Publications by authors named "Masashi Yamanami"

Cell transplantation is expected to be another strategy to treat lysosomal diseases, having several advantages compared to enzyme replacement therapy, such as continuous enzyme secretion and one-time treatment to cure diseases. However, cell transplantation for lysosomal diseases holds issues to be resolved for the clinical field. In this study, we developed a new ex vivo gene therapy platform using a transplant pack, which consists of a porous membrane made of ethylene-vinyl alcohol in the pack-type and spheroids with scaffolds.

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Background: We have previously applied in vivo tissue-engineered vascular grafts constructed in patients' subcutaneous spaces. However, since the formation of these vascular grafts depends on host health, their application is challenging in patients with suppressed regenerative ability. Therefore, the allogeneic implantation of grafts from healthy donors needs to be evaluated.

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In vivo tissue-engineered vascular grafts constructed in the subcutaneous spaces of graft recipients have functioned well clinically. Because the formation of vascular graft tissues depends on several recipient conditions, chemical pretreatments, such as dehydration by ethanol (ET) or crosslinking by glutaraldehyde (GA), have been attempted to improve the initial mechanical durability of the tissues. Here, we compared the effects of short-duration (10 min) chemical treatments on the mechanical properties of tissues.

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Fabry disease is caused by a decrease in or loss of the activity of alpha-galactosidase, which causes its substrates globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) to accumulate in cells throughout the body. This accumulation results in progressive kidney injury due to glomerulosclerosis and in heart failure due to hypertrophy. Enzyme replacement therapy (ERT) has been used as the standard therapy for Fabry disease, but it causes a significant financial burden, and regular administration is inconvenient for patients.

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Purpose: Autologous pericardium is an ideal material for cardiovascular reconstruction including pulmonary artery plasty. Despite the fact that dehydration by ethanol has been used to improve its surgical handling, the effects of the ethanol on mechanical properties of the pericardium have not been previously investigated. The effects of short-duration ethanol dehydration on the mechanical properties of porcine pericardium were evaluated.

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Purpose: This study sought to evaluate the histologic and mechanical properties of autologous in vivo tissue-engineered vascular grafts (in vivo TEVGs) used for pediatric heart surgery.

Description: Molds of in vivo TEVGs made of silicone drain tubes were embedded into subcutaneous spaces in 2 boys during their first operation and were used as patch materials to treat pulmonary artery stenosis during the second operation. The remaining pieces of the patches were evaluated histologically and mechanically.

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In earlier studies, we developed in vivo tissue-engineered, autologous, small-caliber vascular grafts, called "biotubes," which withstand systemic blood pressure and exhibit excellent performance as small-caliber vascular prostheses in animal models. However, biotube preparation takes 4 weeks; therefore, biotubes cannot be applied in emergency situations. Moreover, for responses to various types of surgery, grafts should ideally be readily available in advance.

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Purpose: The ideal material for pediatric pulmonary artery (PA) augmentation is autologous pericardium. However, its utility for multistaged operations is limited. In this study, we applied an in vivo tissue-engineered autologous Biotube graft to a patient with congenital heart disease for the first time.

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The use of stent grafts for endovascular aortic repair has become an important treatment option for aortic aneurysms requiring surgery. This treatment has achieved excellent outcomes; however, problems like type 1 endoleaks and stent graft migration remain. Bio stent grafts (BSGs), which are self-expanding stents covered with connective tissue, were previously developed using "in-body tissue architecture" technology.

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In this study, we aimed to describe the development of tissue-engineered self-expandable aortic stent grafts (Bio stent graft) using in-body tissue architecture technology in beagles and to determine its mechanical and histological properties. The preparation mold was assembled by insertion of an acryl rod (outer diameter, 8.6 mm; length, 40 mm) into a self-expanding nitinol stent (internal diameter, 9.

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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.

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We designed a novel method for constructing an autologous heart valve with a stent, called a stent-biovalve. In constructing completely autologous heart valves, named biovalves, which used in-body tissue architecture technology, tissues for leaflets were formed via ingrowths into narrow apertures in the preparation molds, frequently leading to delayed or incomplete biovalve preparation. In this technique, self-expandable nitinol stents after everting were mounted on an acrylic column-shaped part and partially covered with an acrylic cylinder-shaped part with three slits.

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Systolic anterior motion (SAM) of the mitral valve after aortic valve replacement (AVR) for severe aortic stenosis (AS) is one of the causes of perioperative left ventricular outflow tract (LVOT) obstruction in older patients. A 90-year-old woman underwent AVR with a 19-mm bioprosthesis for symptomatic aortic valve stenosis. Preoperative transthoracic echocardiography (TTE) showed left ventricular hypertrophy, with LVOT obstruction and mild mitral regurgitation (MR).

