title: Polysurgery of cell sheet grafts overcomes diffusion limits to produce thick, vascularized myocardial tissues.
abstract: 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.
authors.affiliation: Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Shimizu
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Sekine
authors.forename: Joseph
authors.initials: J
authors.lastname: Yang
authors.forename: Yuki
authors.initials: Y
authors.lastname: Isoi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamato
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kikuchi
authors.forename: Eiji
authors.initials: E
authors.lastname: Kobayashi
authors.forename: Teruo
authors.initials: T
authors.lastname: Okano
mesh_terms: D000818:Animals; D021522:Bioartificial Organs; D018929:Cell Culture Techniques / Q000379:methods*; D004058:Diffusion; D016027:Heart Transplantation / Q000379:methods*; D006354:Heart, Artificial; D008297:Male; D009200:Myocardial Contraction; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000637:transplantation; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D023822:Tissue Engineering / Q000379:methods*