Bioethics, hearing loss research, research finance, stem cells

We’ve heard this (stem cell) story before

Stanford scientists are working on a “stem cell treatment” to cure hearing loss due to lost nerves.

The Science Guy at the Houston Chronicle references a Wired News article, that links to the American Association for the Advancement of Science and the San Francisco Gate and an interview with Stefan Heller.

Here’s a slightly better review from Medical News Today.

I believe that reading about the evolution of Heller’s research will give us some indication about future treatments that result from “stem cell treatments.”

Dr. Heller found stem cells in the hearing and balance systems in the ear of humans and mice.

He found that the hearing, inner-ear adult stem cells of mice don’t grow and divide much after birth, but that the balance nerve cells, the vestibular hair cells are “pluripotent” (“can give rise to a variety of cell types in vitro and in vivo, including cells representative of ectodermal, endodermal and mesodermal lineages”) and can be induced to form either the vestibular, balance cells or the hearing sensory cells.

Then, Heller’s team discovered (free abstract, here)that human bone marrow stem cells can become progenitor cells – or the dedicated adult stem cells – that can repair damaged hearing sensory nerve cells.

[Editing note: I had the url of that abstract wrong. Also, I many have the timeline wrong, since a closer look at the abstract shows that it was only published in January, 2007.]

However, Heller and his team ignored the bone marrow cell findings and began focusing on embryonic stem cells. Why would he leave a field of inquiry that would allow each of us to have access to genetically matched cells to repair our own hearing?

Nevertheless, it turns out that the goal is to regenerate the patient’s own stem cells to repair damage where it’s needed in the body, when it’s needed.

From the January 29, 2007 San Francisco Gate article:

On this day he is finally starting his first experiment — growing inner ear cells in a culture dish, to test the new equipment — and already people in the medical school are asking, “When are the first transplantations taking place?” he says. “I’m a little careful of that, because we have to do animals first.”

He wouldn’t be here answering this question at all if he hadn’t found stem cells in the vestibular organ, which controls balance. Both balance and hearing are controlled by hair cells. When the hearing cells are damaged by illness or noise, they die off and don’t come back. A University of Virginia study 15 years ago found that cells in the vestibule have shown a small and limited ability to regenerate. Heller took that further and within these cells was able to isolate stem cells that continuously multiply. In culture dishes, these regenerative balance cells can be engineered to produce hearing cells.

The logical next step would be to transplant these into the auditory canal. “The problem with any surgical approach to the ear is you have the potential of doing more damage than you can do any good,” he says. “So I don’t think this will be successful any time soon.”

That means 10 years and 10,000 mice, maybe more of each. The immediate future is drugs.

They can be tested directly on embryonic inner ear cells to see if any lead to over-production of hair cells. If a drug could be found that stimulates enough productivity within the damaged ear, this drug could be applied to a deaf ear. These can then be tested on animals, starting in a year or so.

About bnuckols

Conservative Christian Family Doctor, promoting conservative news and views. (Hot Air under the right wing!)


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