Hepatic progenitor cells from adult human livers for cell transplantation.

Objective: Liver regeneration is mainly based on cellular self-renewal including progenitor cells. Efforts have been made to harness this potential for cell transplantation, but shortage of hepatocytes and premature differentiated progenitor cells from extra-hepatic organs are limiting factors. Histological studies implied that resident cells in adult liver can proliferate, have bipotential character and may be a suitable source for cell transplantation. Methods: Particular cell populations were isolated after adequate tissue dissociation. Single cell suspensions were purified by Thy-1 positivity selection, characterised in vitro and transplanted in immunodeficient Pfp/Rag2 mice. Results: Thy-1+ cells that are mainly found in the portal tract and the surrounding parenchyma, were isolated from surgical liver tissue with high yields from specimens with histological signs of regeneration. Thy-1+ cell populations were positive for progenitor (CD34, c-kit, CK14, M2PK, OV6), biliary (CK19) and hepatic (HepPar1) markers revealing their progenitor as well as hepatic and biliary nature. The potential of Thy-1+ cells for differentiation in vitro was demonstrated by increased mRNA and protein expression for hepatic (CK18, HepPar1) and biliary (CK7) markers during culture while progenitor markers CK14, chromogranin A and nestin were reduced. After transplantation of Thy-1+ cells into livers of immunodeficient mice, engraftment was predominantly seen in the periportal portion of the liver lobule. Analysis of in situ material revealed that transplanted cells express human hepatic markers HepPar1 and albumin, indicating functional engraftment. Conclusion: Bipotential progenitor cells from human adult livers can be isolated using Thy-1 and might be a potential candidate for cell treatment in liver diseases

Tumor-associated fibroblasts (Part II): functional impact on tumor tissue

The article focuses on the functional impact of tumor-associated fibroblasts (TAF) on its surrounding cells. It intends to cover the recent knowledge on TAF, the phenotype, and expression profile of which have been described in the first part of the rev i ew series ( Kunz-Schughart and Knuechel, 2002). The present r ev i ew is subdivided into two main chapters: (1) functional impact of TAF on tumor cells and (2) fibroblast-host cell interactions in tumor tissue. In the first paragraph of chapter (1) about the role of fibroblasts in tumor cell growth and differentiation it is reve a l e d , h ow strongly cellular interaction is dependent on fibroblast and tumor cell type as well as the spatial ratio between the cells. The variation of cellular behav i o r depending on quantity of molecules holds also true for the group of ECM molecules, e.g. the balance between MMPs and TIMPs, which provide an interesting therapeutic target in tumor tissue. This is one of the topics addressed in the second paragraph which focuses on tumor cell dissemination. Chapter (2) addresses the relation of TAF to other intra- or peritumoral host cells. The hypoxia-related angiogenesis induction of fibroblasts via growth factor secretion (e.g. VEGF) is considered as important as the immune modulatory properties of fibroblasts on immune cells, such as m o n o cytes/macrophages. These cellular properties can be tested under controlled conditions in threedimensional heterologous cultures of human cells, p r oviding the chance for systematic modification to assess therapeutic effects in an in vivo like environment

Tumor-associated fibroblasts (Part I): active stromal participants in tumor development and progression?

Phenotypic and functional characteristics of tumor associated fibroblasts (TAF) in contrast to normal fibroblasts are re v i e wed in this first synopsis (part I). Terms as tumor stroma, desmo-plasia, T A F , myofibroblast, and fetal-type fibroblast are defined, and experimental systems to study heterologous cell interactions are presented. While we only start to gather information on the genotype of T A F , a broad range of data deals with the e xpression profile of these cells, co v ering e.g. ECM and ECM-modulating molecules, growth factors and cytokines. Summarizing the recent state of kno w l e d g e indicates that TAF provide sources for tumor diagnosis and therap y , that ha v e to be further defined in an or g an- s p e c i f ic approach in terms of the functional impact on the tumor cell and its environment (see part II)

