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 New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State

nachricht Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>