The researchers already have shown in a series of experiments that bone and cartilage cells in petri dishes attach better to materials that possess smaller surface bumps than are found on conventional materials used to make artificial joints. The smaller features also stimulate the growth of more new bone tissue, which is critical for the proper attachment of artificial joints once they are implanted.
Now the biomedical engineers have seen the same kind of increased attachment for endothelial and vascular smooth muscle cells lining the insides of arteries, said Thomas Webster, an associate professor of biomedical engineering at Purdue.
The stents are small metal scaffolds that are inserted inside arteries to prop them open during or after surgery to remove dangerous plaque deposits from the vessels. The stents, which are made of titanium and other metals, enable the arteries to grow new tissue after vessel-clogging plaque deposits have been removed. A major problem, however, is that the body often perceives the metal devices as foreign invaders, hindering endothelial cells from attaching to the scaffolding and prompting the creation of scar tissue, which can build up inside blood vessels and interfere with blood flow.
"If a stent doesn't attach firmly it can become loose, and parts of it will actually break off and go down the bloodstream," Webster said. "Essentially, what we've been trying to do is find new materials that cause the endothelial cells to attach better to these stents without creating as much dangerous scar tissue."
The researchers tested discs of titanium containing surface bumps about as wide as 100 nanometers ?or billionths of a meter. The metals used to make conventional stents have features about 10