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 Borophene shines alone as 2-D plasmonic material
21.11.2017 | Rice University

nachricht Quantum dots amplify light with electrical pumping
21.11.2017 | DOE/Los Alamos National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>