A groundbreaking achievement in biomedical research has seen scientists successfully breed mice with fully developed human immune systems. This milestone could revolutionize drug development and vaccine testing, as these ‘humanized’ mice provide a more accurate model for studying human immune responses.
The researchers, whose findings were published in the journal *Nature*, have created mice that, unlike previous attempts, exhibit a truly human immune response. When confronted with infection, these mice produce immune cells that mirror the structure and diversity of those found in humans. They also accurately replicate human reactions to certain conditions, such as lupus, a chronic autoimmune disease.
Previous efforts to create humanized mice have resulted in approximations of the human immune system, lacking key features. The team behind this new breakthrough tackled this challenge by first breeding mice with weakened immune systems. These mice were then injected with human stem cells extracted from umbilical cord blood, capable of developing into any type of immune cell.
These stem cells were injected into the mice’s hearts, which then pumped them into the bone marrow, the primary site of immune cell production. The mice’s weakened immune systems allowed the human stem cells to easily establish themselves in the bone marrow.
To further enhance the humanization process, the researchers introduced a human version of the sex hormone estrogen into the mice. Estrogen plays a vital role in shaping immature stem cells into mature immune cells, including T cells, natural killer cells, and B cells, which produce antibodies to combat pathogens.
The success of this approach is evident in the mice’s response to various stimuli. When injected with the Pfizer-BioNTech COVID-19 vaccine, the mice produced human antibodies against the coronavirus. Similarly, they produced antibodies against the typhoid fever bacterium when exposed to its proteins.
These findings highlight the potential of these humanized mice as a valuable tool for biomedical research. They can be utilized for vaccine development, especially in the early stages where human trials are ethically impossible.
Additionally, these mice can facilitate the development of new therapies that target the immune system, such as immunotherapies for cancer. By using mice with a fully human immune system, researchers can potentially eliminate the need for non-human primate models, a significant advancement in ethical research practices.
This groundbreaking research marks a significant leap forward in our understanding of the human immune system and its potential for developing new treatments and therapies.
