such as "Introduction", "Conclusion"..etc
Sticky is good. A University of California, San Diego bioengineer is the first author on an article in the journal Science
that provides insights on the "stickiness of life." The big idea is
that cells, tissues and organisms hailing from all limbs of the tree of
life respond to stimuli using basic biological "modules."
For example, the researchers outlined similar strategies across
biology for fulfilling the tasks of "sticking together" (cell-cell
interactions), "sticking to their surroundings" (cell-extracellular
matrix [ECM] interactions), and responding to forces.
Adam Engler, a bioengineering assistant professor from UC San
Diego's Jacobs School of Engineering, is the first author of the Review
article entitled "Multiscale Modeling of Form and Function" published
in the 10 April issue of the journal Science. According to Engler,
there is something inherent in the nature of the ever-present tasks of
sticking together and responding to forces that causes common form and
function to emerge. For example, even though the cells within bacteria,
fungi, sponges, nematodes and humans do not use exactly the same
proteins to stick together, all of these organisms rely on fundamental
components of cell-cell adhesions for survival. For this reason, the
capacity to form complex multilayer organisms through cell-cell
interactions is likely based on the evolutionary advantage to adhere to
new environments and survive in potentially hostile environments, the
The team also described a universal need for cells, tissues, organs
and organisms to respond to forces. Two examples of very different
biological structures that nevertheless rely on responsiveness to
forces for proper function are leg bones and breast acini. Breast acini
are hollow spherical objects at the ends of breast ducts that are made
of a layer of cells that secrete milk proteins. Breast acini form
hollow spheres, according to Engler, because this form maximizes the
surface to volume ratio. When pressure builds up, acini can hold more
and more volume until they need to push the milk proteins down the duct.
"This kind of structure is conserved in a variety of dissimilar
systems that respond to forces in a manner similar," said Engler. The
long bones of the human skeleton are another example, where their
elongated and cylindrical form optimizes the distribution of body
weight while remaining very light.
Engler hopes that the observations and connections he and his
coauthors make regarding the ubiquitous need for vastly different
cells, tissues, organs and organisms to use common biological modules
will encourage other scientists and engineers to think beyond their
specific areas of specialization.
"In our Science paper, I think we have arrived at an interesting way
to describe known biological processes and bring concepts together that
are traditionally not considered," said Engler. "I hope this paper will
encourage researchers to interact with disciplines previously assumed
to be dissimilar and foster new interdisciplinary interactions like we
have here at UCSD with the Institute for Engineering in Medicine."
Engler's primary appointment is in the Department of Bioengineering
at UC San Diego's Jacobs School of Engineering. The Department of
Bioengineering ranks 2nd in the nation for biomedical engineering,
according to the latest US News rankings. The bioengineering department
has ranked among the top five programs in the nation every year for the
Engler has secondary appointments in Material Science and Biomedical
Sciences. He is a member of the UCSD Stem Cell Institute and the UCSD
Institute for Engineering in Medicine.
Engler is a bioengineer and mechanical engineer by training. He
earned a Ph.D. in mechanical engineering from the University of
Pennsylvania, and went on to a post doctoral fellowship in molecular
biology at Princeton University before coming to UC San Diego in 2008.
He is already involved in a number of interdisciplinary collaborations
at UC San Diego.
One collaboration involves Engler, Shu Chien, who is University
Professor of Bioengineering and Medicine, and Director of UC San
Diego's Institute of Engineering in Medicine (IEM), and materials
science professor Sungho Jin from the Jacobs School of Engineering's
Mechanical and Aerospace Engineering (MAE) and NanoEngineering
departments. In a January 2009 paper in the journal PNAS, researchers
led by this team unveiled a new way to help accelerate bone growth
through the use of nanotubes and stem cells. This new finding could
lead to quicker and better recovery, for example, for patients who
undergo orthopedic surgery.
Engler's lab recently began a collaboration with Rick Lieber, Ph.D.,
Professor and Vice Chair of UC San Diego's Department of Orthopedic
Surgery and Director of the National Center for Skeletal Muscle
Rehabilitation Research, based at UC San Diego. Lieber is also Senior
Research Career Scientist at the Veterans Affairs San Diego Health
System. The team is trying to uncover the cause of unexplained lower
back pain in patients with no obvious disk degeneration, pinched nerves
or other known causes of lower back pain.
"No matter what your area of expertise, there is someone that has a
complementary area of expertise that can really help you ask new and
interesting questions," said Engler.
Mathematicians, engineers and stem cell biologists have not
traditionally worked together, but these kinds of interdisciplinary
collaborations have been the key to developing new techniques and new
disciplines, explained Engler, who told a story of how his own dabbling
into interdisciplinary research led to fruitful results.
As a graduate student, Engler helped put an experimental
stem-cell-based surgical technique into a more appropriate mechanical
context. The project began when he was approached by a surgeon puzzled
by the results he was getting after injecting stem cells into damaged
rat heart tissue in hopes of regenerating healthy heart tissue.
"As a matrix biologist and a mechanical engineer I said, 'Perhaps we
need to look at what the host tissue is actually doing. What is being
damaged and what is changing within the tissue due to the lack of
oxygen?'" Engler and his collaborators found the cells in the damaged
heart tissue were excreting collagen and making stiff scar tissue. "The
engineer in me then analyzed the mechanical properties of the tissue
and found out it was three to four times more rigid than the background
healthy muscle. The biologist in me then characterized the cells in
vitro and was able to show that these cells do respond to the
mechanical properties of their environment."
Engler published his findings in 2006 in the high profile journal
Cell and in the American Journal of Physiology. (Read New Scientist's
description of Engler's findings.) One idea for improving such
cell-based therapies, according to Engler, could involve injecting
"smarter stem cells" that have been programmed to respond to some
environmental stimuli but ignore other stimuli.
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