Trophoblast Stem Cells - An Overview

(Lay)

The trophoblast stem cells (TSC) are a special type of stem cell. However, unlike most stem cells, these cells do not form new cells of the body. They are only found during the development of the baby inside the mother's womb during pregnancy. Instead of forming into the different cell types that make up a healthy baby, they mature into the cells that make it possible for a baby to develop in the womb (see Figure).

There are two very important roles that TSCs play during the development of the baby. First, in order for the baby to develop, it must be positioned correctly inside the mother's womb. After the egg and sperm meet, the egg must attach itself to the inside walls of the mother's womb. TSCs are found on the outer surface of the developing egg and develop cells that are responsible for this attachment. Once the egg is attached to the mother's womb, it can receive nourishment from the mother so that it can grow into a baby. At this time, TSCs mature into cells that form the placenta, which is the organ that provides nourishment to the developing baby. Without the cells produced by TSCs, the developing baby cannot make the important connection inside the womb with the mother, cannot receive the necessary nourishment, and cannot grow.

It is important to distinguish TSCs from embryonic stem cells (ESC), which are the types of stem cells that can develop into any type of cell in the body. They are derived from the inside of the embryo, which is the term for the developing baby inside the womb. TSCs are the cells found on the outside surface of that embryo, and do not form into any of the body's cells. They are only involved in the development and nourishment of the baby during pregnancy.

TSCs are also important for research. There are controversies, which is prominent in the news on the use of ESCs. Some believe that the use of ESCs is illegal and/or unethical. The main problem is that destroying the ESC could prevent the development of a person. One possible is to use TSCs, without destroying the embryo. However, research needs to be done to determine how one can harvest the TSCs without destroying the blastocyts. A bonus of working with TSCs is to gain insights in birth defects and also, infertility. TSCs could help to partly alleviate the ethical concerns surrounding ESCs.

Acknowledgements

This review was prepared by the following graduate students in the Stem Cell Biology Class, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey:

Roger Diaz, Thomas Finocchio, Shannon Henning, Gaurav Gandhi, Nicole Pannucci (in alphabetical order).

Teaching Assistant: Elaine Wong

The review was edited by two stem cell biologists.