Seaweed Transformed Into Stem Cell Technology
Engineers develop degradable scaffold that releases
stem cells in the body
Troy, N.Y. — Engineers at Rensselaer Polytechnic Institute
have transformed a polymer found in common brown seaweed into a
device that can support the growth and release of stem cells at
the site of a bodily injury or at the source of a disease.
The findings, which are detailed in the December 2007
edition of Biomaterials, mark an important step in
efforts to develop new medical therapies using stem cells.
The new stem cell scaffold. Circled in
black: a cluster of proliferating neural stem cells.
Circled in white: a separate microbead releases alginate
lyase that will break down the outer layer of the
scaffold, releasing stem cells into the body.
Photo credit: Rensselaer Polytechnic Institute/Randolph
“We have developed a scaffold for stem cell culture that can
degrade in the body at a controlled rate,” said lead researcher
Ravi Kane, professor of chemical and biological engineering.
“With this level of control we can foster the growth of stem
cells in the scaffold and direct how, when, and where we want
them to be released in the body.”
Kane and his collaborators, which include the author of the
paper and former Rensselaer graduate student Randolph Ashton,
created the device from a material known as alginate. Alginate
is a complex carbohydrate found naturally in brown seaweed.
When mixed with calcium, alginate gels into a rigid,
The device could have wide-ranging potential for use in
regenerative medicine, Kane explains. For example, the
scaffolds could one day be used in the human body to release
stem cells directly into injured tissue. Kane and his
colleagues hope that the scaffold could eventually be used for
medical therapies such as releasing healthy bone stem cells
right at the site of a broken bone, or releasing neural stem
cells in the brain where cells have been killed by diseases
such as Alzheimer’s.
Kane and his team encapsulated healthy neural stem cells in
the alginate mesh, producing a three-dimensional scaffold that
degrades at a tunable, controlled rate. Once the scaffold is
implanted in the body, the researchers use an enzyme called
alginate lyase, which eats away at alginate, to release the
stem cells. Alginate lyase is naturally produced in some marine
animals and bacterial strains, but not in humans.
In order to control the degradation of the alginate
scaffold, the researchers encapsulated varying amounts of
alginate lyase into microscale beads, called microspheres. The
microspheres containing the alginate lyase were then
encapsulated into the larger alginate scaffolds along with the
stem cells. As the microspheres degraded, the alginate lyase
enzyme was released into the larger alginate scaffold and
slowly began to eat away at its surface, releasing the healthy
stem cells in a controlled fashion.
The microspheres also can be filled with more than just
alginate lyase. “We can add drug molecules or proteins to the
microspheres along with the alginate lyase that, when released
into the larger alginate scaffold, could influence the fate of
the encapsulated stem cells,” Kane said. “By adding these
materials to the larger scaffold, we can direct the stem cells
to become the type of mature, differentiated cell that we
desire, such as a neuron. This will prove very valuable for
applications of stem cells in regenerative medicine.”
Kane and Ashton were assisted in their research by Professor
David V. Schaffer of the University of California at Berkeley;
Akhilesh Banerjee, a Rensselaer graduate student; and Supriya
Punyani, a Rensselaer postdoctoral associate.
The research was funded with a grant from New York
Contact: Gabrielle DeMarco
Phone: (518) 276-6542