I've heard that it's safe. Doctors don't really know how it works but it's great for some medical issues.
Last I checked (about
2 years ago) it was not approved for use for Chrohn's/ UC and would have cost about
$10K per infusion to pay yourself without insurance. It was also unknown whether one infusion would help or whether you'd then need to go every month or some interval.
I'd thought that it was an interesting option to try but the price tag was just a teensy deterrent.