Essay Example on Mother-Child Symbiosis: Fetal Microchimerism Explained

During pregnancy, there is an incredible symbiosis between mother and child since her bloodstream and that of the baby are connected. In this way, an exchange of cells occurs between mother and child that causes some stem cells (which can transform into any type of cell) to pass from the fetus and the placenta to the mother and some cells from the mother to pass into the bloodstream of the fetus. Among other things, they share blood and cells in what is known as fetal microchimerism.

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The concept of microchimerism refers to that situation in which a person or creature has cells from other individuals in their body, having within them a small percentage of DNA different from their own (Gadi & Nelson, 2007). These cells establish a relationship with the subject's genetically specific ones, being able to create a link between both types of cells, which gives rise to both positive and negative consequences. Microchimerism occurs both in humans and in other animal species, such as rodents or dogs. In the human case, the amount of fetal cells found in the mother's blood samples increases as the pregnancy progresses. In the second trimester, it is possible to see up to 2 or 3 fetal cells for each milliliter of blood in a sample, an amount that declines rapidly postpartum until a minimum concentration is left (Hahn et al., 2019). This does not happen the same in all pregnant women.

Although the first indications of this phenomenon were discovered through the transplantation of animals, the microchimerism that occurs most frequently in nature between two multicellular organisms is the one that occurs during pregnancy. During pregnancy, mother and child are connected by the umbilical cord and the placenta, and through this connection, they exchange some cells that pass into the other's organism and are integrated into it (Ferretti et al., 2018). It is suspected to have a higher incidence than previously thought and even some experts consider that it occurs in all pregnancies. Specifically, they have been found that from the fourth week of gestation, fetal cells can already be found in the maternal organism, and it is generally considered that from the seventh week it can be identified in all pregnancies.

This relationship between mother and child cells is not transient and is lost after a few months or years after childbirth: the presence of the child's cells in the mother's body has been observed for more than twenty years after giving birth (Fjeldstad, Johnsen, & Staff, 2019). These cells spread throughout the body, being in the heart, liver, or even brain and interacting with the subject's cells. Cells from the other organism become integrated into the structures and tissues themselves, including the nervous system. The fact that part of the DNA itself is in the other may imply a higher rate of protection at the behavioral level, generating a higher level of attachment and the perception of greater similarity.

Fetal cells often contribute to healing internal wounds and injuries, as well as participating in the reduction of symptoms of disorders such as pain in osteoarthritis both during pregnancy and in the long term (Miech, 2010). It also improves the immune system and facilitates the development of future pregnancies. It has also been proposed that the presence of these cells may help explain why women have a greater capacity for resistance and a longer life expectancy, noting that many women who had given birth and had such microchemical cells tend to have a better hope of life (possibly due to an improvement of the autoimmune system, although this is mere speculation at the moment) (Mahmood & O’Donoghue, 2014). It has also been detected that it reduces the probability of cancer and that they tend to participate in tissue regeneration, observing its implication in the recovery of heart or liver diseases.

Fetal microchimerism causes some pluripotential stem cells from the blood of the fetus and the placenta (which can be transformed into any type of cell) to pass into the circulation of the baby and the mother, and help to repair its organs. The objective of these cells is to ensure the survival of the mother (and therefore that of the fetus).

Pluripotent stem cells are a type of cell that has not yet specified the type of cell they will be, so they can end up being any cell. Thus, when they reach the maternal body, it can become the cell that is most needed. Furthermore, these fetal cells that pass to the mother have a great ability to renew and collaborate with adult stem cells in the regenerative function of the female body. Some studies have confirmed the participation of these cells in the repair of the heart of mothers suffering from heart disease (Asnicar et al., 2017; Hahn et al., 2019; Miech, 2010). When analyzing these cells of the heart it was observed that they contained the Y chromosome, exclusively of the male, and therefore they were cells that came from the previous pregnancy of a boy (Hahn et al., 2019). Similar regenerations have been documented in other maternal organs such as the liver, kidney, and even the brain of women, perhaps preventing the onset of Alzheimer's and other brain diseases.

The latest research even suggests that these cells could help stop cancer cells (Kajbafzadeh, Sabetkish, & Sabetkish, 2018). Cells that reach a woman through fetal microchimerism are thought to positively influence her immune system. A baby's stem cell is recognized by the immune system as its own, because it shares half of the mother's genetic code, and at the same time as foreign, because the other half is from the father's genetic code. This could somehow prepare the immune system to be on the lookout for cells that are similar to oneself, but with some genetic differences (Gammill & Nelson, 2010). Cancer cells are like this, similar, but with genetic mutations. Some studies suggest that fetal cells passed from baby to mother may stimulate the mother's immune system to stop the growth of tumors. For example, it is known that there are more cells from the fetus in the blood of healthy women than in women who have had breast cancer.

