A specific microRNA, a short set of RNA (ribonuclease) sequences, naturally packaged into minute (50 nanometers) lipid containers called exosomes (see image), are released by stem cells after a stroke and contribute to better neurological recovery according to a new animal study by Henry Ford Hospital researchers. The important role of a specific microRNA transferred from stem cells to brain cells via the exosomes to enhance functional recovery after a stroke was shown in lab rats. This study provides fundamental new insight into how stem cells affect injured tissue and also offers hope for developing novel treatments for stroke and neurological diseases, the leading cause of long-term disability in adult humans. The study was published online on April 30, 2013 in Stem Cells. Although most stroke victims recover some ability to voluntarily use their hands and other body parts, nearly half are left with weakness on one side of their body, while a substantial number are permanently disabled. Currently, no treatment exists for improving or restoring this lost motor function in stroke patients, mainly because of mysteries about how the brain and nerves repair themselves. "This study may have solved one of those mysteries by showing how certain stem cells play a role in the brain's ability to heal itself to differing degrees after stroke or other trauma," says study senior author Michael Chopp, Ph.D., scientific director of the Henry Ford Neuroscience Institute and vice chairman of the department of Neurology at Henry Ford Hospital. The experiment began by isolating mesenchymal stem cells (MSCs) from the bone marrow of lab rats. These MSCs were then genetically altered to release exosomes that contain specific microRNA molecules. The MSCs then become "factories" producing exosomes containing specific microRNAs.
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