Performing fetus surgery increases a number of health risks to the unborn baby. Researchers are developing a new glue, inspired by the tenacious grip of mussels, that could save the lives of patients requiring this kind of surgery.
“One of the biggest risks [of fetus surgery] is the insertion of a fetal scope through the amniotic sac,” Diederik Balkenende, Ph.D., says. “The small hole where the scope penetrated the membrane can start to tear. If it tears completely, premature labor is likely. Because these operations are often done before the fetus is developed, early delivery increases the risk of fetal morbidity. An adhesive that prevents the amniotic sac from tearing could help the fetus remain in the womb longer, which would potentially lead to a healthier future for the baby.”
In the past surgeons had to cut open the abdomen and womb to fix problems with the fetus. Now, doctors can use skinny endoscopic tools to perform operations through a tiny hole. Because of the hole’s fragility, however, it doesn’t close easily and is difficult to heal. The membrane’s wetness makes sealing it with an adhesive challenging, but delivering a surgical glue post-operation is also a major hurdle.
To address the problem of wet adhesion, researchers have turned to mussels. The shellfish produce sticky substances that allow them to cling to rocks in wet environments and pounding waves. Developing mimics of these substances for surgical use requires converting them into hydrogels – a process that requires chemical crosslinkers which could be toxic to fetuses.
Balkenende, a postdoctoral researcher in the lab of Philip Messersmith, University of California, wanted to eliminate crosslinkers. Balkenende infused an adhesive ingredient from the mussel foot called dihydroxyphenylalanine into a special polymer that dissolves in a biocompatible solvent. Researchers used pieces of a membrane surrounding a cow heart as a model of the amniotic sac to test their material. Applying the solution with a syringe to pieces of the wet tissues, they found the mixture immediately became rubbery on contact with moisture. After about an hour, the glue set and held the pieces together.
Even with the right polymer and solvent, however, researchers still need to figure out how the solution might work in a real surgery. “In addition to the novel polymer we’re making, we’re approaching its delivery from a new angle, which is what we call pre-sealing,” Messersmith says. “Injecting the liquid polymer between the inner wall of the uterus and the amniotic sac and letting it harden before surgery could provide the mechanical support needed to prevent the hole from tearing and causing a catastrophic rupture.”
Incorporating the adhesive into clinical practice will take additional work. The researchers are still perfecting the glue and examining biocompatibility. Pre-clinical testing on animals must also be completed, Balkenende says.