Sunday, March 11, 2007

Advance in stem cell therapy

Human therapy with embryonic stem cells is now possible, according to a new study published in the scientific journal Nature Medicine by researchers from the Burnham Institute and an international team. Here is my story on the study.

Human embryonic stem cells, turned into neural stem cells, reduced symptoms and increased life expectancy of mice bred to have the fatal genetic disorder Sandhoff's disease, related to Tay-Sachs.

Evan Y. Snyder, a top stem cell researcher at the Burnham, told me he is prepared to go into the clinic and test the therapy on humans.

The study has three exciting implications:

1: The embryonic stem cells did not cause tumors or other adverse reactions. That has been a big problem with embryonic stem cells, and a reason why there is no human therapy yet with these cells.

2: "Adult" human neural stem cells, also tested, were just as effective as the neural stem cells created from the embryonic stem cells. (However, it was easier to "scale up" production of the neural cells from embryonic stem cells).

3: The human embryonic stem cells were from a line approved by President Bush in August, 2001. These cell lines were thought to be of little use in therapy, partially because they had been grown on "feeder cells" from animals, exposing them to animal viruses and proteins, which could cause diseases and rejection by the immune sytem. But the cells used were grown without the animal cells for three years, Snyder said. And in the mice tests, no immunnosuppresive drugs were needed. That's important for human therapy, because such drugs make people more vulnerable to infection.

4: The stem cells repair brain damage (partially, this is not a cure) by multiple mechanisms, Snyder said. They work on several levels to restore normal brain activity.

Newswise has a 7-point recap of the paper's significant findings:

1. First successful use of human embryonic stem cells (hESCs) in a degenerative disease, significantly preserving function and prolonging life in this animal model, and laying the groundwork for a potential clinical trial.
2. First demonstration that stem cells employ multiple mechanisms – not just cell replacement -- to benefit disease
3. First use of hESCs grown in a manner suitable for clinical use (i.e., without contaminating mouse cells).
4. First head-to-head comparison of human embryonic and “adult” stem cells in the same disease model using the same metrics in the hands of the same investigators.
5. First evidence that stem cells, including hESCs may also have anti-inflammatory actions.
6. First demonstration that immunosuppression may not be necessary for successful transplantation in some diseases, making applications to a broad range of patients easier
7. First evidence that stem cell-derived nerve cells may integrate electrically and functionally into a diseased brain.

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