Mamoru Arakawa

In-body tissue-engineered aortic valve (Biovalve type VII) architecture based on 3D printer molding

In-body tissue architecture--a novel and practical regeneration medicine technology--can be used to prepare a completely autologous heart valve, based on the shape of a mold. In this study, a three-dimensional (3D) printer was used to produce the molds. A 3D printer can easily reproduce the 3D-shape and size of native heart valves within several processing hours. For a tri-leaflet, valved conduit with a sinus of Valsalva (Biovalve type VII), the mold was assembled using two conduit parts and three sinus parts produced by the 3D printer. Biovalves were generated from completely autologous connective tissue, containing collagen and fibroblasts, within 2 months following the subcutaneous embedding of the molds (success rate, 27/30). In vitro evaluation, using a pulsatile circulation circuit, showed excellent valvular function with a durability of at least 10 days. Interposed between two expanded polytetrafluoroethylene grafts, the Biovalves (N = 3) were implanted in goats through an apico-aortic bypass procedure. Postoperative echocardiography showed smooth movement of the leaflets with minimal regurgitation under systemic circulation. After 1 month of implantation, smooth white leaflets were observed with minimal thrombus formation. Functional, autologous, 3D-shaped heart valves with clinical application potential were formed following in-body embedding of specially designed molds that were created within several hours by 3D printer.

Dual-Modality Activity-Based Probes as Molecular Imaging Agents for Vascular Inflammation

Macrophages are cellular mediators of vascular inflammation and are involved in the formation of atherosclerotic plaques. These immune cells secrete proteases such as matrix metalloproteinases and cathepsins that contribute to disease formation and progression. Here, we demonstrate that activity-based probes (ABPs) targeting cysteine cathepsins can be used in murine models of atherosclerosis to noninvasively image activated macrophage populations using both optical and PET/CT methods. The probes can also be used to topically label human carotid plaques demonstrating similar specific labeling of activated macrophage populations. Methods: Macrophage-rich carotid lesions were induced in FVB mice fed on a high-fat diet by streptozotocin injection followed by ligation of the left common carotid artery. Mice with carotid atherosclerotic plaques were injected with the optical or dual-modality probes BMV109 and BMV101, respectively, via the tail vein and noninvasively imaged by optical and small-animal PET/CT at different time points. After noninvasive imaging, the murine carotid arteries were imaged in situ and ex vivo, followed by immunofluorescence staining to confirm target labeling. Additionally, human carotid plaques were topically labeled with the probe and analyzed by both sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunofluorescence staining to confirm the primary targets of the probe. Results: Quantitative analysis of the signal intensity from both optical and PET/CT imaging showed significantly higher levels of accumulation of BMV109 and BMV101 (P < 0.005 and P < 0.05, respectively) in the ligated left carotid arteries than the right carotid or healthy arteries. Immunofluorescence staining for macrophages in cross-sectional slices of the murine artery demonstrated substantial infiltration of macrophages in the neointima and adventitia of the ligated left carotid arteries compared with the right. Analysis of the human plaque tissues by sodium dodecyl sulfate polyacrylamide gel electrophoresis confirmed that the primary targets of the probe were cathepsins X, B, S, and L. Immunofluorescence labeling of the human tissue with the probe demonstrated colocalization of the probe with CD68, elastin, and cathepsin S, similar to that observed in the experimental carotid inflammation murine model. Conclusion: We demonstrate that ABPs targeting the cysteine cathepsins can be used in murine models of atherosclerosis to noninvasively image activated macrophage populations using both optical and PET/CT methods. The probes could also be used to topically label human carotid plaques demonstrating similar specific labeling of activated macrophage populations. Therefore, ABPs targeting the cysteine cathepsins are potentially valuable new reagents for rapid and noninvasive imaging of atherosclerotic disease progression and plaque vulnerability.

