The Possibilities of Mother-Baby Cell Exchange

Fetal cells do cross the placental barrier and enter the mother's body. This happens even if the pregnancy doesn't go to term (for example, if the woman has a miscarriage).

It's always been assumed that there would always be some mixture of cells, especially during the process of delivery. But what's amazed researchers is that they've also found these cells many years - sometimes decades - later. The process is called "microchimerism," after the chimera - the mythological animal that contained parts of other animals.

Fetal cells in the mother
It's been theorized that the presence of fetal cells in the mother's body may cause an autoimmune response that could lead to the development of a serious disease like rheumatoid arthritis. In fact, several years ago researchers studied the blood and skin of patients with scleroderma, an autoimmune disease that primarily attacks women in their 40s and 50s. They found unusually large numbers of male cells (identified by the Y chromosome in the cells' DNA). All of these women had had male children.

At first it seemed that the retained fetal cells were harmful - that they might have triggered the development of the disease. But later it was discovered that these cells were present in large numbers in organs damaged by sclerosis (an advanced stage of the disease) and in the spleen. It seemed that, like other cells produced by the spleen, these cells were actually trying to repair the damaged tissue.

Maternal cells in the child
But what about cells traveling in the other direction - from the mother to the baby? Could they produce an immune reaction that caused problems in the child?

The most recent research, conducted on just that premise, was surprising. Scientists studied children with Type 1 (insulin-dependent) diabetes, thinking that perhaps it was a reaction to the mother's cells that had caused the pancreatic cells of the child to stop functioning.

They did not find evidence of this process. There were high levels of maternal DNA in the children. But maternal cells that had lodged in the pancreas were not only not hurting it, they were actually producing insulin - improving its function, and possibly even promoting tissue regeneration.

Conclusion
The subject of maternal-fetal cell exchange is fascinating. It's one that will almost certainly be explored in more depth in the future, especially since so many of the results so far have been surprising.

Scientific research is always based on a carefully constructed theory. But that doesn't mean the theory will be proved. With much of this research the results have been especially gratifying because the theories were negative - the potential harmful effects of cell exchange - but the results, at least so far, have been more positive.