Stem cells

Stem cells restore hearing, vision in animals

Researchers said: stem cells from tiny embryos can be used to restore lost hearing and they believe it is a 1st step toward helping people. Their findings help describe some of the most basic biological processes underlying the development of hearing and sight, and may help in the development of the new field of regenerative medicine.

Dr. Sujeong Jang of Chonnam National University in Gwang-ju, South Korea, and colleagues used mesenchymal stem cells from human bone marrow to restore hearing in guinea pigs whose hearing had been destroyed using chemicals. They grew the stem cells into neuron-like cells in lab dishes and then transplanted them into the inner ears of the guinea pigs. Three months later, the animals appeared to have some hearing, Jang told a meeting of the Society for Neuroscience.

They would eventually like to try something similar in humans, Jang told a news conference. Jang said: "When sensitive hair cells in the inner ear of humans and other mammals are killed by loud noise, autoimmune attack, toxic drugs, or aging the damage is permanent." "Birds and reptiles are luckier. Their damaged hair cells apparently regenerate and can restore normal hearing."

Usually, frog stem cells just form skin when grown in a dish. Zuber's team added seven different genetic "factors" that turned on eye formation genes. When they transplanted the transformed cells into frog embryos, the resulting tadpoles could see out of those eyes. They tested the tadpoles by putting white tissue paper over their tank, Zuber said in an interview. Normal tadpoles will stay in the lighter side of the tank, covered by the white paper. Genetic tests showed that the stem cells had transformed, a process called differentiation, into many different cell types.