for better neurological outcomes in patients with ischemic stroke.

Peroxisome proliferator-activated receptor-gamma targeting nanomedicine promotes cardiac healing after acute myocardial infarction by skewing monocyte/macrophage polarization in preclinical animal models.

Aims: Monocyte-mediated inflammation is a major mechanism underlying myocardial ischaemia-reperfusion (IR) injury and the healing process after acute myocardial infarction (AMI). However, no definitive anti-inflammatory therapies have been developed for clinical use. Pioglitazone, a peroxisome proliferator-activated receptor-gamma (PPARγ) agonist, has unique anti-inflammatory effects on monocytes/macrophages. Here, we tested the hypothesis that nanoparticle (NP)-mediated targeting of pioglitazone to monocytes/macrophages ameliorates IR injury and cardiac remodelling in preclinical animal models. Methods and results: We formulated poly (lactic acid/glycolic acid) NPs containing pioglitazone (pioglitazone-NPs). In a mouse IR model, these NPs were delivered predominantly to circulating monocytes and macrophages in the IR heart. Intravenous treatment with pioglitazone-NPs at the time of reperfusion attenuated IR injury. This effect was abrogated by pre-treatment with the PPARγ antagonist GW9662. In contrast, treatment with a pioglitazone solution had no therapeutic effects on IR injury. Pioglitazone-NPs inhibited Ly6Chigh inflammatory monocyte recruitment as well as inflammatory gene expression in the IR hearts. In a mouse myocardial infarction model, intravenous treatment with pioglitazone-NPs for three consecutive days, starting 6 h after left anterior descending artery ligation, attenuated cardiac remodelling by reducing macrophage recruitment and polarizing macrophages towards the pro-healing M2 phenotype. Furthermore, pioglitazone-NPs significantly decreased mortality after MI. Finally, in a conscious porcine model of myocardial IR, pioglitazone-NPs induced cardioprotection from reperfused infarction, thus providing pre-clinical proof of concept. Conclusion: NP-mediated targeting of pioglitazone to inflammatory monocytes protected the heart from IR injury and cardiac remodelling by antagonizing monocyte/macrophage-mediated acute inflammation and promoting cardiac healing after AMI.