In the quest to replace failed or injured body parts, fabricating them out of one of the most durable materials in the body – elastin – makes a lot of sense. Today, Dr. Ken Gregory, director of the Oregon Medical Laser Center at Providence St. Vincent Medical Center in Portland, OR, is using the material to engineer all kinds of quasi-natural structures: blood vessels, patches for internal injuries, replacement ear drums, bladders, and more.
Elastin is one of the essential proteins that hold the human body together. As the name implies, its elasticity allows body structures such as skin, blood vessels, and lungs to expand and contract. And it doesn’t break down – the elastin you’re born with lasts a lifetime. Furthermore, elastin is biocompatible, so that if it’s implanted in a living body, pure elastin won’t trigger a rejection by the immune system. To Gregory, these attributes signify enormous potential for elastin and elastin-coated synthetics as a biomaterial.
“Mother Nature doesn’t use metal or plastic,” says Gregory. “We’re built of proteins, so I figured, why not do it the same way?”
As a cardiac surgeon, Gregory had experienced first-hand the limitations of metal and plastic replacement devices. Convinced that biomedicine is better off copying, or at the least seeking guidance from, Nature’s designs, he turned to elastin.
Several years ago, he began sending assistants on missions to a slaughterhouse to salvage discarded pig parts. Back at the lab, he separated and purified the elastin in it. Then his team identified the elastin-producing gene, enabling them to produce the protein using standard recombinant techniques.
After the elastin is made into sheets or tubes of tissue, a graft is implanted into an organism, at which point “cells move in,” according to Gregory, filling the spaces in between the elastin protein, which acts like a scaffolding. Gregory has found that blood vessel cells are populating the walls of the graft, while other potentially clotting cells so far are not appearing.
Gregory and his colleagues at the Oregon Medical Laser Center are pursuing research into medical uses for elastin with the aid of a $28 million grant from the Army. Last year, a surgeon at Tripler Army Medical Center in Hawaii, Chet Morrison, made incisions in the small intestines of 36 anesthetized pigs to investigate if they could be patched up with elastin.
Each wound was sewn up with a four-square-inch swatch of pure elastin from Gregory’s lab. All but one of the pigs survived (the one died from an unrelated cause) – and some were even eating normally the following day. Weeks later, when Morrison’s team opened up the pigs, some of the patches had been incorporated so completely into the organ tissue that they were difficult to locate. One researcher recalls that other doctors at the Center wished the patch was approved by the Food and Drug Administration, so they could use it on a patient who was suffering from a small-intestine tumor that required removal, prevented the patient from eating, and burdened him with a waste-collecting bag.