The human body undergoes through a big step in development after several weeks from the conception that is the growth of a tail and head from a symmetric ball of cells(starts from a step called gastrulation). But it has been a source of great mystery how the body cells figure it out.
Researchers have obtained a better idea of the biochemistry as to how this process actually occurs in the human body. They were able to do this by arranging a collection of stem cells that acted very similar to a real human embryo. The study has been published in Nature Cell Biology.
The diverse group of researchers from Rockefeller University used a combination of physics and biology backgrounds for developing a model of a 10-day old embryo from sphere to a less symmetrical entity. Due to the restrictions of studying the human embryo that is older than 14 days, the research work of the earliest stages of human development faces ethical and practical restrictions.
For demonstrating the exact sequence of early changes that are needed to transform tissues to a human body, scientists can use the same type of nondescript stem cells which form an embryo and arrange them for showing a major step in development. These models resemble the embryonic organoids, the synthetic structures which mimic some of the most important characteristics of the biological counterparts. These embryoids have been used for studying cellular development of the embryo for several years, hence they are are not a new type of equipment.
However, using synthetic approximations it is very difficult to obtain the exact structure for representing a specific developmental stage. Mijo Simunovic, a biochemist and physicist said that several techniques from physics, bioengineering and developmental biology were used for creating the model. Researchers now possess a 3D system that not only resembles the genetic fingerprint of the embryo but also the shape and size.
Several studies on mice embryoids have shown how a line is drawn on a ball of dividing cells which shows which part will develop into a head and which part to a tail. This is known as symmetry breaking.
Symmetry breaking also known as gastrulation is a very significant stage as our heads do not resemble our legs in any way. The embryo divides into two parts, anterior and posterior. Researchers found evidence of it in human embryonic stem cells. For understanding the biochemistry behind the gastrulation, the group tested a growth factor which was found in mice and human embryos, known as bone morphogenetic protein 4. After adding of BMP4, one part of the 3D culture developed to posterior and the other to anterior. This also helps in understanding when an embryo develops and when it fails.
Researchers are not worried about the ethical implications as they are sure that their embryoids would never grow to human beings if allowed.