Induction of inner ear hair cell-like cells from Math1-transfected mouse ES cells

Area of Science:

• Developmental Biology
• Stem Cell Biology
• Otolaryngology

Background:

• Math1 is a transcription factor crucial for sensory hair cell (HC) development in the inner ear.
• Embryonic stem (ES) cells can differentiate into HC-like cells, but the precise role of Math1 in this process requires further investigation.

Purpose of the Study:

• To investigate the role of Math1 in the efficient generation of HC-like cells from ES cells.
• To establish a system for controlled Math1 expression in ES cells for HC-like cell induction.

Main Methods:

• Generation of Tet-inducible Math1-expressing ES cells (Math1-ES cells) using a Tet-On system.
• Induction of HC-like cell differentiation by doxycycline (Dox)-controlled Math1 expression in embryoid bodies (EBs).
• Analysis of HC-related marker expression (myosin6, myosin7a, calretinin, α9AchR, Brn3c) and stereocilia-like structure formation.
• Reporter assays to assess Math1's regulatory effect on the Brn3c promoter.
• In vivo transplantation of differentiated cells into chick embryos to evaluate their integration into the developing inner ear.

Main Results:

• Doxycycline-induced Math1 expression in Math1-ES cells led to approximately 10% of cells in EB outgrowths expressing multiple HC-related markers and forming stereocilia-like structures.
• Control EBs without Dox showed minimal expression of these markers.
• Reporter assays confirmed Math1's positive regulation of the Brn3c promoter.
• Transplanted HC-like cells derived from Math1-ES cells were successfully incorporated into the developing chick inner ear.

Conclusions:

• Math1 is a key factor for inducing HC-like cells from differentiating ES cells.
• Math1-ES cells provide an efficient source for generating ES-derived HC-like cells.
• This approach holds potential for regenerative medicine strategies targeting hearing loss and inner ear disorders.