Cells and tissues created through nuclear transfer can be rejected by the body because of a previously unknown immune response to the cell’s mitochondria, according to a study researchers of the Hamburg’s University Medical Center (UKE) published in the the renowned medical magazine “Cell Stem Cell”. This is due to genetic components of the recipient cell, located outside the nucleus that are not replaced in this process.
A Word of Caution In Regard To SCNT
The promise of the SCNT method is that the nucleus of a patient’s skin cell, for example, could be used to repair a parts of its body. “One attraction of SCNT has always been that the genetic identity of the new pluripotent cell would be the same as the patient’s, since the transplanted nucleus carries the patient’s DNA”, said cardiothoracic surgeon Dr Sonja Schrepfer, head of the Transplant and Stem Cell Immunobiology Laboratory in Hamburg. “The hope has been that this would eliminate the problem of the patient’s immune system attacking the pluripotent cells as foreign tissue, which is a problem with most organs and tissues when they are transplanted from one patient to another,” she added.
Surprised By Rejection
In her experiments she used cells from mice that were created by transferring the nuclei of adult mouse cells into enucleated eggs cells from genetically different mice. When transplanted back into the nucleus donor strain, the result was not the one she expected: “We were surprised to find that just two small differences in the mitochondrial DNA was enough to cause an immune reaction”, she said. “We didn’t do the experiment in humans, but we assume the same sort of reaction could occur”, Schrepfer added.
Interdisciplinary Research with British and US-American Scientists
Involved in the research project were researchers from various institutes of UKE, who co-operated with fellow researchers in the U.S. from the Stanford University School of Medicine and Cambridge’s MIT plus British colleagues in Newcastle upon Tyne (GB) and a German team from Erlangen. The project is integrated into the research programme of the German Center for Cardiovascular Research (DZHK). It was funded, inter alia, by the German Research Foundation (DFG), the Else Kröner-Fresenius-Foundation, and the Fondation Leducq.
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