Characterlzation Of β-gactosidase Expression Of Rosaβgeo26mouse Brain And Neural Stem Cells

ROSAβgeo26 (ROSA26) mouse strain, derived from an embryonic stem cellline, expresses a LacZ reporter gene in all cells throughout embryonic developmentand has been useful as a marker line in bone marrow transfer experiments.β-galactosidase, which is the product of LacZ gene, is widely expressed in all tissuesof ROSA26 mouse strain. However, cellular distribution ofβ-galactosidase in thisstrain brain and utility of transgenic neural stem cells in transplantation remain to bedetermined. In the present study, we used X-Gal staining, Nissl staining,immunohistochemistry and immunocytochemistry to investigate characterization ofβ-galactosidase expression in ROSA26 mouse brain and neural stem cells. We foundthatβ-galactosidase was ubiquitously expressed in NSCs and neurons of newbornand adult ROSA26 mouse brains but down-regulated in astrocytes. Transgenic NSCsand astrocytes culture experiments further confirmed these in vivo findings.Consistently, transplantation experiments showed transgenic NSCs integrated intohost rat brain andβ-galactosidase activity remained in the differentiated neurons butnot astrocytes. The present study suggests that transgenic LacZ gene in ROSA26mouse is silenced during the differentiation of NSCs toward astroglial lineage and itmust be cautious to evaluate fate of transgenic cells in the host body intransplantation studies.