Animal models have long since been an important instrument in biomedical research. They are used on the one hand in basic research, and on the other for testing new therapeutic agents, thus proving to be essential from an ethical point of view. Nevertheless, it is quite common that the findings resulting from these models are not able to be applied in the human context. For instance, even if a drug has not caused side effects during animal testing, severe side effects may still occur in the case of humans during the clinical testing period. In less serious cases, there is merely a difference between the pathological mechanism that causes a disease in the animal model and the actual human pathological mechanism. In an effort to avoid these inadequacies, the concept of the humanized mouse was developed in the 1980s. This model is based on the idea of recreating a human immune system in a useful format in the laboratory.
The NOD-scid Il2r-gamma-0 mouse strain produces excellent insights into the growth of a human stem cell transplant. These animals are highly immune deficient. The mice are therefore less able to respond to the human stem cells, rendering a rejection of the transplant unlikely. Furthermore, a functional human immune system develops in the mouse from the stem cells which are usually extracted from umbilical cord blood.
In order to determine whether the existing human cells are indeed functional, several parameters are tested. Different, activated immune cells have been found during testing. Moreover, human cytokines and antibodies can be detected. The humanized mouse thus opens up a broad range of research areas. On the one hand, it can be regarded as a contribution to the research of malign tumor diseases and HIV or Dengue virus infections. On the other hand, it can be vital for gaining a new understanding of the symptoms of sepsis. Despite the fact that establishing a new model is an extensive procedure that is dependent upon a number of variables, it offers an excellent opportunity to gain a more comprehensive understanding of human disease mechanisms and will shed light on several topic areas due to its flexible use.