By: Kevin Chi
This is a summary of a paper published by a research group from Dusseldorf, Germany in the journal Brain.
Original article: Schira, J., Gasis, M., Estrada, V., Hendricks, M., Schmitz, C., Trapp, T., Kruse, F., Kögler, G., Wernet, P. and Müller, H.W. (2011) Significant clinical, neuropathological and behavioural recovery from acute spinal cord trauma by transplantation of a well-defined somatic stem cell from human umbilical cord blood. Brain 135; 431-446.
Stem cell therapy is a potential treatment strategy for spinal cord injury (SCI), as well as other neurological disorders. However, there is no agreement about the best source or type of stem cells for treatment of SCI.
In this study, published in Brain, the researchers used an animal model of acute SCI and transplanted only “unrestricted somatic stem cells” (USSCs). These are a type of stem cell retrieved from human umbilical cord blood, discovered by German researchers in 2004. These cells are pluripotent, meaning they can become nearly any type of cell, including nerve, bone, cartilage, liver, heart, or blood cells. After transplantation of USSCs into animals with acute SCI, the researchers noticed some very interesting results. However, it remains to be shown whether such pluripotent cells will bear an increased tumour risk.
What was the most important finding?
The researchers first showed that the USSC treatment promotes regrowth of axons — the connecting arms of nerve cells. They also showed that injured animals with the USSC treatment had smaller amounts of tissue damage.
In general, it is also important to look at functional outcomes, since smaller lesion sizes and regrowth of axons do not always translate into improvements in function. The axons must demonstrate sufficient regrowth and reconnection to result in actual improvements such as improved motor functions. In this study, the researchers examined several different functional outcomes in their animal model, all of which evaluated different aspects of locomotion: stepping, hindlimb movements, coordination of forelimbs and hindlimb, and paw placement. The results therefore showed that treatment with USSCs resulted in improved motor function.
What are some things we need to consider?
How do stem cell therapies actually result in functional improvements? It is often assumed that the healing effects of stem cells are a result of the cells specializing into cells that replace the tissue damaged in SCI. Interestingly, this study suggested that this assumption might not be true. Instead, the researchers found that there may be different mechanisms that explain the findings: they showed evidence that the USSCs release substances that may promote axon growth. Understanding exactly how stem cells accomplish their beneficial effects will do a great deal to optimize their use as treatments.
We must also take into consideration that this study was carried out in an animal model. Although this study does show promising results in the model, we must always be cautious in translating this to a human population. Many animal studies have shown promising treatments for SCI, but these results do not always translate into useful therapies for humans.
What does this mean for people with SCI?
Given the results seen in this animal model, USSCs may be a suitable stem cell source to provide clinical applications for people with SCI.