GM rats promise better disease models
Scientists have created a ‘knockout rat' that can be used to model certain diseases in the same way as mice. Researchers made knockout rats by extracting embryonic stem cells (ESCs) from rat embryos, then genetically engineered the cells so that a specific gene no longer functions.
The altered ESCs were then injected into early stage rat embryos. The resulting mixture of embryonic cells was implanted into the womb of a rat foster mother. This creates offspring that are chimeras, born containing tissue from both the normal embryo and the altered ESC.When the rats' germline cells (sperm and eggs) are derived from the manipulated cells, the rats pass those genetic changes onto their offspring resulting in new strains of pure breeding knockout rats.
Rats have long been a popular model system for many aspects of biomedical research. Their liver enzyme systems and nervous systems are surprisingly similar to humans and, as rats are more socially sophisticated than mice, they could provide better models for studying psychiatric disorders.
This powerful technique, already widely used in mice, provides greater control than previous methods used to create GM rats.