Biomedical engineering's brave new world

ASEE Prism, Apr 1999 by Schrof, Joannie M

Engineers are fighting disease and building healthier people, but the tough questions have yet to be answered.

While millions of people are eating carrots and tofu, sweating their way through workouts, and downing herbal concoctions in hopes of living longer, healthy human cells are just lounging around in petri dishes in Menlo Park, California, enjoying immortality, thanks to the biologists who decoded the aging mechanisms in the cells' DNA. Up the coast at the University of California, San Francisco, geneticist Roger Pederson leaves a collection of "stem" cells-the human cells that have not yet decided which of the 210 types of body tissue they will become-to themselves in a dish for two weeks, and returns to discover them all beating in unison as heart tissue.

The early days of an era that seems like science fiction are here. Biologists are beginning to understand what it takes to reverse or even stop human aging, to build fresh organs, and to alter the genes and proteins that make each one of us who we are. The medical possibilities are endless, the ethical dilemmas tougher than ever. Not only is medicine on a path to double the human life span, it may even revolutionize our notions of what constitutes the good life.

But none of this will ever come to fruition without the brainpower of a key group of professionals-engineers. Whether the goal is to make a drug stick to a tiny molecule within a blood vessel without getting washed away by the current, to grow structurally perfect organs and body parts, or to make a model of the body that will allow researchers to experiment on "virtual" human guinea pigs rather than real ones, bioengineers are crucial to today's most exciting medical advances.

In fact, National Institutes of Health Director Harold Varmus has declared that there no longer is such a thing as biology without engineering, and set up the Bioengineering Consortium at NIH to help usher in the new era of biomedicine. More than 40 universities now have both undergraduate and graduate bioengineering degree programs; at most schools it has become the fastest-growing enrollment category and, at some, bioengineering has already become the most popular engineering specialty.

New Body Parts

It's no wonder students are flocking to the field-biomedical engineers are in the mind-blowing business of literally building better humans. Tissue engineering is perhaps the most developed of the fledgling biomedical specialties; two types of cultured human tissue have already been approved by the Food and Drug Administration and are now in use. One is skin, grown by Advanced Tissue Sciences in huge sheets in a San Diego lab, cultured from, of all things, foreskin. The other is Genzyme's bioengineered cartilage, created by taking cells from a person's body, setting them inside a scaffolding made of a polymer that will dissolve over time, and manipulating the cartilage cells so that they will multiply and fill out the scaffolding in a shape and size tailored to fit the individual. The process is already used to replace knee and hip joints.

This same approach is being used to create full-fledged organs, such as a liver or a lung. By creating a scaffold shaped like a liver and "seeding" it with liver cells, researchers hope to encourage the growth of those cells in just the right way to create a functioning organ. In this way, physicians avoid transplant rejection by starting with cells taken from a patient's own liver. Already, researchers in Wisconsin have created an early version: a "bioartificial" liver, which is a set of liver cells housed inside a shell that is inserted into the body and acts like a liver, purifying the blood.

Virtual Patients

One of the best ways to find out how a new bit of tissue or organ-or for that matter a drug, surgery, or any other therapy-will affect the human body is to create a computerized model of the body that is sophisticated enough to respond to input. The first step in this modeling is combining information obtained from a variety of imaging methods-including computer tomography, magnetic resonance imaging (MRI), and optical imaging-to produce a single, very elaborate composite image. For example, at some medical centers, physicians preparing for hip replacement surgery can now image the patient's actual hip, then feed that data into a rapid prototyping machine that will create a 3-D model of the patient's hip for the doctor to hold and study to better prepare for surgery.

At Johns Hopkins University, bioengineer Raymond Winslow takes things a step further by actually treating a virtual heart. First, he prompts the computerized heart, created from reams of data that biologists have garnered for decades about how the heart functions, to have a virtual heart attack. Then, he can treat the heart with any number of virtual drugs to see how it responds. He also uses the model to better understand things like how congestive heart failure can lead to arrhythmia. Data from the model also helped prove that a new blood pressure medication was unlikely to cause arrhythmia, a dangerous side effect that has kept many other drugs off the market.