Identification of factors that maintain mammalian outer hair cells in adult organ of Corti explants.
Both outer hair cells (OHCs) and inner hair cells (IHCs) survive and mature in 3 days old rat organ of Corti explants cultured for 1 month in a minimal essential medium. In contrast, under the same culture conditions, only IHCs survive in explants from adult guinea pig organ of Corti while many of the OHCs are lost within the first 48 h. Hair cell counts show OHCs loss to be greater in the lower portion (i.e. middle turn) of the cochlea than at the apex. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) indicates that there is DNA damage in adult OHCs within 8 h of explantation. Treatment of the adult organ of Corti explants with either actinomycin D (10(-7) M) or cycloheximide (10(-6) M) prevents most OHC losses. According to these results apoptosis may be the mechanism of OHC loss in adult organ of Corti explants. Stable membrane potentials recorded from the OHCs in both uncultured and actinomycin D-treated organ of Corti explants cultured for 72 h demonstrate the functional integrity of these hair cells. OHC losses in the adult guinea pig organ of Corti cultures can also be prevented by treatment with several of the growth factors tested, i.e. acidic fibroblast growth factor (aFGF), insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), transforming growth factor-beta1 (TGF-beta1), and glial cell-derived neurotrophic factor (GDNF). The results of this study suggest that growth factor therapy may be applicable to the treatment of some hearing disorders.
Center for Cellular and Molecular Neuroscience, University of Liège, 17 Place Delcour, B-4020, Liège, Belgium. bmalgrange@ulg.ac.be
Brigitte
B
Malgrange
Jean-Michel
JM
Rigo
Paul
P
Coucke
Marc
M
Thiry
Grégory
G
Hans
Laurent
L
Nguyen
Thomas R
TR
van de Water
Gustave
G
Moonen
Philippe P
PP
Lefebvre
D000818:Animals; D017209:Apoptosis; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003470:Culture Media / Q000494:pharmacology; D046508:Culture Techniques; D003609:Dactinomycin / Q000494:pharmacology; D004594:Electrophysiology; D006133:Growth Substances / Q000494:pharmacology; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000502:physiology; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology; D009925:Organ of Corti / Q000166:cytology*
D003470:Culture Media; D006133:Growth Substances; D018696:Neuroprotective Agents; D003609:Dactinomycin