Assessment of Elastin Deficit in a Marfan Mouse Aneurysm Model Using an Elastin-Specific Magnetic Resonance Imaging Contrast Agent

Background—Ascending aortic dissection and rupture remain a life-threatening complication in patients with Marfan syndrome. The extracellular matrix provides strength and elastic recoil to the aortic wall, thereby preventing radial expansion. We have previously shown that ascending aortic aneurysm formation in Marfan mice (Fbn1C1039G/+) is associated with decreased aortic wall elastogenesis and increased elastin breakdown. In this study, we test the feasibility of quantifying aortic wall elastin content using MRI with a gadolinium-based elastin-specific magnetic resonance contrast agent in Fbn1C1039G/+ mice. Methods and Results—Ascending aorta elastin content was measured in 32-week-old Fbn1C1039G/+ mice and wild-type (n=9 and n=10, respectively) using 7-T MRI with a T1 mapping sequence. Significantly lower enhancement (ie, lower R1 values, where R1=1/T1) was detected post–elastin-specific magnetic resonance contrast agent in Fbn1C1039G/+ compared with wild-type ascending aortas (1.15±0.07 versus 1.36±0.05; P<0.05). Post–elastin-specific magnetic resonance contrast agent R1 values correlated with ascending aortic wall gadolinium content directly measured by inductively coupled mass spectroscopy (P=0.006). Conclusions—Herein, we demonstrate that MRI with elastin-specific magnetic resonance contrast agent accurately measures elastin bound gadolinium within the aortic wall and detects a decrease in aortic wall elastin in Marfan mice compared with wild-type controls. This approach has translational potential for noninvasively assessing aneurysm tissue changes and risk, as well as monitoring elastin content in response to therapeutic interventions.

Long‐term miR‐29b suppression reduces aneurysm formation in a Marfan mouse model

Aortic root aneurysm formation and subsequent dissection and/or rupture remain the leading cause of death in patients with Marfan syndrome. Our laboratory has reported that miR‐29b participates in aortic root/ascending aorta extracellular matrix remodeling during early aneurysm formation in Fbn1C1039G/+ Marfan mice. Herein, we sought to determine whether miR‐29b suppression can reduce aneurysm formation long‐term. Fbn1C1039G/+ Marfan mice were treated with retro‐orbital LNA‐anti‐miR‐29b inhibitor or scrambled‐control‐miR before aneurysms develop either (1) a single dose prenatally (pregnant Fbn1C1039G/+ mice at 14.5 days post‐coitum) (n = 8–10, each group) or (2) postnatally every other week, from 2 to 22 weeks of age, and sacrificed at 24 weeks (n = 8–10, each group). To determine if miR‐29b blockade was beneficial even after aneurysms develop, a third group of animals were treated every other week, starting at 8 weeks of age, until sacrificed (n = 4–6, each group). miR‐29b inhibition resulted in aneurysm reduction, increased elastogenesis, decreased matrix metalloproteinase activity and decreased elastin breakdown. Prenatal LNA‐anti‐miR‐29b inhibitor treatment decreased aneurysm formation up to age 32 weeks, whereas postnatal treatment was effective up to 16 weeks. miR‐29b blockade did not slow aortic growth once aneurysms already developed. Systemic miR‐29b inhibition significantly reduces aneurysm development long‐term in a Marfan mouse model. Drug administration during aortic wall embryologic development appears fundamental. miR‐29b suppression could be a potential therapeutic target for reducing aneurysm formation in Marfan syndrome patients.

Gene expression profiling of acute type A aortic dissection combined with in vitro assessment

OBJECTIVES The mechanisms underlying aortic dissection remain to be fully elucidated. We aimed to identify key molecules driving dissection through gene expression profiling achieved by microarray analysis and subsequent in vitro experiments using human aortic endothelial cells (HAECs) and aortic vascular smooth muscle cells (AoSMCs). METHODS Total RNA, including microRNA (miRNA), was isolated from the intima‐media layer of dissected ascending aorta obtained intraoperatively from acute type A aortic dissection (ATAAD) patients without familial thoracic aortic disease (n = 8) and that of non‐dissected ascending aorta obtained from transplant donors (n = 9). Gene expression profiling was performed with mRNA and miRNA microarrays, and results were confirmed by quantitative polymerase chain reaction (qPCR). Target genes and miRNA were identified by gene ontology analysis and a literature search. To reproduce the in silico results, HAECs and AoSMCs were stimulated in vitro by upstream cytokines, and expression of target genes was assessed by qPCR. RESULTS Microarray analysis revealed 1536 genes (3.6%, 1536/42 545 probes) and 41 miRNAs (3.0%, 41/1368 probes) that were differentially expressed in the ATAAD group (versus donor group). The top 15 related pathways included regulation of inflammatory response, growth factor activity and extracellular matrix. Gene ontology analysis identified JAK2 (regulation of inflammatory response), PDGFA, TGFB1, VEGFA (growth factor activity) and TIMP3, TIMP4, SERPINE1 (extracellular matrix) as the target genes and miR‐21‐5p, a TIMP3 repressor, as target miRNA that interacts with the target genes. Validation qPCR confirmed the altered expression of all 7 target genes and miR‐21‐5p in dissected aorta specimens (all genes, P < 0.05). Ingenuity pathway analysis showed TNF‐&agr; and TGF‐&bgr; to be upstream cytokines for the target genes. In vitro experiments showed these cytokines inhibit TIMP3 expression (P < 0.05) and enhance VEGFA expression (P < 0.01) in AoSMCs but not HAECs. miR‐21‐5p expression increases in AoSMCs under TNF‐&agr; and TGF‐&bgr; stimulation (fold change: 1.36; P = 0.011). CONCLUSIONS Results of our novel approach, integrating in vitro assessment into gene expression profiling, implicated chronic inflammation characterized by MMP‐TIMP dysregulation, increased VEGFA expression, and TGF‐&bgr; signalling in the development of dissection. Further investigation may reveal novel diagnostic biomarkers and uncover the mechanism(s) underlying ATAAD.