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Using simple, safe, and economical in-body tissue engineering, autologous valved conduits (biovalves) with the sinus of Valsalva and without any artificial support materials were developed in animal recipients' bodies. In this study, the feasibility of the biovalve as an aortic valve was evaluated in a goat model. Biovalves were prepared by 2-month embedding of the molds, assembled using two types of specially designed plastic rods, in the dorsal subcutaneous spaces of goats.

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We developed autologous vascular grafts, called "biotubes," by simple and safe in-body tissue architecture technology, which is a practical concept of regenerative medicine, without using special sterile conditions or complicated in vitro cell treatment processes. In this study, biotubes of extremely small caliber were first auto-implanted to rat abdominal aortas. Biotubes were prepared by placing silicone rods (outer diameter 1.

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Argatroban is a powerful synthetic anticoagulant, but due to its water-insoluble nature, it is unsuitable for use as a coating material to reduce the thrombogenic potential of natural or tissue-engineered blood-contacting cardiovascular tissues. On the other hand, anionic compounds could adsorb firmly onto connective tissues. Therefore, in this study, an anionic form of argatroban was prepared by neutralization from its alkaline solution, dialysis, and freeze-drying.

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In-body tissue, architecture technology represents a promising approach for the development of living heart valve replacements and preparation of a series of biovalves. To reduce the degree of regurgitation and increase the orifice ratio, we designed a novel mold for a type VI biovalve. The mold had an outer diameter of 14 mm for implantation in beagles, and it was prepared by assembling two silicone rods with a small aperture (1 mm) between them.

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Article Synopsis
  • A silicone rod was used to create a mold for a tissue-engineered blood vessel called a "biotube," which was implanted in rabbits to develop surrounding tissues for two months.
  • The biotubes showed a thin connective tissue wall, composed mainly of collagen and fibroblasts, and were successfully autoimplanted in rabbits' carotid arteries with no complications during a 26-month follow-up.
  • Results indicated that the biotube's wall thickness was comparable to that of native arteries, featuring a complete endothelial layer and well-organized smooth muscle and collagen structures, making them promising small-caliber vascular prostheses.
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The autologous biotube, developed by using in-body tissue architecture technology, is one of the most promising small-diameter vascular grafts in regenerative medicine. The walls of the biotubes obtained by a traditional silicone mold-based method were very thin, and this is still the primary obstacle while handling anastomosis, even though these biotubes have adequate pressure resistance ability. This pilot study showed the effect of optical stimulation of subcutaneous tissue formation in the body during the preparation of the biotubes.

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Background: We developed autologous prosthetic implants by simple and safe in-body tissue architecture technology. We present the first report on the development of autologous valved conduit with the sinus of Valsalva (BIOVALVE) by using this unique technology and its subsequent implantation in the pulmonary valves in a beagle model.

Methods And Results: A mold of BIOVALVE organization was assembled using 2 types of specially designed silicone rods with a small aperture in a trileaflet shape between them.

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A novel autologous valved conduit with the sinus of Valsalva-defined as a type IV biovalve-was created in rabbits by "in-body tissue-architecture" technology with a specially designed mold for the valve leaflets and the sinus of Valsalva and a microporous tubular scaffold for the conduit. The mold included 2 rods composed of silicone substrates. One was concave shaped, with 3 projections resembling the sinus of Valsalva; the other was convex shaped.

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In the development of small-caliber vascular grafts (diameter; less than 3 mm), animal implantation studies have been mostly performed by using rat abdominal aortas, and their certain patency must evaluate with sacrificing every observation periods, which is both labor-intensive and time-consuming when performing a large number of experiments. This study is the first to demonstrate the application of 3-Tesla contrast-free time-of-flight magnetic resonance angiography (TOF-MRA) in the continuous assessment of the status of a tissue-engineered vascular graft in rat. As a model graft, a single connective tubular tissue (diameter; 1.

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The aim of this study was to prepare completely autologous heart-valve-shaped constructs without using any artificial scaffold materials by in-body tissue architecture technology, which is a practical concept of regenerative medicine based on the biological defense mechanism against foreign bodies. Silicone rods were used as molds to achieve the tubular shape of the arteries, which were implanted in the subcutaneous spaces of rabbits. After 2 weeks of primary in-body tissue incubation, the silicone rods were completely encapsulated within a thin membranous connective tissue mainly consisting of collagen and having a thickness of approximately 100 microm.

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