Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A bed of microneedles: Johns Hopkins scientists’ gadget measures muscle cell force

28.01.2003


Using the same technology that creates tiny, precisely organized computer chips, a Johns Hopkins research team has developed beds of thousands of independently moveable silicone "microneedles" to reveal the force exerted by smooth muscle cells.



Each needle tip in the gadget, whose development and testing is reported this week in the advance online edition of the Proceedings of the National Academy of Sciences, can be painted with proteins cells tend to grab onto. By measuring how far a contracting muscle cell moves each needle, the scientists can calculate the force generated by the cell.

"What we have is a tool to measure and manipulate mechanical interactions between a single cell and its physical and biochemical surroundings," says Christopher Chen, Ph.D., associate professor of biomedical engineering at Johns Hopkins. "Cellular mechanics is really important to many normal and pathologic processes in people, and there’s a lot we don’t understand, even with available technology."


Because smooth muscle cells control the expansion and contraction of airways and blood vessels, the microneedle bed’s ability to measure how a cell’s environment affects the strength, duration and timing of cellular contractions should one day help shed light on medical conditions like asthma and high blood pressure, the researchers say.

The new device complements an ever-growing array of techniques to measure forces exerted by a contracting cell and overcomes some of their limitations, the researchers say. For example, one common method examines a cell lying on a thin sheet of material, which wrinkles when the cell contracts.

"This is like a person lying on a bed sheet and scrunching up part of the sheet," says first author John Tan, a graduate student in biomedical engineering. "Wrinkles appear all over the place, and it can be hard to figure out where the initial force was applied."

To overcome that complexity, scientists have to make mathematical assumptions -- which are difficult to verify. The one-piece microneedle bed, however, lends itself to much simpler calculations because each needle moves independently of the others and requires exactly the same force to move.

"We know how difficult each needle is to move, and we know where it was originally," says Tan. "By measuring the direction and magnitude of the deflection of each needle, we can calculate the force the cell exerts."

Tan and his colleagues painted the needle tips with fibronectin, a protein that forms part of the natural scaffolding between cells. Each smooth muscle cell spread out on the bed of microneedles and then contracted, displacing the needles.

From their experiments, the researchers have already discovered that a cell’s shape affects how it contracts. For example, a cell confined to a small area of fibronectin-painted needles, unable to spread out, exerted little force (i.e., didn’t contract).

They also uncovered the answer to what seemed to be conflicting scientific reports about cellular forces. Some reports indicated that the greater an area grasped by a cell, the greater force the cell exerted, while other reports showed no such correlation. Because the microneedle bed is the first device that can directly measure the forces generated at the cell’s "adhesions," or gripping regions, the researchers were able to prove that both observations are actually correct.

"Force increases with adhesion size only above a certain level; for smaller areas, force and size aren’t correlated," says Tan. "The same cell can actually exhibit both scenarios."

The Johns Hopkins team, composed of three biomedical engineers, a physicist, a molecular biologist and a chemical engineer, next plans to use the device to measure the effects of various proteins thought to stimulate or reduce cells’ contraction, see how the amount of protein affects force, and determine how different types of cells react on the bed. The scientists also plan to make grids with needles of different lengths (shorter posts are harder to bend) to challenge cells’ contractile forces.


The studies were funded by the National Institute of Biomedical Imaging and Bioengineering, the Defense Advanced Research Planning Agency, the Whitaker Foundation, and the Office of Naval Research. Authors on the paper are Tan, Chen, Joe Tien, Dana Pirone, Darren Gray and Kiran Bhadriraju, all of Johns Hopkins. Tien is now at Boston University.

Johns Hopkins Medical Institutions’ news releases are available on an EMBARGOED basis on EurekAlert at http://www.eurekalert.org and from the Office of Communications and Public Affairs’ direct e-mail news release service. To enroll, call 410-955-4288 or send e-mail to bsimpkins@jhmi.edu.

Joanna Downer | EurekAlert!
Further information:
http://www.pnas.org

More articles from Life Sciences:

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

nachricht The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>