Neuronal differentiation of human neural stem cell grafts in adult rat spinal cord
Human neural stem cell grafts can show neuronal differentiation in the normal and injured spinal cord of adult rats. Researchers from Johns Hopkins University and Neuralstem Inc, led by Vassilis Koliatsos, grafted neural stem cell grafts derived from spinal cord of a single eight week fetus, into the lower spinal cord of normal or injured immune deficient adult rats. As part of the differentiation, the researchers found that some of these cells grew axons (the long arms of nerve cells) and some were able to form cell to cell contacts (synapses) with motor neurons of the host rats. These results challenge previous assumptions that the spinal cord is unable to support the differentiation of neurons from stem cell grafts.
Although these results are encouraging there is a long way to go before these results might be translated into benefit for patients. For example, although the researchers used neuron-specific cell markers to identify the cells derived from the stem cells, they did not show whether or not these cells can function correctly as neurons, such as by producing electrical impulses. In addition, they did not investigate whether there was any recovery of movement in the injured rats.
A related perspective article by Sally Temple and Natalia Lowry of Albany Medical College discusses the paper's findings further, stressing both the crucial need to repeat this work using different primary lines established from other human embryonic spinal cord cells, the necessity of using different animal models that are not immune deficient, and also the need for future studies that include behavioral analysis of the experimental animals.
Citation: Yan J, Xu L, Welsh AM, Hatfield G, Hazel T, et al. (2007) Extensive neuronal differentiation of human neural stem cell grafts in adult rat spinal cord. PLoS Med 4(2): e39.