Researchers have very limited opportunities to study the earliest stages of human development, but a groundbreaking discovery led by a team in Australia will now provide them with a valuable new model to investigate the science behind matters like infertility and congenital disease. Using skin cells as the starting point, the researchers have produced the first complete model of an early human embryo, which they say opens up new possibilities for research into IVF treatments and the many factors that can impact the important early stages of human life.
The research was led by scientists at Australia's Monash University and centers on what are known as human blastocysts. These are structures formed in the initial days after fertilization as the cells divide and gather into a 3D structure made up of an inner cluster and a protective outer layer.
But investigating this early and critical stage of embryonic development has proven challenging, with the availability of human embryos limited and also clouded by ethical and legal concerns. So, the authors of the new study had been investigating how artificial versions engineered in a lab can provide a model for study that sidesteps these issues, through what's known as nuclear reprogramming.
This technique involves inducing changes in the gene expression of one cell type so that it exhibits the behavior of another, by introducing it to a new environment and growth factors. In this case, the researchers took human skin cells and placed them into a jelly-like scaffold, reprogramming them into the building blocks of a blastocyst, which then organized into the desired structure.
The team's artificial blastocysts, which they've dubbed iBlastoids, aren't identical to natural ones. They are missing an outer membrane known as the zone pellucida, and they have trouble developing beyond the first few days. This is important as it keeps the team's research well within international guidelines that dictate human blastocysts can't be cultured beyond day 14, when a transient structure called the primitive streak develops. This is known as the "primitive streak rule."
But the iBlastoids still carry enough structural similarities to constitute a complete model of a human embryo. They feature an inner mass of cells, an outer layer of cells and an interior cavity, mirroring the overall genetics and architecture of their natural counterparts.
“iBlastoids will allow scientists to study the very early steps in human development and some of the causes of infertility, congenital diseases and the impact of toxins and viruses on early embryos – without the use of human blastocysts and, importantly, at an unprecedented scale, accelerating our understanding and the development of new therapies,” says Monash University's Professor Jose Polo.
You can hear more about iBlastoids from Polo in the video below, while the research was published in the journal Nature.
Source: Monash University