In vitro differentiated neural stem cells express functional glial glutamate transporters.
The possibility to isolate stem cells from the adult central nervous system and to maintain and propagate these cells in vitro has raised a general interest with regards to their use in cell replacement therapy for degenerative brain diseases. Considering the critical role played by astrocytes in the control of glutamate homeostasis, we have characterised the expression of functional glutamate transporters in neural stem cells exposed to selected culture conditions favouring their differentiation into astrocytes. Commonly, neural stem cells proliferate in suspension as neurospheres in serum-free medium. The addition of serum or a supplement of growth factors (G5) to the culture medium was found to trigger cell adhesion on coated surfaces and to favour their differentiation. Indeed, after 7 days in these conditions, the vast majority of the cells adopted markedly distinct morphologies corresponding to protoplasmic (with serum) or fibrous (with G5 supplement) astrocytes and approximately 35-40% acquired the expression of the glial fibrillary acidic protein (GFAP). Immunocytochemical analysis also revealed that the treatments with serum or with the G5 supplement triggered the expression of the glial glutamate transporters GLT-1 (35 and 21%, respectively) and GLAST (29 and 69%, respectively). This effect was correlated with a robust increase in the Na+ -dependent [3H]-d-aspartate uptake, which was partially inhibited by dihydrokainate, a selective blocker of GLT-1. Together, these results indicate that in vitro differentiation of cultured neural stem cells can give rise to distinct populations of astrocytes expressing functional glutamate transporters.
Laboratoire de Pharmacologie Expérimentale (FARL), Université Catholique de Louvain 54.10, Avenue Hippocrate 54, B-1200 Brussels, Belgium.
Nicolas
N
Vanhoutte
Isabelle
I
de Hemptinne
Céline
C
Vermeiren
Jean-Marie
JM
Maloteaux
Emmanuel
E
Hermans
D027322:Amino Acid Transport System X-AG / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D026603:D-Aspartic Acid / Q000378:metabolism; D004622:Embryo, Mammalian; D005455:Fluorescent Antibody Technique / Q000379:methods; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D007608:Kainic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D009457:Neuroglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology
D027322:Amino Acid Transport System X-AG; D017077:Culture Media, Conditioned; D005904:Glial Fibrillary Acidic Protein; D007211:Indoles; C007293:DAPI; D026603:D-Aspartic Acid; C020889:dihydrokainic acid; D012964:Sodium; D007608:Kainic Acid