Mechanical Stress Can Help Or Hinder Wound Healing Depending On Time Of Application

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," said 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.