According to Gammill et al., 2013, research has shown that fetal cells contribute to healing internal wounds and injuries, and also participate in the reduction of symptoms of disorders such as pain in osteoarthritis, in the improvement of the immune system, facilitate the development of future pregnancies, reduce the probability of cancer and tend to participate in tissue regeneration, observing its implication in the recovery of heart or liver diseases, and they are even stored in the bone marrow forming part of the natural reserve of cells that all human beings have (Ferretti et al., 2018). As they are cells younger than those of the mother, they have a great capacity to regenerate the woman's body, as in the case of male fetus cells converted into cardiomyocytes that have participated in the repair of the heart of the mother with heart disease; this is because they are pluripotential, PACP cells (cell parents associated with pregnancy). Due to their fetal origin, PACPs have a great capacity for self-renewal and collaborate with adult stem cells in the regenerative function of the female body.

However, microchimerism can also affect it negatively. It has been observed that the immune system of some women react to these cells as if they were invasive, linked to the emergence of some autoimmune diseases. These are more common in the mother than in the fetus (Fjeldstad, Johnsen, & Staff, 2019). They could also be linked to some types of cancer, although their existence is a protective factor against this type of disease. Conversely, fetal cells could disrupt the mother's immune system, creating persistent inflammation, and long-term autoimmune diseases. According to Boddy et al. (2015), this immune disorder could explain why women suffer more from rheumatoid arthritis or lupus.

The degree of positive and negative consequences appears to be related to the maternal immune system's ability to counteract invasion by fetal cells. Once the pregnancy ends, the mother begins to remove the fetal cells in a process that differs from woman to woman (Asnicar et al., 2017). Fetal cells can respond to this elimination process by increasing their proliferation or destroying the maternal immune system. The exact mechanism is unknown, but the result, in any case, is the survival of some fetal cells in maternal tissues. If these cells are integrated into the tissue, the consequences can be positive, as in the case of the most effective post-injury regeneration (Gadi & Nelson, 2007). However, if fetal cells are continuously recognized as foreign agents, they favor sustained inflammation. Fetal cells are similar to maternal cells in at least half of their genetic makeup (the other half is paternal), so the mother's immune system will mount an inflammatory response against cells similar to their own (Fjeldstad et al., 2019). In the worst case, the response will spread to cells that belong to the mother and will lead to autoimmune disease.

Conclusion

This relationship of mother and baby cells is not lost after childbirth, research has found the presence of fetal cells in the mother's body after decades of giving birth. These cells are expanded by mother-baby organisms and can be found in the heart, liver, and brain among others, interacting with the cells of both, (from 2 to 6 cells per milliliter in the blood according to research) (Gammill et al., 2013). These cells from the other organism even integrate tissues, structures, and the nervous system. Scientific experts have described the effects of these cells, one of them being the filial maternal affection, so the fact that part of the DNA itself is in the other makes this bond between mother and baby strong throughout life. Even cases of Microchimerism have been described in women who have aborted (natural or provoked) showing that fetal microchimerism demonstrates that the mother-child bond goes far beyond bonding.

References

Asnicar, F., Manara, S., Zolfo, M., Truong, D. T., Scholz, M., Armanini, F., & Segata, N. (2017). Studying vertical microbiome transmission from mothers to infants by strain-level metagenomic profiling. M-Systems, 2(1), e00164-16. https://doi.org/10.1128/mSystems.00164-16

Boddy, A. M., Fortunato, A., Wilson Sayres, M., & Aktipis, A. (2015). Fetal microchimerism and maternal health: a review and evolutionary analysis of cooperation and conflict beyond the womb. BioEssays, 37(10), 1106-1118. https://doi.org/10.1002/bies.201500059

Ferretti, P., Pasolli, E., Tett, A., Asnicar, F., Gorfer, V., Fedi, S., & Beghini, F. (2018). Mother-to-infant microbial transmission from different body sites shapes the developing infant gut microbiome. Cell host & microbe, 24(1), 133-145. https://doi.org/10.1016/j.chom.2018.06.005

Fjeldstad, H. E., Johnsen, G. M., & Staff, A. C. (2019). Fetal microchimerism and implications for maternal health. Obstetric Medicine, 1753495X19884484. https://doi.org/10.1177%2F1753495X19884484

Fjeldstad, H. E., Staff, A. C., Chae, A., Redman, C., Gammill, H. S., & Johnsen, G. M. (2018). 313. Fetal microchimerism in pregnancy and placental dysfunction. Pregnancy Hypertension, 13, S122. https://doi.org/10.1016/j.preghy.2018.08.362

Gadi, V. K., & Nelson, J. L. (2007). Fetal microchimerism in women with breast cancer. Cancer Research, 67(19), 9035-9038. https://cancerres.aacrjournals.org/content/67/19/9035.full-text.pdf

Gammill, H. S., Aydelotte, T. M., Guthrie, K. A., Nkwopara, E. C., & Nelson, J. L. (2013). Cellular fetal microchimerism in preeclampsia. Hypertension, 62...