My understanding is that there is no donor matching with uc cells, because whole blood or plasma is not being given. All you are being given are cells, either CD34+ or mesenchymal which are isolated in a lab. They are sometimes (usually) expanded (multiplied) in a lab as well so one donor can make a huge number of uc doses. There is still (theoretically) a potential for graft-vs-host disease getting uc cells. I have never received uc cells.
At this point (again, theoretically) marrow cells can not be programmed to go to any particular location in the body. The two "schools of thought" on administering them are a.) give them IV and they will go where needed and b.) get them to, or close to the place needed in the body. Again, none of this is proven anywhere or by anybody.
UC cells can not be proven to be programmable either, although that doesn't stop certain doctors and clinics and labs from claiming that they can "create" certain cell combinations for certain organs in the body or certain ailments. I personally believe this to be hogwash in that the current "state of the art" of stem cell therapy is rather weak.
Clinical trials are a pain to qualify for, and a pain to participate in, but it has become painfully obvious to me that they need to be funded well, flourish and lead to peer-reviewable results.
Right now (for example) if 50 people go for stem cell treatments at 10 clinics, a certain percentage will say they are better after 3-6 months, but how many of those feel better due to placebo effect? Especially after spending a lot of money, a lot of people want to feel better. Nobody is going back to a clinic for follow-up tests that could prove improvement.
And as Barbara pointed out, perhaps they did receive potent, capable cells that "decided" to go to work helping some other unrelated symptom in their bodies.
The bottom line is that the "results" from those of us that have been treated at foreign clinics can be tossed. It has no real meaning or value.