Stem Cells Turn Hearing Back On

Scientists have enabled deaf gerbils to hear again—with the help of transplanted cells that develop into nerves that can transmit auditory information from the ears to the brain. The advance, reported in Nature, could be the basis for a therapy to treat various kinds of hearing loss.

In humans, deafness is most often caused by damage to inner ear hair cells—so named because they sport hairlike cilia that bend when they encounter vibrations from sound waves—or by damage to the neurons that transmit that information to the brain. When the hair cells are damaged, those associated spiral ganglion neurons often begin to degenerate from lack of use. Implants can work in place of the hair cells, but if the sensory neurons are damaged, hearing is still limited.

"Obviously the ultimate aim is to replace both cell types," says Marcelo Rivolta of the University of Sheffield in the United Kingdom, who led the new work. "But we already have cochlear implants to replace hair cells, so we decided the first priority was to start by targeting the neurons."

In the past, scientists have tried to isolate so-called auditory stem cells from embryoid bodie—aggregates of stem cells that have begun to differentiate into different types. But such stem cells can only divide about 25 times, making it impossible to produce them in the quantity needed for a neuron transplant.

Rivolta and his colleagues knew that during embryonic development, a handful of proteins, including fibroblast growth factor (FGF) 3 and 10, are required for ears to form. So they exposed human embryonic stem cells to FGF3 and FGF10. Multiple types of cells formed, including precursor inner-ear hair cells, but they were also able to identify and isolate the cells beginning to differentiate into the desired spiral ganglion neurons. Then, they implanted the neuron precursor cells into the ears of gerbils with damaged ear neurons and followed the animals for 10 weeks. The function of the neurons was restored.

"We’ve only followed the animals for a very limited time," Rivolta says. "We want to follow them long-term now"—both to assess the possibility of increased cancer risk and to observe the long-term function of the new neurons, he adds.

"It’s very exciting," says neuroscientist Mark Maconochie of Sussex University in the United Kingdom, who was not involved in the new work. "In the past, there has been work where someone makes a single hair cell or something that looks like one neuron [from stem cells], and even that gets the field excited. This is a real step change."

The question now, he says, is whether the procedure can be fine-tuned to allow more efficient production of the relay neurons—currently, fewer than 20% of the stem cells treated develop into those ear neurons. By combining growth factors other than FGF3 and FGF10 with the stem cell mix, researchers could harvest even more ear progenitor cells, he hypothesizes.

"The next big challenge will be to do something as effective as this for the hair cells," Maconochie adds.

A team of Australian researchers, led by University of Melbourne has developed a genetic test that is able to predict the risk of developing Autism Spectrum Disorder, ASD.

Lead researcher Professor Stan Skafidas, Director of the Centre for Neural Engineering at the University of Melbourne said the test could be used to assess the risk for developing the disorder.
 
“This test could assist in the early detection of the condition in babies and children and help in the early management of those who become diagnosed,” he said.
 
“It would be particularly relevant for families who have a history of Autism or related conditions such as Asperger’s Syndrome,” he said. 
 

Autism affects around one in 150 births and is characterized by abnormal social interaction, impaired communication and repetitive behaviours.

The test correctly predicted ASD with more than 70 per cent accuracy in people of central European descent. Ongoing validation tests are continuing including the development of accurate testing for other ethnic groups.

The brain is a notoriously difficult organ to treat, but Johns Hopkins researchers report they are one step closer to having a drug-delivery system flexible enough to overcome some key challenges posed by brain cancer and perhaps other maladies affecting that organ.

In a report published online on August 29 in Science Translational Medicine, the Johns Hopkins team says its bioengineers have designed nanoparticles that can safely and predictably infiltrate deep into the brain when tested in rodent and human tissue.

“We are pleased to have found a way to prevent drug-embedded particles from sticking to their surroundings so that they can spread once they are in the brain,” says Justin Hanes, Ph.D., Lewis J. Ort Professor of Ophthalmology, with secondary appointments in chemical and biomolecular engineering, biomedical engineering, oncology, neurological surgery and environmental health sciences, and director of the Johns Hopkins Center for Nanomedicine.

In a recent study, investigators at Boston University Schools of Medicine (BUSM) and Public Health (BUSPH) identified a gene linking age-related cataracts and Alzheimer’s disease. The findings, published online in PLoS ONE, contribute to the growing body of evidence showing that these two diseases, both associated with increasing age, may share common etiologic factors.

