What if sutures could actually promote wound healing? Scientists have designed so-called smart sutures that not only stitch up damaged tissue, but they also detect inflammation and secrete drugs. These sutures are coated with hydrogels that could be packed with sensors, or a variety of molecules including therapeutics. The work has been reported in the journal Matter. It may one day be possible to use these sutures to help patients with invasive surgical incisions, such as Crohn's disease patients who undergo procedures that remove part of the intestine, for example. Sutures could prevent serious complications if they are able to detect high levels of inflammation and send a warning that healing is not occurring correctly.
Synthetic sutures that dissolve are already made and used. But sutures are also still made from animal tissues, like catgut sutures made from purified cow, sheep, or goat (but not cat) collagen. These sutures create strong knots that dissolve on their own in about ninety days.
In this work, the researchers used this type of bioderived suture as a platform for drug delivery or diagnostics. Pig tissue was 'decellularized' with detergents so that it would not cause a reaction when placed into a recipient. A cell-free material the scientists called "De-gut" was retained; it contains material like collagen protein and molecules in the extracellular matrix. This stuff was then dehydrated and twisted into strands. The researchers found that it was about as strong, but causes far less inflammation in the surrounding tissue than catgut sutures. The addition of a hydrogel enables the scientists to add many potential new functions to the sutures.
The hydrogel could hold treatments like monoclonal antibodies or sensors that indicate dangerous immune responses are happening. This remarkable hydrogel coating can also serve as a reservoir of viable cells, noted senior study author Giovanni Traverso, an associate professor of mechanical engineering at MIT and gastroenterologist at Brigham and Women's Hospital. When stem cells were embedded into the sutures, they remained viable for seven days after being implanted in a mouse model. These cells also generated vascular endothelial growth factor (VEGF), which stimulates blood cell growth.
To add sensors to the hydrogel, the investigators developed microparticles that are coated with peptides, which are released if inflammation-indicating enzymes called MMPs are present in the tissue.
The hydrogel was able to carry inflammatory bowel disease treatments including a steroid called dexamethasone and adalimumab, a monoclonal antibody. The microparticles were made from FDA-approved polymers like PLGA and PLA that can control the rate at which drugs are released. The study authors noted that this methodology cold be adapted for the delivery of drugs like antibiotics or chemotherapy.
Now, the sutures are being tested for more potential uses, and the scale-up of production is being investigated.