Baby Steps Toward Healing Hearing

first_imgThere is no biological cure for deafness—yet. We detect sound using sensory cells sporting microscopic hairlike projections, and when these so-called hair cells deep inside the inner ear are destroyed by illness or loud noise, they are gone forever. Or so scientists thought. A new study finds specific cells in the inner ear of newborn mice that regenerate these sensory cells—even after damage, potentially opening up a way to treat deafness in humans.Researchers knew that cells in the inner ear below hair cells—known as supporting cells—can become the sensory cells themselves when stimulated by a protein that blocks Notch signaling, which is an important mechanism for cell communication. Albert Edge, a stem cell biologist at Harvard Medical School in Boston, and his colleagues, attempted to identify the exact type of supporting cells that transform into sensory ones and fill in the gaps left by the damaged cells.The researchers removed the organ of Corti, which is housed within a seashell-shaped cavity called the cochlea and contains sensory hair cells, from newborn mice and kept the cells alive in culture plates. They damaged the hair cells using the antibiotic gentamicin, which destroys its sound-sensing projections. When they examined the organ of Corti under the microscope, they saw that small numbers of hair cells had regenerated on their own. But if they blocked Notch signaling, they saw even more regenerated hair cells, the team reports today in Stem Cell Reports. The number that developed varied, but in the base of cochlea, where the tissue received the most damage, hair cell numbers returned to about 40% of the original. “It’s interesting and encouraging that they are capable of regenerating,” Edge says.Sign up for our daily newsletterGet more great content like this delivered right to you!Country *AfghanistanAland IslandsAlbaniaAlgeriaAndorraAngolaAnguillaAntarcticaAntigua and BarbudaArgentinaArmeniaArubaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBolivia, Plurinational State ofBonaire, Sint Eustatius and SabaBosnia and HerzegovinaBotswanaBouvet IslandBrazilBritish Indian Ocean TerritoryBrunei DarussalamBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaChristmas IslandCocos (Keeling) IslandsColombiaComorosCongoCongo, The Democratic Republic of theCook IslandsCosta RicaCote D’IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFalkland Islands (Malvinas)Faroe IslandsFijiFinlandFranceFrench GuianaFrench PolynesiaFrench Southern TerritoriesGabonGambiaGeorgiaGermanyGhanaGibraltarGreeceGreenlandGrenadaGuadeloupeGuatemalaGuernseyGuineaGuinea-BissauGuyanaHaitiHeard Island and Mcdonald IslandsHoly See (Vatican City State)HondurasHong KongHungaryIcelandIndiaIndonesiaIran, Islamic Republic ofIraqIrelandIsle of ManIsraelItalyJamaicaJapanJerseyJordanKazakhstanKenyaKiribatiKorea, Democratic People’s Republic ofKorea, Republic ofKuwaitKyrgyzstanLao People’s Democratic RepublicLatviaLebanonLesothoLiberiaLibyan Arab JamahiriyaLiechtensteinLithuaniaLuxembourgMacaoMacedonia, The Former Yugoslav Republic ofMadagascarMalawiMalaysiaMaldivesMaliMaltaMartiniqueMauritaniaMauritiusMayotteMexicoMoldova, Republic ofMonacoMongoliaMontenegroMontserratMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew CaledoniaNew ZealandNicaraguaNigerNigeriaNiueNorfolk IslandNorwayOmanPakistanPalestinianPanamaPapua New GuineaParaguayPeruPhilippinesPitcairnPolandPortugalQatarReunionRomaniaRussian FederationRWANDASaint Barthélemy Saint Helena, Ascension and Tristan da CunhaSaint Kitts and NevisSaint LuciaSaint Martin (French part)Saint Pierre and MiquelonSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint Maarten (Dutch part)SlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSouth Georgia and the South Sandwich IslandsSouth SudanSpainSri LankaSudanSurinameSvalbard and Jan MayenSwazilandSwedenSwitzerlandSyrian Arab RepublicTaiwanTajikistanTanzania, United Republic ofThailandTimor-LesteTogoTokelauTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTurks and Caicos IslandsTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVenezuela, Bolivarian Republic ofVietnamVirgin Islands, BritishWallis and FutunaWestern SaharaYemenZambiaZimbabweI also wish to receive emails from AAAS/Science and Science advertisers, including information on products, services and special offers which may include but are not limited to news, careers information & upcoming events.Required fields are included by an asterisk(*)The researchers then tracked which supporting cells turned into hair cells by tagging them with a fluorescent chemical and watching the tissues for at least 4 days. By following the tag, they saw that only cells carrying a protein found in stem cells, called Lgr5, turned into new hair cells. “Knowing about these Lgr5 cells is valuable for us because it gives us a target cell population to study as we try to figure out how to better manipulate them and turn them into hair cells in an adult,” Edge says.The work contradicts previous studies that found that multiple types of unidentified supporting cells transform into hair cells when Notch signaling is blocked. In these studies, the hair cell growth occurred without any initial damage to the organ of Corti.The recent study follows a similar paper published earlier this month by developmental neurobiologist Jian Zuo, of St. Jude Children’s Research Hospital in Memphis, Tennessee, who damaged sensory cells in live mice. Zuo also saw regeneration of hair cells from supporting cells, but most of the new cells died within 2 weeks. In humans, the organ of Corti matures in the womb, but in mice, the organ continues to mature for the first 10 days of life, so these same findings may not hold true in humans.Most people suffering from hearing loss are adults, so understanding how older cells turn off their ability to regenerate will be important in turning that ability back on. “We need to focus more into why does this work early [in life], and not later. That will be key,” says Alain Dabdoub, a developmental neuroscientist at the University of Toronto in Canada.last_img read more

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first_img Comments   Share   Top Stories Big things were expected out of Arizona Cardinals receiver John Brown this past season, and the second-year pro delivered.Brown caught 65 passes for 1,003 yards and seven touchdowns, and according to ProFootballFocus.com, he was one of the top 25 breakout players of the 2015 NFL season.2014 cumulative grade: +0.7 on 715 snaps2015 cumulative grade: +7.3 on 962 snapsBrown would be higher on this list but for a disappointing championship game performance. Still, his production in his second year was impressive. He caught 20 more passes, improved his catch percentage from 52.5 to 62.6, caught two more scores, and broke six more tackles, taking both tallies to seven. Brown stepped up during Michael Floyd’s absence, staking his claim for a starting berth.Brown did struggle in Arizona’s 49-15 NFC Championship Game loss to the Carolina Panthers, catching two of the eight passes thrown in his direction for 23 yards, but he was not alone in posting a disappointing performance that night in Charlotte. But one bad night does not erase all of what the 25-year-old accomplished in his second professional season, one in which he paired with Larry Fitzgerald to become the first Cardinals receiving duo to each amass at least 1,000 yards since Fitz and Anquan Boldin accomplished the feat in 2009.– / 8 The 5: Takeaways from the Coyotes’ introduction of Alex Meruelo Grace expects Greinke trade to have emotional impact Derrick Hall satisfied with D-backs’ buying and selling Former Cardinals kicker Phil Dawson retires Arizona Cardinals wide receiver John Brown (12) evades a tackle-attempt by San Francisco 49ers cornerback Kenneth Acker (20) during the first half of an NFL football game in Santa Clara, Calif., Sunday, Nov. 29, 2015. (AP Photo/Tony Avelar)last_img read more