Celso Kiyochi Takimura

Emerging technologies: Polymer-free phospholipid encapsulated sirolimus nanocarriers for the controlled release of drug from a stent-plus-balloon or a stand-alone balloon catheter

Drug-eluting stents have proven to be effective in reducing the risk of late restenosis. In order to achieve a controlled and prolonged release of the antiproliferative agent, current drug-eluting stents utilise various biodegradable as well as non-erodible polymeric blends to coat the stent surface and to serve as drug carriers. The utilisation of polymeric compounds in current drug-eluting stents may eventually limit their performance as well as their clinical applicability due to the potential induction of undesirable local reactions. The development of alternative, polymer-free drug carriers has the potential to overcome some of the limitations of current drug-eluting stent formulations. Moreover, improvements in drug carriers may also result in an expansion of the technological possibilities for other intravascular drug delivery systems, such as metal-free or even implant-free solutions. This article describes the structure and the preclinical validation profile of a novel phospholipid encapsulated sirolimus nanocarrier, used as a coating in two formulations: a coronary stent-plus-balloon system and a stand-alone balloon catheter. The nanoparticles provided a stable, even and homogenous coating to the devices in both formulations. Dose-finding studies allowed the most appropriate identification of the best nanoparticle structure associated with an extremely efficient transfer of drug to all layers of the vessel wall, achieving high tissue concentrations that persisted days after the application, with low systemic drug leaks.

Intravascular Ultrasound Guidance to Minimize the Use of Iodine Contrast in Percutaneous Coronary Intervention: The MOZART (Minimizing cOntrast utiliZation With IVUS Guidance in coRonary angioplasTy) Randomized Controlled Trial

Objective To evaluate the impact of IVUS guidance on the final volume of contrast agent utilized in patients undergoing PCI.

Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery: Report of an Adult Case

We report the clinical findings, pathophysiology, diagnostic characteristics, and surgical repair of anomalous origin of the left coronary artery from the pulmonary artery in a 26-year-old female patient with a clinical diagnosis of coronary heart disease.

Myocardial homing after intrapericardial infusion of Bone Marrow Mononuclear Cells

Erika Branco1, Emerson Ticona Fioretto2, Rosa Cabral3, Carlos Alberto Sarmento Palmera4, Guilherme Buzon Gregores4, Angelo Joao Stopiglia4, Paulo Cesar Maiorka4, Pedro Alves Lemos5, Carlos Campos5, Celso Takimura5, Jose Antonio Franchini Ramires5, Maria Angelica Miglino4 Faculdade de Medicina Veterinaria da Universidade Federal Rural da Amazonia – UFRA1, Belem, PA; Universidade Federal do Sergipe – UFS2, Aracaju, SE; Universidade Feral do Piaui – UFPI3, Teresina, PI; Faculdade de Medicina Veterinaria e Zootecnia FMVZ/USP4, Sao Paulo, SP; Instituto do Coracao – Incor5, Sao Paulo, SP, Brasil

Stent coronário de liga cobalto-cromo concebido no Brasil: achados histológicos preliminares em modelo experimental porcino

SUMMARY Cobalt-Chromium Coronary Stent Conceivedin Brazil: Preliminary Histologic Findings inan Experimental Porcine Model Background: This study aims to evaluate, in an experimen-tal porcine model, a new and pioneer cobalt-chromiumthin-strut coronary stent conceived in Brazil. Also, it aimsto report the initial experience of a Brazilian center forpre-clinical validation of endovascular devices. Method: The new bare Cobalt-Chromium stent (Scitech ProdutosMedicos Ltda) was implanted in the coronary arteries oftwelve domestic pigs. The stent was designed in short rings(for increased homogeneity of vessel scaffolding), thin struts(75 µm) and inter-strut angle engineered to optimize theradial strength. The inter-ring connection was made by ashort and very thin link (65 µm) in a curved format, witha circumferential diameter of 6 mm for side branch access.Another two animals received conventional bare metalstents as controls (Driver®, Medtronic Inc., e Matrix®,Sahajanand Medical Technologies). After one month, theimplanted stents were excised for microscopic analysis.

