So do we know if Mr. Recipient is on immunosuppresants?
One of the recipients is Bruno Grollo, a prominent property developer in Australia, and he is not on immunosuppresants.
People make it sound as if we didn't transplant stem cells every day.
Agreed, bone marrow transplants have been occuring for many years and in that bone marrow hemopoietic stem cells are present. That is not the point, however. We are talking about the transplantation of less differentiated stem cells that are possibly totipotential. Furthermore, these cells are not going to be transplanted into a specific tissue compartment such as bone marrow where they are in a reasonably stuctured environment that will dictate their differentiative destiny. In order for systemic benefits to take place, they will have to be localized in regions associated with all the key stem cell reservoirs in the body. Where and how would this take place?
Most importantly, there is still some debate wheter ESC's exibit MHC.
If that it is the case, it would only be for a brief period. The only cells in the human body that do not express MHC molecule on the cell surface are red blood cells and that may have to do with the fact that they pocess no nucleus either (just heaps of mRNA with which to translate to protein during their lifetime). In contrast ESC's have a nucleus, and in that nucleus are the genes that encode for their particular MHC type which unless they have undergone nuclear transfer still carries the alleles of the donor MHC. Consequently, even if during some developmental stage the expression of MHC molecule may be downmodulated and temporarily less likely to induce an immunogeneic response that is only until the ESC's have differentiated sufficiently to express a full suite of their own MHC molecules.