Cardiomyocyte formation by skeletal muscle-derived multi-myogenic stem cells after transplantation into infarcted myocardium.
BACKGROUND
Cellular cardiomyoplasty for myocardial infarction has been developed using various cell types. However, complete differentiation and/or trans-differentiation into cardiomyocytes have never occurred in these transplant studies, whereas functional contributions were reported.


RESULTS
Skeletal muscle interstitium-derived CD34(+)/CD45(-) (Sk-34) cells were purified from green fluorescent protein transgenic mice by flowcytometory. Cardiac differentiation of Sk-34 cells was examined by in vitro clonal culture and co-culture with embryonic cardiomyocytes, and in vivo transplantation into a nude rat myocardial infarction (MI) model (left ventricle). Lower relative expression of cardiomyogenic transcription factors, such as GATA-4, Nkx2-5, Isl-1, Mef2 and Hand2, was seen in clonal cell culture. However, vigorous expression of these factors was seen on co-culture with embryonic cardiomyocytes, together with formation of gap-junctions and synchronous contraction following sphere-like colony formation. At 4 weeks after transplantation of freshly isolated Sk-34 cells, donor cells exhibited typical cardiomyocyte structure with formation of gap-junctions, as well as intercalated discs and desmosomes, between donor and recipient and/or donor and donor cells. Fluorescence in situ hybridization (FISH) analysis detecting the rat and mouse genomic DNA and immunoelectron microscopy using anti-GFP revealed donor-derived cells. Transplanted Sk-34 cells were incorporated into infarcted portions of recipient muscles and contributed to cardiac reconstitution. Significant improvement in left ventricular function, as evaluated by transthoracic echocardiography and micro-tip conductance catheter, was also observed.


CONCLUSIONS
Skeletal muscle-derived multipotent Sk-34 cells that can give rise to skeletal and smooth muscle cells as reported previously, also give rise to cardiac muscle cells as multi-myogenic stem cells, and thus are a potential source for practical cellular cardiomyoplasty.
Tamaki
Tetsuro
T
Muscle Physiology & Cell Biology Unit, Tokai University School of Medicine, Isehara, Kanagawa, Japan. tamaki@is.icc.u-tokai.ac.jp
Akatsuka
Akira
A
Okada
Yoshinori
Y
Uchiyama
Yoshiyasu
Y
Tono
Kayoko
K
Wada
Mika
M
Hoshi
Akio
A
Iwaguro
Hideki
H
Iwasaki
Hiroto
H
Oyamada
Akira
A
Asahara
Takayuki
T
D000818:Animals; D002454:Cell Differentiation; D017690:Cell Transplantation; D018920:Coculture Techniques; D049452:Green Fluorescent Proteins / Q000235:genetics; D016130:Immunophenotyping; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000166:cytology*; D009206:Myocardium / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology*
D049452:Green Fluorescent Proteins