Multicellular tumor spheroids: an underestimated tool is catching up again

The present article highlights the rationale, potential and flexibility of tumor spheroid mono- and cocultures for implementation into state of the art anti-cancer therapy test platforms. Unlike classical monolayer-based models, spheroids strikingly mirror the 3D cellular context and therapeutically relevant pathophysiological gradients of in vivo tumors. Some concepts for standardization and automation of spheroid culturing, monitoring and analysis are discussed, and the challenges to define the most convenient analytical endpoints for therapy testing are outlined. The potential of spheroids to contribute to either the elimination of poor drug candidates at the pre-animal and pre-clinical state or the identification of promising drugs that would fail in classical 2D cell assays is emphasised. Microtechnologies, in the form of micropatterning and microfluidics, are also discussed and offer the exciting prospect of standardized spheroid mass production to tackle high-throughput screening applications within the context of traditional laboratory settings. The extension towards more sophisticated spheroid coculture models which more closely reflect heterologous tumor tissues composed of tumor and various stromal cell types is also covered. Examples are given with particular emphasis on tumor-immune cell cocultures and their usefulness for testing novel immunotherapeutic treatment strategies. Finally, tumor cell heterogeneity and the extraordinary possibilities of putative cancer stem/tumor-initiating cell populations that can be maintained and expanded in sphere-forming assays are introduced. The relevance of the cancer stem cell hypothesis for cancer cure is highlighted, with the respective sphere cultures being envisioned as an integral tool for next generation drug development offensives

Mutant IDH1 Differently Affects Redox State and Metabolism in Glial Cells of Normal and Tumor Origin

Contains fulltext : 215221.pdf (publisher's version ) (Open Access)IDH1(R132H) (isocitrate dehydrogenase 1) mutations play a key role in the development of low-grade gliomas. IDH1(wt) converts isocitrate to alpha-ketoglutarate while reducing nicotinamide adenine dinucleotide phosphate (NADP(+)), whereas IDH1(R132H) uses alpha-ketoglutarate and NADPH to generate the oncometabolite 2-hydroxyglutarate (2-HG). While the effects of 2-HG have been the subject of intense research, the 2-HG independent effects of IDH1(R132H) are still ambiguous. The present study demonstrates that IDH1(R132H) expression but not 2-HG alone leads to significantly decreased tricarboxylic acid (TCA) cycle metabolites, reduced proliferation, and enhanced sensitivity to irradiation in both glioblastoma cells and astrocytes in vitro. Glioblastoma cells, but not astrocytes, showed decreased NADPH and NAD(+) levels upon IDH1(R132H) transduction. However, in astrocytes IDH1(R132H) led to elevated expression of the NAD-synthesizing enzyme nicotinamide phosphoribosyltransferase (NAMPT). These effects were not 2-HG mediated. This suggests that IDH1(R132H) cells utilize NAD(+) to restore NADP pools, which only astrocytes could compensate via induction of NAMPT. We found that the expression of NAMPT is lower in patient-derived IDH1-mutant glioma cells and xenografts compared to IDH1-wildtype models. The Cancer Genome Atlas (TCGA) data analysis confirmed lower NAMPT expression in IDH1-mutant versus IDH1-wildtype gliomas. We show that the IDH1 mutation directly affects the energy homeostasis and redox state in a cell-type dependent manner. Targeting the impairments in metabolism and redox state might open up new avenues for treating IDH1-mutant gliomas

Identification of three gene candidates for multicellular resistance in colon carcinoma

Solid tumours display elevated resistance to chemo- and radiotherapies compared to individual tumour derived cells. This so-called multicellular resistance (MCR) phenomenon can only be partly explained by reduced diffusion and altered cell cycle status; even fast growing cells on the surface of solid tumours display MCR. Multicellular spheroids (MCS) recapture this phenomenon ex vivo and here we compare gene expression in exponentially growing MCS with gene expression in monolayer culture. Using an 18,664 gene microarray, we identified 42 differentially expressed genes and three of these genes can be linked to potential mechanisms of MCR. A group of interferon response genes were also up-regulated in MCS, as were a number of genes that that are indicative of greater differentiation in three-dimensional cultures