Stem cell therapy for hearing loss: Math1 overexpression in VOT-E36 cells.
OBJECTIVE
VOT-E36 cells acquire mechanosensitivity after mammalian atonal homolog 1 (Math1) overexpression.


BACKGROUND
VOT-E36 cells are derived from a population of epithelial cells in the ventral region of the otocyst at embryonic Day 10.5, before hair cell differentiation. These cells express a number of specific molecular markers for hair cells under both proliferation and differentiation states. Overexpression of Math1 can convert nonsensory epithelial cells into hair cells in the cochlea. Based on this information, we tested whether VOT-E36 cells can be converted into hair cells by Math1 overexpression.


METHODS
Using reverse transcriptase-polymerase chain reaction-based analysis, we first compared the expression patterns of various molecular markers for hair cell development in VOT-E36 cells between proliferation and differentiation states, and also before and after overexpression of Math1. Subsequently, with a standard calcium imaging method, we examined whether VOT-E36 cells overexpressing Math1 could detect mechanical vibrations and activate spiral ganglion neurons in a coculture model. In addition, using confocal and scanning electron microscopes, we examined morphologic changes of VOT-E36 cells after Math1 overexpression.


RESULTS
Consistent with previous reports, this study has shown that VOT-E36 cells express a number of specific molecular markers for hair cells in both proliferation and differentiation states. Under appropriate culture conditions, Math1 is transiently expressed in this cell line during conditional differentiation. In VOT-E36 cells overexpressing Math1, the normal expression pattern of certain molecular markers for mature hair cells is partially restored. Interestingly, after coculture with spiral ganglion neurons, VOT-E36 cells overexpressing Math1 are able to respond to mechanical vibrations and activate spiral ganglion neurons. Possible molecular mechanisms underlying this novel finding have been explored.


CONCLUSIONS
Math1 overexpression can partially restore presumably downstream signaling cascades for normal hair cell differentiation in VOT-E36 cells, which are able to detect mechanical vibrations after being cocultured with spiral ganglion neurons.
Liu
Jan-Jan
JJ
Department of Otolaryngology, Center for Aging, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Shin
June Ho
JH
Hyrc
Krzysztof L
KL
Liu
Su
S
Lei
Debin
D
Holley
Matthew C
MC
Bao
Jianxin
J
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis* / Q000235:genetics; D002454:Cell Differentiation; D002460:Cell Line; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006198:Hair Cells, Auditory / Q000166:cytology*; D034381:Hearing Loss / Q000628:therapy*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008855:Microscopy, Electron, Scanning; D016133:Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology
D051792:Basic Helix-Loop-Helix Proteins; C500943:Atoh1 protein, mouse