Bone marrow-derived nonreactive astrocytes in the mouse brain after permanent middle cerebral artery occlusion

We studied the effect of permanent unilateral middle cerebral artery occlusion (PMCAO) on the generation of bone marrow (BM)-derived astrocytes in female mice previously transplanted with enchanced green fluorescent protein-expressing BM from male donors. In addition to an untreated PMCAO group, one group of mice also received intracerebral infusion of transforming growth factor-alpha, resulting in a decrease in the size of the infarct. Two months after PMCAO, we found a specific type of astrocyte of BM origin in the side of the injury, near the lesion. These astrocytes did not express glial fibrillary acidic protein (GFAP) by conventional fluorescence immunostaining; however, GFAP was easily detectable by tyramide signal amplification. These cells also expressed S100β, confirming their astrocytic character. Unlike the endogenous reactive astrocytes, these BM-derived astrocytes did not proliferate during the first week of ischemia and did not contribute to the glial scar formation. Transforming growth fac...