Surgical Tape
Engineers at the Massachusetts Institute of Technology have developed a durable, flexible and biocompatible adhesive patch that can be easily and quickly applied to living tissues and organs to close ruptures.
In numerous experiments, the group has shown that the patch can be quickly glued to large ruptures in the colon, stomach and small intestine of various animal models. The glue adheres firmly to the fabrics for a few seconds and lasts for more than a month. It is flexible and able to stretch and contract together with a functioning organ as it heals. When the defect is restored, the patch gradually decomposes without causing inflammation and without sticking to the surrounding tissues.
The group suggests that the new surgical patch can be used in operating rooms as a quick and safe alternative to suture material or to strengthen stitched defects in the intestine and other hollow organs.
The new surgical patch is based on the double-sided tape design developed by the group in 2019. It was sticky on both sides and was intended to connect two wet surfaces. The glue in it was made of polyacrylic acid, an absorbent material that dries and absorbs moisture when in contact with a wet surface or fabric, temporarily sticking to the fabric in the process. The researchers added complex NHS esters - chemical compounds that can bind to proteins, forming stronger bonds. The glue was also reinforced with gelatin or chitosan – natural ingredients that help maintain the shape of the tape.
This double-sided tape binds various fabrics together firmly. But after consulting with surgeons, the researchers realized that the one-sided version is more practical.
Surgeons usually eliminate defects in the organs of the gastric tract with surgical sutures. But suturing requires skill, and after surgery they can lead to scarring around the injury. The stitched fabric can also disperse, causing secondary complications, including sepsis.
The researchers first improved the sticky part by replacing gelatin and chitosan with a more resistant hydrogel – in this case, polyvinyl alcohol. This made it possible to maintain the physical stability of the glue for more than a month – long enough for a typical intestinal injury to heal. They also added a second, non-adhesive top layer to prevent the patch from sticking to the surrounding tissue. This layer was made of biodegradable polyurethane, which has about the same extensibility and stiffness as the intestinal tissue.
In experiments, this version of the patch stuck to the tissues, but then swelled due to the saturation of the hydrogel with liquid. This led to the tension and rupture of the tape and the disclosure of the defect that it was supposed to seal.
The hydrogel naturally swells, and to overcome this problem, the researchers used a simple trick: they stretched the sticky layer a little, then introduced a non-adhesive layer so that when applied to living tissue, this preliminary stretching eliminated swelling.
The design and mechanism of action of the surgical patch. (A) A scheme for eliminating gastrointestinal tract defects using sutures. (B) A scheme for the seamless elimination of gastrointestinal tract defects using a patch. (C) Dry patch image and schematic illustration (bottom left) its structure, consisting of a smooth upper layer and a bioadhesive (sticky) lower layer. (D) Schematic representation of the patch components and algorithm for seamless elimination of gastrointestinal tract defects.
The effectiveness of the new version of the patch has been tested in experiments. When it was placed in a culture with human epithelial cells, the cells continued to grow, proving that the patch is biocompatible. When implanted under the skin of rats, the patch decomposed after about 12 weeks without any toxic effects.
The researchers also applied a patch to defects in the colon and stomach of rodents and found that it is firmly held until complete healing, leading to minimal scarring and inflammation compared to standard suturing.
Finally, the group applied a patch to close the defects of the pigs' colon and noted that the animals continued to eat normally without showing fever, lethargy or other adverse health effects. After four weeks, the defects completely healed.
Thus, experiments show that a surgical patch can potentially safely repair damage to the gastrointestinal tract and other hollow organs. The authors will refine the adhesive and hope to get FDA approval to test the patch in clinical trials.
Article by J.Wu et al. An Off-the-Shelf Bioadhesive Patch for Sutureless Repair of Gastrointestinal Defects is published in the journal Science Translational Medicine, the full text can be read on the bioRxiv preprint website.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of the Massachusetts Institute of Technology: Engineers develop surgical "duct tape" as an alternative to sutures.