Recently I was watching a crime investigation show and they arrested one man for murder because of blood DNA found at the crime scene. He was later released because though the DNA was his, he wasn’t there, he had donated bone marrow earlier in life and the victim was the recipient hence why the accused’s DNA was at the scene. This was a surprising thought and I decided to look into it, thinking about it it made sense, but I wasn’t sure. I found that this is indeed true, since bone marrow is the site for blood cell synthesis white blood cells from the donor bone marrow will have the donor DNA. This type of blood is called chimerism, since like the mythical creature there are 2 different DNA’s in one body. In an investigation done by Ginsburg et. al. they found that the cells from the host and donor can be found in the donor blood even between siblings in 95% of transplant cases1. The ones who didn’t exhibit any chimerism are believed to have rejected the transplanted bone marrow since functioning marrow should be putting out its own blood cells with its DNA. In the study they found one person who was very severely immune compromised was found to have DNA T-cells exclusively from purely donor origin2. As the person get sicker their own cells are not producing sufficient amounts of white blood cells so more are from the donor marrow. Clinically looking at chimerism can be one way to test how well the recipient is accepting the donated bone marrow. Such diseases include “chronic graft-versus-host disease (GVHD), nonrelapse mortality (NRM), relapse, and overall mortality.”3 These diseases are significant risks to people who have had bone marrow transplants so being able to test for them will help predict if they are doing well and then allow them to be treated if they are not. People at risk for these diseases are ones who have had more serious illnesses before receiving the transplant, these people typically have greater than 95% of their white blood cells coming from the donor marrow.4 So it would seem that looking at chimerism would help predict the disease resulting from bone marrow transplant, and while it worked in the trials, in a clinical setting it proved less than useful. Even though chimerism lacks a practical clinical use right now, it is an interesting idea to be researching. Also, if you donate bone marrow your DNA will be in 2 places at once!
Citation:
1,2 D Ginsburg, J H Antin, B R Smith, S H Orkin and J M Rappeport. Origin of cell populations after bone marrow transplantation. Analysis using DNA sequence polymorphisms.The Journal of Clinical Investigation. 1985;75(2):596–603. doi:10.1172/JCI111736.
3,4Mossalam, G. Kamel, A. Storer, B. Martin, P. Prognostic Utility of Routine Chimerism Testing at 2 to 6 Months after Allogeneic Hematopoietic Cell Transplantation. Biology of Blood and Marrow Transplantation.2009; 15(3):352-359. doi:10.1016/j.bbmt.2008.12.496
I was curious about this as well. My cousin had a cord blood transplant 5 years ago when she was 23 to cure her cancer. Before her transplant she had straight, blonde hair. When her hair started growing back after her transplant, it was black and extremely curly. About a year after her transplant, her hair turned from black to a reddish brown. I was curious if this could be caused by the same sort of chimerism. I thought that it was not possible since one of the main advantages to cord blood transplants is that there are fewer incompatibilities between the donor’s undifferentiated stem cells and the recipients cells (Vanderson et al., 2004.) However, I read a study by Barker et al. (2003), in which they found that cord blood transplant recipients displayed partial chimerism. This could easily be what led to my cousin’s drastic change in hair color and texture. It seems odd but it is very interesting to see how much someone else’s stem cells could so drastically change someone’s phenotype.
ReplyDeleteReferences:
Vanderson Rocha, M.D., Ph.D., Myriam Labopin, M.D., Guillermo Sanz, M.D., William Arcese, M.D., Rainer Schwerdtfeger, M.D., Alberto Bosi, M.D., Niels Jacobsen, M.D., Tapani Ruutu, M.D., Marcos de Lima, M.D., Jürgen Finke, M.D., Francesco Frassoni, M.D., and Eliane Gluckman, M.D.. (2004). The New England Journal of Medicine, 351: 2276-2285.
Barker, J.N, Weisdorf, D.J, DeFor, T.E., Blazar, B.R., Miller, J.S.& Wagner, J.E.(2003). Rapid and complete donor chimerism in adult recipients of unrelated donor umbilical cord blood transplantation after reduced-intensity conditioning. Blood,102(5): 1915-1919.