dr. gitt tells his patients the procedure can help but is not necessarily a cure. >> it's a recipe for exploitation. >> reporter: but leading stem cell researchers like harvard's dr. george daly, say these doctors are preying on vulnerable people. >> it's dramatically premature to actually be charging patients for therapy that we don't yet know is safe or effective. >> it was $7,000. >> reporter: per treatment? >> per treatment. >> reporter: when robert called his former neurologist for advice, he was told not to do it. he says he has had at least a dozen patients call him about the treatments they find online. some costing $15,000 or more. >> legitimate scientific breakthroughs are not marketed through youtube or slick websites. you know, it's the wild west out there. >> not one person has been harmed, injured, killed, died -- >> reporter: we sat down with dr. gitt. >> the majority of them in the 60 to 80% range have a positive outcome in terms of improvement. >> reporter: and how do you meas

not one person has been harmed, injured, killed, died -- >> reporter: we sat down with dr. gitty probably in the 60% to 80% range have a very positive outcome in terms of improvement. >> reporter: and how do you measure improvement? >> well, there's a quality of life scale that is followed and tracked for each patient. >> reporter: dr. gitt says patients who are paying for stem cell therapy are also participating in a study, a practice considered unorthodox. give me one clinical trial where patients pay to get in. >> well, the fact of the matter is ultimately we all pay when research is done. >> reporter: he says patients have to pay because neither pharmaceutical companies nor universities will fund his work. he says he is not doing it for the money. most of his income comes from his plastic surgery practice. the fda told nbc news that it is wary of this treatment but that it does not regulate it. people should consult with a trusted physician before trying anything experimental like this, brian. >> dr. nancy snyderman back here with us with an important story. thank you as alw