Spring is in the air on the campus of the University of Pennsylvania in Philadelphia. Students take their time going to class and staff members chat unhurriedly under newly budded trees outside a 19th -- century edifice known as the Wistar Institute.

Wistar has been a center for biology research at Penn for more than 100 years. Inside, the first floor appears to have changed little since its early days. A wide staircase with iron grillwork graces the center hall, and glass cases house the skeletons of long-dead animals and the notations of long-ago researchers in brown ink.

But to move to the second floor of Wistar is to take a trip in a time machine. Gone are the Victorian amenities, replaced by cubicles and computers, freezers and fax machines. These are the offices of the Institute for Human Gene Therapy, founded at Penn in late 1992 and presided over since March 1993 by Dr. James Wilson. Here, the spring weather doesn't seem to matter; everyone is hard at work and in a hurry.

THE WINNING EDGE

James Wilson

"I guess I'm a little nuts," says the 43-year-old doctor, who uses no alcohol or caffeine and works out with a personal trainer at his home three mornings a week from 5:30 to 6 a.m. Without this kind of discipline, he says, "you lose your edge." And that edge is what Wilson wants to keep in the race to develop gene therapy for human disease.

Under Wilson's intensive care, the IHGT has grown from a small academic unit at Penn to an institute at which 190 faculty members contribute their efforts toward gene therapy development in different diseases. Among the disorders being studied are muscular dystrophy, cystic fibrosis and other genetic diseases, as well as cancer, cardiovascular diseases and other conditions.

The first stop on a tour is the Human Applications Lab, affectionately known as "HAL." The environment here, a short walk from Wistar and the offices of the IHGT, is so sterile that visitors must don two gowns, a mask, cap, two types of booties and disinfectant-coated gloves just to enter its corridors.

Inside thick-walled rooms off these corridors is conducted some of the most important work of the institute -- developing viral "vectors," biological delivery vehicles designed to carry therapeutic genes into cells. One false move or one tiny bit of viral DNA from a technician's nose could delay a project for months, because these vectors must be made to exacting Food and Drug Administration standards; they're being created for human use.

"This is the kind of thing that's usually done by industry," Wilson says. But he has his reasons for wanting to do it here, and he's recruited the best and the brightest to do it, including molecular virologists Joseph Hughes and Nelson Wivel.

Hughes, Wilson's associate director of the Translational and Clinical Research Program, has a doctorate in microbiology and years of experience at the pharmaceutical companies Merck, Sharpe and Dohme, and Sterling Winthrop. Wivel, who's also an internist and a pathologist, was at the National Institutes of Health for 25 years and spent several years overseeing its Recombinant DNA Advisory Committee. He's been deputy director of the IHGT since Wilson recruited him in 1996.

'HOW WILL THIS HELP MY SON?'

Wilson seems to have always had a passion for science shot through with streaks of organizational skills and pragmatism. As early as his undergraduate days at Albion College in Albion, Mich., he knew he loved the physical sciences and chose chemistry as his major, but also considered alternative careers as a biologist or doctor and wondered how he could combine these ambitions.

In the spring of 1977, Wilson was interviewing for medical school at the University of Michigan in Ann Arbor and met Bill Kelley, a physician who was both chairman of the Internal Medicine Department and a professor of biochemistry. Wilson was impressed and decided to apply to one of the then fairly new physician-scientist programs, to earn an M.D. and a Ph.D. in seven years.

The meeting with Kelley would prove even more fortuitous. Wilson, ever one to get the jump on things, started working in Kelley's laboratory that summer of 1977 before school started. The lab was studying two types of "inborn errors of metabolism," conditions in which a flawed enzyme disrupts a key metabolic pathway, usually with disastrous consequences for patients.

One disorder under study by Kelley's group was ADA deficiency, in which a missing or flawed ADA enzyme leads to major disruptions in T cells, key players in the body's immune system. The result is a severe immunologic deficiency disease.

The other disorder was HPRT deficiency, another inborn error, in which a lack of a functional HPRT enzyme leads to major neurological deficits, including mental retardation and a bizarre self-mutilation syndrome that causes patients to bite through their own fingers and lips. It's also known as Lesch-Nyhan syndrome.

