"We can make a scaffold in the actual shape and size of the defect site, and you'd get complete regeneration to match the shape of what should have been there," Elangovan says.
The team started with a collagen scaffold. The researchers then loaded the bio patch with synthetically created plasmids, each of which is outfitted with the genetic instructions for producing bone. They then inserted the scaffold on to a 5-millimeter by 2-millimeter missing area of skull in test animals. Four weeks later, the team compared the bio patch's effectiveness to inserting a scaffold with no plasmids or taking no action at all.
The plasmid-seeded bio patch grew 44-times more bone and soft tissue in the affected area than with the scaffold alone, and was 14-fold higher than the affected area with no manipulation. Aerial and cross-sectional scans showed the plasmid-encoded scaffolds had spurred enough new bone growth to nearly close the wound area, the researchers report.
The plasmid does its work by entering bone cells already in the body usually those located right around the damaged area that wander over to the scaffold. The team used a polymer to shrink the particle's size (like creating a zip file, for example) and to give the plasmid the positive electrical charge that would make it easier for the resident bone cells to take them in.
"The delivery mechanism is the scaffold loaded with the plasmid," Salem says. "When cells migrate into the scaffold, they meet with the plasmid, they take up the plasmid, and they get the encoding to start producing PDGF-B, which enhances bone regeneration."
The researchers also point out that their delivery system is nonviral. That means the plasmid is less likely to cause an undesired immune response and is easier to produce in mass quantities, which lowers th
|Contact: Richard Lewis|
University of Iowa