Immune cells receive training against tumors

Image: macrophages kill a cancer cell.

Under normal circumstances, macrophages protect our bodies from harmful invaders. Immune cells surround, absorb and destroy harmful particles. But in a cancer patient’s body, cancer cells are able to penetrate some of the macrophages, as it were. “Infiltrating” macrophages no longer fight cancer cells, but help them spread throughout the body.

A team of bioengineers at the University of Twente think they have an answer to these infiltrating cancer cells. The researchers engineered nanoparticles that train macrophages against a tumor.

Initially, the scientists had to transfer the nanoparticles to the right macrophages in the body. To this end, they engineered nanoparticles with a double layer of phospholipids. This coat usually consists of long tails that are waterproof on the inside and hydrophilic heads on the outside. “We replaced some of the fat with the fat with a short, charged tail that can turn outward,” explains Jay Prakash, who led the study. Infiltrated macrophages can recognize the nanoparticles via those spinning tails outside. This is how the particles are absorbed.

Once the nanoparticles are incorporated into the macrophages, training can begin. The researchers fused a piece of bacterial cell wall into the rotating tails. This gives the infiltrated macrophages a defense against cancer cells. It also ensures that the nanoparticles are recognized only by the infiltrated macrophages and do not cause harm anywhere else in the body.

Research in mice shows that treatment with nanoparticles is not only able to make infiltrated macrophages to fight cancer cells again. It can also prevent the tumor from spreading throughout the body. The researchers used the treatment to treat mice with breast cancer cells in their bodies. The results were promising: Tumor growth slowed by 70 percent.

Source: University of Twente, The Netherlands