Phenotyping clonal populations of glioma stem cell reveals a high degree of plasticity in response to changes of microenvironment.

The phenotype of glioma-initiating cells (GIC) is modulated by cell-intrinsic and cell-extrinsic factors. Phenotypic heterogeneity and plasticity of GIC is an important limitation to therapeutic approaches targeting cancer stem cells. Plasticity also presents a challenge to the identification, isolation, and propagation of purified cancer stem cells. Here we use a barcode labelling approach of GIC to generate clonal populations over a number of passages, in combination with phenotyping using the established stem cell markers CD133, CD15, CD44, and A2B5. Using two cell lines derived from isocitrate dehydrogenase (IDH)-wildtype glioblastoma, we identify a remarkable heterogeneity of the phenotypes between the cell lines. During passaging, clonal expansion manifests as the emergence of a limited number of barcoded clones and a decrease in the overall number of clones. Dual-labelled GIC are capable of forming traceable clonal populations which emerge after as few as two passages from mixed cultures and through analyses of similarity of relative proportions of 16 surface markers we were able to pinpoint the fate of such populations. By generating tumour organoids we observed a remarkable persistence of dominant clones but also a significant plasticity of stemness marker expression. Our study presents an experimental approach to simultaneously barcode and phenotype glioma-initiating cells to assess their functional properties, for example to screen newly established GIC for tumour-specific therapeutic vulnerabilities.

Review article: Adenosine use in the emergency department.

OBJECTIVE: To perform a review of the efficacy of adenosine, including its potential role as first-line treatment in unstable supraventricular tachycardia (SVT) and its use in wide complex tachycardias and diagnosing difficult arrhythmias. The dose and administration, nature and frequency of side-effects and relevant interactions and dosage adjustments are also discussed. METHODS: A search of the Medline database from 1950 to 2007 and the Embase Database from 1974 to 2007 was carried out. A manual search was performed of references of each article. RESULTS: Adenosine is efficacious at treating stable SVT, but it is no more effective than cheaper alternatives. It has a possible role in the first-line treatment of unstable SVT and is generally safe and effective when used to treat and/or diagnose wide complex tachycardias. There is a small risk of inducing serious arrhythmias, such as prolonged atrioventricular blockade and ventricular fibrillation. There is evidence that recommended initial doses for infants might be too low, but initial doses for children and adults are adequate. There is evidence that central venous administration requires lower doses, but there are no studies addressing peripheral sites of administration and size of flush. Minor and self-limiting side-effects are common. The need for dosage adjustments in the presence of interacting medications is well documented, but no studies have addressed how to rationally effect these adjustments. CONCLUSION: There is extensive evidence showing adenosine to be efficacious at treating SVT, but no more efficacious than cheaper alternatives. More studies are required to investigate other areas of adenosine use.