Biomedical subjects

Hidekazu Sekine

Publications and source records attributed to Hidekazu Sekine.

6 recordsLinked to original sources

PubMed2006

Pulsatile myocardial tubes fabricated with cell sheet engineering.

BACKGROUND: Tissue engineering approaches involving the direct transplantation of cardiac patches have received significant attention as alternative methods for the treatment of damaged hearts. In contrast, we used cardiomyocyte sheets harvested from temperature-responsive culture dishes to create pulsatile myocardial tubes and examined their in vivo function and survival. METHODS AND RESULTS: Neonatal rat cardiomyocyte sheets were sequentially wrapped around a resected adult rat thoracic aorta and transplanted in place of the abdominal aorta of athymic rats (n=17). Four weeks after transplantation, the myocardial tubes demonstrated spontaneous and synchronous pulsations independent of the host heartbeat. Independent graft pressures with a magnitude of 5.9+/-1.7 mm Hg due to their independent pulsations were also observed (n=4). Additionally, histological examination and transmission electron microscopy indicated that the beating tubes were composed of cardiac tissues that resemble the native heart. Finally, when myocardial tubes used for aortic replacement were compared with grafts implanted in the abdominal cavity (n=7), we observed significantly increased tissue thickness, as well as expression of brain natriuretic peptide, myosin heavy chain-alpha, and myosin heavy chain-beta. CONCLUSIONS: Functional myocardial tubes that have the potential for circulatory support can be created with cell sheet engineering. These results also suggest that pulsation due to host blood flow within the lumen of the myocardial tubes has a profound effect on stimulating cardiomyocyte hypertrophy and growth. These results demonstrate a novel approach for the future development of engineered cardiac tissues with the ability for independent cardiac assistance.

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PubMed2006

Cell delivery in regenerative medicine: the cell sheet engineering approach.

Recently, cell-based therapies have developed as a foundation for regenerative medicine. General approaches for cell delivery have thus far involved the use of direct injection of single cell suspensions into the target tissues. Additionally, tissue engineering with the general paradigm of seeding cells into biodegradable scaffolds has also evolved as a method for the reconstruction of various tissues and organs. With success in clinical trials, regenerative therapies using these approaches have therefore garnered significant interest and attention. As a novel alternative, we have developed cell sheet engineering using temperature-responsive culture dishes, which allows for the non-invasive harvest of cultured cells as intact sheets along with their deposited extracellular matrix. Using this approach, cell sheets can be directly transplanted to host tissues without the use of scaffolding or carrier materials, or used to create in vitro tissue constructs via the layering of individual cell sheets. In addition to simple transplantation, cell sheet engineered constructs have also been applied for alternative therapies such as endoscopic transplantation, combinatorial tissue reconstruction, and polysurgery to overcome limitations of regenerative therapies and cell delivery using conventional approaches.

Acrylic Resins↗

PubMed2006

Polysurgery of cell sheet grafts overcomes diffusion limits to produce thick, vascularized myocardial tissues.

Recently, the field of tissue engineering has progressed rapidly, but poor vascularization remains a major obstacle in bioengineering cell-dense tissues, limiting the viable size of constructs due to hypoxia, nutrient insufficiency, and waste accumulation. Therefore, new technologies for fabricating functional tissues with a well-organized vasculature are required. In the present study, neonatal rat cardiomyocytes were harvested as intact sheets from temperature-responsive culture dishes and stacked into cell-dense myocardial tissues. However, the thickness limit for layered cell sheets in subcutaneous tissue was approximately 80 microm (3 layers). To overcome this limitation, repeated transplantation of triple-layer grafts was performed at 1, 2, or 3 day intervals. The two overlaid grafts completely synchronized and the whole tissues survived without necrosis in the 1 or 2 day interval cases. Multistep transplantation also created approximately 1 mm thick myocardium with a well-organized microvascular network. Furthermore, functional multilayer grafts fabricated over a surgically connectable artery and vein revealed complete graft perfusion via the vessels and ectopic transplantation of the grafts was successfully performed using direct vessel anastomoses. These cultured cell sheet integration methods overcome long-standing barriers to producing thick, vascularized tissues, revealing a possible solution for the clinical repair of various damaged organs, including the impaired myocardium.

