Human Stem Cells Can
Develop Into Functional
Muscle Tissue
The discovery by Weill Medical College of Cornell University
researchers that a specific type of human fetal stem cell can
co-differentiate simultaneously into both muscle and blood
vessel cells may unlock the door to therapies that replace
damaged tissue in the heart and other organs. This finding
could be a breakthrough in using stem cells to repair damaged
hearts.
Heart attacks and other events can destroy cardiac muscle
and the surrounding vasculature (blood vessels). Effective
heart repair requires concurrent replacement of both these
types of tissues. The new finding moves us one big step closer
to that goal, the investigators say.
“This discovery comes at a time when research into these
types of stem-cell-based regenerative therapies have faced
major hurdles,” said Dr. Shahin Rafii, Arthur B. Belfer
Professor of Genetic Medicine and newly announced Howard Hughes
Medical Institute (HHMI) investigator at Weill Cornell Medical
College in New York City.
Dozens of papers have confirmed the potential of bone-marrow-derived
stem cells to develop into cardiac tissue cells, and for a
while it looked like purified stem cells from adult bone marrow
might do the trick. However, those hopes were dashed last spring,
when a group of researchers found the ability of these stem
cells to incorporate into ailing heart tissue was much less
robust than originally thought.
“So, it was Ôback to the drawing board’ for
this type of stem-cell research,” said study lead author
Dr. Sergey V. Shmelkov, postdoctoral fellow working in Dr.
Rafii’s lab. Fortunately, for almost five years, the
Weill Cornell team had evidence that a specific type of stem
cell—bearing a surface antigen called CD133—was
unusually adept at differentiating (developing) into a myriad
of organ-specific cell types. While cells bearing this CD133
biomarker are very rare in adult tissues, they are particularly
abundant in the fetal liver.
“We wondered if, given the right conditions, these cells
might fulfill the requirement of growing into both myocytes
(muscle cells) and angiogenic (blood-vessel-wall) cells, both
of which are needed for efficient heart repair,” Dr.
Shmelkov explained.
Using human fetal liver
tissues, the Weill Cornell team isolated CD133+ stem cells,
and then bathed them in a culture rich in growth factors
and other biochemicals. “Importantly,
only stem cells with the CD133 antigen developed into endothelial
blood vessel cells and myocytes,” Dr. Rafii said. “Stem
cells without this surface antigen failed to do so.”
“This is really an important discovery,” Dr. Shmelkov
said, “Because it proves that, given the right micro-environmental
clues, we can encourage the regrowth of vascularized heart
tissue. Muscle cells need vasculature to grow and survive,
so we need to find stem cells capable of forming both myocytes
and angiogenic cells. We think we’ve found them.”
“All of these findings are re-igniting interest in using
these biochemically activated stem cells to regenerate vascularized
tissue,” Dr. Rafii said. “Some of our research
may even help find new sources of expandable CD133+ stem cells
within umbilical cord blood or adult bone marrow, livers, or
other organs.”
“Each year thousands of adults succumb to heart attack.
We hope our study will provide the impetus to initiate clinical
trials that can help ease the tremendous physical and socio-economic
burden caused by vascular diseases,” he added. #
