Human embryonic stem cell research reveals the earliest phase of human development mystery

Researchers from the Johns Hopskin Research Institute have recently discovered the molecular key of one of the earliest stages of human development using embryonic stem cells. Their discovery of the signal produced by the BMP-4 protein causes stem cells to transform into what later becomes placenta, which will be published in the April issue of Cell Stem Cell.

According to scientists, their findings also underscore an aspect in the field of human cell biology that has not been repeated in other animal model systems. It is almost impossible to use anything other than human embryonic stem cells to gather information for this study.

The study's investigator said, an interesting reason is that the system could provide a model of research to understand the early stage of human development, including embryonic formation from fetal embryos. the beginning.

Dr. Linzhao Cheng, an assistant professor of gynecology and obstetrics and co-director of stem cell research at the Johns Hopkins Cellular Technology Institute, said: 'This discovery comes at random and is an additional source. Important to our understanding of the early stage of human development. This is the stem cell biology limit, which is the difference between mice and humans. We will never be able to discover if we narrow down our studies by using only mouse stem cells. Adult stem cells do not work in this study. '

Scientists have developed a new model of research to understand the early stages of human development, including the formation of the placenta from early embryos.(Photo: iStockphoto)

The team was discovered when trying to understand a rare human blood disorder caused by a mutation in a gene called PIG-A. According to Cheng, the appropriate model to study the disease does not exist because the lab mice without this gene died before birth, or did not have human-like symptoms.

Therefore, by using conventional genetic engineering tools, researchers have been trying for years to eliminate PIG-A in adult stem cells without success. They then switched to separating PIG-A in human embryonic stem cells.

"Only with human embryonic stem cells can we develop rare cells that are manipulated to remove PIG-A," Cheng said . The result is the formation of two human embryonic stem cell lines without PIG-A, so these two cell lines do not contain glycosylphosphatidylinositol (GPI) anchor proteins on the cell surface. GPI anchor protein binds to many other proteins involved in communication between the internal and external cells. Without certain types of GPI proteins, it is possible that the cell will not function properly.

The researchers then took another step to verify their manipulated embryonic stem cells act like normal stem cells.'We just want to make sure that separated PIG-A cells can still divide and specialize'.

One of the earliest stages of embryonic stem cell division during normal embryonic development is the development of embryonic leaf. It is a layer of granular cells that then form the placenta. According to Cheng, embryo-leaf formation occurs when embryonic stem cells come into contact with BMP-4 protein either in the natural environment or in the laboratory.

Contrary to expectations, however, when scientists exposed exposed PIG-A cells to BMP-4, they did not form embryos.

Only when they put the PIG-A gene back into the cell did the BMP-4 complete its work, turning the cells into leaf-forming cells. Since then researchers have been able to conclude that embryo-leaf formation depends on certain surface proteins that receive signals from BMP-4.

Other authors of the study include Guibin Chen, Zhaohui Ye, Xiaobing Yu, Jizhong Zou, Prashant Mali, Robert Brodsky and Cheng (Johns Hopkins Institute).