New stem cell therapy may lead to treatment for deafness

Sheffield, England – March 23, 2009 - Deafness affects more than 250 million people worldwide. It typically involves the loss of sensory receptors, called hair cells, for their "tufts" of hair-like protrusions, and their associated neurons. The transplantation of stem cells that are capable of producing functional cell types might be a promising treatment for hearing impairment, but no human candidate cell type has been available to develop this technology.

A new study led by Dr. Marcelo N. Rivolta of the University of Sheffield has successfully isolated human auditory stem cells from fetal cochleae (the auditory portion of the inner ear) and found they had the capacity to differentiate into sensory hair cells and neurons. The study is published in the April issue of STEM CELLS.

The researchers painstakingly dissected and cultured cochlear cells from 9-11 week-old human fetuses. The cells were expanded and maintained in vitro for up to one year, with continued division for the first 7 to 8 months and up to 30 population doublings, which is similar to other non-embryonic stem cell populations, such as bone marrow. Gene expression analysis showed that all cell lines expressed otic markers that lead to the development of the inner ear as well as markers expressed by pluripotent embryonic stem cells, from which all tissues and organs develop.

They were able to formulate conditions that allowed for the progressive differentiation into neurons and hair cells with the same functional electrophysiological characteristics as cells seen in vivo.

"The results are the first in vitro renewable stem cell system derived from the human auditory organ and have the potential for a variety of applications, such as studying the development of human cochlear neurons and hair cells, as models for drug screening and helping to develop cell-based therapies for deafness," say the authors.

Although the hair cell-like cells did not show the typical formation of a hair bundle, the authors suggest that future studies will aim to improve the differentiation system. They are currently working on using the knowledge gleaned from this study to optimize the differentiation of human embryonic stem cells into ear cell types.

"Although considerable information has been obtained about the embryology of the ear using animal models, the lack of a human system has impaired the validation of such information," the authors note.

"Access to human cells that can differentiate should allow the exploration of features unique to humans that may not be applicable to animal models," says Donald G. Phinney, co-editor of the journal. The protocol they developed to expand and isolate human fetal auditory stem cells may be able to be adapted for deriving clinical-grade cells with potential therapeutic applications.

Dr Ralph Holme, director of biomedical research for Royal National Institute for Deaf and Hard of Hearing People, said: "There are currently no treatments to restore permanent hearing loss so this has the potential to make a difference to millions of deaf people."

This study is published in STEM CELLS. Media wishing to receive a PDF of this article may contact journalnews@bos.blackwellpublishing.com

Dr. Marcelo N. Rivolta is a Senior Research Fellow at the University of Sheffield and can be reached for questions at m.n.rivolta@sheffield.ac.uk.

STEM CELLS, a peer reviewed journal published monthly, provides a forum for prompt publication of original investigative papers and concise reviews. The journal covers all aspects of stem cells: embryonic stem cells/induced pluripotent stem cells; tissue-specific stem cells; cancer stem cells; the stem cell niche; stem cell epigenetics, genomics and proteomics; and translational and clinical research. For more information, please visit http://www3.interscience.wiley.com/journal/121607285/grouphome/home.html. STEM CELLS is co-published by AlphaMed Press and Wiley-Blackwell.

Established in 1983, AlphaMed Press with offices in Durham, NC and Craigavon, United Kingdom publishes two internationally renowned peer-reviewed journals: STEM CELLS®, now in its 27th year, is the world's first journal devoted to this fast paced field of research. The Oncologist® (www.TheOncologist.com), also a monthly peer-reviewed publication, is in its 14th year and is devoted to community and hospital-based oncologists and physicians entrusted with cancer patient care. Both journals are premier periodicals with globally recognized editorial boards dedicated to advancing knowledge and education in their focused disciplines. AlphaMed Press publishes the Stem Cells Portal online (www.StemCellsPortal.com), as well as freestanding monographs and books, and is renowned for its excellence and speed in the publication of the peer-reviewed proceedings of major international symposia. For more information on AlphaMed Press, please visit www.alphamedpress.org.

Wiley-Blackwell was formed in February 2007 as a result of the acquisition of Blackwell Publishing Ltd. by John Wiley & Sons, Inc., and its merger with Wiley's Scientific, Technical, and Medical business. Together, the companies have created a global publishing business with deep strength in every major academic and professional field. Wiley-Blackwell publishes approximately 1,400 scholarly peer-reviewed journals and an extensive collection of books with global appeal. For more information on Wiley-Blackwell, please visit www.wiley-blackwell.com or http://interscience.wiley.com.