Tough adhesive could aid in neurosurgery

A strong, stretchy hydrogel adhesive tightly seals protective nervous system tissue better than commercially available glues and could help prevent complications from neurosurgery (Sci. Transl. Med. 2024, DOI: 10.1126/scitranslmed.adj0616). Unlike existing glues, “our adhesive interacts very well with wet, moving tissue surfaces,” says Benjamin Freedman, a bioengineer at Harvard University.

Up to one-third of patients undergoing neurosurgery can experience dangerous complications due to leakage of cerebrospinal fluid, the nourishing, protective fluid that surrounds the nervous system. Surgeons prevent such leaks by suturing the dense dural membrane that covers the brain and spinal cord.

Because it can be challenging to create a leak-proof seal with sutures, surgeons often also use glues. But commercially available dural glues, typically made of polyethylene glycol hydrogels, do not adhere strongly to wet tissue, and they fracture easily, Freedman says.

Freedman, neurosurgeon Kyle Wu of the Ohio State University, chemical engineer David Mooneyof Harvard, and their colleagues turned to an adhesiveinspired by slug mucus and developed in Mooney’s lab. The two-part adhesive consists of a tough hydrogel and a sugary chitosan solution. The hydrogel is made of two cross-linked polymers: alginate and polyacrylamide. The chitosan infuses the hydrogel and the tissue, bridging them tightly. The key to the hydrogel’s strong adhesion is the strong cohesive attraction between its own molecules, Freedman says. “That enables the really tough, robust adhesion to underlying soft tissue surfaces.”

In mechanical tests, surgical glues broke apart when stretched or compressed, while the new adhesive did not show any damage. The researchers also tested the new adhesive and a commercial glue to close incisions in the dural membranes in live pigs. With mild increases in fluid pressure, the commercial product failed 40% of the time, while the new one withstood much higher pressures. The new material has the potential to supplant sutures, Freedman says.

But first, like sutures, the sealant would need to be made easily removable or dissolvable, says Michael McDowell, a neurosurgeon at the University of Pittsburgh. If the researchers can do that, he says, given the material’s superior adhesion over that of commercial glues, the material could be very valuable. “I’m cautiously optimistic,” he says. “There’s always room for improvement because current adhesives are not perfect. We’re always interested in potential new ways to enhance our ability to close wounds in general.”