medical illustration of the function of stem cells in the human body

What should I be cautious about if I am considering a stem cell therapy?

Claims based on  patient testimonials:

Patients want to believe so much that a treatment is helping them that they can convince themselves that it has. They may even have experienced some recovery unrelated to the treatment. Unless there has been carefully evaluated clinical research it is very difficult to know what is a true effect of the treatment and what you can expect.