Scientists have grown embryo-like structures in the laboratory that produce human blood cells, opening up new possibilities for regenerative medicine.
The ability to generate blood stem cells in the laboratory could one day make it possible to treat patients in need of bone marrow transplants using their own cells.
The achievement is the latest in a fast-growing field in which embryo models are created from stem cells without the need for eggs or sperm, opening a window into the earliest stages of human development.
“It was an exciting moment when the blood red color appeared in the dish – it was visible even to the naked eye,” said Dr Jitesh Neupane, a researcher at the Gurdon Institute at the University of Cambridge and first author of the study.
He and his colleagues are using the model system to understand the earliest stages of heart and blood development.
“This sheds light on how blood cells naturally form during human embryogenesis, offering potential medical advances for drug screening, studying early blood and immune development, and modeling blood diseases such as leukemia,” Neupane said.
Human stem cells, used to grow embryo-like structures, can be created from any cell in the body. This means that this approach could also pave the way to producing blood that is completely compatible with the patient's own body.
While there are other methods for creating human blood stem cells in the laboratory, they require a cocktail of additional proteins, whereas the new method mimics the natural developmental process in which self-organizing structures lead to the formation of different cell types.
“Although the ability to produce human blood cells in the laboratory is still in its early stages, this is a significant step towards future regenerative therapies that use the patient's own cells to repair and regenerate damaged tissue,” said Professor Azim Surani from the Gurdon Institute, senior author of the paper.
In this latest study, scientists used human stem cells to replicate some of the cells and structures that typically appear in the third and fourth weeks of pregnancy. The model was specifically designed to lack the tissue that forms the placenta and yolk sac of a natural embryo, meaning it had no theoretical potential for fetal development and did not develop tissue that would later form the brain.
“It’s a minimalist system,” Neupane said.
The team observed the emergence of three-dimensional embryo-like structures under a microscope. By the second day, they self-organized into three germ layers – ectoderm, mesoderm and endoderm – the basic structure of the human body. By the eighth day, beating heart cells have formed, the cells that eventually give rise to the heart of the developing human embryo.
By day 13, the team noticed red blood spots appearing. Blood stem cells from the model were also shown to be able to differentiate into various types of blood cells, including oxygen-carrying red blood cells and white blood cells, which are critical to the immune system.
The results were published in the journal Cell reports.
