[Show abstract][Hide abstract] ABSTRACT: The therapeutic benefits of adult adherent stem cells are currently being investigated in clinical trials for a variety of diseases. Data from initial clinical studies are promising and as a consequence of moving to later stage clinical studies, have resulted in larger scale clinical-grade cell production strategies. Therefore it becomes imperative to examine the epigenetic flux and genomic stability of stem cells in long-term culture to determine that minimal risk is associated with these therapies. Multipotent adult progenitor cells (MAPC) are an adherent adult stem cell population that can be derived from bone marrow and was the first of a class of adult stem cells that have broad developmental potential both in vitro and in vivo. Here, we report a panel of tests to characterize MultiStem, a multipotent adult stem cell type based on MAPC, and establish its genomic stability during culture expansion. A variety of techniques were employed that consisted of miRNA expression to characterize and define the cell population; chromosomal SNP analysis and G-banding to determine karyotypic stability; and methylation pattern and telomerase expression to examine potential changes in epigenetic and chromosomal stability with prolonged in vitro culture of cells. This panel of test was applied to cultures at early isolation stages and compared to cultures harvested at population doublings greater than those reached in current MultiStem clinical trials. These tests also provide a baseline for quality control of cells prepared from various biological donor sources for subsequent large scale propagation and preparation of cell banks for downstream applications.
[Show abstract][Hide abstract] ABSTRACT: Recruitment and retention of circulating progenitor cells at the site of injured or ischemic tissues facilitates adult neo-vascularization. We hypothesized that cell therapy could modulate local neo-vascularization through the vascular endothelial growth factor (VEGF)/stromal cell-derived factor-1 (SDF-1) axis and by paracrine effects on local endothelial cells. We isolated from rat bone marrow a subset of multipotent adult progenitor cell-derived progenitor cells (MDPC). In vitro, MDPCs secreted multiple cytokines related to inflammation and angiogenesis, including monocyte chemotactic protein-1, SDF-1, basic fibroblast growth factor, and VEGF, and expressed the chemokine receptors CXCR4 and VEGFR1. To investigate in vivo properties, we transplanted MDPCs into the ischemic hind limbs of rats. Elevated levels of the chemokine SDF-1 and colocalization of CD11b(+) cells marked the initial phase of tissue remodeling after cell transplantation. Prolonged engraftment was observed in the adventitial-medial border region of arterioles of ischemic muscles. However, engrafted cells did not differentiate into endothelial or smooth muscle cells. Limb perfusion normalized 4 weeks after cell injection. Inhibition of SDF-1 reduced the engraftment of transplanted cells and decreased endothelial cell proliferation. These findings suggest a two-stage model whereby transplanted MDPCs modulate wound repair through recruitment of inflammatory cells to ischemic tissue. This is an important potential mechanism for cell transplantation, in addition to the direct modulation of local vascular cells through paracrine mechanisms.
Journal of Molecular Medicine 09/2008; 86(11):1221-32. DOI:10.1007/s00109-008-0390-7 · 4.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study examined whether transplantation of adherent bone marrow-derived stem cells, termed pMultistem, induces neovascularization and cardiomyocyte regeneration that stabilizes bioenergetic and contractile function in the infarct zone and border zone (BZ) after coronary artery occlusion.
