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Vision, Hearing Restored In Animals Using Stem Cells

Posted on: Wednesday, 19 November 2008, 14:10 CST

Researchers said on Tuesday that stem cells from tiny embryos can be used to restore lost hearing and vision in animals, in what they believe is a first step toward helping people.

A team of researchers repaired hearing in guinea pigs using human bone marrow stem cells, while another group grew functioning eyes in tadpoles using frog cells.

Both teams said 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 for humans.

Anand Swaroop, a stem cell researcher at the National Eye Institute, said the discoveries illustrate stem cell research's continuing extraordinary potential to treat a wide range of deadly and disabling diseases that affect millions.

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.

Jang told a meeting of the Society for Neuroscience that his team grew the stem cells into neuron-like cells in lab dishes and then transplanted them into the inner ears of the guinea pigs. The animals appeared to have some hearing three months later.

The goal was to regrow the tiny hair cells that are essential for mammals to hear, said Jang. However, she is not sure yet how the stem cells made this happen.

Jang told a news conference they would eventually like to try something similar in humans.

"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," Jang said.

"Birds and reptiles are luckier. Their damaged hair cells apparently regenerate and can restore normal hearing."

The research team led by Michael Zuber and colleagues at the SUNY Upstate Medical University in Syracuse, New York, grew functioning eyes in blinded frog embryos using stem cells.

Zuber's team said frog stem cells usually just form skin when grown in a dish. But they added seven different genetic "factors" that turned on eye formation genes.

Zuber told the meeting that when they transplanted the transformed cells into frog embryos, the resulting tadpoles could see out of those eyes.

The researchers tested the tadpoles by putting white tissue paper over their tank. Normal tadpoles will stay in the lighter side of the tank, covered by the white paper, Zuber said.

Zuber and colleagues showed video of blind tadpoles swimming randomly around the tank while the tadpoles with the transplanted cells stayed on the light side.

Genetic tests showed that the stem cells had transformed, a process called differentiation, into many different cell types.

Zuber said all the cells that make an eye are in there. However, he does not see any immediate uses for people but noted that regrowing many different cell types is the goal of regenerative medicine.

"The retina, like all body organs, contains multiple, distinct cell types. Therefore, successful recovery from blindness due to injury or disease will require the functional replacement of multiple retinal cell types," he said.

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On the Net:

• National Eye Institute
• Chonnam National University
• Society for Neuroscience
• SUNY Upstate Medical University

Source: redOrbit Staff & Wire Reports

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