Scientists at the University of Cambridge in the UK have constructed "blood like cells" using human stem cells, which can simulate multiple key stages of early human development, including the generation of blood stem cells, in a three-dimensional embryonic like structure. This "blood like cell" structure has self-organizing ability and begins to produce blood after about two weeks of development, successfully simulating the blood development process of human fetuses in the laboratory. The research results were published in the latest issue of Cell Reports. The new human embryo like model reproduces the initial stages of organ and blood system formation. Under the microscope, it was observed that these structures had already self organized into the ectoderm, mesoderm, and endoderm on the second day of cultivation, which are the three fundamental germ layers for the development of all tissues and organs in the human body. On the 8th day, beating heart cells appeared in the model, which will eventually develop into hearts in real embryos. On the 13th day, the team observed obvious red blood spots, further confirming the generation of functional blood cells. They also verified that these hematopoietic stem cells can differentiate into multiple types of blood cells, including key immune cells. Due to the fact that human embryos are implanted into the mother's uterus between weeks 4 and 5, the developmental process during this stage cannot be directly observed in real embryos. Therefore, embryonic models derived from stem cells have become an important means of studying this "black box" period. All studies conducted this time strictly adhere to international ethical standards, have been approved by the ethics committee, and have passed peer review. The team expressed that it was very exciting when the visible blood red color first appeared in the culture dish. This new model accurately reproduces the initiation process of the hematopoietic system in human embryos, revealing the mechanism of natural formation of blood cells during embryonic growth, providing a powerful tool for drug screening, early blood and immune system development research, and modeling of blood diseases. Although still in its early stages, the ability to produce human blood cells in the laboratory marks a crucial step in regenerative medicine, which utilizes patients' own cells to repair or regenerate damaged tissue. This means that in the future, it will be possible to create blood cells that are perfectly matched with the patient's genes, thereby avoiding immune rejection reactions and demonstrating great potential in personalized medicine. At the same time, blood like cells have captured the "second wave" of hematopoietic events during human development. Due to the ability to produce adaptive lymphocytes, including T cells, during this stage, it has opened up new avenues for studying blood development in both healthy and cancerous states. Researchers have used human stem cells to construct a three-dimensional structure called "blood like cells" in a culture dish. This structure can realistically simulate the key process of early human embryonic blood system formation. It has opened an unprecedented window for us to directly observe and understand how the blood system in the early stages of life "emerged from nothing". It is crucial for studying the causes of certain congenital diseases or early pregnancy failures. One day in the future, perhaps we can use this technology to provide tailored and perfectly matched blood cells or hematopoietic stem cells for patients with leukemia and other blood diseases, thus saving more lives. (New Society)