eP371 - Developing an Ideal Biomaterial: Electroadhesive Hydrogels Are a Novel Way to Augment Anastomotic Healing and Prevent Leak

Purpose/Background: Anastomotic leak (AL) is associated with an altered microbiome with increased epithelial invasion and tissue-degrading capacity. Despite many technical advances and development of varied surgical adhesives, AL rates have not meaningfully improved. However, most materials have not been developed in the context of our current understanding of AL pathophysiology.

Hydrogels are water-filled solids with mechanical properties similar to living tissue. They can act as depots for small molecules which can then be delivered slowly to the external medium. A variety of hydrogels are known to be biocompatible and are approved by the FDA for use in humans. We have recently adhered thin strips of hydrogels synthesized by polymerization of cationic monomers to biological tissues by applying a low electric field for a short time. Such electroadhesion (EA) persists after the field is removed. Our gels have been shown to be biocompatible with mammalian cells and our protocols have been used safely in studies done in live mice.

In this work, we review the current state of hydrogel research in colonic healing and we hypothesize that hydrogels can be used to address the problem of AL in conjunction with a new technique, EA, to affix these materials to bowel.Methods/Interventions: PubMed and Embase databases were searched from inception to October 2023. Articles were included if they involved direct or rectal hydrogel application in models of colitis or colon injury. The hydrogel characteristics, incorporation of drugs, delivery method, site of adhesion, method of adhesion, in vivo durability, and major study findings were compiled and analyzed.

Strips of our hydrogel and segments of ex vivo chicken bowel were cut to the same size, placed into contact and compressed by hand. Next, a silver anode (+) was made to touch the gel and a silver cathode (–) the tissue. A 10 V DC was applied for 20 s. The voltage was removed. The strength of adhesion to both the serosal and mucosal surfaces was measured by pull-off tests: the gel and tissue were affixed to metal clamps and adhered by EA. The stress needed to separate the pair was recorded.Results/Outcomes: Several studies have examined hydrogel use in animal models of colonic injury or anastomoses. All were applied to the serosal surface of the bowel to promote sealing of the anastomosis. However, none of these gels were in the form described here and no studies used EA. As for the mucosal side, only injectable (paste-like) gels loaded with drugs have been tested. Such gels were administered via enema on a daily or every other day basis. No studies were able to demonstrate retained mucosal hydrogel more than 12 hours after administration. Most studies reported a positive impact of the gels on mucosal healing and inflammation.

For our gel, the contact adhesion with the mucosal and serosal surfaces was very low; the gel did not appear to adhere at all after compression alone. After EA, adhesion between the tissue and the gel appeared to be robust. Pull-off tests demonstrated EA strength of 7-8 kPa with both the serosal and the mucosal surfaces.Conclusion/

Discussion: Our ex vivo studies have shown that hydrogels can be adhered to both the mucosal and serosal surfaces of the bowel. This adhesion is induced by a mild electric field and is termed electroadhesion (EA). Our studies show that this adhesion is strong and durable. Hydrogels may be a novel and effective way to bolster anastomotic strength. On the mucosal side, hydrogels may be used to physically protect the epithelium from a virulent microbiome and can be loaded with drugs to promote mucosal healing.