Even in 1977, doctors were aware that the root cause of these inborn errors was flawed DNA, but they lacked the tools to learn the precise DNA abnormalities, let alone the tools to fix them.

"At that time, we knew very little about specific genetic mutations that caused diseases," Wilson says. "There were probably about 25 papers on the subject."

Wilson was assigned to determine the structure of the normal HPRT enzyme, using an extremely laborious process called protein microsequencing, and to compare it to the structures of abnormal HPRT enzymes found in patients with Lesch-Nyhan syndrome.

He was successful, in a few patients, in determining the precise difference between their HPRT enzymes and a normal HPRT enzyme.

One patient was E.S., a 14-year-old boy from North Carolina who left a lasting impression on the young investigator. Wilson was often as-signed to accompany the sometimes difficult Lesch-Nyhan patients on journeys between their homes or institutions and the University of Michigan, where they were being studied.

At the Raleigh-Durham airport, E.S. became extremely agitated. "We had to strap him into a special movable seat," Wilson recalls. Escorting the agitated, retarded and self-mutilated teen-ager through the airport strapped into a chair, Wilson saw the boy's mother up ahead.

"I've got great news," he said eagerly to her hopeful face. "We've figured out what caused his disease."

The mother's face didn't match Wilson's for enthusiasm. "How will this help my son?" she asked.

Wilson was confused for a moment. "Then I knew," he says, "that if I was going to spend all this time doing all that work, I wanted to treat genetic diseases, not just study them. I knew that's what I was going to do."

NAVIGATING THE REGULATORY PATH

After earning his medical degree and a doctorate in biological chemistry in 1984, Wilson entered a residency training program in internal medicine at Massachusetts General Hospital in Boston. He spent two years "dreaming about gene therapy but not doing it." Then, in 1986, he moved to the Massachusetts Institute of Technology to study under Richard Mulligan, an expert in retroviruses, and learn techniques for working with DNA.

Mulligan was working on ADA deficiency, just as Kelley's lab had been nearly 10 years earlier. Wilson was interested in that disorder but decided to focus on another target for gene therapy -- familial hypercholesterolemia (FH). This is a genetic disorder in which blood cholesterol levels are sky-high, leading to strokes and heart disease, even in young children.

The genetic cause of FH is a defect in a protein known as the LDL receptor. These receptors sit on the surface of cells, particularly in the liver, and remove excess cholesterol from the blood. Once inside the liver cells, metabolic pathways actually suppress the synthesis of new cholesterol. Without functioning LDL receptors, the whole process is sabotaged; Wilson wanted to provide these proteins without doing organ transplants. He intended to do gene therapy instead.

One of the reasons for the choice was that Wilson thought the liver a particularly promising gene therapy target because of the nature of its cells and its role in metabolic processes.

Another was the story of S.J., a 6-year-old girl with FH who had been the subject of a case presentation during Wilson's residency program. The child's serum cholesterol level had been over 1,000, about five times the norm, and she had undergone liver and heart transplants.

In 1988, Wilson returned to the University of Michigan, this time as an assistant professor of internal medicine and biological chemistry.

Working first in rabbits, Wilson demonstrated that the genetic defect in FH could be repaired and serum cholesterol levels lowered. His strategy was to remove liver cells from the rabbits, inject them with new LDL receptor genes that had been inserted into retroviruses, and then reinject them back into the rabbits' livers.

In 1991, he got a chance to test the approach in humans. "We enrolled five patients, kids and adults. Three out of the five had significant, stable decreases in their serum cholesterols; two out of five didn't. All the cholesterol levels were still dangerously high. However, we had no patient complications and we navigated a regulatory path that had never been navigated when we started."

Wilson's was actually the second human gene therapy trial ever done. The first was one for ADA deficiency, conducted by French Anderson at the National Institutes of Health in 1990. In that trial, as in Wilson's, there were no complications, but no spectacular results either.

"We knew gene therapy had to become significantly more efficient," Wilson says.

