Hypoxic preconditioning of human cardiosphere-derived cell sheets enhances cellular functions via activation of the PI3K/Akt/mTOR/HIF-1α pathway.
Cell sheet technology is a promising therapeutic strategy for the treatment of ischemic diseases such as myocardial infarction. We recently developed a novel protocol, termed "hypoxic preconditioning," capable of augmenting the therapeutic efficacy of cell sheets. Following this protocol, the pro-angiogenic and anti-fibrotic activity of cell sheets were enhanced by brief incubation of cell sheets under hypoxic culture conditions. However, the precise molecular mechanism underlying the hypoxic preconditioning of cell sheets is unclear. In the present study, we examined signal transducers in cell sheets to identify those responsive to hypoxic preconditioning, using cardiosphere-derived cell (CDC) sheets. We initially tested whether sheet-like structures were suitable for hypoxic preconditioning by comparing them with individual cells. Hypoxic preconditioning was more effective in sheeted cells than in individual cells. Expression of hypoxia inducible factor-1α (HIF-1α) and mammalian target of rapamycin (mTOR) were induced upon hypoxic preconditioning of cell sheets, as was the phosphoinositide 3-kinase (PI3K)/Akt pathway. In addition, hypoxic preconditioning increased phosphorylation of epidermal growth factor receptor (EGFR) and heat shock protein 60 (HSP60) in CDC sheets. Our findings provide novel insights into the utility of hypoxic preconditioning in cell sheet-based technologies for the treatment of ischemic diseases.
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Yuya
Y
Tanaka
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan; Center for Regenerative Medicine, Graduate School of Medicine, Yamaguchi University1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Tohru
T
Hosoyama
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Akihito
A
Mikamo
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan; Department of Surgery, Saiseikai Yamaguchi Hospital2-11 Midoricho, Yamaguchi, Yamaguchi 753-8517, Japan.
Hiroshi
H
Kurazumi
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Arata
A
Nishimoto
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Koji
K
Ueno
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Bungo
B
Shirasawa
Department of Surgery and Clinical Science, Graduate School of Medicine, Yamaguchi University 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan.
Kimikazu
K
Hamano
Cell sheet; HIF-1α; cardiosphere; hypoxic preconditioning