One of the most interesting emerging treatments for certain types of cancer aims to starve the tumour to death. The strategy involves destroying or blocking the blood vessels that supply a tumour with oxygen and nutrients. Without its lifeblood, the unwanted growth shrivels up and dies.
One way to do this is with drugs called angiogenesis inhibitors which prevent the formation of new blood vessels that tumours rely on for sustenance. But there is another approach as well, physically blocking the surrounding blood vessels so that blood can no longer flow into the tumour. Researchers have experimented with a number of blocking mechanisms such as blood clots, gels, balloons, glue, nanoparticles and so on. However, these techniques have never been entirely successful because the blockages can be washed away by the blood flow itself and the materials do not always fill blood vessels entirely, allowing blood to flow round them.
Today, Qian Wang and a couple of pals at Tsinghua University in Beijing propose a different approach. These guys say that it is possible to block blood vessels completely by filling them with liquid metal. And they have tested their idea both in vitro and in vivo on mice and rabbits to get a sense of how well it might work. (All their experiments were approved by their university’s ethics committee.) The team have experimented with two liquid metals, pure gallium and which melts at around 29 degrees centigrade and a gallium indium alloy with a slightly higher melting point. Both are liquid at body temperature.
Qian and co first tested the cytotoxicity of gallium and indium by allowing cells to grow in its presence and measuring the number that survive after 48 hours. If more than 75 per cent, a substance is deemed safe by China’s national standards. After 48 hours just over 75 percent of cells in both samples were still alive unlike those grown in the presence of copper which almost all die. Indeed, that corresponds with other studies that suggest that gallium and indium are relatively benign in biomedical situations.