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 Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>