Humanised mice herald new era in drug testing and disease research

Scientists have successfully created mice with an immune system typical of humans for the first time. These so-called "humanised" animals open new possibilities for drug testing and research on diseases that affect humans.

A team of researchers from the University of Texas Health Science Center in San Antonio describes the groundbreaking achievement in animal medical research. Scientists have created mice with a human immune system and a gut microbiome characteristic of humans.

Mice have long served as a model in biomedical research. These small rodents are easy to breed and share many traits with humans, including aspects of the immune system. However, many genes associated with the immune system differ significantly from humans, making research challenging.

As early as the 1980s, scientists first attempted to modify mice so that their immune system would resemble that of humans. These modified rodents were then used to study the virus that causes AIDS.

Since then, similar animals have been bred, introducing human immune and stem cells into their organisms. However, until now, it has not been possible to replicate the human immune system in mice completely. Additionally, genetically modified mice usually had shorter lifespans.

The latest mice were bred using procedures involving human cells taken from umbilical cord blood and hormonal therapy using a potent form of oestrogen. This hormone supports the survival of stem cells and the creation of lymphocytes and antibodies.

Mice named TruHuX (truly human, THX) have a fully functional human immune system, including lymph nodes, thymus, various types of lymphocytes, and other immune cells. The antibodies they produce are also identical to those in humans.

Breeding THX mice paves the way for a new type of experiment on the development of various human diseases, immunotherapies (including cancer), and vaccines. It may also eliminate the need for testing on primates.

"Thanks to the unique use of oestrogen activity to support the differentiation of human stem cells, human immune cells, and the formation of antibodies, THX mice provide a platform for research on the human immune system, the development of human vaccines, and the testing of new therapies," said Prof. Paolo Casali, the author of the accomplishment.

His team is already using THX mice for research on SARS-CoV-2 and various mechanisms operating in the human immune system.