Background: Complex carbohydrate structures, glycans, are essential components of glycoproteins, glycolipids, and proteoglycans. While individual glycan structures including the SSEA and Tra antigens are already used to define undifferentiated human embryonic stem cells (hESC), the whole spectrum of stem cell glycans has remained unknown. We undertook a global study of the asparagine-linked glycoprotein glycans (N-glycans) of hESC and their differentiated progeny using MALDI-TOF mass spectrometric and NMR spectroscopic profiling. Structural analyses were performed by specific glycosidase enzymes and mass spectrometric fragmentation analyses.

Human cord blood (CB)-derived CD133؉ cells carry characteristics of primitive hematopoietic cells and proffer an alternative for CD34 ؉ cells in hematopoietic stem cell (HSC) transplantation. To characterize the CD133 ؉ cell population on a genetic level, a global expression analysis of CD133 ؉ cells was performed using oligonucleotide microarrays. CD133؉ cells were purified from four fresh CB units by immunomagnetic selection. All four CD133؉ samples showed significant similarity in their gene expression pattern, whereas they differed clearly from the CD133 ؊ control samples. In all, 690 transcripts were differentially expressed between CD133؉ and CD133 ؊ cells. Of these, 393 were increased and 297 were decreased in CD133 ؉ cells. The highest overexpression was noted in genes associated with metabolism, cellular physiological processes, cell communication, and development. A set of 257 transcripts expressed solely in the CD133 ؉ cell population was identified. Colonyforming unit (CFU) assay was used to detect the clonal progeny of precursors present in the studied cell populations. The results demonstrate that CD133؉ cells express primitive markers and possess clonogenic progenitor capacity. This study provides a gene expression profile for human CD133 ؉ cells. It presents a set of genes that may be used to unravel the properties of the CD133 ؉ cell population, assumed to be highly enriched in HSCs. STEM CELLS 2006;24: 631-641

Somatic mutations contribute to tumorigenesis. Although these mutations occur in all proliferating cells, their accumulation under non-malignant conditions, such as in autoimmune disorders, has not been investigated. Here, we show that patients with newly diagnosed rheumatoid arthritis have expanded CD8+ T-cell clones; in 20% (5/25) of patients CD8+ T cells, but not CD4+ T cells, harbour somatic mutations. In healthy controls (n=20), only one mutation is identified in the CD8+ T-cell pool. Mutations exist exclusively in the expanded CD8+ effector-memory subset, persist during follow-up, and are predicted to change protein functions. Some of the mutated genes (SLAMF6, IRF1) have previously been associated with autoimmunity. RNA sequencing of mutation-harbouring cells shows signatures corresponding to cell proliferation. Our data provide evidence of accumulation of somatic mutations in expanded CD8+ T cells, which may have pathogenic significance for RA and other autoimmune diseases.

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