Can hearing loss in children be treated with stem cells?
A study by a local husband and wife team is showing promising results for the use of umbilical cord blood to treat children with hearing loss.
In their clinical trial, Linda Baumgartner, a listening and spoken language specialist at Clarke School for Hearing and Speech, and her husband, Dr. James Baumgartner, surgical director of Comprehensive Epilepsy Program at Florida Hospital for Children, showed that the use of umbilical cord blood is safe and feasible in children who have sensorineural hearing loss.
Sensorineural hearing loss is caused when hair cells in the inner ear or the nerve from the inner ear to the brain are damaged.
This type of hearing loss affects 2 in 1,000 newborns, 5 in 1,000 children between ages 3 and 17, and more than one-third of adults between 65 and 74 years old, according to the study authors.
Why the study matters
Existing treatments for hearing loss include hearing aids and cochlear implants. Although the devices improve the symptoms of hearing loss, they don’t repair sensory hair cells in the inner ear, which is the underlying cause of hearing loss.
“Cochlear implants and hearing aids are augmenting the function of cochlea or bypassing it, but this is the natural repair,” said Linda Baumgartner.
Hair cells are necessary for hearing by transforming sound waves into electrical impulses that reach the brain. When they’re lost or damaged, auditory input to the brain is reduced.
Local researchers believe their research could open new doors to finding a pathway to repair the damaged hair cells. Their study was published in the Journal of Audiology & Otology.
Umbilical cord blood
Umbilical cord blood is a rich source of stem cells. Unlike embryonic and fetal stem cells, which are surrounded by ethical and scientific issues, umbilical cord blood is readily available and is a cheap source of stem cells that can form many other cell types. (Here’s a good explainer).
Researchers believe the cord blood cells regenerated cochlear hair cells through several pathways.
Several animal studies have suggested that umbilical cord blood transplantation helped repair the structures within the inner ear.
“It’s an area of active research because it’s a big problem,” said Dr. James Baumgartner. “People have tried to engineer viruses to deliver gene therapy or they’ve tried to engineer hair cells. We’re the only ones doing it so simply.”
Methodology
The Baumgartners and their team conducted a phase 1 study, to find out whether human umbilical cord blood is a safe treatment for moderate to severe hearing loss in children.
In phase 1 human clinical trials, researchers have to show that a treatment is safe before they can start looking into its effectiveness.
The local team sent emails to families who had children with hearing loss and had banked their children’s umbilical cord blood with Cord Blood Registry at birth.
They enrolled in the study 11 children — seven girls and four boys — between 6 months to 6 years old with moderate to severe hearing loss.
Enrollment began in November 2013 and follow-up evaluations were completed in February 2017.
The cord blood was injected into patients’ arms under the supervision of a hematologist experienced in bone marrow transplantation.
Children had follow-ups at one, six and 12 months after the injection. They had physical and neurological exams and had their hearing and speech-language capabilities tested.
Audiologic data was reviewed by a senior audiologist. And a speech pathologist tested the kids’ language skills.
Results
Researchers recorded no adverse events from the cord blood injection.
They also learned that about half of the patients showed improvements in their auditory brainstem response as early as the one-month follow-up testing, researchers reported. One child had a worsening of language score.
“Also, kids who got higher amounts of cord blood did better than those who got lower amounts, so there’s a suggestion of correlation with dose,” said James Baumgartner. “We think that for treatment to take effect, you have to have enough cord blood for the body to react.”
Researchers said it is possible that some of the cord blood cells may have actually reached to the cochlea and induced repair. It’s also possible that the repair was induced through another pathway involving the immune system.
“We think by altering the immune system, there’s an ability that allows cochlea to repair itself. It’s possible,” said James Baumgartner.
Researchers measured hearing, language abilities and performed MRI before and after the treatment.
They said the preliminary data, although from a small study, warrants the implementation of larger controlled phase 2 and 3 trials of children with sensorineural hearing loss.
“We’re the first people to try this,” said Linda Baumgartner. “But there’s a lot of work yet to be done.”
The study was supported by a grant from Cord Blood Registry and support from Wayne Densch Charities. Authors reported no financial conflicts of interest.
The original article can be viewed here.
