Last Piece in the Puzzle

Article excerpt

Researchers used to think that artificial devices were the way to go when someone needed a new body part, but now they're finding that skin, bones-even the heart-can he created using the body's own tissue. They've been called cyborgs, vital machines, and bionic men and women. Characters who are part human and part machine have inspired countless science-fiction stories. In that vision of the future, space-age materials and electronics not only replace damaged flesh but make it better than before-- bestowing new strength and power on the human body that nature alone might not ever provide.

But now, at the beginning of the 21st century, scientists are crafting another vision-one that's more realistic but no less fantastic. They've discovered that the body's own tissues are really the superior materials, perfectly suited for their intended purposes. Bone, for example, is strong, flexible, and self-healing-a characteristic that steel or titanium has yet to acquire. Scientists and engineers are calling on all their creative energies to replicate the physical and chemical properties of materials that nature created, slowly, over millions of years.

"That's been an evolution of thinking in this whole field," says Michael Miller, a plastic surgeon at the M.D. Anderson Cancer Center in Houston. "In the past, everyone expected to have artificial parts to replace living parts, but it's becoming clearer that having a living part is going to be much superior to having an artificial part."

To that end, researchers are searching for ways to grow human tissues from the bottom up: In the mid 1980s, the National Science Foundation created a program called Emerging Technologies Initiation, whose purpose was to fund high-risk research with strong potential in the early stages. One of the first areas funded was tissue engineering. NSF poured about $2 million into the project, and required the research teams to include scientists from several disciplines. By working together today, individuals with backgrounds in biology, chemistry, medicine, and engineering are developing techniques to encourage the body's own tissues to regenerate. They're doing this by tapping into the potential of stem cells-immature cells that have the ability to develop into many different tissue types in the body. Researchers are also making artificial scaffolds to support and guide tissues during their growth. It will be many years before scientists have the ability to create custom-made organs and replacement parts, but they are closer than ever before.

A BETTER WAY?

Modern medicine has made many once life-threatening injuries and diseases almost routine to cure. For the patient, however, the results of treatment can sometimes cause as much distress as the initial trauma. A treatment that involves surgery, perhaps removing a tumor or repairing a wound, sometimes leaves large openings that the body simply can't return to its original state.

Currently, surgeons do have ways to minimize these so-called defects. They can perform what's known as an autograft, replacing missing tissue with the patient's own by taking it from another part of the body. Tissue engineers commonly describe this dilemma as robbing Peter to pay Paul. This solution, while workable, is not ideal. Sometimes, there simply isn't enough tissue to take, and more importantly, a second defect is being created in order to repair the first one. Take bone, for example. "The limitations of current surgical ways of replacing bone are that you have to destroy-sacrifice-an existing bone in order to reconstruct a more important bone somewhere else," says Miller. "So there's a loss involved that becomes a trade-off the patient has to make."

What's more, Miller adds that remolding a bone is a difficult skill for surgeons to learn and to get right. "It's a technical challenge to change the shape of a bone into the right shape that you need. You have to take a straight bone, say, and make cuts in it, and use plates and screws to create the right shape. …