I have seen stem cell patients after the fact and the results do not seem to be very good. Admittedly, if the patients would be doing well after stem cell injection, they would not be in my office.
That being said, you have to remember that stem cells are not a miracle treatment. Stem cells have to have two conditions to work well. First, they have to be in a nurturing environment. That is, there has to be a good blood supply. The intervertebral disc is a hostile environment for any cells, let alone stem cells. The inside of the disc is avascular (no blood supply) and highly acidic. This is due to anaerobic metabolism (lactic acid builds up).
There was a study sometime back that took the malfunctioning chondrocyte cells in the middle of the disc space and placed them in a nutrient system. These cells started functioning normally again indicating that they were living in a hostile environment. This is not a good place to inject stem cells.
The other worry is that these stem cells need the right protein trigger to turn into the cells that are needed and attach to the correct location to provide what is missing (proteins or hyaluronic acids). What if these cells differentiate into the wrong cell line, produce the wrong material or even worse, turn into cancer cells?
Stem cell treatment is not benign and many factors have to be taken into consideration. The current fad of injection of these cells does not have enough science yet in my opinion to consider this treatment on my patients. Maybe in 5-10 years, we will have enough information to make appropriate decisions on stem cells.