Peri/Epicellular Protein Disulfide Isomerase Sustains Vascular Lumen Caliber Through an Anticonstrictive Remodeling Effect

Whole-vessel remodeling critically determines lumen caliber in vascular (patho)physiology, and it is reportedly redox-dependent. We hypothesized that the cell-surface pool of the endoplasmic reticulum redox chaperone protein disulfide isomerase-A1 (peri/epicellular=pecPDI), which is known to support thrombosis, also regulates disease-associated vascular architecture. In human coronary atheromas, PDI expression inversely correlated with constrictive remodeling and plaque stability. In a rabbit iliac artery overdistension model, there was unusually high PDI upregulation (≈25-fold versus basal, 14 days postinjury), involving both intracellular and pecPDI. PecPDI neutralization with distinct anti-PDI antibodies did not enhance endoplasmic reticulum stress or apoptosis. In vivo pecPDI neutralization with PDI antibody-containing perivascular gel from days 12 to 14 post injury promoted 25% decrease in the maximally dilated arteriographic vascular caliber. There was corresponding whole-vessel circumference loss using optical coherence tomography without change in neointima, which indicates constrictive remodeling. This was accompanied by decreased hydrogen peroxide generation. Constrictive remodeling was corroborated by marked changes in collagen organization, that is, switching from circumferential to radial fiber orientation and to a more rigid fiber type. The cytoskeleton architecture was also disrupted; there was a loss of stress fiber coherent organization and a switch from thin to medium thickness actin fibers, all leading to impaired viscoelastic ductility. Total and PDI-associated expressions of &bgr;1-integrin, and levels of reduced cell-surface &bgr;1-integrin, were diminished after PDI antibody treatment, implicating &bgr;1-integrin as a likely pecPDI target during vessel repair. Indeed, focal adhesion kinase phosphorylation, a downstream &bgr;1-integrin effector, was decreased by PDI antibody. Thus, the upregulated pecPDI pool tunes matrix/cytoskeleton reshaping to counteract inward remodeling in vascular pathophysiology.

Avaliação pela tomografia de coerência óptica de stent nacional recoberto com polímero biodegradável eluidor de sirolimus vs. stent eluidor de biolimus A9 em artérias coronárias porcinas

BACKGROUND: InspironTM, a chrome-cobalt sirolimus-eluting stent covered by a mixture of bioabsorbable polymers on its abluminal side is being developed in Brazil. Our objective was to compare in an experimental study the findings of optical coherence tomography for the InspironTM and BioMatrix™ stents. METHODS: Stents were implanted in porcine coronary arteries. Each individual received two types of stents, one in each artery (left anterior descending and left circumflex artery). After 28 days, a new angiography was performed and optical coherence tomography was used to assess neointimal hyperplasia. RESULTS: Seven Inspiron™ stents and 7 BioMatrixTM stents were implanted in 7 domestic pigs. The reference diameter of the treated vessels was 2.16 ± 0.37 mm and the balloon to artery ratio was 1.17 ± 0.16 atm, with no statistical difference between groups. In-stent late loss was 0.53 ± 0.56 mm and 0.32 ± 0.37 mm (P = 0.43) for the InspironTM and BioMatrixTM stents, respectively. There was one case of angiographic restenosis in the InspironTM group (14% vs 0; P = 0.2). Optical coherence tomography showed an instent neointimal area of 1.61 ± 0.57 mm2 for the InspironTM stent and 1.36 ± 0.66 mm2 for the BioMatrixTM stent (P = 0.47). The percentage of neointimal area was 31% for the InspironTM stent vs 23% for the BiomatrixTM stent (P = 0.21). CONCLUSIONS: Twenty-eight days after implantation in porcine coronary arteries the InspironTM stent showed a similar degree of neointimal hyperplasia as the BiomatrixTM stent.

Catheter‐based induction of renal ischemia/reperfusion in swine: description of an experimental model

Several techniques to induce renal ischemia have been proposed: clamp, PVA particles, and catheter‐balloon. We report the development of a controlled, single‐insult model of unilateral renal ischemia/reperfusion (I/R) without contralateral nephrectomy, using a suitable model, the pig. This is a balloon‐catheter‐based model using a percutaneous, interventional radiology procedure. One angioplasty balloon‐catheter was placed into the right renal artery and inflated for 120 min and reperfusion over 24 h. Serial serums were sampled from the inferior vena cava and urine was directly sampled from the bladder throughout the experiment, and both kidneys were excised after 24 h of reperfusion. Analyses of renal structure and function were performed by hematoxylin–eosin/periodic Acid‐Schiff, serum creatinine (SCr), blood urea nitrogen (BUN), fractional excretion of ions, and glucose, SDS‐PAGE analysis of urinary proteins, and serum neutrophil gelatinase‐associated lipocalin (NGAL). Total nitrated protein was quantified to characterize oxidative stress. Acute tubular necrosis (ATN) was identified in every animal, but only two animals showed levels of SCr above 150% of baseline values. As expected, I/R increased SCr and BUN. Fractional sodium, potassium, chloride, and bicarbonate excretion were modulated during ischemia. Serum‐nitrated proteins and NGAL had two profiles: decreased with ischemia and increased after reperfusion. This decline was associated with increased protein excretion during ischemia and early reperfusion. Altogether, these data show that the renal I/R model can be performed by percutaneous approach in the swine model. This is a suitable translational model to study new early renal ischemic biomarkers and pathophysiological mechanisms in renal ischemia.

