The umbilical cord contains an inexhaustible, noncontroversial source of stem cells for therapy. In the U.S., stem cells found in the umbilical cord are routinely placed into biohazardous waste after birth. Here, stem cells derived from human umbilical cord Wharton's Jelly, called umbilical cord matrix stem (UCMS) cells, are characterized. UCMS cells have several properties that make them of interest as a source of cells for therapeutic use. For example, they 1) can be isolated in large numbers, 2) are negative for CD34 and CD45, 3) grow robustly and can be frozen/thawed, 4) can be clonally expanded, and 5) can easily be engineered to express exogenous proteins. UCMS cells have genetic and surface markers of mesenchymal stem cells (positive for CD10, CD13, CD29, CD44, and CD90 and negative for CD14, CD33, CD56, CD31, CD34, CD45, and HLA-DR) and appear to be stable in terms of their surface marker expression in early passage (passages 4 -8). Unlike traditional mesenchymal stem cells derived from adult bone marrow stromal cells, small populations of UCMS cells express endoglin (SH2, CD105) and CD49e at passage 8. UCMS cells express growth factors and angiogenic factors, suggesting that they may be used to treat neurodegenerative disease. To test the therapeutic value of UCMS cells, undifferentiated human UCMS cells were transplanted into the brains of hemiparkinsonian rats that were not immune-suppressed. UCMS cells ameliorated apomorphine-induced rotations in the pilot test. UCMS cells transplanted into normal rats did not produce brain tumors, rotational behavior, or a frank host immune rejection response. In summary, the umbilical cord matrix appears to be a rich, noncontroversial, and inexhaustible source of primitive mesenchymal stem cells. STEM CELLS 2006;24:781-792

Wild-type, full-length (40-and 42-residue) amyloid β-peptide (Aβ) fibrils have been shown by a variety of magnetic resonance techniques to contain cross-β structures in which the β-sheets have an in-register parallel supramolecular organization. In contrast, recent studies of fibrils formed in vitro by the Asp23-to-Asn mutant of 40-residue Aβ (D23N-Aβ 1-40 ), which is associated with early onset neurodegeneration, indicate that D23N-Aβ 1-40 fibrils can contain either parallel or antiparallel β-sheets. We report a protocol for producing structurally pure antiparallel D23N-Aβ 1-40 fibril samples and a series of solid state nuclear magnetic resonance and electron microscopy measurements that lead to a specific model for the antiparallel D23N-Aβ 1-40 fibril structure. This model reveals how both parallel and antiparallel cross-β structures can be constructed from similar peptide monomer conformations and stabilized by similar sets of interactions, primarily hydrophobic in nature. We find that antiparallel D23N-Aβ 1-40 fibrils are thermodynamically metastable with respect to conversion to parallel structures, propagate less efficiently than parallel fibrils in seeded fibril growth, and therefore must nucleate more efficiently than parallel fibrils in order to be observable. Experiments in neuronal cell cultures indicate that both antiparallel and parallel D23N-Aβ 1-40 fibrils are cytotoxic. Thus, our antiparallel D23N-Aβ 1-40 fibril model represents a specific "toxic intermediate" in the aggregation process of a disease-associated Aβ mutant.Alzheimer's disease | amyloid structure | solid state NMR A lzheimer's disease (AD) is thought to be a consequence of aggregation of the amyloid β-peptide (Aβ) into amyloid fibrils or related assemblies in brain tissue. Numerous structural studies of Aβ fibrils and oligomers have been reported (1-17), motivated by the dual goals of contributing to preventive and therapeutic approaches to AD and of elucidating the biophysical basis for amyloid formation. A defining structural characteristic of an amyloid fibril is the presence of a cross-β motif; i.e., a ribbon-like β-sheet running the length of the fibril, with β-strands approximately perpendicular to and interstrand hydrogen bonds approximately parallel to the long fibril axis. Studies of the 40-residue and 42-residue forms of Aβ (Aβ 1-40 and Aβ 1-42 ) have shown that these peptides can form multiple distinct fibril structures (11,18,19), but that the cross-β motifs within wild-type (WT) Aβ fibrils are invariably comprised of in-register parallel β-sheets (1, 5, 6, 8-10, 13, 14). Parallel β-sheets have also been found in Aβ 1-40 oligomers (4) and in amyloid fibrils formed by amylin (20, 21), α-synuclein (22), β 2 -microglobulin (23, 24), prion proteins of yeast (25-27) and mammalian PrP (28, 29); in contrast, antiparallel β-sheets have been found in fibrils formed by Aβ fragments with 15 or fewer residues (30-32) and in amyloid-like crystals of certain Aβ fragments (33). These observations suggest that in-register parallel β-shee...

We compared gene expression profiles of mouse and human ES cells by immunocytochemistry, RT-PCR, and membrane-based focused cDNA array analysis. Several markers that in concert could distinguish undifferentiated ES cells from their differentiated progeny were identified. These included known markers such as SSEA antigens, OCT3/4, SOX-2, REX-1 and TERT, as well as additional markers such as UTF-1, TRF1, TRF2, connexin43, and connexin45, FGFR-4, ABCG-2, and Glut-1. A set of negative markers that confirm the absence of differentiation was also developed. These include genes characteristic of trophoectoderm, markers of germ layers, and of more specialized progenitor cells. While the expression of many of the markers was similar in mouse and human cells, significant differences were found in the expression of vimentin, beta-III tubulin, alpha-fetoprotein, eomesodermin, HEB, ARNT, and FoxD3 as well as in the expression of the LIF receptor complex LIFR/IL6ST (gp130). Profound differences in cell cycle regulation, control of apoptosis, and cytokine expression were uncovered using focused microarrays. The profile of gene expression observed in H1 cells was similar to that of two other human ES cell lines tested (line I-6 and clonal line-H9.2) and to feeder-free subclones of H1, H7, and H9, indicating that the observed differences between human and mouse ES cells were species-specific rather than arising from differences in culture conditions.

Human embryonic stem (huES) cells have the ability to differentiate into a variety of cell lineages and potentially provide a source of differentiated cells for many therapeutic uses. However, little is known about the mechanism of differentiation of huES cells and factors regulating cell development. We have used high-quality microarrays containing 16 659 seventy-base pair oligonucleotides to examine gene expression in 6 of the 11 available huES cell lines. Expression was compared against pooled RNA from multiple tissues (universal RNA) and genes enriched in huES cells were identified. All 6 cell lines expressed multiple markers of the undifferentiated state and shared significant homology in gene expression (overall similarity coefficient > 0.85). A common subset of 92 genes was identified that included Nanog, GTCM-1, connexin 43 (GJA1), oct-4, and TDGF1 (cripto). Gene expression was confirmed by a variety of techniques including comparison with databases, reverse transcriptase-polymerase chain reaction, focused cDNA microarrays, and immunocytochemistry. Comparison with published "stemness" genes revealed a limited overlap, suggesting little similarity with other stem cell populations. Several novel ES cell-specific expressed sequence tags were identified and mapped to the human genome. These results represent the first detailed characterization of undifferentiated huES cells and provide a unique set of markers to profile and better understand the biology of huES