Absence of CD34 on murine skeletal muscle satellite cells marks a reversible state of activation during acute injury.
BACKGROUND
Skeletal muscle satellite cells are myogenic progenitors that reside on myofiber surface beneath the basal lamina. In recent years satellite cells have been identified and isolated based on their expression of CD34, a sialomucin surface receptor traditionally used as a marker of hematopoietic stem cells. Interestingly, a minority of satellite cells lacking CD34 has been described.


RESULTS
In order to elucidate the relationship between CD34+ and CD34- satellite cells we utilized fluorescence-activated cell sorting (FACS) to isolate each population for molecular analysis, culture and transplantation studies. Here we show that unless used in combination with alpha7 integrin, CD34 alone is inadequate for purifying satellite cells. Furthermore, the absence of CD34 marks a reversible state of activation dependent on muscle injury.


CONCLUSIONS
Following acute injury CD34- cells become the major myogenic population whereas the percentage of CD34+ cells remains constant. In turn activated CD34- cells can reverse their activation to maintain the pool of CD34+ reserve cells. Such activation switching and maintenance of reserve pool suggests the satellite cell compartment is tightly regulated during muscle regeneration.
Department of Pathology, School of Medicine, University of Washington, Seattle, Washington, USA.
Nicholas
N
Ieronimakis
Gayathri
G
Balasundaram
Sabrina
S
Rainey
Kiran
K
Srirangam
Zipora
Z
Yablonka-Reuveni
Morayma
M
Reyes
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D005434:Flow Cytometry; D016130:Immunophenotyping; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology / Q000276:immunology* / Q000293:injuries; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018952:Antigens, CD34