Oct. 5, 2007
By Krishna Ramanujan
One day soon, laboratories may grow synthetically engineered tissues
such as muscle or cartilage needed for transplants. In a major step
forward, Cornell engineers describe in the journal Nature Materials a
microvascular system they have developed that can nourish growing
tissues.
The researchers have engineered tiny channels within a water-based
gel that mimic a vascular system at the cellular scale and can supply
oxygen, essential nutrients and growth factors to feed individual
cells. The so-called gel scaffold can hold tens of millions of living
cells per milliliter in a 3-D arrangement, such as in the shape of a
knee meniscus, to create a template for tissue to form.
In theory, the system could accommodate many kinds of tissue.
"A significant impediment to building engineered tissues is that you
can't feed the core," said Abraham Stroock, Cornell assistant
professor of chemical and biomolecular engineering and one of the
paper's senior authors. "Simply embedding this mimic of a
microvascular system allows you to maintain the core of the tissue
during culture." Gel scaffolds, he said, "are the culture flasks of
the future."
The embedded microchannels allow fluid with oxygen, sugar and
proteins to travel through the system. The researchers can control
the distributions of these solutes over both time and space within
the developing tissue, allowing the fine-tuning of the biochemical
environment of the cells while the tissue develops. For example, the
tissue may need to develop into bone on one side and cartilage on the
other. Now the researchers can supply the right nutrients and
proteins to certain parts of the growing tissue to ensure an intended
outcome.
The research provides solutions to the physical engineering aspects
of growing tissues synthetically. Still, many biological challenges
remain, such as finding a source of cells that can be harvested from
a patient and grown without changing the cell's characteristics. Co-
author Lawrence Bonassar, a Cornell associate professor of biomedical
engineering who was instrumental in developing the gel for tissue
growth and in determining the proper biological requirements for cell
growth, is also among those trying to direct stem cells to produce
desired tissue types. Currently, stem cell-derived cartilage has been
made but is not functional.
As new tools develop, researchers hope to use these engineered
tissues in non-clinical applications, such as replacements for
animals in the testing of pharmaceuticals and chemicals. The
technology, researchers believe, also offers the hope of growing
implants from the patient's own cells to replace damaged or diseased
tissue.
The research was funded by the Office of Naval Research, Cornell's
Nanobiotechnology Center, Beckman Foundation, the Center for Life
Science Enterprise at Cornell and the Cornell Center for Materials
Research.
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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