GENE THERAPY FOR GENETIC DISEASE

A researcher at the IHGT examines a muscle sample with an electron microscope. The image appears on the computer screen.

In the spring of 1992, Wilson was advancing in his career at the University of Michigan, "figuring out how to run a lab" and thinking about gene therapy, particularly for cystic fibrosis, a genetic disease that mostly affects the lungs.

He was also thinking about whether he should make a move to industry to develop gene therapy. "I thought gene therapy would be very significant in its impact on medicine, in a broad way," he recalls.

"I wasn't convinced we could count on industry, though. Industry limits its investments to diseases in which there's a big up side and minimal risk. That's not gene therapy, and that's not inherited diseases. The market is too small."

By 1992, many people were taking gene therapy seriously, but, ironically, industry wasn't as interested in gene therapy for genetic diseases, the targets for which it had been originally developed. Biotechnology companies were turning their attention to marketing genetic diagnostic tests and to gene therapy for bigger diseases, such as cancer, hoping to deliver therapeutic genes that would act like cancer-killing drugs.

Late that spring, Wilson got a call from his former mentor, Bill Kelley, who had become dean of the School of Medicine at the University of Pennsylvania. He wanted to offer his former student the directorship of the new Institute for Human Gene Therapy at Penn.

"I thought long and hard about that decision," Wilson says. It meant giving up a prestigious position with substantial grants at Michigan and uprooting his growing family.

But, in the end, he decided to make the move, believing the IHGT would be the best place to bring his gene therapy dreams to fruition.

Ever the pragmatist, he also founded Genovo, a private corporation dedicated to gene therapy development, about the same time.

MOVING TO MUSCLE

Hansell Stedman

Wilson came to Penn not only as the IHGT director, but also as a professor of medicine, chief of the Division of Medical Genetics, and professor and chair of Molecular and Cellular Engineering. "They gave me enough authority to do what I needed to do," he says.

In 1997, he received a $3.2 million grant from MDA to develop gene therapy for muscular dystrophy. At the time, most of the animal gene therapy research in muscular dystrophy had been done in the Duchenne (DMD) form of the disease, and there were problems. (See "Overcoming Hurdles in Gene Therapy for DMD.")

Although fully committed -- then and now -- to developing gene therapy for DMD, by 1996, Wilson was looking at other options as a way to start on muscle gene therapy.

That year, two new ideas were taking center stage. One was that you could use one of four recently identified genes for muscle proteins known as sarcoglycans to do gene therapy for another form of muscular dystrophy -- a type known as limb-girdle dystrophy (LGMD).

The other was that you could put a sarcoglycan gene, which is much smaller than a dystrophin gene, into a virus that was beginning to get a lot of attention as a gene therapy vector -- the adeno-associated virus. Far less provocative to the immune system than the larger adenovirus being tried in DMD, the AAV would eventually be elected as the best gene therapy vehicle for muscle. "It goes in without an immune response, and it's stable," Wilson says of animal experiments.

Wilson had three people start working on the AAV in late 1995. He now has 15 working on various aspects of its development, including the possibility of delivering it to muscle tissue via the bloodstream.

Among the new recruits is Hansell Stedman, a young surgeon who lost two brothers to DMD and is as committed as anyone could be to the development of gene therapy for muscular dystrophies. Stedman is doing animal experiments to develop a systemic delivery system for vectors bearing muscle protein genes.

Wilson admits that moving from DMD to LGMD about a year ago was a hard choice. But, he says, "It's very important to start with a success. If we had had the technology, we would have done Duchenne. With the gutted adenovirus, that's starting to come along. If we can start with a success, that would help all of us in the field."

'I CONSIDER THIS A MARATHON'

Wilson works seven days a week and rarely leaves the university before 7:30 in the evening, after a day that begins by 6 a.m. with either a workout or office work. During the winter, he breaks up his weekend workdays to coach his children's basketball teams. The rest of the year, his recreation is mountain biking, running on a treadmill or lifting weights.

"I consider this a marathon," he says of his gene therapy goals. "You've got to have the stamina."