The International Journal of Developmental Biology

Int. J. Dev. Biol. 53: 615 - 622 (2009)

Vol 53, Issue 4

A novel in vitro system for studying cardiomyocyte differentiation with medaka embryonic cells

Short Communication | Published: 30 November -0001

Masao Hyodo*,1, Shinji Makino2, Yasunori Awaji1, Yohei Sakurada1, Tomoichi Ohkubo3, Mitsushige Murata2, Keiichi Fukuda2 and Michio Tsuda2

1Department of Biological Science and Technology, Tokai University, Numazu, Japan, 2Department of Regenerative Medicine and Advanced Cardiac Therapeutics, Keio University School of Medicine, Shinjuku, Tokyo, Japan, 3Teaching and Research Support Center, and 4Department of Molecular Life Science, Tokai University School of Medicine, Boseidai, Isehara, Japan


Our studies revealed that dissociated cells from medaka (the fresh-water fish, Oryzias latipes ) blastula-stage embryos differentiate into many rhythmically contracting cells when incubated with a conditioned medium from a cell line. Analyses of these cells by immunostaining, electron microscopy, expression of marker genes, action potential recordings and pharmacological responses all showed the characteristics of myocardial cells. We succeeded in purifying the cardiac cell-inducing factor from the conditioned medium by 523,100-fold with 8% recovery of the protein. Analysis of its amino-acid sequence by mass spectrometry revealed the factor to be medaka activin A2 (homodimer of inhibin betaA2 subunit). Recombinant human activin A showed the same cardiac cell-inducing activity toward medaka embryonic cells. Our results demonstrate that activin A is a potent factor for medaka myocardial cell differentiation. This culture method should provide a novel and simple experimental system to study cardiomyocyte differentiation in vitro.


medaka, activin, cardiomyocyte, embryonic cell culture

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