2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Forensic scientists have discovered a man in whom, after bone marrow transplantation, donor cells have replaced not only his blood, but also part of the epithelium of the tongue and cheek, reports The New York Times. In addition, in four years, foreign cells completely displaced the patient's own sperm. Despite the fact that the man is feeling well and has no plans to have children, his story shows that a bone marrow transplant can lead to unforeseen results, up to and including mistakes in police investigations.
A person who receives a transplant of any organ - be it skin, kidney or red bone marrow - becomes a chimera: cells of two different genotypes begin to coexist in his tissues. By itself, this neighborhood does not threaten anything, unless there is an immune rejection. In the same case, when the genotypes are similar, as is the case with relatives or carefully selected donor-recipient pairs, cells can coexist peacefully side by side for decades.
Natural chimerism occurs, for example, during pregnancy: the mother and the fetus exchange cells, and then they remain in the tissues for a long time. Also, people can become chimeras even before birth if they receive the cells of their twin. In most such cases, the percentage of chimerism is low and foreign cells do not manifest themselves in any way, therefore, they are invisible, unless they are specifically searched for by genetic markers.
When transplanting hematopoietic blood cells, they can displace the host cells from the bone marrow in whole or in part, but until now it was believed that this does not affect other tissues. The new case shows that the magnitude of the impact in this area can be very different.
In 2014, doctors diagnosed American forensic scientist Chris Long with acute myeloid leukemia and prescribed a course of chemotherapy, and then bone marrow transplanted into him. After that, Long managed to fully recover.
Fragment of Long and Romero's presentation
Long's forensic colleagues became interested in the possible consequences of the transplant: they suspected that foreign cells could affect the results of his DNA tests. At the urging of his colleagues, Long donated a sample of buccal epithelium (cheek scraping) before the procedure, and after that, cells were taken from him from other places: blood, cheeks, lips, tongue, hair and semen.