BackgroundThe growth and recurrence of several cancers appear to be driven by a population of cancer stem cells (CSCs). Glioblastoma, the most common primary brain tumor, is invariably fatal, with a median survival of approximately 1 year. Although experimental data have suggested the importance of CSCs, few data exist regarding the potential relevance and importance of these cells in a clinical setting.MethodsWe here present the first seven patients treated with a dendritic cell (DC)-based vaccine targeting CSCs in a solid tumor. Brain tumor biopsies were dissociated into single-cell suspensions, and autologous CSCs were expanded in vitro as tumorspheres. From these, CSC-mRNA was amplified and transfected into monocyte-derived autologous DCs. The DCs were aliquoted to 9–18 vaccines containing 107 cells each. These vaccines were injected intradermally at specified intervals after the patients had received a standard 6-week course of post-operative radio-chemotherapy. The study was registered with the ClinicalTrials.gov identifier NCT00846456.ResultsAutologous CSC cultures were established from ten out of eleven tumors. High-quality RNA was isolated, and mRNA was amplified in all cases. Seven patients were able to be weaned from corticosteroids to receive DC immunotherapy. An immune response induced by vaccination was identified in all seven patients. No patients developed adverse autoimmune events or other side effects. Compared to matched controls, progression-free survival was 2.9 times longer in vaccinated patients (median 694 vs. 236 days, p = 0.0018, log-rank test).ConclusionThese findings suggest that vaccination against glioblastoma stem cells is safe, well-tolerated, and may prolong progression-free survival.Electronic supplementary materialThe online version of this article (doi:10.1007/s00262-013-1453-3) contains supplementary material, which is available to authorized users.

It was long held as an axiom that new neurons are not produced in the adult human brain. More recent studies have identified multipotent cells whose progeny express glial or neuronal markers. This discovery may lead to new therapeutic strategies for CNS disorders, either by stimulating neurogenesis in vivo or by transplanting multipotent progenitor cells (MPCs) that have been propagated and differentiated in vitro. The clinical application of such approaches will be limited by the ability of these cells to develop into functional neurons. To facilitate an understanding of mechanisms regulating neurogenesis in the adult human brain, we characterized the developmental processes MPCs go through when progressing to a neuron. Human tissue was harvested during temporal lobe resections because of epilepsy, and cells were cultured as neurospheres. Our findings demonstrate that at an early stage, these cells often stain with neuronal markers without possessing any functional neuronal properties. Over a period of 4 weeks in culture, cells go through characteristic steps of morphological and electrophysiological development towards functional neurons; they develop a polarized appearance with multiple dendrites, whereas the membrane potential becomes more negative and the input resistance decreases [from -48 +/- 10 mV/557 +/- 85 MOmega (n = 15) between days 7 and 11 to -59 +/- 9 mV/380 +/- 79 MOmega (n = 9) between days 25 and 38, respectively]. Active membrane properties were first observed on day 7 and consisted of a voltage-gated K+-current. Later in the second week the cells developed voltage-gated Ca2+-channels and fired small Ca2+-driven action potentials. Immature Na+-driven action potentials developed from the beginning of the third week, and by the end of the fourth week the cells fired repetitive action potentials with a completely mature waveform generated by the combined action of the voltage-gated ionic channels INa, IA and IK. After 4 weeks, the newly formed neurons also communicated by the use of GABAergic and glutamatergic synapses. The adult human brain thus harbours MPCs, which have the ability to develop into neurons and in doing this follow characteristic steps of neurogenesis as seen in the developing brain.

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Multiple sclerosis is an inflammatory disease of the central nervous system characterized by inflammation, demyelination, axonal degeneration and accumulation of neurological disability. Previously, we demonstrated that stem cells constitute a possible endogenous source for remyelination. We now addressed the question of whether neurogenesis can occur in neuroinflammatory lesions. We demonstrated that, in experimental autoimmune encephalomyelitis, induced in rats 1,1'-dioctadecyl-6,6'-di(4sulphopentyl)-3,3,3',3'tetramethylindocarbocyanin(DiI)-labelled ependymal cells not only proliferated but descendants migrated to the area of neuroinflammation and differentiated into cells expressing the neuronal markers beta-III-tubulin and NeuN. Furthermore, these cells were immunoreactive for bromodeoxyuridine and PCNA, markers for cells undergoing cell proliferation. Using the whole-cell patch-clamp technique on freshly isolated 1, DiI-labelled cells from spinal cord lesions we demonstrated the ability of these cells to fire overshooting action potentials similar to those of immature neurones. We thus provide the first evidence for the initiation of neurogenesis in neuroinflammatory lesions in the adult spinal cord.