Repair capacity of adult rat glial progenitor cells determined by an in vitro clonogenic assay after in vitro or in vivo fractionated irradiation

Demyelination is one condition identified as a late response of the central nervous system (CNS) to irradiation. In the present study the repair capacity of glial stem cells was investigated and compared with the repair capacity of the CNS in vivo using functional endpoints. For this purpose, glial stem cells, derived from the adult rat optic nerve, were subjected to fractionated irradiation in vivo and in vitro and their survival was quantified with an in vitro clonogenic assay. The data were analysed by three different methods all based on the LQ-model (single dose survival curve; 'βRR', 'Fe-plot'). The resulting value of the β-parameter of adult glial stem cells is consistent with values obtained for functional endpoints after irradiation of the CNS in vivo. The α/β-ratio (4.9-7.3 Gy) of adult glial stem cells, however, is higher than the α/β-ratio (∼ 2 Gy) obtained for CNS in vivo and is closer to that of an acute responding tissue. (Author)