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Glues inspired by mussels could help in life-saving repairs of the membranes surrounding developing fetuses, researchers say.
Scientists want to copy the compounds mussels use to stick to surfaces, given how the shellfish can tenaciously glom onto virtually all organic and inorganic substances, and hang on even amidst wind and waves.
"Mussels are masters of adhesion in wet environments," researcher Phillip Messersmith, a materials scientist at Northwestern University, told TechNewsDaily. "Manmade adhesives don't do as well."
The key to the mussels' stickiness is a family of unique molecules called mussel adhesive proteins. These contain a high concentration of the amino acid DOPA (dihydroxyphenylalanine).
Now Messersmith and his colleagues are creating new substances that contain a synthetic form of DOPA, essentially copying the mussel's glues. Synthetic versions of these glues are easier and cheaper to manufacture than the original proteins, Messersmith said.
"In almost all situations in a surgical environment where you would want to seal a hole in a tissue or bond a medical device to a tissue, the tissue is wet, and learning from mussels can help us there," Messersmith said.
For instance, these glues could help repair the amniotic sac, which envelops developing fetuses and is made up of membranes. These membranes can rupture prematurely before childbirth, either spontaneously or due to surgical procedures used to treat some birth defects. Such damage often leads to miscarriage, early labor, premature birth and other serious complications, and these membranes only have a limited ability to heal themselves.
"There are no existing materials that surgeons have available to them to repair these ruptures," Messersmith said. In part, this is because the membranes are too thin to hold stitches.
The new injectable glue from Messersmith and his colleague consists of two parts: molecules containing DOPA that make up the bulk of the glue, and a catalyst that causes the glue molecules to react with each other. When mixed, the combination rapidly solidifies in seconds to minutes and can stick to wet tissue, sealing wounds in fetal membranes.
In experiments with human fetal tissue grown on lab dishes, the researchers found they could repair tiny holes they punched in these membranes. The scientists are now collaborating with researchers in Europe for tests in live rabbits, and next plan to work on sheep.
"So far if you poke a hole in a rabbit fetal membrane and you do nothing, the survival rate of the fetus is on the order of 35 to 40 percent," Messersmith said. "If you seal it, survival increases to 80 percent, so far. These are encouraging results, but we're still early in the developmental stage."
The researchers are also using the glues in rodent studies to help improve the implantation of parts of the pancreas known as islets, work that might one day help diabetics secrete insulin. In addition, the adhesives could help in prenatal surgery to fix spina bifida, a disorder in which a portion of the spinal cord protrudes through an opening in the bones.
Since this disorder is "due to incomplete closure of connective tissue around the spinal cord," the mussel glue could offer a solution, Messersmith said. "The idea is to use our adhesive to help close off the defect in prenatal surgery, which could have significant benefits for the development and survival of the fetus."
The scientists detailed their findings Feb. 16 at the annual meeting of the American Association for the Advancement of Science in Boston.