In a path-breaking discovery, researchers at University of Wisconsin-Madison have discovered a novel way to make large concentrations of skeletal muscle cells from human stem cells.
The new method could be used to generate large numbers of muscle cells and muscle progenitors directly from human pluripotent stem cells.
These stem cells, such as embryonic (ES) or induced pluripotent stem (iPS) cells, can be made into virtually any adult cell in the body.
"The novelty of this technique is that it generates a larger number of muscle stem cells without using genetic modification which is required by existing methods for making muscle cells," explained Masatoshi Suzuki, an assistant professor of comparative biosciences in school of veterinary medicine at University of Wisconsin-Madison.
Adapting a method previously used to make brain cells, Suzuki directed universal stem cells to become both adult muscle cells and muscle progenitors.
Importantly, the new technique grows the pluripotent stem cells as floating spheres in high concentrations of two growth factors - fibroblast growth factor-2 and epidermal growth factor.
These growth factors 'urge' the stem cells to become muscle cells.
"The new protocol avoids some techniques that would prohibit clinical applications. We think this new method has great promise for alleviating human suffering," added co-author Jonathan Van Dyke, a post-doctoral fellow in Suzuki's laboratory.
The new technique can also be used to grow muscle cells from iPS cells from patients with neuromuscular diseases like amyotrophic lateral sclerosis (ALS), spinal muscular atrophy and muscular dystrophy.
Thus, the technique could produce adult muscle cells in a dish that carry genetic diseases.
The new protocol incorporates a number of advantages.
First, the cells are grown in defined supplements without animal products such as bovine serum, enhancing the clinical safety for the muscle stem cells.
Second, when grown as spheres, the cells grow faster than with previous techniques.
Third, 40 to 60 percent of the cells grown using the process are either muscle cells or muscle progenitors, a high proportion compared to traditional non-genetic techniques of generating muscle cells.
"These cells could then be used as a tool for studying these diseases and screening potential drug compounds," Suzuki noted in a paper published in the journal Stem Cells Translational Medicine.
