Isolation and culture of human muscle-derived stem cells able to differentiate into myogenic and neurogenic cell lineages.
BACKGROUND
Skeletal-muscle-derived stem cells seem to be a distinct population of immature progenitors of satellite cells, but their functional properties remain unclear, especially in human adult tissue. We investigated their differentiation in samples of skeletal muscle obtained from adults undergoing cardiovascular surgery.


METHODS
Samples were obtained from the brachioradialis muscle of 12 patients in whom the radial artery was the conduit for myocardial revascularisation. The stem cells were isolated by a procedure similar to that used for rat gastrocnemius and cultured in medium optimised for growth of neural stem cells. Cytometry was used for phenotypic characterisation and immunocytochemistry and RT-PCR to assess differentiation. Immunohistochemistry was used to examine engraftment of skeletal-muscle-derived stem cells into injured rat spinal cord.


RESULTS
The skeletal-muscle stem cells consisted of two distinct types: one with the typical spindle morphology of satellite cells, the other of rounded cells. Some cultures could be maintained for longer than 6 months. The cells were mainly positive for desmin and to a lesser extent CD105, vimentin, and AC133/CD133, but negative for FLK-1/KDR, CD34, CD31, CD45, von Willebrand factor, Ve-cadherins, and BCL2. After in-vitro differentiation, the cells were able to organise skeletal-muscle fibres and stained positively for striated-muscle actin, smooth-muscle actin, and desmin. Moreover, they differentiated into astrocytes and neurons, as confirmed by positive staining for characteristic proteins.


CONCLUSIONS
Adult human skeletal muscle includes a population of progenitor stem cells that can generate cells of the same lineage and cells with neurogenic properties. Muscle may therefore be a tissue source for the isolation of pluripotent stem cells for development of cell-based therapies for human myogenic and neurogenic diseases.
Alessandri
Giulio
G
Laboratory of Neurobiology and Neuroregenerative Therapies, Carlo Besta Neurological Institute, Via Celoria 11, 20131 Milan, Italy. neurofarmacologia1@istituto-besta.it
Pagano
Stefano
S
Bez
Alessandra
A
Benetti
Anna
A
Pozzi
Stefano
S
Iannolo
Gioacchin
G
Baronio
Manuela
M
Invernici
Gloria
G
Caruso
Arnaldo
A
Muneretto
Claudio
C
Bisleri
Gianluigi
G
Parati
Eugenio
E
D000199:Actins / Q000032:analysis; D000368:Aged; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D002455:Cell Division / Q000187:drug effects; D019070:Cell Lineage; D002469:Cell Separation / Q000379:methods; D002999:Clone Cells; D003893:Desmin / Q000032:analysis; D005260:Female; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000166:cytology*; D009419:Nerve Tissue Proteins / Q000032:analysis; D009474:Neurons / Q000166:cytology*; D039904:Pluripotent Stem Cells / Q000737:chemistry / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord; D033581:Stem Cell Transplantation; D014746:Vimentin / Q000032:analysis
D000199:Actins; D003893:Desmin; D006133:Growth Substances; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D014746:Vimentin