Surgeons still find it tricky to quickly and reliably stick a wet, slippery organ back together during invasive procedures. The currently available selection of ‘stick-you-together’ products – staples and chemical glues – do a decent job, but make a bit of a mess of nearby nerves and blood vessels, and often cause swelling, itching, scarring and, sometimes, infection.
Yet lots of parasitic organisms have evolved excellent ways of entering – and sticking to – their host. The freshwater fish parasite, Pomphorhynchus laevis, also known as the spiny-headed worm, gets eaten by an unsuspecting fish and travels through the digestive tract. Once it reaches a prime spot, it anchors itself firmly in the slippery intestines, ramming its proboscis deep into the intestine wall, inflating the tip, and forming a tight, interlocking grip on the tissue.
A team of researchers from Harvard have taken inspiration from this ingenious design to develop a small microneedle patch (shown below) to hold together organs. The patch glides smoothly and non-invasively into tissues and, once embedded, the tips of each tiny needle absorb water from the interstitial fluid that bathes every cell. These tips swell to their maximum size within 10 minutes, forming a bulbous end like an arrow head that gives the patch great sticking power.
In a test run on a pig, the microneedle patch attached skin grafts better than the current gold standard (staples), and there was less associated contamination from nasty bacteria. After the tissue healed, the microneedle mat could be easily removed, and the tiny holes it left behind sealed within a few hours. Once out of the liquid tissue environment, the swollen tips shrank back to their original size and shape, and were ready to be sterilised and re-used.
All-in-all, a mightily impressive bit of bioengineering!
Yang SY, O'Cearbhaill ED, Sisk GC, Park KM, Cho WK, Villiger M, Bouma BE, Pomahac B, & Karp JM (2013). A bio-inspired swellable microneedle adhesive for mechanical interlocking with tissue. Nature communications, 4 PMID: 23591869