Side population cells in the human vocal fold.
OBJECTIVE
The regenerative processes of the vocal fold, or the existence of stem cells in the folds, are unknown. Side population (SP) cells are defined as cells that have the ability to exclude the DNA binding dye, Hoechst 33342. They are regarded as a cell population enriched with stem cells and can be isolated from non-SP cells by a fluorescence-activated cell sorter. This study was designed to determine whether SP cells exist in the human vocal fold, as a first step in elucidating the regenerative mechanisms of the vocal fold.


METHODS
Seven human excised larynges were used in this study. Two were used for fluorescence-activated cell sorter analysis, and 5 were subjected to immunohistochemical analysis with antibodies against an adenosine triphosphate binding cassette transporter family member, ABCG2, which is expressed in SP cells.


RESULTS
The number of SP cells in the human vocal fold was about 0.2% of the total number of cells. ABCG2-positive cells were identified in both the epithelium and subepithelial tissue throughout the entire vocal fold.


CONCLUSIONS
This preliminary study demonstrated the existence of SP cells in the human vocal fold. Further studies are warranted to clarify how these cells work in the vocal fold, particularly in the regenerative process.
Yamashita
Masaru
M
Division of Otolaryngology-Head and Neck Surgery, Dept of Surgery, University of Wisconsin-Madison, K4/723 Clinical Science Center, 600 Highland Ave, Madison, WI 53792, USA.
Hirano
Shigeru
S
Kanemaru
Shin-ichi
S
Tsuji
Shunichiro
S
Suehiro
Atsushi
A
Ito
Juichi
J
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D018432:Drug Resistance, Multiple; D006801:Humans; D007150:Immunohistochemistry; D009363:Neoplasm Proteins / Q000378:metabolism; D012038:Regeneration / Q000502:physiology; D013234:Stem Cells / Q000166:cytology*; D014827:Vocal Cords / Q000166:cytology* / Q000378:metabolism
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D015415:Biomarkers; D009363:Neoplasm Proteins