Beatriz Domínguez-Gil
Director of the National Transplant Organisation
Importantly, the generation of tolerance (reduced immune response against a graft in the absence of immunosuppressive treatment) is one of the great challenges in the field of transplantation, as it would eliminate the immunosuppression that organ recipients currently require for life with a significant burden of side effects and would prolong graft survival time.
The study is an advance on previous results published by the same group, which had already succeeded in inducing tolerance to kidney grafts in humans and non-human primates by combined transplantation with bone marrow from the same donor. In this study, performed in non-human primates, the authors observe that when bone marrow and kidney from the same donor are transplanted, the kidney seems to collaborate with the tolerogenic effect of haematopoietic tissue, which allows the acceptance of third organs, such as the heart (which does not have this effect on its own) and even on fourth grafts, such as the skin, which they also evaluate. The authors do not demonstrate the cause, which is a limitation of the study, although they correlate their findings with the appearance of certain lymphoid tissue in the kidney, in which the presence of foxP3-positive T-regulatory lymphocytes stands out.
The work is methodologically sound, although another limitation is that the results are not the same in all cases in the study group, and some even develop rejection of the heart graft after some time.
In short, the study represents an advance towards achieving immunological tolerance in the field of organ transplantation, although it is difficult to assess whether these results would be reproducible in humans.