[RD (OP)]

This American doctor claims "umbilical cord stem cells" can be successfully transplanted into anyone , (i.e. without tissue-matching)

https: //vimeo.com/219199334#t=2m56s

That seems unbelievable.

[chris]

You can  transplant cells into anyone, but whether they survive or not is another matter. Although umbilical cord stem cells may be relatively low in immunogenicity, they are nonetheless recognised as foreign tissue by the immune system and, as such, destroyed.

However - and it was something of a shock to me to learn this a year or so ago - the reason that people are doing stem cell transplants in certain cases is not with the goal of achieving long-term engraftment so much as for the benefits of short-term immune modulation that these cells may achieve. Manoj Lalu talks about a study he did recently to look at the efficacy of stem cell transplants in this podcast for eLife.

So it may be that a lot of the clinical benefit arising from some of these transplants may be an immune-manipulation effect, or provoking endogenous (your own) tissues to repair better, rather than long term engraftment of the donor cells.

[RD (OP)]

I did read that "stem-cell tourists" occasionally get a match, and end up with a tumour made from donor cells ... http://www.nejm.org/doi/full/10.1056/NEJMc1600188

[evan_au]

Umbilical cord cells don't provoke a strong immune response in the mother - but this is partly because the mother's immune system is desensitised.
Some women with autoimmune diseases report a reduction in symptoms when pregnant.
Cord cells are one possible source of immune suppression factors - but so is the mother's side of the uterus.