Previously, the only way to study the early days of human embryo development was to use blastocysts. The so-called clusters of cells that are formed at the earliest stages of embryogenesis, within a few days after fertilization of the egg. These studies were greatly complicated by the inaccessibility of blastocysts, which fell into the hands of scientists from people who donated their surplus embryos obtained as a result of the IVF procedure. In addition to the paucity of material, the use of human blastocysts has raised ethical objections. By law, researchers can only study human embryos until they are 14 days old.
A group of scientists from different countries, led by researchers from Monash University (Melbourne), made an important discovery that will help circumvent all these problems. The researchers succeeded in reprogramming skin cells into a three-dimensional cellular structure that is morphologically and molecularly similar to human blastocysts. Such structures, called i-blastoids, can be used as analogs of early human embryos in the study of their development, phys.org reports.
It was possible to create i-blastoids using the method of the so-called nuclear reprogramming. Human skin cells were placed in a three-dimensional scaffold filled with the chemicals needed to form blastocysts - the extracellular matrix. After six to eight days of cultivation, the skin cells changed their identity and organized themselves into i-blastoids - a kind of blastocysts. Some of them were attached to the machines of laboratory plastic cups, simulating the process of implantation into the uterus.
According to experts, i-blastoids will allow studying the earliest stages of human development, as well as understanding the causes of infertility, congenital diseases and the effect on embryos of toxins and viruses. Now it will be possible to do all this without the use of human blastocysts and on a much larger scale.
The work was published in the journal Nature.