Glioblastoma is among the most lethal forms of brain cancer, and scientists have uncovered a surprising factor that may help its cells become more invasive. The fluid surrounding the outer edges of these tumors is much thicker than the fluid near their centers, forcing cancer cells to encounter increasing resistance as they move into healthy brain tissue. Rather than simply slowing their movement, however, this environment appears to help the cells adapt in ways that make invasion easier.

To investigate this unexpected behavior, researchers created an innovative microfluidic chip that recreates the physical conditions encountered by glioblastoma cells. They found that spending extended periods in thick fluid caused the cells to become smaller, more flexible, and better able to squeeze through narrow openings. The discovery suggests that fluid viscosity does more than obstruct cancer cells.…