Global cerebral ischemia is basically the lack of blood flow and oxygenation to the brain, as is encountered during cardiac arrest. The prognosis when this occurs is very poor, with 33-50% of patients who have survived a witnessed cardiac arrest having severe neurological deficits. If a patient actually survives an unwitnessed cardiac arrest (which is rare, in and of itself), there has been a 100% rate of occurence for severe neurological deficit.
The only proven therapy to date, and the current standard of care, is to induce hypothermia. This lowering of body temperature is basically meant to decrease metabolism and swelling. However, this therapy is hard to deliver in practice, with many technical difficulties that can interfere with its overall effectiveness. Plus, there are complications associated with this, such as infection and blood clotting issues.
The Korean team found that stem cells given intravenously immediately after global ischemia had significant protective effects when compared to those rats not receiving stem cells. They looked at a variety of different end-points to analyze the efficacy of this therapy, and all results were promising.
- Stem cells reduced neuronal death after ischemia, as measured in the hippocampus of the brain. The hippocampus is known to be particularly vulnerable to delayed nerve death after an ischemic event.
- Stem cells diminished the disruption of the blood-brain barrier, by either restoring the barrier or actually protecting it from disruption.
- The stem cells also helped to reduce the damage to the blood vessels in the brain, and decreased the number of neutrophil blood cells that infiltrate the damaged area. Neutrophils tend to accumulate in areas of inflammation, so this reduction implies a decrease in the inflammatory response after ischemia.
- Stem cell therapy reduced the behavioral impairment, again implying that the neurological deficit was significantly less when compared to the non-stem cell rats.
All of these factors showed promise for a possible future treatment in ischemia-related scenarios. One limitation of this study is that it did not directly compare stem cell treatment with induced hypothermia (the current gold standard therapy). That would be a good study to see undertaken in the future in order to have a direct comparison, but this research still seems to show that stem cells are an effective treatment. This is very early reaearch, but promising nonetheless.
