Researchers from the University of Iowa have developed a remarkable new procedure for regenerating missing or damaged bone. It's called a "bio patch" — and it works by sending bone-producing instructions directly into cells using microscopic particles embedded with DNA.
In experiments, the gene-encoding patch has already regrown bone fully enough to cover skull wounds in test animals. It has also stimulated new growth in human bone marrow stromal cells. Eventually, the patch could be used to repair birth defects involving missing bone around the head or face. It could also help dentists rebuild bone in areas which provides a concrete-like foundation for implants.
To create the bio patch, a research team led by Satheesh Elangovan delivered bone-producing instructions to existing bone cells inside a living body, which allowed those cell to produce the required proteins for more bone production. This was accomplished by using a piece of DNA that encodes for a platelet-derived growth factor called PDGF-B. Previous research relied on repeated applications from the outside, but they proved costly, intensive, and more difficult to replicate with any kind of consistency.
"We delivered the DNA to the cells, so that the cells produce the protein and that's how the protein is generated to enhance bone regeneration," explained Aliasger Salem in a UoI statement. "If you deliver just the protein, you have keep delivering it with continuous injections to maintain the dose. With our method, you get local, sustained expression over a prolonged period of time without having to give continued doses of protein." Salem is a professor in the College of Pharmacy and a co-corresponding author on the paper.
While performing the procedure, the researchers made a collagen scaffold in the actual shape and size of the bone defect. The patch — which was loaded with synthetically created plasmids and outfitted with the genetic instructions for building bone did the rest, achieving complete regeneration that matched the shape of what should have been there. This was followed by inserting the scaffold onto the missing area. Four weeks is usually all that it took — growing 44-times more bone and soft tissue in the affected areas compared to just the scaffold alone.
"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 note that the delivery system is nonviral, meaning that the plasmid is not likely to cause an undesired immune response, and that it's easier to mass produce, which lowers the cost.
Read the entire study at Biomaterials: "The enhancement of bone regeneration by gene activated matrix encoding for platelet derived growth factor."