"It’s not the future. It’s now."
So says Dr. James Baumgartner, pediatric neurosurgeon at Florida Children’s Hospital with regard to the use of cord blood stem cells to treat a number of prevalent, devastating conditions in children.
Dr. Baumgartner recently released the results of his phase I study using umbilical cord blood in the treatment of acquired hearing loss. In the trial, which comprised 11 children between 6 months and 6 years of age with moderate to severe acquired hearing loss, not only was the therapy determined to be safe and feasible but also effective in nearly half, with 45% of participants showing statistically significant improvements in their Auditory Brainstem Response (ABR). ABR uses brainwave activity to determine if there is a response to sound.
"We found a statistically significant improvement in a measure of hearing based on one of the tests we performed," said Dr. Baumgartner. "This may be an indication that newborn stem cells help the ear repair itself in some children with hearing loss."
What is Acquired Hearing Loss?
If a child is deprived of sound for 18 months, they will never speak normally.
Childhood acquired hearing loss is any hearing loss that is not present at birth but identified at a later date. Approximately three per 1,000 children will be identified as having childhood acquired or late onset hearing loss. Half of those cases are caused by genetics, and the other half are considered acquired (for example, as a result of prematurity, antibiotic exposure or recurrent ear infections.) The loss is often progressive for many children.
Hearing loss in a child is akin to a neurologic emergency. According to research presented by Dr. Baumgartner, approximately 12 months of normal auditory input is necessary before a child can speak. There is a limited time window during which the necessary brain development for language can occur. If a child is deprived of sound for 18 months, they will never speak normally. If a child is deprived of sound for more than 3.2 years, they will never acquire spoken language.
“It’s a really big deal and a lot of people don’t realize that,” reflects Dr. Baumgartner.
What Leads to the Hearing Loss?
The organ of corti, a sensitive element located in the inner ear, can be thought of as the body's microphone. It is situated on the basilar membrane in one of the three compartments of the Cochlea and contains four rows of hair cells which protrude from its surface. Auditory nerve fibers rest below the hair cells and pass signals on to the brain. Acquired hearing loss appears to be caused by a loss of hair cells in the organ of corti.
How can cord blood help?
Current treatment options to address acquired loss in children include hearing aids or cochlear implants, which treats the symptom but does not cure the condition. Current trials are investigating ways to regenerate the lost hair cells in the organ of corti. There is hope regeneration can be induced or stem cells can be used to build up new hair cells.
In a previous trial, infusing human umbilical cord blood stem cells to treat a murine model of hearing loss, the mice showed replacement of hair and support cells within the cochlea.
“We thought this was meaningful,” reports Baumgartner.
The latest trial was further inspired by the results of a Duke University retrospective analysis of 30 patients treated with cord blood transplants to treat sensorineural hearing loss as a result of mucopolysaccharidosis. (Mucopolysaccharidoses are a group of metabolic disorders.) The results of the transplants on hearing loss was measured in terms of ABR. ABR improvement suggests an increase in the number of functioning hair cells.
“There was a pretty significant improvement,” says Baumgartner, “in particular if the stem cell transplant was done before 25 months of age. I can say the results from that Duke paper is something we are encouraged by.”
The Duke analysis suggests that this treatment did replace hair cells.