Hear­ing

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gen­er­ate im­ma­ture au­di­tory hair cells in adult lab­o­ra­tory mice.

Lo­cated in the cochlea, the cells — called hair cells be­cause of the rows of ex­ten­sions that os­cil­late with noise — are vi­tal to hear­ing. They trans­form sound vi­bra­tions into neu­ral sig­nals that the brain can in­ter­pret.

But these cells often die af­ter chemo drugs such as cis­platin, a widely used med­i­ca­tion con­tain­ing plat­inum, are in­jected into can­cer pa­tients. As a re­sult, about half of all pa­tients with solid tu­mors or brain tu­mors ex­pe­ri­ence some de­gree of hear­ing loss, said Jian Zuo, a cor­re­spond­ing au­thor of the study and a mem­ber of St. Jude’s De­part­ment of De­vel­op­men­tal Neu­ro­bi­ol­ogy.

Au­di­tory hair cells also can die as a re­sult of pro­longed ex­po­sure to loud noise, ac­ci­dents, ill­ness or ag­ing.

In mak­ing the break­through, in­ves­ti­ga­tors took cues from the an­i­mal world. Although au­di­tory hair cells don’t nat­u­rally re­gen­er­ate in hu­mans, they do in fish and chicken, Zuo said.

By ac­ti­vat­ing one gene and delet­ing an­other, the re­searchers essen­tially repli­cated in spe­cially bred mice the process that oc­curs nat­u­rally in fish and chicken. The ma­nip­u­la­tion of the two genes in­duced cells in the in­ner ears of the mice to take on the ap­pear­ance of im­ma­ture hair cells and to be­gin pro­duc­ing sig­na­ture pro­teins of the sen­sory cells.

The study find­ings mean that, the­o­ret­i­cally, sci­en­tists some­day could use a virus to de­liver the right genes to cells in the in­ner ear to in­sti­gate the re­gen­er­a­tion process.

But that’s still a long way off — at least five to 10 years, Zuo said. One prob­lem is that the hair cells re­gen­er­ated in the mice are im­ma­ture.

“This is a very long process ...” Zuo said. “We’re still miss­ing sev­eral fac­tors.”

Reach Tom Char­lier at thomas. char­lier@com­mer­cialap­peal.com or 901-529-2572 and on Twit­ter at @thomasr char­lier.

JIM WE­BER/THE COM­MER­CIAL AP­PEAL

Delaney Wells, 11, (with fa­ther Demetrius and mother Mary) fought off liver can­cer with the help of po­tent chemo­ther­apy drugs that rav­aged au­di­tory hair cells in her in­ner-ear.

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