The results of a study published in Stem Cell Reports indicate the electrical stimulation can be used to guide neural stem cells to the site of damaged brain tissue. This is a breakthrough finding since it will allow scientists to more minutely control stem cell treatment.
The flow of neural stem is normally controlled by chemical guides. This means that stem cells introduced into the brain end up in a default location. Scientists have been trying to more tightly control the flow of neural stem cells so that they can be directed to damaged brain tissue instead of healthy tissue at the default site.
Alan Trounson, a stem cell expert at Australia’s Hudson Institute, has led the study in which electrodes were applied to rat brains to coax neural stem cells to move towards the lateral ventricle and subventricular zone instead of the olfactory bulb which is the default site. The technique has great potential for clinical application as it would allow doctors to guide neural stem cells to severely damaged brain tissue.
Co-author of the study, Min Zhao, from UC-Davis explains that the effect of the electrical stimulation was unexpected. “We didn’t think it was possible to reverse the direction of flow of the cells,” he says. The chemicals that direct flow within the brain are very powerful. The experiments prove that electrical stimulation can overcome the commanding influence of these chemicals.
The group in Australia tagged human neural stem cells with a fluorescent marker and injected them into a migration stream in rat brains. This stream typically carries nerve cells to the olfactory bulb. However, the scientists then applied electrodes and changed the direction of the cell stream against the usual rostral migration stream. When tested 3 weeks and then again 4 months later, the effect was persistent and the stem cells were continuing to migrate to the target area and differentiate into the various types of brain cells.
Researchers are particularly interested in guiding neural stem cells to damaged tissue to treat conditions such as stroke and Parkinson’s disease which affect specific areas of the brain. The idea is to regenerate healthy neural cells in these areas to reverse the effects of the disease. In mammals, neural stem cells are stored deep in the brain and must travel long distances to the site of damage. Chemical cues do guide neural stem cells to damaged tissue, but the scientists wanted to develop a more direct approach for stem cell therapies.
Currently, scientists rely on chemical guides, both natural and those developed in the laboratory, to move cells to the desired location. Although past studies have shown that electrical stimulation is successful in coaxing a change in direction in a laboratory dish, this is the first time such results have been observed in a living animal. Since rodent brains are different from mammals, the next step is to test this concept in primates. As far as applying the technique to humans is concerned, the scientists acknowledge that a less invasive method than electrical stimulation needs to be evaluated. In the meantime, the findings are a big step forward in treating neurodegenerative diseases with stem cells in the future.