Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanotextured Implant Materials: Blending in, Not Fighting Back

12.04.2007
Texture turns out to be nearly as important as chemistry when designing materials for use in the human body. In two related experiments Brown University engineers Thomas Webster and Karen Haberstroh found that cells responded differently to materials with identical chemistry but different surface textures. On both titanium and polymer materials, nanoscale surface textures yielded a more natural, accepting response, while microscale patterns typical of engineered materials spurred a rejection response.
Biomedical engineers are constantly coming up with ways to repair the human body, replacing defective and worn out parts with plastic, titanium, and ceramic substitutes – but the body does not always accept such substitutes seamlessly. Engineers from Brown and Purdue universities have found that simply changing the surface texture of implants can dramatically change the way cells colonize a wide variety of materials.

Two recent experiments have focused on the materials used in stents – those springy little cylinders that hold open once-clogged arteries – and artificial blood vessels. Currently only about 30 percent of small diameter blood vessel grafts (less than 6 mm diameter) last more than five years, and up to 20 percent of stents need to be replaced because the artery walls thicken in and around them in a process known as restenosis. Drug-coated stents were introduced years ago as one way to combat this problem, but concerns have surfaced recently about increased clotting.

Instead of using chemistry to fight the body’s response to such foreign materials, Thomas Webster, an associate professor of engineering, and Karen Haberstroh, an assistant professor of engineering, thought maybe they could use physical structure to allow the foreign materials to blend in better. “What we’re trying to do is fundamentally different,” says Webster. “We’re trying to find materials that the body accepts, rather than develop drugs or develop materials that will kill a cell – no matter if it kills a bad cell or a good cell. We’re trying to find materials that accept good cells, as opposed to killing off bad cells.”

Normal healthy blood vessels have a thin lining of specialized cells called the endothelium, surrounded by a thicker layer of smooth muscle cells that make up the arterial wall. The proteins collagen and elastin make up much of this lining and create a texture of fine nanoscale bumps on the inside of the blood vessel. This contrasts strongly with most of the materials used in implants, which have microscale texture, but are nearly smooth at the nanoscale.

When the researchers changed the surface texture of implant materials to better match the natural texture of the endothelium, they found that endothelial cells quickly colonized the foreign surfaces, effectively camouflaging them and preventing smooth muscle cells from overgrowing the implants. Once the endothelial cells form a single, solid layer, they stop piling on and switch to producing the proteins collagen and elastin.

In one experiment, published with Purdue University graduate student Saba Choudhary in the journal Tissue Engineering, Webster and Haberstroh pressed together titanium particles that were less than 1 micron in size to create titanium with nanoscale surface texture. When they compared samples of the nanostructured material to conventional titanium in mixed cell culture, they found that the nanoscale surface features encouraged endothelial cells to colonize the material and spread much faster than smooth muscle cells. Where endothelial cells established themselves, they formed a single thin layer that inhibited overgrowth of the smooth muscle cells that tends to narrow stented arteries.

In another experiment, published in the Journal of Biomedical Materials Research with Purdue graduate student Derick Miller, the team molded pieces of PLGA, a biodegradable polymer often used for blood vessel grafts, so they came out completely covered with bumps that were 100, 200 or 500 nanometers in diameter. The surface with 200-nanometer features strongly favored the adsorption and spreading of fibronectin, a protein that helps endothelial cells quickly coat the graft.

Webster and Haberstroh’s next step will be to test such nanostructured implants in live animals. If the same behavior holds true for materials placed in the body, the rapid growth of endothelial cells would help the implants to integrate quickly into existing blood vessels, provoking less immune response and a longer-lasting repair.

Martha Downs | alfa
Further information:
http://www.brown.edu

More articles from Materials Sciences:

nachricht High-tech sensing illuminates concrete stress testing
20.07.2017 | University of Leeds

nachricht Here's a tip: Indented cement shows unique properties
20.07.2017 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

Leipzig HTP-Forum discusses "hydrothermal processes" as a key technology for a biobased economy

12.07.2017 | Event News

 
Latest News

Researchers create new technique for manipulating polarization of terahertz radiation

20.07.2017 | Information Technology

High-tech sensing illuminates concrete stress testing

20.07.2017 | Materials Sciences

First direct observation and measurement of ultra-fast moving vortices in superconductors

20.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>