Researchers Created Structures That Produced Blood Cells in the Lab—With a Process That Mimics Real Human Embryos

The advance could carry significant implications for studying blood diseases and early human development

Margherita Bassi – Daily Correspondent

Stem cells are precursors of a variety of different cells: They can turn into anything from blood to bone to muscle. Human blood stem cells, known as hematopoietic stem cells, are the forerunners of various types of blood cells, including red and white blood cells.

Now, researchers have mimicked how human embryos create these blood cells in the first few weeks after fertilization. While there are other ways to lab-produce human blood stem cells, this approach recreates the natural developmental process.

The results, detailed in a study published October 13 in the journal Cell Reports, could carry significant implications for studying diseases like leukemia and the medical use of stem cells.

The team used human stem cells to create embryo-like structures dubbed “hematoids” that mirror some features of early human development, when organs and the blood system start to take shape. Like in real human embryos, blood stem cell production in the hematoids starts around week two of development.

By the second day of the trial, the hematoids had organized themselves into ectoderm, mesoderm and endoderm—three layers that make up the foundation of the human body’s future development. By the 8th day, the researchers identified beating heart cells, and by the 13th, they saw blood in the hematoids. The team also revealed that blood stem cells in hematoids can turn into different blood cells, including specific immune cells.

Did you know? You’re teeming with “red gold”

How valuable is blood? Consider everything it does in the human body, from delivering immune cells to help the body fight off intruders to circulating nutrients, oxygen and more throughout your system. As a result, it’s one of the most precious substances on Earth—often called “red gold” due to its enduring value.

“It was an exciting moment when the blood red color appeared in the dish—it was visible even to the naked eye,” Jitesh Neupane, a co-first author of the study and a stem cell and developmental biologist at the University of Cambridge Gurdon Institute in England, says in a statement.

The hematoid’s blood cells developed to a point that more or less corresponded to a human embryo in its fourth or fifth week—a mysterious stage scientists cannot observe directly in an actual pregnancy because the embryo is implanted in the uterine wall.

The growth of the hematoids could shed light on blood formation during early human development, per the statement, and might one day help researchers simulate blood disorders or create enduring blood stem cells for transplants.

“Stem cell-derived embryo models are crucial for investigations to advance our knowledge of early human development,” the researchers write in the paper.

In a 2019 interview with the California Institute of Technology, Magdalena Zernicka-Goetz, a developmental biologist who was not involved with the study, explained that understanding the earliest stages of development is important, because any issues in this phase influence every function of that future human. “This is the time when the foundation for every single tissue in our bodies is set up,” she said. “So we want to understand how this foundation is built.”

Though the new models contain human cells, they are starkly different from real human embryos. The cells cannot grow into embryos, either—they were designed without a variety of embryonic tissues and don’t have the supporting yolk sac or placenta they’d need to survive longer-term. “This is a minimalistic system,” Neupane tells the Guardian’s Hannah Devlin.

Nonetheless, since hematoids are derived from stem cells that can be created from any human cell, the recent paper carries significant implications for future medicine. “Although it is still in the early stages, the ability to produce human blood cells in the lab marks a significant step toward future regenerative therapies—which use a patient’s own cells to repair and regenerate damaged tissues,” says Azim Surani, director of germline and epigenetics research at the University of Cambridge Gurdon Institute and the study’s senior author, in the statement.

Today’s lab-based embryonic models could lay the foundation for tomorrow’s futuristic—and effective—regenerative medicine.

Margherita Bassi

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