Human bone marrow stem cells co-cultured with neonatal rat cardiomyocytes display limited cardiomyogenic plasticity.
OBJECTIVE
This study investigated whether neonatal rat cardiomyocytes (NRCM), when co-cultured, can induce transdifferentiation of either human mesenchymal stromal cells (MSC) or hematopoietic stem cells (HSC) into cardiomyocytes. Stem cells were obtained from patients with ischemic heart disease.


METHODS
Ex vivo-expanded MSC or freshly isolated HSC were used to set-up a co-culture system between NRCM and MSC or HSC. 5-azacytidin (5-aza) or dimethylsulfoxide (DMSO) was used as differentiation-inducing factor. Co-cultured stem cells were separated from NRCM by flow sorting, and cardiac gene expression was analyzed by reverse transcriptase-polymerase chain reaction. Cellular morphology was analyzed by immunofluorescence and transmission electron microscopy (TEM).


RESULTS
Co-culturing MSC induced expression of troponin T and GATA-4. However, no expression of alpha-actinin, myosin heavy chain or troponin I was detected. In the case of HSC, only expression of troponin T could be induced. Immunofluorescence and TEM confirmed the absence of sarcomeric organization in co-cultured MSC and HSC. Adding 5-aza or DMSO to the co-cultures did not influence differentiation.


CONCLUSIONS
This in vitro co-culture study obtained no convincing evidence of transdifferentiation of either MSC or HSC into functional cardiomyocytes. Nevertheless, induction of troponin T was observed in MSC and HSC, and GATA-4 in MSC. However, no morphologic changes could be detected by immunofluorescence or by TEM. These data could explain why only limited functional improvement was reported in clinical stem cell trials.
Koninckx
Remco
R
Laboratory of Experimental Hematology, Virga Jesse Hospital, Hasselt, Belgium.
Hensen
Karen
K
Daniëls
Annick
A
Moreels
Marjan
M
Lambrichts
Ivo
I
Jongen
Hanne
H
Clijsters
Christel
C
Mees
Urbain
U
Steels
Paul
P
Hendrikx
Marc
M
Rummens
Jean-Luc
JL
D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D054338:Cell Transdifferentiation; D018920:Coculture Techniques; D003451:Cryoprotective Agents / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D050991:GATA4 Transcription Factor / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017154:Stromal Cells / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D020107:Troponin T / Q000378:metabolism
D003451:Cryoprotective Agents; D004791:Enzyme Inhibitors; D050991:GATA4 Transcription Factor; D020107:Troponin T; D001374:Azacitidine; D004121:Dimethyl Sulfoxide