Permanent left anterior descending artery occlusion in swine caused left ventricular remodeling with a decrease of ejection fraction from 55+/-5.6% to 30+/-5.4% (magnetic resonance imaging). Four weeks after left anterior descending artery occlusion, BZ myocardium demonstrated profound bioenergetic abnormalities, with a marked decrease in subendocardial phosphocreatine/ATP (31P magnetic resonance spectroscopy; 1.06+/-0.30 in infarcted hearts [n=9] versus 1.90+/-0.15 in normal hearts [n=8; P<0.01]). This abnormality was significantly improved by transplantation of allogeneic pMultistem cells (subendocardial phosphocreatine/ATP to 1.34+/-0.29; n=7; P<0.05). The BZ protein expression of creatine kinase-mt and creatine kinase-m isoforms was significantly reduced in infarcted hearts but recovered significantly in response to cell transplantation. MRI demonstrated that the infarct zone systolic thickening fraction improved significantly from systolic "bulging" in untreated animals with myocardial infarction to active thickening (19.7+/-9.8%, P<0.01), whereas the left ventricular ejection fraction improved to 42.0+/-6.5% (P<0.05 versus myocardial infarction). Only 0.35+/-0.05% donor cells could be detected 4 weeks after left anterior descending artery ligation, independent of cell transplantation with or without immunosuppression with cyclosporine A (with cyclosporine A, n=6; no cyclosporine A, n=7). The fraction of grafted cells that acquired an endothelial or cardiomyocyte phenotype was 3% and approximately 2%, respectively. Patchy spared myocytes in the infarct zone were found only in pMultistem transplanted hearts. Vascular density was significantly higher in both BZ and infarct zone of cell-treated hearts than in untreated myocardial infarction hearts (P<0.05).
Thus, allogeneic pMultistem improved BZ energetics, regional contractile performance, and global left ventricular ejection fraction. These improvements may have resulted from paracrine effects that include increased vascular density in the BZ and spared myocytes in the infarct zone.
[Show abstract][Hide abstract] ABSTRACT: Analogues of the natural product noscapine were synthesized and their potential as antitumor agents evaluated. The discovery of a novel regioselective O-demethylation facilitated the synthesis of the potent aniline 6, which arrests mammalian cells in the G2/M phase of the cell cycle at 0.1 μM and also affects tubulin polymerization. Aniline 6 is orally bioavailable and is 250-fold more potent than noscapine in reducing cell proliferation in rapidly dividing cells. copy; 2005 American Chemical Society.
[Show abstract][Hide abstract] ABSTRACT: Analogues of the natural product noscapine were synthesized, and their potential as antitumor agents were examined. The discovery of a novel regio- and stereoselective O-demethylation led to the synthesis of several O-alkylated analogues that induced an unexpected S-phase arrest of mammalian cells. Compound 4a was the most potent analogue inhibiting cell proliferation at an EC(50) of 1.9 microM.
[Show abstract][Hide abstract] ABSTRACT: Flap endonuclease-1 (FEN1) is a key enzyme involved in base excision repair (BER), a primary pathway utilized by mammalian cells to repair DNA damage. Sensitization to DNA damaging agents is a potential method for the improvement of the therapeutic window of traditional chemotherapeutics. In this paper, we describe the identification and SAR of a series of low nanomolar FEN1 inhibitors. Over 1000-fold specificity was achieved against a related endonuclease, xeroderma pigmentosum G (XPG). Two compounds from this series significantly potentiate the action of methyl methanesulfonate (MMS) and temozolamide in a bladder cancer cell line (T24). To our knowledge, these are the most potent endonuclease inhibitors reported to date.
[Show abstract][Hide abstract] ABSTRACT: There have been several recent reports of chemopotentiation via inhibition of DNA repair processes. Flap endonuclease 1 (FEN1) is a key enzyme involved in base excision repair (BER), a primary pathway utilized by mammalian cells to repair DNA damage. In this report, we describe the identification and SAR of a series of 2,4-diketobutyric acid FEN1 inhibitors.
[Show abstract][Hide abstract] ABSTRACT: Here we report the use of random activation of gene expression (RAGE) to create genome-wide protein expression libraries. RAGE libraries containing only 5 x 10(6) individual clones were found to express every gene tested, including genes that are normally silent in the parent cell line. Furthermore, endogenous genes were activated at similar frequencies and expressed at similar levels within RAGE libraries created from multiple human cell lines, demonstrating that RAGE libraries are inherently normalized. Pools of RAGE clones were used to isolate 19,547 human gene clusters, approximately 53% of which were novel when tested against public databases of expressed sequence tag (EST) and complementary DNA (cDNA). Isolation of individual clones confirmed that the activated endogenous genes can be expressed at high levels to produce biologically active proteins. The properties of RAGE libraries and RAGE expression clones are well suited for a number of biotechnological applications including gene discovery, protein characterization, drug development, and protein manufacturing.