One method of observing how cells grow in a living animal over time is to remove the animal's organs at multiple time points, stain the specimens, and observe them under a microscope or similar instrument. However, this method requires many experimental resources, including animals.
A research group led by Professor Hideki Katagiri of the Tohoku University School of Medicine has succeeded in developing mice from which live proliferating cells can be observed by simply drawing a very small amount of blood when needed. Mice were genetically modified to produce luciferase and release it into the bloodstream when certain cells proliferate. Luciferase is an enzyme that catalyzes a luminescent reaction not found in mammals. By measuring luciferase in a small amount of blood from these mice, it is possible to detect the target cell proliferation occurring in the body in real time. Therefore, the state of cell proliferation can be observed in the same mouse repeatedly. By changing the combination of genetic modifications according to the cell type, the proliferation of different cell types can be confirmed.
In fact, blood samples taken over time after partial removal of the liver from transgenic mice allowed the researchers to detect the time course of liver cell proliferation with extreme sensitivity. Additionally, when the proliferation of pancreatic beta cells (insulin-producing cells) was stimulated, their process of proliferation could also be detected with high sensitivity.
Aside from making efficient use of experimental resources, the application of this research is expected to lead to the development of treatments for various diseases, such as regenerative therapies for diabetes mellitus that increase insulin-producing cells and drugs that inhibit the growth of cancer cells.