Using a novel form of gene therapy, scientists from Harvard Medical School and Massachusetts General Hospital have managed to restore partial hearing and balance in mice born with a genetic condition that affects both. The new model overcomes a long-standing barrier to accessing hair cells, the delicate sensors in the inner ear that capture sound and head movement and convert them to neural signals for hearing and balance. These cells have been notoriously difficult to treat with previous gene-delivery techniques. The team’s findings, published in the February issue of Molecular Therapy, show that the treatment leads to notable gains in hearing and allows mice that would normally be completely deaf to hear the equivalent of a loud conversation. The approach also improved the animals’ sense of balance.