TOP NEWS and HEADLINES in May
- National Awareness Month Used to Promote Better Hearing
- Stanford Scientists Dish Up Functional Inner-Ear Cells
- Unilateral Hearing Loss Affects Children’s Language Skills
- Roller Coasters Linked to Common Ear Injury
- Starkey Introduces S Series iQ and S Series iQ OtoLens
- Appeals Court Affirms Patent Infringement Ruling Against Shure
- GN ReSound Introduces Alera
- Peer-Reviewed Article Highlights SoundBite Hearing Device
- Hearing Loss May Be Associated with Use of Viagra
- HearUSA Rolls Out AARP Hearing Care Program Nationwide
- GN Store Nord Plans to Pursue Damages in German Case
Stanford research team grows cochlear hair cells in a petri dish. Ten years ago, Stefan Heller, PhD, professor of otolaryngology at the Stanford University School of Medicine, came up with the idea that if you could create hair cells in the laboratory from stem cells, it would go a long way toward helping scientists understand the molecular basis of hearing in order to develop better treatments for deafness.
After years of lab work, researchers in Heller’s lab report in the May 14 issue of Cell that they have found a way to develop mouse cells that look and act just like the animal’s inner-ear hair cells—the linchpin to our sense of hearing and balance—in a petri dish.
If they can further perfect the recipe to generate hair cells in the millions, it could lead to significant scientific and clinical advances along the path to curing hearing loss and deafness.
“This gives us real hope that there might be some kind of therapy for regenerating hair cells,” said David Corey, PhD, professor of neurobiology at Harvard University who was not involved in the study. “It could take a decade or more, but it’s a possibility.”
Using both embryonic stem cells from mice, as well as reprogrammed mouse fibroblasts (a type of relatively undifferentiated cell found in many parts of the body), the researchers present a step-by-step guide on how to coax these cells into the sensory cells that normally reside in the inner ear.
“We knew it was really working when we saw them in the electron microscope,” Heller said. “They really looked like they were more or less taken out of the ear.”
Humans are born with 30,000 cochlear and vestibular hair cells per ear. (By contrast, one retina harbors about 120 million photoreceptors.) When a significant number of these cells are lost or damaged, hearing loss occurs. The major reason for hearing loss and certain balance disorders is that—unlike other species such as birds—humans and other mammals are unable to spontaneously regenerate these hearing cells.
One of the roadblocks to understanding the molecular basis of hearing is the paucity of hair cells available for study, said Heller. While researchers will ultimately need human hair cells, the mouse version is a good model for the initial phases of experimentation. In addition to using mouse embryonic stem cells, the researchers used fibroblasts that had been reprogrammed to behave like stem cells: These are known as induced pluripotent stem cells, or iPS cells.
“Our study offers a protocol to generate millions of functional hair cells from a renewable source,” Heller said. “We can now generate these cells and don’t have to go through dozens of mice for a single experiment. This allows us to do molecular studies with much higher efficiency.”
The study details how the researchers succeeded in coaxing the mouse embryonic stem cells and the iPS cells through different phases of development that occur in the womb. According to lead author Kazuo Oshima, MD, PhD, a research instructor at Stanford who works in Heller’s lab, they started by turning the stem and iPS cells into the type of cells that form a young embryo’s ectoderm—the embryo’s outer layer of cells that eventually differentiate into many tissues and structures, such as skin and nerve cells. Next they used specific growth factors to transform them into “otic-progenitor” cells. After that, they varied the chemical soup in the dish, so that the cells clustered in a manner similar to hair cells and developed stereociliary bundles, which are also characteristic of hair cells.
“We looked at how the ear develops in an embryo, at the developmental steps, and mimicked these steps in a culture dish,” Heller said.
Hair cells in the inner ear contain tiny clumps of hair-like projections, known as stereocilia. Sound vibrations cause the stereocilia to bend slightly, causing mechanical vibrations that are then converted into an electrochemical signal that the brain interprets as sound.
The cells in the petri dish, under close examination, had this same structure. “These cells have a very intriguing structure,” Heller said. “They look like they have hair tufts of stereocilia.”
