We all owe a debt of gratitude to laboratory mice. Without their sacrifice, drug development would be even more slow and dangerous. However, as useful as they are in determining how the body reacts to drugs, they are still mice and their organs are mouse organs. Take the liver, for example. Liver enzymes in mice differ from their human counterparts' in how they metabolize drugs. So, an experimental drug might prove safe in mice, yet unexpectedly create harmful metabolites in humans. That's where artificial human liver tissue designed by scientists at the Massachusetts Institute of Technology might come in handy.
The National Institutes of Health's Research Matters blog tells us about the work of MIT's Alice Chen, who produced improved artificial human liver tissues that can begin functioning in mice in less than a week without harming their immune systems or liver. Previous attempts at "humanizing" mouse livers have taken weeks or months for the human liver cells to latch onto and expand in the mouse liver, the NIH reports.
Here's how they did it. First, they grew human liver cells mixed with mouse cells called fibroblasts. The cells were then encapsulated with human liver endothelial cells in a disc-shaped polymer scaffold. These cells keep the human liver cells alive while the polymer gel scaffold protects against immune system attack. When the researchers implanted the liver tissue into a mouse, it became integrated into the circulatory system within a week. As a result, drugs can reach the liver, and human proteins produced by the liver can enter the bloodstream. This gives researchers more of an idea of what will happen inside the human body in reaction to drugs being tested.