“Doctor” or “Darling”: The Subtle Differences of Speech

Human speech comes in countless varieties: When people talk to close friends or partners, they talk differently than when they address a physician. These differences in speech are quite subtle and hard to pinpoint. In a recent special issue of the journal Frontiers in Human Neuroscience, Johanna Derix, Dr. Tonio Ball, and their colleagues from the Bernstein Center and the University Medical Center in Freiburg report that they were able to tell from brain signals who a person was talking to. This discovery could contribute to the further development of speech synthesizers for patients with severe paralysis.

In contrast to the experimental research common in human neuroscience, the scientists studied natural, non-experimental behavior. Patients who, for medical reasons, had electrodes implanted underneath their skull allowed their brain activity to be recorded during daily life in the hospital. The Freiburg researchers compared data recorded during natural conversations that the patients had with their physicians and their life partners. They found pronounced differences in the anterior temporal lobe, a brain area well known for its significance in social interaction. Several components of neural signals that are detectable on the brain surface can convey such information.

“This study is only the first step towards elucidating the neural basis of human everyday behavior,” explains the neuroscientist and physician Tonio Ball. “Such investigations will become especially important in developing new neurotechnological treatment options for patients with impaired motor and language functions that work in real life situations.” The restoration of speech production becomes necessary in some forms of neurological diseases and chronic paralysis. A computer could synthesize speech for patients suffering from such conditions by using their brain signals. Information on who the patient is addressing could help the device to select the degree of formality – and to prevent it from calling the doctor “darling.”

Slow-wave sleep, or ‘deep sleep’, is intimately involved in the complex control of the onset of puberty, according to a recent study accepted for publication in The Endocrine Society’s Journal of Clinical Endocrinology and Metabolism (JCEM).

The many changes that occur in boys and girls during puberty are triggered by changes in the brain. Previous studies have shown that the parts of the brain that control puberty first become active during sleep, but the present study shows that it is deep sleep, rather than sleep in general, that is associated with this activity.

"If the parts of the brain that activate the reproductive system depend on deep sleep, then we need to be concerned that inadequate or disturbed sleep in children and young adolescents may interfere with normal pubertal maturation," said Harvard researcher, Natalie Shaw, MD, of Massachusetts General Hospital and Boston Children’s Hospital who led the study. "This is particularly true for children who have been diagnosed with sleep disorders, but may also have more widespread implications as recent studies have found that most adolescents get less sleep than they require."

In the study, researchers examined pulses of luteinizing hormone (LH) secretion in relation to specific sleep stages in children ages 9-15. LH is essential for reproduction and triggers ovulation in females and stimulates the production of testosterone in males. Researchers found that the majority of LH pulses that occur after sleep are preceded by deep sleep suggesting that deep sleep is intimately involved in pubertal onset.

(Image credit: ©Monkey Business - Fotolia.com)

The world continues to be a noisy place, and Purdue University researchers have found that all that background chatter causes the ears of those with hearing impairments to work differently.

"When immersed in the noise, the neurons of the inner ear must work harder because they are spread too thin," said Kenneth S. Henry, a postdoctoral researcher in Purdue’s Department of Speech, Language and Hearing Sciences. "It’s comparable to turning on a dozen television screens and asking someone to focus on one program. The result can be fuzzy because these neurons get distracted by other information."

The findings, by Henry and Michael G. Heinz, an associate professor of speech, language and hearing sciences, are published as a Brief Communication in Nature Neuroscience. The work was funded by the National Institutes of Health and the National Institute on Deafness and Other Communication Disorders.

Have you ever wondered why some people find it so much easier to stop smoking than others?

New research shows that vulnerability to smoking addiction is shaped by our genes. A study from the Montreal Neurological Institute and Hospital - The Neuro, McGill University shows that people with genetically fast nicotine metabolism have a significantly greater brain response to smoking cues than those with slow nicotine metabolism. Previous research shows that greater reactivity to smoking cues predicts decreased success at smoking cessation and that environmental cues promote increased nicotine intake in animals and humans. This new finding that nicotine metabolism rates affect the brain’s response to smoking may lead the way for tailoring smoking cessation programs based on individual genetics.