January 05, 2004
NIST Research On Tissue Engineering

A pair of press releases from the National Institute of Standards and Technology (NIST) draw attention to efforts of NIST researchers to come up with assays and instrumentation to enable the acceleration of research on tissue engineering. Tissue engineering is a very important discipline for the development of the means to grow replacement organs and to fix existing organs and other tissues. I especially love research and engineering into tools and techniques that essentially enable other researchers to solve problems that provide direct benefit. The development of enabling tools and techniques can shrink the amount of time needed to do biomoedical research by years and even decades and, in my view, the development of enabling tools does not get the attention it deserves.

The first report is for a new technique for testing the biocompatibility of synthetic materials.

A new method for quantitatively measuring the compatibility of materials with living tissues has been developed by researchers at the National Institute of Standards and Technology (NIST). Described in a Dec. 11 presentation at the Tissue Engineering Society International's conference in Orlando, Fla., the technique should provide a more sensitive and reliable means to evaluate the biocompatibility of new materials for a wide range of applications from contact lenses to dental coatings to bone implants.

A paper outlining the new method has been accepted for publication in the Journal of Biomedical Materials Research.

The new method, which represents a novel application of existing bench-top scientific instruments, is a two-step process. The first step involves using a device called a polymerase chain reaction instrument to measure the levels of an organism's cytokines when exposed to a given material. Cytokines are signaling molecules released by white blood cells to protect the body from foreign materials. Higher levels of cytokine production generally indicate non-biocompatible materials have caused inflammation. The second step involves testing exposed cells for a specific protein in the cell membrane, the presence of which indicates cells are dying. This is a complementary test for more serious responses to materials because dying cells are often not capable of producing cytokines. The NIST tests were conducted on cultured mouse cells, which produce similar responses as whole tissues.

NIST post-doctoral researcher LeeAnn Bailey called the new method a "barometer" of biocompatibility.

Whereas current means to test biocompatibility produce a yes/no result that a material is minimally biocompatible or not, the new analysis can tell which materials are more biocompatible than others. Industry and researchers should be able to use this method to produce new materials for dentistry and other medical applications that are even more well matched to the human body.

The second report is about a technique to combine an optical coherence microscope and a confocal fluorescence microscope to watch deeply into tissue-engineering scaffolds to watch tissue growth.

In the November issue of Optics Express*, National Institute of Standards and Technology (NIST) scientists describe a novel combination of microscopes that can peer deep into tissue-engineering scaffolds and monitor the growth and differentiation of cells ultimately intended to develop into implantable organs or other body-part replacements.

The new dual-imaging tool provides a much needed capability for the emerging tissue engineering field, which aims to regenerate form and function in damaged or diseased tissues and organs. Until now, scrutiny of this complicated, three-dimensional process has been limited to the top-most layers of the scaffolds used to coax and sustain cell development.

Composed of biodegradable polymers or other building materials, scaffolds are seeded with cells that grow, multiply, and assemble into three-dimensional tissues. Whether the cells respond and organize as intended in this synthetic environment depends greatly on the composition, properties, and architecture of the scaffolds' porous interiors. Tools for simultaneously monitoring microstructure and cellular activity can help scientists to tease apart the essentials of this interactive relationship. In turn, such knowledge can speed development of tissue-engineered products ranging from skin replacements to substitute livers to inside-the-body treatments of osteoporosis.

NIST scientist Joy Dunkers and her colleagues paired an optical coherence microscope---a high-resolution probe of the scaffold interior---with a confocal fluorescence microscope---used to track cells stained with a fluorescent dye. The instruments provide simultaneous images that can be merged to create a comprehensive rendering of microstructure and cellular activity. By stacking the sectional images, they can create a top-to-bottom movie showing structural and cellular details throughout the scaffold's volume.

*J. P. Dunkers, M. T. Cicerone, and N. R. Washburn, "Collinear optical coherence and confocal fluorescence microscopies for tissue engineering," Optics Express, Vol. 11, No. 23, pp. 3074-3079. [http://www.opticsexpress.org].

If I could make one change in US government research funding policy I'd rechannel funding in biomedical sciences away from clinical trials and away from people who are trying to use existing tools and techniques and toward researchers who are developing new tools. So, for instance, some of the money spent sequencing genomes would be reallocated toward research in microfluidics and nanopore technology to develop new means of DNA sequencing that will eventually be orders of magnitude faster and cheaper. Also, I'd channel more money in the direction of people like the NIST researchers above who are working on enabling technologies for tissue engineering.

With the right set of tools any question can be answered very quickly. The fact that we are spending decades trying to develop cures for cancer, heart disease, degenerative neurological diseases and the like is a sign that our tools are inadequate for the problems which researchers are attempting to solve. We need better tools.

Share |      Randall Parker, 2004 January 05 03:45 PM  Biotech Organ Replacement

Fly said at January 7, 2004 3:41 PM:

Here's another tissue engineering advance:


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