Marjolein van der Meulen, assistant professor of mechanical and aerospace engineering, with a mechanical testing system in her Upson Hall laboratory. Doug Hicks
Marjolein van der Meulen, Cornell assistant professor of mechanical and aerospace engineering, has received a 1999 Faculty Early Career Development Program (CAREER) grant from the National Science Foundation (NSF) to continue her research into skeletal disorders such as osteoporosis.
The value of the four-year grant, which is for her project "Orthopaedic Biomechanics Research and Education," is $200,000.
Under the NSF grant, van der Meulen is exploring the effect of mechanical stimuli on the cross-sectional growth of mammalian bones. Exactly how the skeleton senses these stimuli and responds remains a mystery.
During a recent seminar at Cornell, van der Meulen said, "The response pathway is presumably a very complex cascade. It may be that certain things turn on different pathways, and they may actually have multiple things that are all leading to the same endpoint."
Her major area of research is mechanobiology, the field that examines the effect of mechanics on biological structures. The important applications of this work include improved understanding of the causes and possible prevention and treatment of osteoporosis. "We know that this response is either to form or to lose bone, but we don't know a lot about the stimulus and we don't know a lot about the pathway," van der Meulen said.
Mechanobiology differs from traditional biomechanics in that it focuses on mechanical influences on biology. Instead of treating bone as a conventional material and only measuring outcomes, like strength or energy absorption, mechanobiologists manipulate the mechanical environment to see how that changes the biological response and resulting structure.
Researchers have determined that the stimulus must be a dynamic load. "We know that there's something dynamic in the stimulus, but we don't know if it's strain rate, strain magnitude or amplitude, pressure or load-induced fluid flow. There's a whole host of things that it could be, and we don't know which or all of these are involved," van der Meulen said.
Much early engineering work in the field has relied solely on theoretical models, but because these have obvious limitations, van der Meulen's research focuses on integrating experiments with computational models.
One of her recent experiments studied the mechanical response pathway by experimentally reducing the mechanical forces experienced by weight-bearing limbs on normal and mutant mice. Using an animal mutation lacking a particular protein called morphogenetic protein- 5 (BMP-5), she examined whether the protein is a necessary part of the mechanical response pathway. She compared the response of the mice first to hind-limb suspension -- thus, reducing the load -- and then to overloading of the limbs, achieved by returning the mice to normal cage activity. The mice lacking BMP-5 showed no difference with unloading but had a delayed response to overloading, indicating a role of BMP-5 in this adaptive pathway.
Before joining the Cornell faculty in 1996, van der Meulen worked for three years as a biomedical engineer at the Rehabilitation R&D Center of the Department of Veterans Affairs in Palo Alto, Calif. As a graduate student at Stanford University, she received a NASA Graduate Student Researchers Fellowship and her experiments were conducted at NASA Ames Research Center, Mountain View, Calif. She obtained her bachelor's degree at the Massachusetts Institute of Technology in 1987 and her Ph.D. at Stanford in 1993, both in mechanical engineering.
This research also is funded by the National Institutes of Health.
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