Project description:The paper describes a model of tumor invasion to bone marrow. Created by COPASI 4.26 (Build 213) This model is described in the article: Modeling invasion of metastasizing cancer cells to bone marrow utilizing ecological principles Kun-Wan Chen, Kenneth J Pienta Theoretical Biology and Medical Modelling 2011, 8:36 Abstract: Background: The invasion of a new species into an established ecosystem can be directly compared to the steps involved in cancer metastasis. Cancer must grow in a primary site, extravasate and survive in the circulation to then intravasate into target organ (invasive species survival in transport). Cancer cells often lay dormant at their metastatic site for a long period of time (lag period for invasive species) before proliferating (invasive spread). Proliferation in the new site has an impact on the target organ microenvironment (ecological impact) and eventually the human host (biosphere impact). Results: Tilman has described mathematical equations for the competition between invasive species in a structured habitat. These equations were adapted to study the invasion of cancer cells into the bone marrow microenvironment as a structured habitat. A large proportion of solid tumor metastases are bone metastases, known to usurp hematopoietic stem cells (HSC) homing pathways to establish footholds in the bone marrow. This required accounting for the fact that this is the natural home of hematopoietic stem cells and that they already occupy this structured space. The adapted Tilman model of invasion dynamics is especially valuable for modeling the lag period or dormancy of cancer cells. Conclusions: The Tilman equations for modeling the invasion of two species into a defined space have been modified to study the invasion of cancer cells into the bone marrow microenvironment. These modified equations allow a more flexible way to model the space competition between the two cell species. The ability to model initial density, metastatic seeding into the bone marrow and growth once the cells are present, and movement of cells out of the bone marrow niche and apoptosis of cells are all aspects of the adapted equations. These equations are currently being applied to clinical data sets for verification and further refinement of the models. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Heterogeneity among iPSC lines with regard to their gene expression profile and differentiation potential has been described and has been at least partly linked to the tissue of origin. We generated iPSCs from primitive (linneg) and non-adherent differentiated (linpos) bone marrow cells (BM-iPSC), and compared their differentiation potential to that of fibroblast-derived iPSCs (Fib-iPSC) and ESCs. In the undifferentiated state, individual iPSC clones but also ESCs proved remarkably similar when analyzed for alkaline phosphatase and SSEA-1 staining, endogenous expression of the pluripotency genes Nanog, Oct4, and Sox2, or global gene expression profiles. However, substantial differences between iPSC clones were observed after induction of differentiation, which became most obvious upon cytokine-mediated instruction towards the hematopoietic lineage. All three BM-iPSC lines derived from undifferentiated cells yielded high proportions of cells expressing the hematopoietic differentiation marker CD41, and in two of these lines, high proportions of CD41+/CD45+ cells were detected. In contrast, little hematopoiesis-specific surface marker expression was detected in linpos BM-iPSC and FIB-iPSC lines. These results were corroborated by functional studies demonstrating robust colony outgrowth from hematopoietic progenitors in two of the linneg BM-iPSCs only. Thus, in summary our data demonstrate efficient generation of iPSCs from primitive hematopoietic tissue as well as efficient hematopoietic redifferentiation for linneg BM-iPSC lines, thereby further supporting the notion of an epigenetic memory in iPSCs. Murine embryonic fibroblasts (MEFs) from C3H mice were cultured in low-glucose DMEM supplemented with 10% heat-inactivated fetal calf serum gold (PAA, Pasching, Austria), penicillin-streptomycin, 1 mM L-glutamine and 0.05 mM beta-mercaptoethanol on gelatine-coated dishes. C3H MEFs were grown to confluence, inactivated with 10 ug/ml Mitomycin C (Sigma) and used as feeder layers. Virus production was performed in a four plasmid-manner. Briefly, 3.5x10^6 293T cells were seeded 24h prior to transfection in 10 cm dishes. 293T cells were cultivated in high-glucose DMEM (Gibco) supplemented with 10% heat-inactivated FCS, penicillin-streptomycin and 1 mM L-glutamine. Cells were transfected with 5 ug lentiviral vector, 8 ug pcDNA3.GP.4xCTE (expressing HIV-1 gag/pol), 5 ug pRSV-Rev and 2 ug pMD.G (encoding the VSV glycoprotein) using the calcium phosphate method in the presence of HEPES and chloroquine. Supernatants were harvested 48h and 72h after transfection, filtered and subsequently 50x concentrated by ultracentrifugation. Titers determined based on real-time PCR, were in the range of 1-5x10^7/ml. For iPSC generation, bone marrow cells were isolated from femurs and tibias of Oct4-GFP transgenic mice (OG2) and immunomagnetically separated into lineage negative (Lin-) and lineage positive (Lin+) populations using the mouse lineage depletion kit (Miltenyi Biotec). Lin- cells were cultivated in serum-free StemSpan medium (Stem Cell Technology) supplemented with 2 mM L-glutamine, penicillin-streptomycin, 10 ng/ml mSCF, 20 ng/ml mTPO, 20 ng/ml, 20 ng/ml IGF-2 and 10 ng/ml FGF-1 (all Peprotech). Lin+ cells were cultivated in Iscove's modified eagle medium (IMDM), supplemented with 15% heat-inactivated FCS, 1 mM L-glutamine, penicillin-streptomycin, 100 ng/ml mSCF, 100 ng/ml mFLT3-L, 10 ng/ml hIL-3 and 100 ng/ml hIL-11. Both Lin- and Lin+ cells were pre-stimulated in the aforementioned media for 48 h. Thereafter, 2x10^5 Lin- and and Lin+ bone marrow cells were transduced on Retronection-coated plates (Takara) with lentiviral vectors encoding for human Oct4, Sox2, Klf4 and c-Myc using a multiplicity of infection (MOI) of 50 per virus. Twenty-four hours after transduction, media were supplemented with 2 mM valproic acid. Transduced bone marrow cells were kept in hematopoietic medium until 5 or 7 days post transduction (p.t.) and then transferred onto Mitomycin C-treated MEF feeders on gelatine-coated dishes. Henceforward, cells were cultivated in ES cell medium (knockout DMEM (Gibco), 15% ES-tested FCS, 1 mM L-glutamine, 0.1 mM non-essential amino acids (Gibco), 100 uM beta-mercaptoethanol (Sigma), penicillin-streptomycin and 103 units/ml leukemia inhibitory factor (LIF, provided by the Max-Planck-Institute, Munster, Germany). Upon appearance of GFP-positive ESC-like colonies, single colonies were picked based on morphology and GFP expression. Murine ESCs and iPSCs were cultured on Mitomycin C-treated MEF feeders in the aforementioned ES medium. Murine ESCs and iPSCs were passaged every 2-3 days. The murine embryonic fibroblast-derived iPSC lines (MEF-iPS, 3FLV2, 4FLV1) were generated by transduction of OG2-MEFs with the same lentiviral vector constructs using standard technology. For iPSC lines 3FLV2 and 4FLV1, complete reprogramming was demonstrated by alkaline phosphatase and SSEA1-staining, pluripotency factor expression and teratoma formation.

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