The Stem Cell Antigen Phenotype Of Glial Cells

Objective To examine the expression of neural stem cell marker on postnatal rat cortex-derived astrocytes and microglias. To provide biological evidence for further investigating the application of significane of these glial cells.Methods (1) Purified glial cells were isolated from newborn rat cortex according to their difference in adhesive potential. Immunocytochemistry labeling for cell-specific antigens had been done to characterize glial cells. (2) O-2A progenitor cells, freshly isolated and plated in 12 well plates and/or PLL-precoated coverslips, were substantially purified in DMEM+F-12 media supplemented with 2% B27,1% N2 and lOng/ml PDGF. Then these progenitor cells were induced to differentiate into T2A(type-2 astrocytes) in medium consisting of 20% FCS. Phenotypes of glial cells were identified by immunoflorescence labeling. (3) By immunoflorescence labeling, the expression of nestin, stage specific embryonic antigen (SSEA-1) and NG2 proteoglycan which served as stem cell markers were examined in astrocytes and microglias.Results (1) We show here that effective isolation of O-2A progenitors and TlA(type-1 astrocytes) from rat cerebral cortex was achieved by mechanical shaking and differential plating. OPC showed typical bipolar morphology and bipotentiality of oligodendrocyte and T2A differentiation. Further, each type of glial cells show their specific markers among which A2B5 were expressed in O-2A progenitor cells while GFAP were expressed in T1A.(2) We also show here that effective isolation of microglia from neonatal rat cerebral cortex was achieved by mechanical shaking and differential plating. They showed typical morphology and were OX42+.(3) O-2A progenitor cells which were fleshly isolated or cultured in PDGF for 7 days show apparent proliferation instead of differentiation, thus O-2A progenitor cells could be substantially purified following PDGF treatment.(4) O-2A progenitor cells in serum-free medium can quickly differentiate into oligodendrocyte whereas they can differentiate into A2B5+/GFAP+ T2A in medium consisting of 20% FCS.(5) Immuno-florescence labeling revealed that mature T2A showed immuno-reactivity for nestin, SSEA-1 and NG2 as well as microglia while no specific stem markers positive in T1A.Conclusions Our study reveals that specific markers of neural stem cells such as nestin, SSEA-1 and NG2 are differentially expressed in the purified glial cells. Both T2A and microglia are positive for nestin, SSEA-1 and NG2, implicating that they may share some characteristics of stem cell antigens. Our findings suggest that T2A and microglia may share some identities of the neural stem cells which indicates that these cells could be used as one potential cellular source for clinical investigations of central nervous system diseases.