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Fetal-maternal cell trafficking, microchimerism and cancer

Recently I was reading the first report about genetically proven evidence for transmission of cancer from mother to offspring [1] and was thinking “what about fetal cells in mother’s organs?” Do they play any role in carcinogenesis? Luckily, a fresh review [2] about the whole issue of fetal-maternal cell trafficking and microchimerism, solved all of my questions.

Some rare reports suspected mother-to-fetus cancer transmission in cases of leukemia and melanoma, but all of them were lacking genetic evidences for a shared materno-fetal malignant clone. Now we got it. 28-yo mother died from uncontrollable bleeding caused by leukemia in about a month after delivery. An infant was diagnosed with leukemia caused by the maternal clone of cancer cells 11 months later.

Placenta plays an important role in immuno-surveillance and can selectively regulate trafficking of cells between mother and fetus. The authors detected [1] HLA deletion on the transmitted cancer cell clone, which provided immunological invisability of leukemia in the fetus.

So, what about fetal cells in mother’s body? This topic is full of controversial reports and uncertainties. First of all I focused on cancer and got the following:

Although their function is not yet known, evidence in skin, breast and thyroid cancer favors the involvement of these fetal cells in repair mechanisms rather than a role as cancer stem cells in cancer propagation.

So, fetal cells actually protect the mother from some kind of cancers. Awesome! Nevertheless, one of the theories proposed that fetal stem/progenitor cells can act as a cancer stem cells, facilitating cancer progression.

Also, I was thrilled by the investigation that baby’s hematopoietic stem cells could be isolated from mother’s blood [3] as long as a year after the baby’s birth. In the first few months after pregnancy hematopoietic progenitors circulate in relatively high concentration – 1-2 cells/ per 1 ml of maternal blood. How cool would it be if someone could develop the technology of isolating and expanding them in case of autologous transplant in case the baby gets a hematological disorder but cord blood was not collected.

Another interesting thing that I discovered in the review is tissue repair magic:

Fetal–maternal microchimerism is associated with tissue repair. It is important to define the possible role of microchimerism in normal organogenesis and determine how cellular aging affects the repair functions of maternal and fetal microchimeric cells.

I’d encourage you to read this review. You will get to know what kind of cells can migrate, how we can detect them, association of fetal cells with autoimmune diseases, cancer, tissue repair and clinical applications of these knowledge.

… clinical ramifications of fetal–maternal microchimerism for stem cell transplantation and therapy, organ repair and cancer therapy are only just beginning to be studied and understood, but represent an exciting new research field and raise fundamental questions about the biological consequences of microchimerism.

The human foetus at about four months (17-18 weeks) showing the head & upper limbs & the umbilical cord which connects the foetus (at the navel) to the placenta…