Your Cells Are My Cells
University of Washington, Seattle, USA. Scientific American
(Impact Factor: 1.07).
03/2008; 298(2):64-71. DOI: 10.1038/scientificamerican0208-72
Many, perhaps all, people harbor a small number of cells from genetically different individuals—from their mothers and, for women who have been pregnant, from their children. What in the world do these foreigners do in the body?
Available from: Jody Ye
- "Over the last decade, elevated levels of maternal cells have been reported in several autoimmune diseases (reviewed in , ) with several different hypotheses proposed; some suggest that MMc are effector cells of the immune response , others that semi-allogeneic MMc in specific host tissues may act as triggers of autoimmunity  while it has also been postulated that some MMc, like fetal microchimeric cells, may play a role in regeneration of damaged tissues . We previously observed increased levels of MMc in the pancreas and periphery of individuals with type 1 diabetes , . "
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ABSTRACT: Maternal microchimeric cells (MMc) transfer across the placenta during pregnancy. Increased levels of MMc have been observed in several autoimmune diseases including type 1 diabetes but their role is unknown. It has been suggested that MMc are 1) effector cells of the immune response, 2) targets of the autoimmune response or 3) play a role in tissue repair. The aim of this study was to define the cellular phenotype of MMc in control (n = 14) and type 1 diabetes pancreas (n = 8).
Using sex chromosome-based fluorescence in-situ hybridization, MMc were identified in male pancreas and their phenotype determined by concomitant immunofluorescence.
In normal pancreas, MMc positive for endocrine, exocrine, duct and acinar markers were identified suggesting that these cells are derived from maternal progenitors. Increased frequencies of MMc were observed in type 1 diabetes pancreas (p = 0.03) with particular enrichment in the insulin positive fraction (p = 0.01). MMc did not contribute to infiltrating immune cells or Ki67+ islet cell populations in type 1 diabetes.
These studies provide support for the hypothesis that MMc in human pancreas are derived from pancreatic precursors. Increased frequencies of MMc beta cells may contribute to the initiation of autoimmunity or to tissue repair but do not infiltrate islets in type 1 diabetes.
Available from: Susan Kelly
- "Other researchers have presented evidence that a woman who has been pregnant is likely to be a chimera; that is, to contain a mixture of her own cells and those of her foetuses (see Johnson and Bianchi, 2004). Cells of apparently maternal origin have also been found in the tissues of children (Nelson, 2008). Another research group reported finding Y-chromosome-bearing cells in the livers of female children and foetuses, and concluded that it is likely that these cells may not only have been transmitted by the mother, but acquired by her from an earlier pregnancy or her own foetal life (Guettier et al., 2005). "
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ABSTRACT: The science of gestational cell transfer—research into the transfer of cells between a pregnant woman and foetus during gestation—and subsequent mingling of transferred cells, or microchimerism, is bringing new attention to the maternal/foetal interface. These findings challenge previous biological understandings of a barrier between the body of a pregnant woman and developing foetus, a barrier maintaining the identity integrity as it were, of two beings, two separate subjects. In this sense, the maternal–foetal interface is an interesting bio-political object, predicated upon understandings of individuals as discrete and bounded organisms, an understanding that has been strongly implicated in immunology, as Donna Haraway, Emily Martin and others have argued. Findings of cellular transfer across this interface raise questions about intermingling and permeability of human organism boundaries. However, these findings are important not only for insight into gestational biology, but because they are emerging in a broader biomedical context of the development of cellular therapies and regenerative medicine. These therapeutic strategies call attention to chimerism as a naturally occurring and iatrogenic biological state, highlighting the permeability and permissiveness of bodies to the intermingling of cells, an idea that runs counter to biological, political and social understandings of selves as individuated, discrete and purely self. A theoretical framework of immuno-politics raises implications of trouble at the maternal/foetal interface, and suggests that chimeric, permeable bodies are of increasing value as cellular therapeutic strategies gain in importance for human health.
Available from: Daniela Ulrich
- "It is established that the fetal immune system has the ability to respond to antigens as early as by 18 weeks of gestation . A limited transfer of cells from the mother to the fetus and vice versa is the basis for the well recognized phenomenon of microchimerism , . Fetal Y-chromosome DNA was detected in the maternal circulation in cellular compartments beginning at 7 to 16 weeks , . "
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ABSTRACT: We describe the distribution of indoleamine 2,3-dioxygenase 1 (IDO1) in vascular endothelium of human first-trimester and term placenta. Expression of IDO1 protein on the fetal side of the interface extended from almost exclusively sub-trophoblastic capillaries in first-trimester placenta to a nearly general presence on villous vascular endothelia at term, including also most bigger vessels such as villous arteries and veins of stem villi and vessels of the chorionic plate. Umbilical cord vessels were generally negative for IDO1 protein. In the fetal part of the placenta positivity for IDO1 was restricted to vascular endothelium, which did not co-express HLA-DR. This finding paralleled detectability of IDO1 mRNA in first trimester and term tissue and a high increase in the kynurenine to tryptophan ratio in chorionic villous tissue from first trimester to term placenta. Endothelial cells isolated from the chorionic plate of term placenta expressed IDO1 mRNA in contrast to endothelial cells originating from human umbilical vein, iliac vein or aorta. In first trimester decidua we found endothelium of arteries rather than veins expressing IDO1, which was complementory to expression of HLA-DR. An estimation of IDO activity on the basis of the ratio of kynurenine and tryptophan in blood taken from vessels of the chorionic plate of term placenta indicated far higher values than those found in the peripheral blood of adults. Thus, a gradient of vascular endothelial IDO1 expression is present at both sides of the feto-maternal interface.
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