Pax3-induced expansion enables the genetic correction of dystrophic satellite cells.
BACKGROUND
Satellite cells (SCs) are indispensable for muscle regeneration and repair; however, due to low frequency in primary muscle and loss of engraftment potential after ex vivo expansion, their use in cell therapy is currently unfeasible. To date, an alternative to this limitation has been the transplantation of SC-derived myogenic progenitor cells (MPCs), although these do not hold the same attractive properties of stem cells, such as self-renewal and long-term regenerative potential.


METHODS
We develop a method to expand wild-type and dystrophic fresh isolated satellite cells using transient expression of Pax3. This approach can be combined with genetic correction of dystrophic satellite cells and utilized to promote muscle regeneration when transplanted into dystrophic mice.


RESULTS
Here, we show that SCs from wild-type and dystrophic mice can be expanded in culture through transient expression of Pax3, and these expanded activated SCs can regenerate the muscle. We test this approach in a gene therapy model by correcting dystrophic SCs from a mouse lacking dystrophin using a Sleeping Beauty transposon carrying the human μDYSTROPHIN gene. Transplantation of these expanded corrected cells into immune-deficient, dystrophin-deficient mice generated large numbers of dystrophin-expressing myofibers and improved contractile strength. Importantly, in vitro expanded SCs engrafted the SC compartment and could regenerate muscle after secondary injury.


CONCLUSIONS
These results demonstrate that Pax3 is able to promote the ex vivo expansion of SCs while maintaining their stem cell regenerative properties.
Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-128 CCRB, 2231 6th St. SE, Minneapolis, MN 55455 USA.
Antonio
A
Filareto
Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-128 CCRB, 2231 6th St. SE, Minneapolis, MN 55455 USA.
Fabrizio
F
Rinaldi
Department of Pediatrics, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455 USA.
Robert W
RW
Arpke
Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-128 CCRB, 2231 6th St. SE, Minneapolis, MN 55455 USA.
Radbod
R
Darabi
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455 USA.
Joseph J
JJ
Belanto
Department of Pediatrics, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455 USA.
Erik A
EA
Toso
Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-128 CCRB, 2231 6th St. SE, Minneapolis, MN 55455 USA.
Auston Z
AZ
Miller
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455 USA.
James M
JM
Ervasti
Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455 USA.
R Scott
RS
McIvor
Department of Pediatrics, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN 55455 USA.
Michael
M
Kyba
Department of Medicine, Lillehei Heart Institute, University of Minnesota, 4-128 CCRB, 2231 6th St. SE, Minneapolis, MN 55455 USA.
Rita Cr
RC
Perlingeiro
Dystrophin; Gene correction; Muscular dystrophy; Pax3; Regeneration; Satellite cells; Sleeping Beauty