Scientists develop new method of growing human embryos

For the first time ever, scientists have been able to grow human embryos outside of a womb almost two weeks into their development. With this breakthrough, humanity has been given new insight into what some consider the most mysterious phase of early human life.

Researchers in two international teams devised a method that allowed embryos to survive outside the womb or “in vitro” 13 days after fertilization. Through this method, scientists were able to observe human embryos beyond the stage they would normally be implanted within a womb.

“This is the most enigmatic and mysterious stage of human development,” said Magdalena Zernicka-Goetz, a U.K. researcher and University of Cambridge professor who helped co-lead the subsequent studies. “It is a time when the basic body shape is determined.”

After an egg is fertilized by sperm, it divides and forms a free-floating ball of stem cells. Soon after, these stem cells cluster together within the embryo and form a stage called the blastocyst. These blastocyst cells will develop into the fetus’ future body, or epiblast, as well as the placenta that will attach the embryo to the womb, making it imperative that the embryo be implanted within a womb before a blastocyst would typically attach itself to a uterus so that the fetus may grow properly. For this reason, though international law allows the study of human embryos to continue up to 14 days in development outside the womb, researchers have previously only conducted human embryos studies up to seven days outside of the womb.

Prior to this research, only embryos in the pre-implantation stage had been extensively studied. The failure of an embryo to attach itself to the uterus is a major of cause of early pregnancy loss, yet many of the cellular changes an embryo undergoes after the blastocyst stage are unknown. However, research on an embryo is difficult to conduct when already implanted within a human womb, leading to a great amount of uncertainty surrounding the stages that an embryo goes through after the seven-day period that scientists have studied human embryos through previously.

Following the typical timeframe in which an embryo would attach itself to the uterus, it was revealed through the new research that the cell types that comprise a blastocyst will reorganize into a new kind of configuration.

“The stem cells in the epiblast that will form the future body have the remarkable ability to self-organize themselves and create a cavity that represent the basic structure of the early post-implantation human embryo,” said Zernicka-Goetz. “Without this cavity, it would be impossible for the embryo to develop further as it is the basis for its future development.”

Prior to this discovery, the cavity was thought to generate from a process called apoptosis, or regulated cell death within human embryos.

With the development of this new embryotic research technique, scientists were able to demonstrate how the reorganization of the embryo’s cells that typically takes place post-implantation can be achieved in a laboratory setting when fostered under the correct conditions.

“Embryo development is an extremely complex process and while our system may not be able to fully reproduce every aspect of this process, it has allowed us to reveal a remarkable self-organizing capacity ... that was previously unknown,” said Marta Shahbazi, a researcher involved in the study.

Zernicka-Goetz spoke on the merits of the new embryotic study technique.

“Until now, it has been impossible to study this in human embryos. This new technique provides us with a unique opportunity to get a deeper understanding of our own development during these crucial stages and help us understand what happens, for example, during miscarriage.”

The development of this new technique and the research that follows it leave repercussions not only for the scientific community, but for humanity as well. Fertility treatments, while popular among couples who are unable to conceive, prove a costly endeavor with an uncertain chance of success. In vitro fertilization, or the process in which mature eggs are collected from a human’s ovaries, fertilized in a lab, and then inserted back into the uterus, is one example of a fertility treatment that could benefit from the new findings on embryotic development. Greater knowledge on an embryo’s process of implantation within the womb could help to increase the success rate of these fertility treatments.

The studies also raise the question of how much further scientists can research human embryotic development, with the current international law imposing a 14-day limit on scientists developing embryos. With these new advances, the limit may need revision.