Dr. Marcelo Rivolta of the University of Sheffield transplanted human embryonic stem cells into deaf gerbils and obtained a functional recovery of, on average, around 46 percent.
The improvement was evident about four weeks after administering the cells, Rivolta said.
"We believe this an important step forward. We have now a method to produce human cochlear sensory cells that we could use to develop new drugs and treatments, and to study the function of genes," Rivolta said in a statement. "And more importantly, we have the proof-of-concept that human stem cells could be used to repair the damaged ear."
The model of hearing loss successfully treated by the scientists was similar to a human condition known as auditory neuropathy -- a form of deafness in which the damage occurs at the level of the cochlear nerve -- involving 15 percent of the population worldwide with profound hearing loss.
The findings were published in the journal Nature.