ABSTRACT
Background and Objectives: The physiological oxygen tension in fetal brains (â¼3%, physioxia) is beneficial for the maintenance of neural stem cells (NSCs). Sensitivity to oxygen varies between NSCs from different fetal brain regions, with midbrain NSCs showing selective susceptibility. Data on Hif-1α/Notch regulatory interactions as well as our observations that Hif-1α and oxygen affect midbrain NSCs survival and proliferation prompted our investigations on involvement of Notch signalling in physioxia-dependent midbrain NSCs performance. Methods and Results: Here we found that physioxia (3% O2) compared to normoxia (21% O2) increased proliferation, maintained stemness by suppression of spontaneous differentiation and supported cell cycle progression. Microarray and qRT-PCR analyses identified significant changes of Notch related genes in midbrain NSCs after long-term (13 days), but not after short-term physioxia (48 hours). Consistently, inhibition of Notch signalling with DAPT increased, but its stimulation with Dll4 decreased spontaneous differentiation into neurons solely under normoxic but not under physioxic conditions. Conclusions: Notch signalling does not influence the fate decision of midbrain NSCs cultured in vitro in physioxia, where other factors like Hif-1α might be involved. Our findings on how physioxia effects in midbrain NSCs are transduced by alternative signalling might, at least in part, explain their selective susceptibility to oxygen.
ABSTRACT
BACKGROUND: Flow cytometry (FCM) is a co-criterion in myelodysplastic syndromes (MDS) diagnostics according to the WHO classification. The presented study compared diagnostic power and prognostic impact of different FCM-based scores. METHODS: A total of 807 bone marrow (BM) samples of patients with cytopenia (543 MDS, 153 non-clonal cytopenias, 111 non-MDS myeloid malignancies) and 78 healthy controls have been investigated using a standardized 8-color-FCM procedure. FCSS, Ogata-score, iFS, RED-score, and ELN-NEC were analyzed for sensitivity and specificity in comparison to standard diagnostic tools. Median follow up for patients was 26 month (range: 0.2-89). RESULTS: The iFS showed the highest accuracy (80%) with the best balance between sensitivity (79%) and specificity (86%). This was also valid in MDS with very low IPSS-R and even in MDS without ring sideroblasts, with normal blast count and karyotype, where iFS could confirm diagnosis in 62% and 65% of patients. Besides the high diagnostic power, the established iFS category "consistent with MDS" was associated with inferior overall survival (OS) independent from WHO classification (median: 51 month vs. not reached, p < 0.0001). Remarkably, this iFS category redefined a subgroup of patients with worse OS within IPSS-R low-risk category (73 month vs. not reached, p = 0.0433). Finally, multivariable analysis showed that iFS added independent prognostic information regarding OS besides IPSS-R. CONCLUSIONS: The iFS separates non-clonal cytopenias and MDS with the highest accuracy, provided information in addition to standard diagnostic procedures, and refined established prognostic tools for outcome prediction.
