Groundbreaking lab-grown embryo models reveal early blood formation
Researchers at the University of Cambridge have created three-dimensional, embryo-like structures from human stem cells that replicate crucial early steps of human development. Named hematoids, these self-organising models begin producing blood stem cells within about two weeks in the lab, offering a window into how the human blood and immune systems first emerge.
What are hematoids and how do they differ from real embryos?
Hematoids are designed to model specific developmental processes without becoming a full human embryo. They lack essential embryonic tissues, as well as the yolk sac and placenta needed for continued growth, so they cannot develop into a human fetus. Nonetheless, the structures recapitulate the self-organising nature of early development and shed light on how blood stem cells form and differentiate in the earliest weeks of life.
How hematoids form and what they reveal about blood development
Under close observation, the researchers watched hematoids progress through three germ layers—ectoderm, mesoderm, and endoderm—by day two, mirroring the foundational steps that pave the way for all organs and tissues. By day eight, beating heart cells appeared in the structures, illustrating how cardiac tissue begins to form in parallel with blood development. By day thirteen, red areas emerged, and the team demonstrated that hematoid-derived hematopoietic stem cells can differentiate into a range of blood cell types, including immune cells such as T cells.
Why this matters for science and medicine
The ability to produce human blood stem cells in a lab environment using a self-organising embryo-like model marks a significant advance. This approach mirrors natural development more closely than some previous methods that rely on a cocktail of growth factors. By better understanding how hematopoietic stem cells form and mature, scientists can model early blood disorders, screen potential drugs, and explore how the immune system develops in the fetal period. Importantly, the research hints at future personalized medicine possibilities, since stem cells can be derived from any patient, enabling the creation of blood compatible with an individual’s body for transplants and therapies.
Implications for disease modeling and regenerative therapies
Hematoids provide a platform to model conditions like leukemia during the earliest stages of blood development, potentially accelerating the discovery of therapies tailored to the unique biology of a patient. Because the model captures stages comparable to weeks four to five of human embryonic development, it allows scientists to study critical transitions in hematopoiesis and immune cell formation that are otherwise inaccessible in real embryos.
Ethics, oversight, and the road ahead
All work with embryo-like models is governed by stringent regulatory and ethical review processes. The Cambridge team obtained the necessary approvals, and the study underwent peer review before publication in Cell Reports. The researchers also secured patent protection through Cambridge Enterprise, aligning scientific discovery with pathways for translation into real-world applications.
Voices from the research team
Dr. Jitesh Neupane described the moment when blood formation became visible in the dish, underscoring the tangible nature of the breakthrough. Professor Azim Surani highlighted the potential of this model to transform regenerative medicine, stressing its foundational role in future therapies that could leverage a patient’s own cells for repair and regeneration. Co-first author Dr. Geraldine Jowett emphasized how hematoids illuminate the second wave of blood development, including immune cell lineages like T cells, opening doors to new disease models and treatment strategies.
Conclusion
Hematoids represent a powerful, ethically governed, and scientifically rich method to study very early human development. By capturing the self-organising dynamics that give rise to blood and heart tissues, these embryo-like models illuminate fundamental biology, enhance our understanding of blood disorders, and pave the way for personalized regenerative therapies in the future.
