LIF Increases Muscle Satellite Expansion in Culture and Transplantation Efficiency

Transplantation of satellite stem cells, which are found in skeletal muscles, might potentially treat degenerative muscle diseases such as Duchenne muscular dystrophy. However, muscle satellite cells have an unfortunate tendency to lose their ability to be transplanted then they are grown in culture.

In order to generate enough cells for transplantation, the cells are isolated from the body and then they must be grown in culture. However, in order to properly grow in culture, the cells must be prevented from differentiating because fully differentiated cells stop growing and die soon after transplantation. Several growth factors, cytokines, and chemicals have been used in muscle satellite cell culture systems. Unfortunately, the optimal culture conditions required to maintain the undifferentiated state, inhibit differentiation, and enhance eventual transplantation efficiency have not yet been established satisfactorily.

Because it is impossible to extract enough satellite cells for therapeutic purposed from biopsies, these cells must be expanded in culture. However this very act of culturing satellite cells renders them inefficient for clinical purposes. How can we break away from this clinical catch-22?

Shin’ichi Takeda from the National Center of Neurology and Psychiatry and his colleagues have used growth factors to maintain muscle satellite cell efficiency during cell culture. In particular, Takeda and others used a growth factor called leukemia inhibitory factor (LIF). LIF effectively maintains the undifferentiated state of the satellite cells and enhances their expansion and transplantation efficiency. LIF is also thought to be involved in muscle regeneration.

This is the first study on the effect of LIF on the transplantation efficiency of primary satellite cells,” said Shin’ichi Takeda of the National Center of Neurology and Psychiatry. “This research enables us to get one step closer to the optimal culture conditions for muscle stem cells.”

The precise mechanisms by which LIF enhances transplantation efficiency remain unknown. Present work is trying to determine the downstream targets of LIF. Identifying the precise mechanisms by which LIF enhances satellite cell transplantation efficiency would help to clarify the functional importance of LIF in muscle regeneration, and, even more importantly, further its potential application in cell transplantation therapy.

The reference for this paper is: N. Ito et al., “Enhancement of Satellite Cell Transplantation Efficiency by Leukemia Inhibitory Factor,” Journal of Neuromuscular Diseases, 2016; 3 (2): 201. DOI: 10.3233/JND-160156.

Umbilical Cord Blood Mesenchymal Stem Cells do Not Cause Tumors in Rigorous Tests

Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) have the ability to self-renew and also can differentiate into a wide range of cell types. However, many clinicians and scientists fear that even these very useful cells might cause tumors.

To that end, Moon and colleagues from the Korean Institute of Toxicology have rigorously tested the tendency for hUBC-MSCs to cause tumors. They used a large battery of tests in living organisms and in culture. hUCB-MSCs were compared to MRC-5 and HeLa cells. MRC-5 cells are known to have no ability to cause tumors and HeLa cells have a robust ability to form tumors, and therefore, constitute negative and positive controls,

To evaluate the ability of cells to cause tumors, Moon and others examined the tendency of these cells to grow without being attached to a substratum. This is a hallmark of tumor cells and is called “anchorage-independent growth” (AIG). To assess AIG, the cells were grown in soft agar, which is a standard assay for AIG. hUCB-MSCs and MRC-5 cells formed few colonies in soft agar, but HeLa cells formed a greater number of larger colonies. This indicated that hUCB-MSCs and MRC-5 cells do not show AIG, a common trait of tumorigenic cells.

The next assay implanted these cells into live laboratory animals. hUCB-MSCs were implanted as a underneath the skin of BALB/c-nu mice (nasty creatures – they bite). All the mice implanted with hUCB-MSCs and NRC-5 cells showed any sign of tumors. Both gross and microscopic examination failed reveal any tumors. However, all mice transplanted with HeLa cells developed tumors that were clearly derived from the implanted cells.

These experiments, though somewhat mundane, rigorously demonstrate that hUCB-MSCs do not exhibit tumorigenic potential. This provides further evidence of these cells clinical applications.

The paper appeared in Toxicol Res. 2016 Jul;32(3):251-8. doi: 10.5487/TR.2016.32.3.251.