Anecdotally, I have seen a case of "stem cells tourism" where the patient traveled to a foreign country to get stem cells injected into their spine. Can't remember why they paid for this treatment. When they came back to their home country they started developing multiple spinal tumors due to the injections...causing significant morbidity. It honestly sounded like a horrifying case. Apparently this is not unheard of. I work in healthcare, but do not have a direct patient care facing role, so unfortunately I do not know what ended up happening to the patient.