Plastic Made by Bacteria Commercialized

Following abdominal surgeries like appendectomies, one in five patients’ abdominal wounds reopen because the dissolvable sutures lose their strength too quickly. The result can be a higher risk of life-threatening infections. But a solution could be on the way. The U.S. Food and Drug Administration (FDA) has approved a new kind of absorbable sutures that are more flexible and far stronger than those currently on the market. The sutures are made out of a polymer produced by genetically engineered bacteria.

Tepha, based in Cambridge, MA, manufactures the polyester sutures. The polyester is made by recombinant E. coli engineered using techniques pioneered by MIT biology professor Anthony Sinskey, a member of Tepha’s board of directors. The FDA’s approval of the sutures makes them the first commercial plastics produced by genetically engineered bacteria, Sinskey says. Tepha will begin marketing the sutures this year.

Beyond its use in sutures, the polyester represents a valuable new material for other medical devices. Other polymers currently used for dissolvable medical devices include ones made from polylactic acid and polyglycolic acid. “Existing materials break down quickly into inflammatory products in the body,” says Simon Williams, president of Tepha. The polyester sutures break down into biocompatible compounds that do not cause inflammation. What’s more, Tepha’s polyester is a thermoplastic–a material that melts at a high temperature and becomes solid when cooled–and thus can be readily molded into different shapes.

Williams expects that because of their strength, Tepha’s sutures will be used for surgeries requiring strong, long-lasting stitches, such as abdominal surgeries and tendon and ligament repair. Not only will that strength benefit patients during long recoveries, but it could also help surgeons during procedures. “Sutures do break in the operating room,” says Williams.

For one out of five patients who have had abdominal surgery, the wound reopens because the sutures dissolve too quickly, leaving the patient at risk for life-threatening infections. Instead of immediately beginning to dissolve at a steady rate, the Tepha sutures have prolonged strength retention before they dissolve.

“The polymer is very versatile,” says Williams. Tepha is developing several other products using the material, including stents and absorbable meshes for hernia repair.

And in collaboration with doctors at Children’s Hospital Boston, Williams is developing a polymer scaffold for tissue-engineered heart valves. Children born with heart-valve abnormalities go through multiple surgeries, first to replace their faulty valve, and then to replace the transplants with larger ones as the rest of the heart grows. “The valve doesn’t grow with the child,” explains Williams. Tepha is developing valve scaffolds that would be seeded with cells from a patient’s heart. Experiments in sheep have shown that as a lamb grows, the valve grows too, even after the scaffold dissolves.