Summary
Stem Cell research has undergone another leap forward in discovering ways to help control developmental disorders that can occur in pregnancies.
In another great milestone of discovery and understanding in stem cell research, scientists have grown trophoblasts (TS cells) from a human placenta for the first time, but what does that mean.
Firstly, what are trophoblasts and what is their function;
Trophoblasts are the specialized cells of the placenta, they play a major role in implantation and formation of the maternal-fetal interface. This is where the immune system allows for successful coexistence between the mother and the growing cells and this serves two purposes, to continue to provide host defense against infection, and to interact with fetal tissues to promote successful formation of the placenta and pregnancy. These cells form the outer layer of the blastocyst eventually develop into an embryo and into a fetus. TS cells become the placenta, providing nutrients to the fetus and taking away waste.
Too few or too many TS cells can mean disaster for the foetus and mother. An imbalance of TS cells may lead to complications such as preeclampsia and miscarriage amongst other conditions later on. That is why it is important to study human TS cell development and function, wrote Arima.
"In our paper, our goal was to establish human trophoblast stem cells [as a tool for future study]."
Human placentas were obtained from healthy women with the consent of the donors, and also by the approval of the Ethics Committee of Tohoku University School of Medicine.
The TS cells were placed in an environment which is conducive to the proliferation of the TS cells in which an attempt to replicate the environment in utero, but after 5 days these cells died. The research team then discovered that using genetic sequencing that the cells needed certain proteins activated and others suppressed to stay alive and maintain the same environment they would have in utero.
The experimental design used two biological replicates which were performed for each experiment. Also no data or samples were excluded from any of the experiments. This has provided us with quantifiable and statistical results.
The invasion of a differentiated TB cell, the extravilliostrophoblast (EVT) into the maternal uterus is a vital stage of establishment of pregnancy. The failure of the invasion stage by insufficient implantation in the uterus can cause problems like pre-eclampsia.
According to the Clinical Obstetrics and Gynecology, Nebraska,
“Pre-eclampsia remains a significant cause of maternal and perinatal death and complications. Once the diagnosis of pre-eclampsia has been made, treatment options are limited. For this reason, much attention has recently been focused on pre-eclampsia prevention.”
If the invasion is too deep then the complications may cause the placenta accreta, placenta increta, or placenta percreta depending on the severity and deepness of the placenta attachment. Approximately 1 in 2,500 pregnancies experience placenta accreta, increta or percreta. This causes concerns for the fetus as it can cause premature delivery which also holds it’s own complications. Bleeding during the third trimester may be a warning sign that placenta accreta exists, and when placenta accreta occurs it commonly results in a premature delivery. The causal factor in this is that the placenta has difficulty separating from the uterine wall. The primary concern for the mother is haemorrhaging during manual attempts to detach the placenta. Severe heamorrhaging can be life threatening. There is also the chance of damage occurring to the uterus or other organs (percreta) during removal of the placenta. The usual medical intervention here inevitably is a hysterectomy involving the removal of the uterus thus rendering the mother unable to conceive.
The conclusion of this is the understanding that there is a need to concentrate future studies on the sub populations and specific markers therein as they are important in identifying the source of the TS cells. Human TS cell having now been established will provide a powerful tool for molecular and functional ways of investigating the human diseases and developmental disorders that exist.
References;
Okae H et al. Derivation of Human Trophoblast Stem Cells. Cell Stem Cell, 2018; 22 (1): 50 DOI: 10.1016/j.stem.2017.11.004
Abrahams, V.M. (2017) Immunology of the maternal-fetal interface. [Internet] Available from: https://www.uptodate.com/contents/immunology-of-the-maternal-fetal-interface [Accessed 26 January 2017].
William”s Obstetrics Twenty-Second Ed. Cunningham, F. Gary, et al, Ch. 35. Danforth’s Obstetrics and Gynecology Ninth Ed. Scott, James R., et al, Ch. 20.
