Will Adult Stem Cell From The Iliac Crest Bone Cause Tumor?

Will own adult stem cell drawn from bone marrow in the iliac crest bone promotes tumor ? or if injected will aggravate an existing benign condition. I have a cartilage defect on my right knee planning to have stem cell therapy where one of the clinic said has got good success in cartilage regeneration with stem cell treatment but bit worried about the tumor promotion. Can you please advise ?