Tissue engineering: a new frontier in medicine

by Pat Curry

Tissue Engineering Ten years ago, scientists said it couldnt be done. Three years ago, researchers were defending themselves against accusations that they were modern-day Dr. Frankensteins. Today, the work taking place in the field of tissue engineering is so radical and exciting that the scientific community is predicting a revolution in health care.

"Were pretty much pushing the envelope," says Dr. David Ku, a mechanical engineer and vascular surgeon at the Georgia Tech Emory Center, a tissue engineering research center in Atlanta funded by the National Science Foundation. "There is a large potential to cure or ameliorate many diseases that just couldnt be treated in the past."

Although it may sound like science fiction, there are products available right now that help people with burns who dont have enough healthy skin of their own for grafts. People with diabetes and/or circulatory problems who had wounds severe enough to be considered for amputation are being healed. And women who have suffered for years with incontinence now have bladder control

Researchers know its possible, because it happens every day inside the womb.

"In nine months [in utero], I went from one cell to 200 cell types and a fully differentiated body," says Dr. Gail Naughton, president of Advanced Tissue Sciences, a tissue engineering company in California. "If nature can do that, we should be able to learn how to do it, too. Were really just mimicking nature and trying to duplicate that process."

Tissue engineering is a field that meshes two life sciences

Another reason that tissue engineering is being explored so rigorously is that current treatments often dont work as well as doctors or patients would hope.

Dr. Cato Laurencin, director of the Center for Advanced Biomaterials and Tissue Engineering in Philadelphia notes that in his work as an orthopedic surgeon, he often uses bone from one place in a patients body to replace bone elsewhere.

But this has its drawbacks. "Theres only so much bone you can get," he says, "and most of the places [from which] you can obtain tissue can be quite painful. If a patient comes in with a fractured forearm, for example, we might take bone from his hip. Six months later, he has no pain in the arm, but now complains of pain in the hip."

Sometimes, bone from a cadaver is used, but theres always the possibility of rejection or the transmission of disease. Dr. Laurencin has been working on developing new synthetic tissues that replace bone. These tissues also can serve as the means to deliver different types of drugs to help with the healing process. That could be particularly helpful in treating osteoporosis, for example.

"In the case of a fractured bone thats not healing well, I think there may be a way to use these implants and release factors that make the bone stronger than it was previously," Dr. Laurencin notes.

One of the fascinating realities of tissue engineering is that the source cells used for a great deal of research and product development come from tissue that normally would be thrown away. The skin tissue made by Advanced Tissue Sciences and Organogenesis comes from foreskin cells of newborn baby boys.

Stem cells, which are the basis for the bodys immune system and are used to treat a wide variety of cancers and blood disorders, are harvested from the blood thats drained from the umbilical cord as its cut. Frozen, these cells can be stored for years.

What both types of cells have in common is that they come from the earliest days of life.

"Foreskin tissue is a good source, not so much because its foreskin but because its from very young donors," says Dr. Nancy Parenteau, chief scientific officer at Organogenesis. "Youre ending up with tissue at the beginning of its life with a lot of growth potential. If you take a foreskin in the first day or two of life, youre harnessing all that potential."

Potential, indeed. One infant foreskin the size of a postage stamp provides enough cells to produce 200,000 units of bioengineered skin tissue, each three inches in diameter.

"If you really stop and think [about it], this is a hallmark event in medical care," Dr. Parenteau says. "You can go to the doctors office and get living tissue. Were on to a new era."

Dr. David Mooney at the University of Michigan, one of the leading researchers in the nation, says that advances in tissue engineering, combined with gene therapy, have tremendous implications for health care.

"It has the potential to one day allow us to repair or replace every tissue and organ in the body," he says. "It wont be five or 10 years from now, but over the long-run, we can replace and repair anything. Combine that with the work in genetics to prevent disease progression and well have a great ability to intervene."

But there is an ethical question. Did nature intend for bodies to progressively age, weaken and die