Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mechanical Stress Can Help or Hinder Wound Healing Depending on Time of Application

25.10.2011
A new study demonstrates that mechanical forces affect the growth and remodeling of blood vessels during tissue regeneration and wound healing. The forces diminish or enhance the vascularization process and tissue regeneration depending on when they are applied during the healing process.

The study found that applying mechanical forces to an injury site immediately after healing began disrupted vascular growth into the site and prevented bone healing. However, applying mechanical forces later in the healing process enhanced functional bone regeneration. The study’s findings could influence treatment of tissue injuries and recommendations for rehabilitation.

“Our finding that mechanical stresses caused by movement can disrupt the initial formation and growth of new blood vessels supports the advice doctors have been giving their patients for years to limit activity early in the healing process,” Robert Guldberg, a professor in the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “However, our findings also suggest applying mechanical stresses to the wound later on can significantly improve healing through a process called adaptive remodeling.”

The study was published last month in the journal Proceedings of the National Academy of Sciences. The research was supported by the National Institutes of Health, the Armed Forces Institute of Regenerative Medicine and the U.S. Department of Defense.

Because blood vessel growth is required for the regeneration of many different tissues, including bone, Guldberg and former Georgia Tech graduate student Joel Boerckel used healing of a bone defect in rats for their study. Following removal of eight millimeters of femur bone, they treated the gap with a polymer scaffold seeded with a growth factor called recombinant human bone morphogenetic protein-2 (rhBMP-2), a potent inducer of bone regeneration. The scaffold was designed in collaboration with Nathaniel Huebsch and David Mooney from Harvard University.

In one group of animals, plates screwed onto the bones to maintain limb stability prevented mechanical forces from being applied to the affected bone. In another group, plates allowed compressive loads along the bone axis to be transferred, but prevented twisting and bending of the limbs. The researchers used contrast-enhanced micro-computed tomography imaging and histology to quantify new bone and blood vessel formation.

The experiments showed that exerting mechanical forces on the injury site immediately after healing began significantly inhibited vascular growth into the bone defect region. The volume of blood vessels and their connectivity were reduced by 66 and 91 percent, respectively, compared to the group for which no force was applied. The lack of vascular growth into the defect produced a 75 percent reduction in bone formation and failure to heal the defect.

But the study found that the same mechanical force that hindered repair early in the healing process became helpful later on.

When the injury site experienced no mechanical force until four weeks after the injury, blood vessels grew into the defect and vascular remodeling began. With delayed loading, the researchers observed a reduction in quantity and connectivity of blood vessels, but the average vessel thickness increased. In addition, bone formation improved by 20 percent compared to when no force was applied, and strong tissue biomaterial integration was evident.

“We found that having a very stable environment initially is very important because mechanical stresses applied early on disrupted very small vessels that were forming,” said Guldberg, who is also the director of the Petit Institute for Bioengineering and Bioscience at Georgia Tech. “If you wait until those vessels have grown in and they’re a little more mature, applying a mechanical stimulus then induces remodeling so that you end up with a more robust vascular network.”

The study’s results may help researchers optimize the mechanical properties of tissue regeneration scaffolds in the future.

“Our study shows that one might want to implant a material that is stiff at the very beginning to stabilize the injury site but becomes more compliant with time, to improve vascularization and tissue regeneration,” added Guldberg.

Georgia Tech mechanical engineering graduate student Brent Uhrig and postdoctoral fellow Nick Willett also contributed to this research.

Research News & Publications Office
Georgia Institute of Technology
75 Fifth Street, N.W., Suite 314
Atlanta, Georgia 30308 USA
Media Relations Contacts: Abby Robinson (abby@innovate.gatech.edu; 404-385-3364) or John Toon (jtoon@gatech.edu; 404-894-6986)

Writer: Abby Robinson

Abby Robinson | Newswise Science News
Further information:
http://www.gatech.edu

More articles from Life Sciences:

nachricht Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg

nachricht Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>