Eventually many people’s hips degenerate to the point that they can no longer walk. Faced with a life of being a cripple, they usually cave in and undergo the surgery we blithely call "hip replacement." But the truth is, the surgeon hammers the hip joint into a bone with a titanium rod and sews the patient back up. These hips work fine, for a decade or even two, but eventually they fail.
The problem is that bone and titanium do not bond well, but help is on the way. Jean Schwarzbauer, professor of molecular biology, and Jeffrey Schwartz, an organometallic chemist and professor of chemistry, both at Princeton University, are collaborating to improve the bond between titanium and human tissue.
Their work falls in the realm of biomedical engineering, a field made possible by advances in engineering in nanotechnology. "Nanotechnology in the generation of biosensors and microchips is a well developed field," says Schwarzbauer. "but over the last few years there has been more integration between nanotechnology and biology, developing ways to make bio-related devices and materials."
It is easy to manufacture something that is large, say an artificial heart, which has been around for a long time, but it is harder to create something microscopic. The smallest blood vessels, for example, are microns in diameter, and scientists have been exploring how to use new polymers to make artificial vessels. "We are not quite there, but we are approaching it," says Schwarzbauer.
Schwarzbauer will speak about her work at the fifth annual New Jersey Biomedical Engineering Showcase, titled "Biomaterials, Tissue Engineering and Regenerative Medicine: Expanding the Cure Corridor Through New Jersey and Beyond," on Friday, March 14, 8:30 a.m. to 2:30 p.m., at the Busch Campus Center in Piscataway. The other speakers are David Shreiber, assistant professor of biomedical engineering at Rutgers University; Mohamed Attawia, senior director at Osteotech; and Sheila MacNeil, professor of tissue engineering at Sheffield University. For registration and additional information, go to http://bmeshowcase.rutgers.edu
The conference is sponsored by New Jersey Institute of Technology, Rutgers, Princeton University, the University of Medicine and Dentistry of New Jersey, Stevens Institute of Technology, Kean University, and the Public Health Research Institute of Technology. Partners are BioNJ, the New Jersey Commission on Science and Technology, the New Jersey Commission on Spinal Cord Research, the HealthCare Institute of New Jersey, and the Biomedical Engineering Alliance for Industrial Internships.
The conference’s goal is to bring together scientists in academe and industry, entrepreneurs, and students working and studying in the biomedical engineering arena. There may be companies, for example, that have developed certain processes but do not see potential biological applications. And there are biologists, like Schwarzbauer, with expertise in certain biological activities but without the engineering knowledge that might lead to useful products.
At the conference presentations by scientists from industry and the university will be followed by panel discussions and poster sessions, with the goal of encouraging conversation about both science and policy issues in groups and between individuals. The hope is that synergies will result. "Princeton has no medical school," explains Schwarzbauer, "so people may not think of it as a place that biomedical engineering takes place. But a lot of the biology that underlays biomedical engineering is done here and there are collaborations between the engineering school and biologists."
Schwarzbauer’s own research on the proteins and genes that determine the size and shape of our organs offers evidence that biomedical engineering is alive and well on the Princeton campus. She works on what are called scaffolds, or frameworks of proteins that help organize the cells in an organ so that they do what they need to do.
Schwarzbauer’s lab studies scaffolds in three different ways.
The first is to look at organ development using nematodes, microscopic soil worms, as a model for human beings. These worms have many genes that function identically to those in worms and people. To figure out the effects these genes have in the body, Schwarzbauer creates mutant worms where they deactivate specific genes. By observing what has gone wrong in the mutant worms, they can deduce the gene’s role. The work with these microscopic worms has helped them figure out which molecules are most critical in a scaffold.
Schwarzbauer’s lab has also developed an in vitro model for wound healing, which mimics much of what occurs during the initial development of scaffolds and tissue, but at an accelerated pace. Because they are interested in the scaffold proteins involved in wound healing, they study blood clots, which are a type of scaffold.
The third approach is the collaboration with Schwartz, where they are trying to modify the surface of titanium to get better integration with the bone. Schwartz has developed ways to put patterns on metals that mimic the points at which tissue cells would normally bind to the scaffolds. The copy is so good that the cells are fooled and attach to the scaffold with a strong bond. The goal is to bind tissue cells to the titanium used for a hip prosthesis because it is strong and can bear heavy loads, and animal tests look promising.
Schwarzbauer got into biology early. Her grandfather had a butcher shop and bought two farms in the 1920s to provide beef and dairy products for his shop. Schwarzbauer grew up on a dairy farm in Wisconsin with 500 acres and 100 head of dairy cattle, run by her parents and uncle. For Schwarzbauer the result was an early biological education in all the essentials: "I saw things being born and things dying," she remembers.
In high school she got interested in chemistry and she received her bachelor’s degree from the University of Wisconsin, Milwaukee, in 1970. She moved to Madison for graduate school in molecular biology and got her doctorate in 1980, with work on bacterial ribosomes, which make proteins in the cell. She then decided she wanted to do something more related to mammals and found a postdoc at MIT where she started working on scaffold proteins. She left MIT in 1986 for Princeton University.
When Schwarzbauer was a postdoctoral fellow, most of the proteins that made up the scaffold were not known, and her work for the first 10 to 15 years involved figuring out what the molecules were and how they fit together. Today they still don’t know every protein, but do know enough to create scaffolds. Furthermore, progress in engineering has given them the jumpstart they need to develop biomedical products that might change peoples’ lives.
"The advances in the last 10 or so years have made some of the ideas thought of 30 years ago possible," says Schwarzbauer.