More importantly, further study showed that the cells also responded to mechanical stimulation by producing currents just like hair cells. Using a probe, researchers stimulated the bundles and recorded the currents that were evoked. Coauthor Anthony Ricci, PhD, professor of otolaryngology, was responsible for this step of the work.
The study was funded by grants from the National Institutes of Health and the California Institute for Regenerative Medicine, and by a Neuroscience of Brain Disorders Award from the McKnight Endowment Fund for Neuroscience.
Other Stanford coauthors include postdoctoral scholars Kunyoo Shin, PhD; Mark Diensthuber, MD; and Anthony Peng, PhD.
Source: Stanford University School of Medicine.
|Stefan Heller, PhD|
Hearing Components wins $4.6 million in patent infringement case against Shure. In the case of Hearing Components Inc versus Shure Inc, the US Court of Appeals for the Federal Circuit ruled last month in favor of plaintiff Hearing Components on Shure’s infringement and validity of two patents on the use of foam tips and sound isolation earphones. The appellate court decision affirms a jury verdict that should result in an award to the company of $4.6 million. The court also ruled that a third Hearing Components patent for wax guards for hearing devices should be incorporated back into the infringement lawsuit against Shure.
Hearing Components, Oakdale, Minn, holds a portfolio of patents incorporated into its products, including its Comply Foam Tips, which are designed to improve the interface between the ear and personal audio devices. “The products patented by Hearing Components were developed from years of research,” says Hearing Components President and CEO Bob Oliveira, PhD. “We take our intellectual property very seriously and are glad to have resolution of the use of foam tips on hearing devices.” For more information, visit the HR Insider story.
Unilateral loss affects kids’ language skills. By the time they reach school age, one in 20 children has hearing loss in one ear, which often poses significant challenges for these children, according to a study at Washington University School of Medicine in St Louis. Researchers found that loss of hearing in one ear hurts the youngsters’ ability to comprehend and use language. The study is scheduled to be published in this month’s edition of Pediatrics.
Unilateral hearing loss can result from congenital abnormalities in the ear, head trauma, or infections such as meningitis. Hearing loss in one ear may go undetected in children because they can appear to have normal hearing. Their difficulty hearing may be mistaken simply for lack of attention or selective hearing, according to a statement from lead author Judith E.C. Lieu, MD, an ENT at Washington University Children’s Hospital and assistant professor of otolaryngology. Even children with recognized one-side hearing loss often aren’t fitted with hearing aids and often do not receive accommodations for their disability.
The researchers studied 74 6- to 12-year-old children with hearing loss in one ear. Each was matched with a sibling with normal hearing so the researchers could minimize the possible effects of environmental and genetic factors on the children’s language skills. The children were tested with the Oral and Written Language Scales (OWLS), a widely used tool to assess language comprehension and expression. An average OWLS score is 100, and hearing loss in one ear caused about a 10-point drop in scores. The oral composite score—which reflects children’s ability to understand what is said to them and their ability to respond or express themselves—averaged 90 in children with hearing loss in one ear.
Lieu said the study demonstrated the strongest effect from hearing loss in one ear in children who are living below the poverty level or with mothers who have little education. Poverty levels and maternal education levels are well-established influences on language skills, and hearing loss in one ear may increase that effect.
The study does not address which possible solutions will be most effective for overcoming the decrease in language skills seen in the children with hearing loss in one ear. But Lieu suggested that studies could be done to see if hearing aids or amplification systems in the classroom will help. Having an educational audiologist as part of an individualized educational plan might be beneficial, researchers said.
Coauthors in the study included Nancy Tye-Murray, Roanne Karzon, and Jay Piccirillo, and the study was supported by the National Institutes of Health.
BHI makes Consumer Guide to Buying Hearing Aids available online. The Better Hearing Institute (BHI), Washington, has published a comprehensive 11-page consumer guide to buying hearing aids, which is now available in eGuide format. The Guide is designed to help consumers understand the steps in the hearing aid fitting process based on the most current practices in hearing care, and is available at www.betterhearing.org/request_information.cfm.
Get Your Weekly Edition of THE INSIDER
Every week The Hearing Review sends out THE INSIDER, a weekly FREE e-newsletter devoted to the top hearing-related news, research, product introductions, fitting topics, and marketing research stories that are influencing your business or practice, as well as the industry at large. [register]Sign up for your free subscription[/register].