Need muscle for a tough spot? Turn to fat stem cells

In diseases like muscular
dystrophy^[1] or a
heart
attack^[2], “muscle^[3]
begins to die and undergoes its normal wounding processes,”
said Engler, a bioengineering^[4]
professor at the Jacobs School of Engineering at UC San Diego.
“This damaged tissue is fundamentally different from a
mechanical perspective” than healthy tissue.

Transplanted stem
cells^[5] might be
able to replace and repair diseased muscle, but up to this
point the transplants haven’t been very successful in muscular
dystrophy patients, he noted. The cells tend to clump into hard
nodules as they struggle to adapt to their new environment of
thickened and damaged tissue.

Engler, postdoctoral scholar Yu Suk Choi and the rest of the
team think their fat-derived stem cells might have a better
chance for this kind of therapy, since the cells seem to thrive
on a stiff and unyielding surface that mimics the damaged
tissue found in people with MD.

In their study in the journal Biomaterials, the
researchers compared the development of bone marrow stem cells
and fat-derived stem cells grown on surfaces of varying
stiffness, ranging from the softness of brain tissue to the
hardness of bone.

Cells from the fat lineage were 40 to 50 times better than
their bone marrow counterparts at displaying the proper
proteins involved in becoming muscle. These proteins are also
more likely to “turn on” in the correct sequence in the
fat-derived cells, Engler said.

Subtle differences in how these two types of cells interact
with their environment are critical to their development, the
scientists suggest. The fat-derived cells seem to sense their
“niche” on the surfaces more completely and quickly than
marrow-derived cells. “They are actively feeling their
environment soon, which allows them to interpret the signals
from the interaction of cell and environment that guide
development,” Choi explained.

Perhaps most surprisingly, muscle
cells^[6] grown from
the fat stem cells fused together, forming myotubes to a degree
never previously observed. Myotubes are a critical step in
muscle development, and it’s a step forward that Engler and
colleagues hadn’t seen before in the lab.

The fused cells stayed fused when they were transferred to a
very stiff surface. “These programmed cells are mature enough
so that they don’t respond the environmental cues” in the new
environment that might cause them to split apart, Engler says.

Engler and colleagues will now test how these new fused cells
perform in mice with a version of muscular dystrophy. The cells
survive in an environment of stiff tissue, but Engler cautions
that there are other aspects of diseased tissue such as its
shape and chemical composition to consider. “From the
perspective of translating this into a clinically viable
therapy, we want to know what components of the environment
provide the most important cues for these cells,” he
said.
^[7]

Provided by University of California - San Diego (news^[8] :
web^[9])

References

1. ^{^} muscular dystrophy
   (www.physorg.com)
2. ^{^} heart attack
   (www.physorg.com)
3. ^{^} muscle
   (www.physorg.com)
4. ^{^} bioengineering
   (www.physorg.com)
5. ^{^} stem cells
   (www.physorg.com)
6. ^{^} muscle cells
   (www.physorg.com)
7. ^{^} cells
   (www.physorg.com)
8. ^{^} news
   (www.physorg.com)
9. ^{^} web
   (www.ucsd.edu)