Estudo da dose excipiente: fármaco com avaliação da hiperplasia neointimal por tomografia de coerência óptica e histopatologia em artérias coronárias porcinas após o emprego do balão eluidor de sirolimus

BACKGROUND: Magic TouchTM is a sirolimus based nano carrier balloon. We aimed at finding the excipient:drug ratio with the highest capacity to inhibit neointimal proliferation 28 days after the use of this balloon after bare metal stenting in porcine coronary arteries. METHODS: Fourteen domestic pigs with coronary bare metal stenting followed by dilation (60 seconds) using balloons with an excipient:sirolimus ratio of 1:1, 0.5:1, 0.25:1, 1:0 or a control balloon were evaluated. After 28 days neointimal hyperplasia was assessed by optical coherence tomography and histopathology. RESULTS: Percent neointimal hyperplasia (%) assessed by optical coherence tomography and histomorphometry was 32.2 and 35.1, 28.1 and 33.4, 17.3 and 20.9, 28.6 and 30.2, and 37.9 and 42.3 in the groups with 0.25:1, 0.5:1, 1:1, 1:0 excipient:sirolimus ratios and control balloon, respectively (P = 0.03 for excipient:sirolimus 1:1 versus control balloon). The neointimal interstrut thickness (mm) was 0.23, 0.30, 0.16, 0.24 and 0.30 in the groups with 0.25:1, 0.5:1, 1:1, 1:0 excipient:sirolimus ratios and control balloon, respectively (P < 0.01 for excipient:sirolimus 1:1 versus control balloon). The scores of inflammation, injury and fibrin deposition were low and there was no significant difference among groups. CONCLUSIONS: There was a stepwise increase in inhibitory efficacy of neointimal proliferation as the excipient concentration increased; the lowest efficacy was observed with the 0.25:1 excipient:sirolimus formulation and the most intensive inhibition was observed with the 1:1 excipient:sirolimus formulation. The 1:1 excipient:sirolimus formulation significantly reduced neointimal proliferation when compared to the control group, with low inflammation and injury scores.

A histopathological comparison of different definitions for quantifying in-stent neointimal tissue: implications for the validity of intracoronary ultrasound and optical coherence tomography measurements.

PURPOSE Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) define neointima as the tissue encompassed between the stent and the lumen boundaries. This approach differs from the gold-standard histopathology, where neointima is traditionally calculated as the tissue between the internal elastic lamina (IEL) and the lumen. We aimed to investigate whether the neointimal assessment using IVUS and OCT-like definitions would correlate with the traditional histopathological quantification of neointima. METHODS Histopathological analysis was obtained from a porcine model of 28-day coronary in-stent neointimal proliferation (n=13 bare stents). Traditional histopathology neointimal area (NIHPATH area) was calculated as the lumen area minus the IEL area, while the percent neointimal obstruction was defined as NIHPATH area divided by the IEL area. The IVUS/OCT-like neointima area (NIHIVUS/OCT area) was defined as the lumen area minus the stent area, while the percent neointimal obstruction was defined as NIHIVUS/OCT area divided by the stent area. RESULTS The neointimal area as well as the percent obstruction were significantly correlated between histopathology and IVUS/OCT-like definitions (R(2)=0.89 and 0.95 respectively; P<0.01 for both). The average absolute difference between the IVUS/OCT-like and the pathology-like measurements was close to zero, however with a relatively wide dispersion (difference for neointimal area: 0.41 mm(2) [95% CI 1.72 to (-)0.90 mm(2)]; difference for percent neointimal obstruction: 2.5% [95% CI 11.5% to (-)6.5%]). CONCLUSIONS The present findings support the use of stent area in replacement to IEL area, as in IVUS & OCT imaging protocols, for the calculation of neointimal parameters in experimental model of restenosis.