Animals↗

PubMed2006

Cardiomyocyte bridging between hearts and bioengineered myocardial tissues with mesenchymal transition of mesothelial cells.

BACKGROUND: For the reconstruction of 3-dimensional (3D) tissues, we exploited an original method of tissue engineering that layers individual cell sheets harvested from temperature-responsive culture dishes. Stacked cardiomyocyte sheets demonstrated electrical and morphologic communication, resulting in synchronously beating myocardial tissue. When these bioengineered 3D tissue grafts are transplanted onto damaged hearts, gap junction communication between graft and host is likely critical for synchronized beating and functional improvement. In this study, these graft-to-heart morphologic communications were examined. METHODS: Neonatal rat cardiomyocyte sheets were harvested from temperature-responsive culture dishes and layered to create 3D tissues. These constructs were then transplanted onto infarcted rat hearts. Histologic analyses and transmission electron microscopy (TEM) were performed to examine morphologic communications. The passage of small molecules through functional gap junctions was also detected using a dye-transfer assay. RESULTS: Transplanted cardiomyocytes bridged between the grafts and hearts in intact areas. Connexin-43 staining and TEM revealed the existence of gap junctions and intercalated disks between the bridging cardiomyocytes. Furthermore, it was confirmed that a low-molecule fluorescent dye, calcein, was transferred from the grafts to the hearts via the bridging cardiomyocytes. Immunohistochemistry with anti-intercellular adhesion molecule-1 antibodies revealed that mesothelial cells in the epicardium scattered and transdifferentiated into mesenchymal cells between the graft and host. CONCLUSIONS: The direct attachment of layered cardiomyocyte sheets on the heart surface promotes mesothelial cell transdifferentiation and cardiomyocyte bridging, leading to functional communication via gap junctions. These results indicate that these bioengineered myocardial tissues may improve damaged heart function via synchronized beating.

Animals↗

PubMed2006

Long-term survival and growth of pulsatile myocardial tissue grafts engineered by the layering of cardiomyocyte sheets.

Recently researchers have attempted to bioengineer three-dimensional (3-D) myocardial tissues using cultured cells in order to repair damaged hearts. In contrast to the conventional approach of seeding cells onto 3-D biodegradable scaffolds, we have explored a novel technology called cell sheet engineering, which layers cell sheets to construct functional tissue grafts. In this study, in vivo survival, function, and morphology of myocardial tissue grafts were examined. Neonatal rat cardiomyocytes were noninvasively harvested as contiguous cell sheets from temperature-responsive culture dishes simply by reducing the culture temperature. Cardiomyocyte sheets were then layered and transplanted into the subcutaneous tissues of athymic rats. The microvasculature of the grafts was rapidly organized within a few days with macroscopic graft beatings observed 3 days after transplantation and preserved up to one year. Size, conduction velocity, and contractile force of transplanted grafts increased in proportion to the host growth. Histological studies showed characteristic structures of heart tissue, including elongated cardiomyocytes, well-differentiated sarcomeres, and gap junctions within the grafts. In conclusion, long-term survival and growth of pulsatile myocardial tissue grafts fabricated by layering cell sheets were confirmed, demonstrating that myocardial tissue regeneration based on cell sheet engineering may prove useful for permanent myocardial tissue repair.

Animals↗

PubMed2005

Cell sheet engineering: recreating tissues without biodegradable scaffolds.

While tissue engineering has long been thought to possess enormous potential, conventional applications using biodegradable scaffolds have limited the field's progress, demonstrating a need for new methods. We have previously developed cell sheet engineering using temperature-responsive culture dishes in order to avoid traditional tissue engineering approaches, and their related shortcomings. Using temperature-responsive dishes, cultured cells can be harvested as intact sheets by simple temperature changes, thereby avoiding the use of proteolytic enzymes. Cell sheet engineering therefore allows for tissue regeneration by either direct transplantation of cell sheets to host tissues or the creation of three-dimensional structures via the layering of individual cell sheets. By avoiding the use of any additional materials such as carrier substrates or scaffolds, the complications associated with traditional tissue engineering approaches such as host inflammatory responses to implanted polymer materials, can be avoided. Cell sheet engineering thus presents several significant advantages and can overcome many of the problems that have previously restricted tissue engineering with biodegradable scaffolds.

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