His blue eyes pierce, even behind wire-rimmed glasses. Al Banes reels off a lightning-quick sentence that makes perfect sense to him.
“We’ve got cells in culture, we apply a cytokine-like interleukin one beta, and we ask the question — what percentage of those cells are turned on to make a matrix-degrading enzyme?”
Banes, professor of orthopaedics and biomedical engineering, took his laptop on his May 2004 honeymoon, fully planning to work. His fellow cruise-ship passengers shamed him into putting the computer away. “I had a great time,” he says, sounding almost surprised.
Banes, a former pole vaulter and boxer, is also president of Flexcell International Corporation, a biotech company he started in the 1980s. The company provides products and services to help researchers exercise cells in culture and grow bioartificial tissue.
For years, Banes and researchers around the world have been using Flexcell’s technology in the lab to study how skin, tendon, or ligament cells behave in response to strain. Sure, Banes would like to see Flexcell’s bioartificial tissue used in the human body. But he has grant proposals to write and students to mentor.
Enter Spero Karas, a team orthopaedic surgeon for Carolina varsity athletics who once tended to knees and shoulders as an associate team doctor for the Denver Broncos and Colorado Rockies. Karas is equally intense, his blue eyes accented by black hair. But while Banes explores ribosomes and cell matrices, Karas spends much of his days navigating people. Karas uses your name every few sentences, offers you water. In five minutes, midconversation, he answers the phone twice, first scheduling a Saturday golf game, then discussing surgery versus a cast for a nightclub owner who just wants to play basketball again. Without missing a beat, he returns to you with a smile.
Banes’ and Karas’ seemingly separate worlds intersected four years ago at a conference in Carolina’s orthopaedics department. A medical student who had done her research rotation with Banes was presenting her work, a study of how calcium blockers affected Flexcell’s bioartificial tendon tissue. “This was very experimental,” Karas says. “After the presentation, I said, ‘Al, you know, you’re looking at things that are very fascinating, but that quite frankly don’t have a lot of clinical applicability to the orthopaedic surgeon.’”
Banes wasn’t offended. Instead he asked, “Are you interested in doing something about it?”
Karas suggested they explore how tendon cells behave with a drug that’s readily available and already used in patients. “So we thought, what’s out there that’s safe, clinically relevant, FDA-approved?” Karas says. Banes adds, “It was Dr. Karas who said, ‘What about nandrolone decanoate?’” The drug, an anabolic steroid, is approved for use in speeding healing in, for example, burn victims, who can easily become catabolic — a state in which the body breaks down muscle to get energy.
Karas was thinking of all the injuries he sees in the rotator cuff, a group of four muscles and their related tendons that help lift and rotate the shoulder. “Rotator cuff problems probably make up forty percent of my practice,” Karas says. Some are in athletes, but many result from regular wear and tear, especially in people older than forty.
When a rotator cuff problem persists, the muscles can enter a catabolic state. “Big tears have less than ideal healing rates,” Karas says. “Anywhere from zero to sixty-three percent, depending on the study you read.” If nandrolone helps burn patients to heal, maybe it could help rotator cuff tendons heal too.
Karas brought in Ioannis Triantafillopoulos, a medical resident from Greece, to concentrate on this work. The team created a bioartificial version of the tendon that connects to the supraspinatus muscle, the most commonly injured muscle in the rotator cuff. To do that, Karas extracted a tiny number of human supraspinatus tendon cells from six volunteers who were already undergoing rotatorcuff surgery. Then the scientists put the cells into culture using Flexcell International’s tissue train plate. This plate grows cells on a flexible elastomer, which allows them to stretch, much as they would inside the body.
Years ago, Banes says, researchers had tried growing cells on hard plastic. “But later work showed that when strain was applied to the cells, they didn’t stretch so much as show a compression effect,” he says. These days, most doctors believe that stretching is vital to normal growth of tendon and muscle cells. Just days after surgery, Karas gets his patients into physical therapy — passive movement, with a therapist moving the patient’s arm while the patient rests. “When possible, I try to start physical therapy the next day,” Karas says. “It’s just I don’t have a clinic the next day, so I usually see them back the following week. But we try to achieve full range of motion immediately, with a passive stretch.”
So, in their bioartificial tendon study, the researchers used stretching as well. They grew the supraspinatus tendons under four conditions — treated with the steroid alone, with stretching alone, with steroid and stretching, and not treated at all.
The work, published June 2004 in The American Journal of Sports Medicine, shows that, compared to the other groups, the cells treated with stretching and steroid produced bioartificial tendons whose cells were stronger, regenerated faster, and were organized more like those of normal tendons.
What do normal tendon cells look like? “Tendon cells typically have elongated nuclei that are oval instead of round,” Karas says. Using digital cameras and microscopes, the researchers looked at the growing tendons up close. The tendons in the stretching-plus-steroid group had nuclei that were more oval than those in the other groups. And the actin filaments (a protein network that stiffens the cells) were elongated and organized “in a normal fashion,” Karas says. “They were more elongated vertically. You’ve got more filaments going in line with the actual tendon axis, as opposed to growing all over the place.”
To test the strength of the tendons, the researchers used Flexcell’s micromechanical materials-testing equipment, which measured how much strain the bioartificial tendons could stand before they would break. The tendons that had been treated with stretching and steroids as they grew could withstand much more strain than those in other groups. These tendons also showed a greater rate of regeneration or remodeling — a sign of faster healing. The researchers determined remodeling rates by, each day, measuring the total surface area and the width of the tendons; essentially, they measured how fast the tendons were growing.
Karas is excited that the study suggests a possible new clinical use for anabolic steroids — to help increase healing and regeneration after surgeries such as rotator cuff repairs. Steroids usually get public attention when an athlete is accused of illegally using them to improve performance. But the drugs have legitimate uses in helping to heal injuries, he says.
“There’s a whole area of appropriate indications for anabolic steroids that most people don’t even think about,” Karas says. The team plans to use animal testing to try to show that anabolic steroid injections can safely be used to aid healing of tendons after surgery.
But their ultimate goal is modifying the bioartificial tendon tissue, with steroids or other methods, so that doctors can use the tissue to augment surgical repairs such as those that Karas performs every week. A similar tissue-engineering procedure is already done in replacements of knee cartilage, for example.
The team will start by also testing the bioartificial tendon tissue in animals. After the success of their recent work, Banes is optimistic. “The animal experimentation, if we can get the funding to do that, we can complete this year,” he says.
That might seem quick. But not to Banes, not at this moment. At an hour-long meeting, when he isn’t talking, he writes on a legal pad. At meeting’s end, he hands Karas two pages of notes. “Here’s some ideas,” he says, “about how we might proceed.”
This research was funded by the National Institutes of Health.