Why are we considering the use of other peoples stem cells for treatment?
Last week we learned that Osiris’ study of stem cells in Crohn’s disease had too high a placebo response, which is the same as saying it didn’t have enough of a treatment response so that the groups (those being treated with Prochymal vs. those who got a placebo) were not statistically different. Is this a study design flaw, or is there a much deeper cause?
When people first started to consider using other people’s stem cells in a vial (allogeneic), big pharma got very excited. The business plan was perfectly matched to it’s current drug development, distribution, and marketing pipeline. Also at the time, most scientists believed that stem cells couldn’t be recognized by the the host (the person getting the cells) as foreign tissue. However, since then, several studies have shown that the body does recognize these cells as foreign, but through a different mechanism than was first considered (killer T-cell system). So in my opinion, the lack of efficacy for both Prochymal and Chondrogen for Osiris is most likely related to the cells being taken out (killed off) by the host’s immune system. So while this problem may be a bugger for stem cells in a vial, making them ultimately much less effective than the patent’s own cells, there are much bigger safety concerns. This has to do with genes. These stem cells from other people have been confirmed to have genes that function in the host. While this could be used for good (it was recently used to cure someone’s AIDS), it could also be a major bummer. Just imagine if you got cells from a patient who has genes that code for a much higher risk of bone cancer. The problem is that it may take 20-30 years of post-marketing surveillance to detect. How about stem cells to cure a brain injury that happen to have genes that code for a higher risk of Alzheimer’s? Until we know everything there is to know about genes (maybe 10-20 years from now), we shouldn’t be taking genes from one person and inserting them into another.
The moral of this story? While the sisterhood of the traveling pants may condone sharing “jeans”, we shouldn’t be trading “genes” with our stem cell therapies.