Nipro extra-corporeal left ventricular assist device fitting after left ventricular reconstruction with mitral valve plasty.

Both left ventricular assist device and left ventricular reconstruction are treatment choices for severe heart failure conditions. Our institution performed a left ventricular assist device installation following a left ventricular reconstruction procedure on a 42-year-old male patient who presented with dilated cardiomyopathy and low cardiac output syndrome. A mitral valve plasty was used to correct the acute mitral valve regurgitation and we performed a Nipro extra-corporeal left ventricular assist device installation on post-operative day 14. Due to the left ventricular reconstruction that the patient had in a previous operation, we needed to attach an apical cuff on posterior apex, insert the inflow cannula with a large curve, and shift the skin insertion site laterally to the left. We assessed the angle between the cardiac longitudinal axis and the inflow cannula using computed tomography. The patient did not complain of any subjective symptoms of heart failure. Although Nipro extra-corporeal left ventricular assist device installation after left ventricular reconstruction has several difficulties historically, we have experienced a successful case.

Thoracic endovascular aortic repair for ruptured pseudocoarctation

From the Department of Cardiovascular Surgery, Nerima Hikarigaoka Hospital, Tokyo, Japan; and Department of Cardiovascular Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan. Disclosures: Authors have nothing to disclose with regard to commercial support. Received for publication July 17, 2018; revisions received Aug 19, 2018; accepted for publication Sept 20, 2018; available ahead of print Nov 2, 2018. Address for reprints: Mamoru Arakawa, MD, PhD, Department of Cardiovascular Surgery, Nerima Hikarigaoka Hospital, 2-11-1 Hikarigaoka, Nerima-Ku, Tokyo 179-0072, Japan (E-mail: a_mamoru@mbn.nifty.com). J Thorac Cardiovasc Surg 2019;157:e101-3 0022-5223/

Postinfarction right ventricular wall dissection with left-to-right shunting

36.00 Copyright 2018 by The American Association for Thoracic Surgery https://doi.org/10.1016/j.jtcvs.2018.09.068 Ruptured pseudocoarctation treated with thoracic endovascular aortic repair.

Regulatory controversy on the pediatric ventricular assist device trial in Japan

Ventricular septal rupture is an uncommon fatal complication of acute myocardial infarction. In rare cases, the rupture can extend into the right ventricular free wall and cause intramyocardial dissection. We describe the case of a patient who developed postinfarction right ventricular free wall dissection with left-to-right shunting and successfully underwent patch repair.

Caregiver Perspectives on End-of-Life Experiences of Patients With Left Ventricular Assist Devices

Everolimus levels were within the recommended range. An assessment of GM-CSF autoantibodies was not performed but might have been helpful to further elucidate the pathophysiology. Cessation of the drug resulted in an improvement in clinical symptoms and radiology, and neither whole-lung lavage nor GM-CSF was required. Drug-induced pulmonary alveolar proteinosis should be considered in the differential diagnosis of new pulmonary pathology in transplant patients receiving mammalian target of rapamycin inhibitor therapy. Onset may be insidious, and discontinuation of everolimus alone may be associated with resolution of pulmonary alveolar proteinosis.