But patients' bodies often see the devices as invaders, building scar tissue that can further impeded blood flow. The attack by the body also keeps stents from being anchored in place by healthy endothelial cells, so stents can break away and travel down the bloodstream.

To prevent all this, researchers at Purdue University are experimenting with nanobumps, tiny surface features 100 nm wide. Conventional stents either have surface features 10 times as large or none at all. Nanobumps on a stent are supposed to mimic the surface qualities of proteins and normal tissue, prompting the body to accept the stent and letting endothelial cells coat it in a layer one-cell thick.

In lab experiments, titanium discs with and without the tiny bumps were placed in a solution of endothelial cells. After an hour, discs with bumps had three times as many cells attached as featureless discs.

Future experiments will be done on stentshaped specimens. Scientists hope the technique can soon be put to work on stents and other implants that come in contact with blood.