The Food and Drug Administration (FDA) has approved a groundbreaking trial to evaluate the safety of using a child's own cord-blood stem cells to regenerate cells in the inner ear—and potentially restore the child's hearing. The year-long Phase 1 study, which began on Jan. 10, will follow 10 children who have a moderate to profound unilateral or bilateral hearing loss.
To date, more than 20,000 umbilical-cord-blood transplants have been performed worldwide to treat a wide range of diseases, including leukemia and specific blood disorders (Mayani, 2011). This area of research has led to clinical trials using a child's own umbilical-cord blood in experimental therapies for patients with various conditions, including cerebral palsy, brain injury, juvenile diabetes—and now hearing loss (Forraz & McGuckin, 2011).
Hearing aids or cochlear implants coupled with therapeutic intervention are currently the standard treatments of choice for hearing loss. Although there have been significant technological advances in the development of hearing aids and cochlear implants, these options do not restore or repair hearing. With medical research heavily focused on regenerative medicine and stem cell therapy, the question looms: Is there a potential medical treatment that uses stem cell therapy to repair a damaged cochlea?
Researching Stem Cell Therapies
Preclinical research in animals with an acquired sensorineural hearing loss shows great promise for improving hearing, with significant cochlear repair occurring after human umbilical-cord-blood stem cell transplants (Revoltella et al., 2008). Stem cells were transplanted into mice deafened by treatment with kanamycin—an antibiotic known to cause hearing loss—and intense noise. The results of the study verified that human umbilical cord stem cells engrafted in the mice cochlea resulted in inner ear repair. Because the stem cells migrated to the Organ of Corti—where they regrew hair cells and repaired spiral ganglion neurons—there was strong evidence that stem cells may emerge as a potential treatment to repair a human's damaged inner ear and to improve hearing.
Researchers at Children's Memorial Hermann Hospital in Houston were spurred by these and other findings to apply for an FDA-regulated Phase 1 trial. They sought to determine the safety of an autologous umbilical-cord-blood transplant for children with an acquired sensorineural hearing loss. This type of stem cell transplant uses the patient's own stem cells to avoid any immune complications that may arise from using donor cells.
If parents choose to bank cord blood for future use, health care providers collect stem cells from the umbilical cord blood immediately after a baby's birth and store them at very low temperatures (approximately –196 degrees Celsius) at a cord-blood bank. Umbilical cord blood provides abundant cells for transplantation, and autologous cord blood transplants historically have a high degree of safety (Mayani, 2011).
FDA-Approved Clinical Trial
FDA approval of this trial marks the first study of stem cells to treat sensorineural hearing loss in children. Ten children—ages 6 weeks to 18 months—will receive transplants; after the procedures, they will participate in educational programs focused on auditory-verbal treatment. Auditory-verbal treatment is used to develop a child's spoken language by building a strong auditory foundation while coaching and guiding parents in individualized treatment. The children will also receive regular post-transplant medical evaluations to determine the safety of the infusion.
Researchers will collect data from aided and unaided audiograms, language samples, and phonetic inventories pre- and post-transplant. Children who were not fitted with hearing aids within 6 months of the diagnosis of a hearing loss, or who are deaf as a result of a genetic anomaly or syndromes, are not eligible to participate in this clinical trial.
Physicians and researchers at Children's Memorial Hermann-Houston Medical Center are hopeful they can demonstrate that medical treatment for a sensorineural hearing loss in young children is viable. "Currently, the only treatment options for sensorineural hearing loss are hearing aids or cochlear implants," said principal investigator Samer Fakhri, surgeon at Memorial Hermann-Texas Medical Center and associate professor and program director in the Department of Otorhinolaryngology–Head & Neck Surgery at the University of Texas School of Medicine. "We hope that this study will open avenues to additional treatment options for hearing loss in children."
Linda Baumgartner—a co-investigator and auditory-verbal therapist from Winter Park, Florida—agreed. "This study is exciting because it might offer a nonsurgical option for some children with profound loss," she said. "More importantly, this is the first treatment with the potential to repair damage and improve hearing."
This clinical trial received support from the Cord Blood Registry® Center for Regenerative Medicine. The Center provides research grants and support to medical institutions and physicians conducting regenerative medicine research and FDA-regulated clinical trials. The TIRR Foundation supplied additional funding.