The aims of our study were to verify whether it was possible to generate in vitro, from different adult human tissues, a population of cells that behaved, in culture, as multipotent stem cells and if these latter shared common properties. To this purpose, we grew and cloned finite cell lines obtained from adult human liver, heart, and bone marrow and named them human multipotent adult stem cells (hMASCs). Cloned hMASCs, obtained from the 3 different tissues, expressed the pluripotent state–specific transcription factors Oct-4, NANOG, and REX1, displayed telomerase activity, and exhibited a wide range of differentiation potential, as shown both at a morphologic and functional level. hMASCs maintained a human diploid DNA content, and shared a common gene expression signature, compared with several somatic cell lines and irrespectively of the tissue of isolation. In particular, the pathways regulating stem cell self-renewal/maintenance, such as Wnt, Hedgehog, and Notch, were transcriptionally active. Our findings demonstrate that we have optimized an in vitro protocol to generate and expand cells from multiple organs that could be induced to acquire morphologic and functional features of mature cells even embryologically not related to the tissue of origin.

To determine whether the peripheral blood in humans contains a population of multipotent progenitor cells (MPCs), products of leukapheresis were obtained from healthy donor volunteers following the administration of granulocyte colony-stimulating factor. Small clusters of adherent proliferating cells were collected, and these cells continued to divide up to 40 population doublings without reaching replicative senescence and growth arrest. MPCs were positive for the transcription factors Nanog, Oct3/4, Sox2, c-Myc, and Klf4 and expressed several antigens characteristic of mesenchymal stem cells. However, they were negative for markers of hematopoietic stem/progenitor cells and bone marrow cell lineages. MPCs had a cloning efficiency of ≈3%, and following their expansion, retained a highly immature phenotype. Under permissive culture conditions, MPCs differentiated into neurons, glial cells, hepatocytes, cardiomyocytes, endothelial cells, and osteoblasts. Moreover, the gene expression profile of MPCs partially overlapped with that of neural and embryonic stem cells, further demonstrating their primitive, uncommitted phenotype. Following subcutaneous transplantation in nonimmunosuppressed mice, MPCs migrated to distant organs and integrated structurally and functionally within the new tissue, acquiring the identity of resident parenchymal cells. In conclusion, undifferentiated cells with properties of embryonic stem cells can be isolated and expanded from human peripheral blood after granulocyte colony-stimulating factor administration. This cell pool may constitute a unique source of autologous cells with critical clinical import.

Oxidative stress is one of the most relevant contributors of cataractogenesis. To identify early protein targets of oxidative stress in lens cells, we used a differential proteomics approach to CD5A human epithelial lens cells treated with 500 µM H₂O₂ for 30 min. This dose of H₂O₂ was assayed to induce efficiently a block of cellular proliferation and to activate the oxidative stress-early inducible transcription factor EGR-1 (early growth response gene product 1), previously reported as stimulated factor in a model of cataractogenesis [Nakajima, Nakajima, Fukiage, Azuma and Shearer (2002) Exp. Eye Res. 74, 231–236]. We identified nine proteins, which sensitively reacted to H₂O₂ treatment by using two-dimensional gel electrophoresis and matrix-assisted laserdesorption ionization–time-of-flight-MS. In addition to cytoskeletal proteins (tubulin 1α and vimentin) and enzymes (phosphoglycerate kinase 1, ATP synthase β, enolase α, nucleophosmin and heat-shock cognate 54 kDa protein), which presented quantitative differences in expression profiles, peroxiredoxin and glyceraldehyde 3-phosphate dehydrogenase showed changes in pI as a result of overoxidation. Mass-mapping experiments demonstrated the specific modification of peroxiredoxin I active-site cysteine into cysteic acid, thus providing an explanation for the increase in negative charge measured for this protein. With respect to other global differential approaches based on gene expression analysis, our results allowed us to identify novel molecular targets of oxidative stress in lens cells. These results indicate that a combination of different approaches is required for a complete functional understanding of the biological events triggered by oxidative stress.

Background: Periostin is a secreted adhesion protein, normally expressed in mesenchime-derived cells. Aberrant expression of the periostin gene in epithelial tumours seems to play a role in angiogenesis and metastases. Aims: To investigate periostin expression in a consecutive series of breast carcinomas and correlate it with established biological and prognostic factors. Methods: A consecutive series of 206 breast carcinomas was investigated by immunohistochemistry with a specific antiperiostin antibody. Immunohistochemical expression of oestrogen and progesterone receptors, Ki-67 (MIB-1), HER-2/neu, VEGF-A, VEGFR-1 and VEGFR-2 was analysed. Periostin expression was also investigated in MCF-7 and MDA-468 cell lines by immunohistochemistry, western blot and quantitative RT-PCR. Localisation of periostin was investigated in MCF-7 cells by the green fluorescent protein (GFP) approach. Results: Periostin was highly expressed in carcinoma cells, but not in normal breast tissues. The pattern of expression was mainly cytoplasmic. However, in 12% of cases a nuclear reactivity was observed. Nuclear periostin significantly correlated with tumour size, and with expression of oestrogen receptor, progesterone receptor, VEGF-A, VEGFR-1 and VEGFR-2. A nuclear localisation of periostin was also observed in MCF-7 and MDA-468 cell lines. In MCF-7 cells the nuclear localisation of periostin was also shown by transfection of a vector expressing a GFP-periostin chimeric protein. Conclusions: Results indicate that the aberrant gene expression of periostin in breast cancer cells is associated with an abnormal nuclear localisation of the protein. The nuclear localisation of periostin in breast cancer may induce significant biological effects.