Sensory cells called hair cells are crucial for the function of the auditory and balance organs. Hair cells die in response to loud sounds and chemotherapeutic and certain anti-bacterial drugs, leading to hearing and balance deficits.

There are currently no therapeutic solutions available to regenerate lost hair cells and to restore sensory deficits associated with the inner ear. In her doctoral dissertation M.Sc. Maarja Laos investigates the regenerative abilities of cells in the inner ear auditory and balance organs.

“This study takes one step closer to revealing why regenerative manipulations become less efficient when the inner ear matures. It demonstrates the regenerative potential in the inner ear, but also shows there is still a long way to go before hair cells can be regenerated in patients with inner ear disorders”, says Laos.

Unlike mammals, other vertebrate groups are able to regenerate hair cells using neighboring supporting cells as a source for the replacement hair cells. Therefore, supporting cells serve as a target for therapeutic manipulations to replace the lost hair cells in mammalian inner ear. In her study Laos aimed to identify the barriers restricting the natural regeneration capacity of supporting cells of the mammalian auditory and balance organs. Her study demonstrated that supporting cells of the mouse inner ear exhibit an age-dependent decline both in the ability to activate mitotic divisions and in transformation into hair cells.

In her study Laos revealed DNA damage accumulation and inefficient DNA repair as important barriers restricting mitotic divisions of mammalian supporting cells. Her research also demonstrates the importance of controlled levels of the cellular stress-response molecule p53 for the survival of cells of the auditory organ. Furthermore, the data of Laos’s study can be extrapolated to other non-dividing, differentiated cell types, such as neurons, when evaluating their potential for regenerative therapies.

Dissertation

 

M.Sc. Maarja Laos defends her doctoral dissertation 'Postmitotic state of a cell as a challenge for regeneration: inner ear as a model' in the Faculty of Biological and Environmental Sciences on 18 August 2017 at 12:00 in Viikki Biocenter 2 (Viikinkaari 5), auditorium 1041. Opponent is Professor Marcelo Rivolta (Professor of Sensory Stem Cell Biology, University of Sheffield, UK) and Custos is Professor Juha Voipio.

The dissertation can be accessed through the E-thesis service.

Contact info:
 

Maarja Laos, tel. 0451171544, maarja.laos@helsinki.fi