This Thursday and Friday, the FDA deliberates on how to decide that cells derived from embryonic stem cells are ready to be tested in humans. On Saturday and Sunday, patient advocates and stem-cell researchers meet in San Francisco to talk about how to accelerate discoveries and therapies.

Both indicate a growing momentum for moving stem cells into applications. I wrote a preview article on the FDA discussions. The FDA’s got a difficult job to do. It has to make sure that it doesn’t slow down therapies for horrible, debilitating diseases and that human subjects aren’t exposed to dangerous procedures. This meeting is regarded as a first step for moving embryonic stem cells into well-regulated clinical testing.

I’ve never attended an FDA Advisory Committee meeting before, and I called several people to get a sense of what to expect. One of them was Michele Keane-Moore, a former cell-product reviewer with FDA who is now with the Biologics Consulting Group. She told me that the public forum marks a good learning opportunity for the agency. FDA officials have discussion with many companies, she says, “but all of that work is confidential and can’t be discussed.” Now, she says, “A lot of the questions will be aired in a public forum, so all the stakeholders can say what their concerns are.” the transcripts will eventually be made available for this meeting. Keane-Moore believes the discussion will be similar to the one held in July 13 on stem cells in neurological diseases. You can get to it here.

You can read more in the Nature article, but the FDA is mainly worried that the animal tests used to assess safety problems aren’t good enough and that they won’t know until too late that the transplanted cells are causing harm rather than benefit. The FDA has to make these calls all the time, but there are a couple reasons why these cells are cause for concern. One is that the animal safety tests often require animals to be bred to lack immune responses or to be on immunosuppressive drugs (mouse bodies would attack human cells otherwise), so they want to figure out the limitations of these tests.

Also, stem cells are very different from drugs because cells can multiply and change. That makes them harder to predict. If you put the cells in an environment where they can grow quickly, a low dose of cells could become a high dose. That can’t happen with drugs. Of course, everyone also hopes that these cells can bring about cures for diseases that so far seem intractable to regular drugs.

If you have something you want me to have my eyes out for at either of these meetings, please send me an email or add a comment below.