Researcher Profile: Jeffrey O. Hollinger

Jeffrey Hollinger is the director of the Bone Tissue Engineering Center. (credit: Jeffrey Hollinger) Jeffrey Hollinger is the director of the Bone Tissue Engineering Center. (credit: Jeffrey Hollinger)

Bone regeneration, the renewal of lost or damaged bone, is an important life process, yet it can also be harmful. Pathological bone often forms after orthopedic surgery or amputation and can lead to further complications in recovery. Jeffrey Hollinger, professor of biological sciences and biomedical engineering at Carnegie Mellon University, as well as the director of Carnegie Mellon’s Bone Tissue Engineering Center, is leading research to develop polymer-based treatments to eradicate pathological bone formation in soft tissue.

Despite his current position, Hollinger did not always plan on a career in biomedical engineering. Originally studying to be a dentist, Hollinger joined the Army where he began in general dentistry and eventually worked in oral surgery at the Walter Reed Army Institute of Research (WRAIR).

Hollinger obtained his Ph.D. in oncology through the army, after which he became the director of the bone program for the U.S. Army Institute of Dental Research. The team’s research involved disassembling bone and analyzing its structure. They determined that bone contains organic and inorganic components along with cells, and investigated the use of synthetic polymers seated with inorganic compounds.

Hollinger notes that much of their success came from the extensive funding they acquired. “We had money, we had people, and we had five thousand square feet of lab space,” Hollinger said. “Most of the ideas failed, but we published a lot and we were successful at getting Department of Defense grants. I think I was dead and gone to heaven.”

After retiring from the Army, Hollinger moved to Oregon and worked as a professor at the Oregon Health & Science University and the director of the Northwest Wound Healing Center. There, Hollinger continued his research with bone regeneration. “We had grants from the National Institutes of Health, the National Institute of Standards and Technology, as well as corporate grants,” Hollinger said. “We worked with organic matrices. We had a strong organic chemistry group, as well as a strong inorganic chemistry group.”

In 1999, Hollinger attended a Gordon Research Conference — a prestigious, international scientific conference — at the Holderness School in New Hampshire and was invited to give a seminar at Carnegie Mellon on tissue engineering.

“I had never heard the term tissue engineer before ... I don’t consider myself an engineer,” Hollinger said. Hollinger explained that his seminar, despite being geared more toward medical students, still contained engineering concepts. “I explained how we took apart bone and discovered it was made of collagen, an inorganic component, and cells. I think it resonated with them because engineers take things apart to make them work better.” After his lecture, Hollinger was offered a position at Carnegie Mellon as a professor of biological sciences and biomedical engineering. “I had never worked with engineers before,” Hollinger said. “It took some getting used to.”

Today, Hollinger is part of a research team at Carnegie Mellon that is responsible for investigating ways to prevent heterotopic ossification, the formation of bone tissue outside the skeleton. The researchers are investigating the use of nanostructured polymer composites, small structures made of multiple components, to deliver unique RNA into cells where heterotopic ossification occurs.

The research has many potential applications, namely with regards to amputation and bone trauma. Heterotopic ossification is highly prevalent in military personnel who sustain bone injuries or require amputations, as well as civilians who have major surgeries such as hip replacement operations. In these instances, it can cause pain and discomfort at the site of injury. The elimination of heterotopic ossification could improve recovery in patients who undergo these types of procedures due to bone trauma.

Although Hollinger did not originally intend to conduct the research he does now, he has the potential to greatly affect the future of bone trauma treatment. “It is really the work of my students,” Hollinger said. “I have had terrific students from undergraduate to graduate … it has been the highlight of my career.”