Scientists at the Wake Forest School of Medicine have more fully characterized a stem cell that was isolated from muscle, but does not differentiate into muscle. Instead, this stem cells expresses several genes normally found in cells that inhabit the nervous system. These cells might serve as a source of material for the treatment of neurodegenerative diseases.
Osvaldo Delbono, professor of internal medicine at Wake Forest University and the senior author of this study said this: “Reversing brain degeneration and trauma lesions will depend on cell therapy, but we can’t harvest neural stem cells from the brain or spinal cord without harming the donor.”
Delbono continued, “Skeletal muscle tissue, which makes up 50% of the body, is easily accessible and biopsies of muscle are relatively harmless to the donor, so we think it may be an alternative source of neural-like cells that potentially could be used to treat brain or spinal cord injury, neurodegenerative disorders, brain tumors and other diseases, although more studies are needed.”
In 2011, Delbono and his colleagues isolated a stem cell from skeletal muscle that expressed several genes that you usually find in very young nervous tissue (the early neural marker Tuj1, light and heavy neurofilament for those who are interested). These cells did not express genes normally expressed in other tissues, such as smooth muscle or blood vessels.
Upon further characterization, the muscle-derived stem cells were able to respond to the neurotransmitter glutamate. This strongly intimates that these stem cells express the types of ion channels normally found in neurons. Also, these neural-like stem cells from muscle were clearly not derived from muscle satellite cells (another muscle stem cell population that produces skeletal muscle in response to muscle injury). Instead this stem cell is interspersed in between muscle fibers. These cells were also able to proliferate and survive in culture (see Birbrair, et al., PLoS ONE 6(2): e16816. doi:10.1371/journal.pone.0016816).
In this new publication, Delbono’s group isolated muscle-specific neural stem cells from non-human primates and aging mice and injected them into the brain. The injected cells not only survived in the brain, but also migrated the those areas of the brain where neural stem cells are located.
The next issue they addressed was whether or not these stem cells will induce tumors upon injection. Neither stem cells from non-human primates nor those from aged mice produced tumors upon injection into the brain or when injected under the skin.
Alexander Birbrair, a postdoctoral student in Debono’s laboratory and the first author in this paper said, “Right now, patients with glioblastomas or other brain tumors have a very poor outcomes and relatively few treatment options.” Birbrair continued: “Because our cells survived and migrated in the brain, we may be able to use them as drug-delivery vehicles in the future, not only for brain tumors but also for other central nervous system diseases.”
Delbono’s team is also investigating whether these neural-like cells also have the capability to differentiate into functional neurons in the central nervous system.
See Alexander Birbrair, et al., Skeletal muscle neural progenitor cells exhibit properties of NG2-glia. http://dx.doi.org/10.1016/j.yexcr.2012.09.008,