Human Adult Stem Cells Benefit Mice After Stroke

Benefits apparently due to modulation of inflammatory and immune responses

TUESDAY, Sept. 16 (HealthDay News) -- Injection of human adult stem cells from the bone marrow into the brains of mice after a stroke can improve neurologic function, evidently due to modulation of inflammatory and immune responses, according to study findings published online Sept. 15 in the Proceedings of the National Academy of Sciences Early Edition.

Hirokazu Ohtaki, Ph.D., from Tulane University Health Sciences Center in New Orleans, and colleagues induced transient global ischemia (by carotid artery occlusion) in adult mice, then injected them with human mesenchymal stromal cells (hMSCs) in the hippocampus one day later.

The researchers found that the mice had improved neurologic function and much lower neuronal cell death in the hippocampus. The hMSCs persisted for less than seven days but down-regulated more than 10 percent of the 586 ischemia-induced mouse genes, which were largely involved in the inflammatory and immune response. The hMSCs also up-regulated three mouse genes, including a neuroprotective gene expressed by activated microglia/macrophages, and 170 genes were up-regulated and 54 genes were down-regulated in the hMSCs themselves. A number of genes were up-regulated in microglia/macrophages in the hippocampus, they note.

"The observed beneficial effects of hMSCs were largely explained by their modulation of inflammatory and immune responses, apparently by alternative activation of microglia and/or macrophages," Ohtaki and colleagues conclude.

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