Isolation, characterization and cold storage of cells isolated from diseased explanted livers.

INTRODUCTION: Livers discarded after standard organ retrieval are commonly used as a cell source for hepatocyte transplantation. Due to the scarcity of organ donors, this leads to a shortage of suitable cells for transplantation. Here, the isolation of liver cells from diseased livers removed during liver transplantation is studied and compared to the isolation of cells from liver specimens obtained during partial liver resection. METHODS: Hepatocytes from 20 diseased explanted livers (Ex-group) were isolated, cultured and stored at 4°C for up to 48 hours, and compared to hepatocytes isolated from the normal liver tissue of 14 liver lobe resections (Rx-group). The nonparenchymal cell fraction (NPC) was analyzed by flow cytometry to identify potential liver progenitor cells, and OptiPrep™ (Sigma-Aldrich) density gradient centrifugation was used to enrich the progenitor cells for immediate transplantation. RESULTS: There were no differences in viability, cell integrity and metabolic activity in cell culture and survival after cold storage when comparing the hepatocytes from the Rx-group and the Ex-group. In some cases, the latter group showed tendencies of increased resistance to isolation and storage procedures. The NPC of the Ex-group livers contained considerably more EpCAM+ and significantly more CD90+ cells than the Rx-group. Progenitor cell enrichment was not sufficient for clinical application. CONCLUSIONS: Hepatocytes isolated from diseased explanted livers showed the essential characteristics of being adequate for cell transplantation. Increased numbers of liver progenitor cells can be isolated from diseased explanted livers. These results support the feasibility of using diseased explanted livers as a cell source for liver cell transplantation.

Microglia and astrocytes attenuate the replication of the oncolytic vaccinia virus LIVP 1.1.1 in murine GL261 gliomas by acting as vaccinia virus traps.

BACKGROUND: Oncolytic virotherapy is a novel approach for the treatment of glioblastoma multiforme (GBM) which is still a fatal disease. Pathologic features of GBM are characterized by the infiltration with microglia/macrophages and a strong interaction between immune- and glioma cells. The aim of this study was to determine the role of microglia and astrocytes for oncolytic vaccinia virus (VACV) therapy of GBM. METHODS: VACV LIVP 1.1.1 replication in C57BL/6 and Foxn1(nu/nu) mice with and without GL261 gliomas was analyzed. Furthermore, immunohistochemical analysis of microglia and astrocytes was investigated in non-, mock-, and LIVP 1.1.1-infected orthotopic GL261 gliomas in C57BL/6 mice. In cell culture studies virus replication and virus-mediated cell death of GL261 glioma cells was examined, as well as in BV-2 microglia and IMA2.1 astrocytes with M1 or M2 phenotypes. Co-culture experiments between BV-2 and GL261 cells and apoptosis/necrosis studies were performed. Organotypic slice cultures with implanted GL261 tumor spheres were used as additional cell culture system. RESULTS: We discovered that orthotopic GL261 gliomas upon intracranial virus delivery did not support replication of LIVP 1.1.1, similar to VACV-infected brains without gliomas. In addition, recruitment of Iba1(+) microglia and GFAP(+) astrocytes to orthotopically implanted GL261 glioma sites occurred already without virus injection. GL261 cells in culture showed high virus replication, while replication in BV-2 and IMA2.1 cells was barely detectable. The reduced viral replication in BV-2 cells might be due to rapid VACV-induced apoptotic cell death. In BV-2 and IMA 2.1 cells with M1 phenotype a further reduction of virus progeny and virus-mediated cell death was detected. Application of BV-2 microglial cells with M1 phenotype onto organotypic slice cultures with implanted GL261 gliomas resulted in reduced infection of BV-2 cells, whereas GL261 cells were well infected. CONCLUSION: Our results indicate that microglia and astrocytes, dependent on their activation state, may preferentially clear viral particles by immediate uptake after delivery. By acting as VACV traps they further reduce efficient virus infection of the tumor cells. These findings demonstrate that glia cells need to be taken into account for successful GBM therapy development.

Intratumoral INF-γ triggers an antiviral state in GL261 tumor cells: a major hurdle to overcome for oncolytic vaccinia virus therapy of cancer.

Oncolytic vaccinia virus (VACV) therapy is an alternative treatment option for glioblastoma multiforme. Here, we used a comparison of different tumor locations and different immunologic and genetic backgrounds to determine the replication efficacy and oncolytic potential of the VACV LIVP 1.1.1, an attenuated wild-type isolate of the Lister strain, in murine GL261 glioma models. With this approach, we expected to identify microenvironmental factors, which may be decisive for failure or success of oncolytic VACV therapy. We found that GL261 glioma cells implanted subcutaneously or orthotopically into Balb/c athymic, C57BL/6 athymic, or C57BL/6 wild-type mice formed individual tumors that respond to oncolytic VACV therapy with different outcomes. Surprisingly, only Balb/c athymic mice with subcutaneous tumors supported viral replication. We identified intratumoral IFN-γ expression levels that upregulate MHCII expression on GL261 cells in C57BL/6 wild-type mice associated with a non-permissive status of the tumor cells. Moreover, this IFN-γ-induced tumor cell phenotype was reversible.

Functionalizable silica-based micron-sized iron oxide particles for cellular magnetic resonance imaging.

Cellular therapies require methods for noninvasive visualization of transplanted cells. Micron-sized iron oxide particles (MPIOs) generate a strong contrast in magnetic resonance imaging (MRI) and are therefore ideally suited as an intracellular contrast agent to image cells under clinical conditions. However, MPIOs were previously not applicable for clinical use. Here, we present the development and evaluation of silica-based micron-sized iron oxide particles (sMPIOs) with a functionalizable particle surface. Particles with magnetite content of >40% were composed using the sol-gel process. The particle surfaces were covered with COOH groups. Fluorescein, poly-L-lysine (PLL), and streptavidin (SA) were covalently attached. Monodisperse sMPIOs had an average size of 1.18 µm and an iron content of about 1.0 pg Fe/particle. Particle uptake, toxicity, and imaging studies were performed using HuH7 cells and human and rat hepatocytes. sMPIOs enabled rapid cellular labeling within 4 h of incubation; PLL-modified particles had the highest uptake. In T2*-weighted 3.0 T MRI, the detection threshold in agarose was 1,000 labeled cells, whereas in T1-weighted LAVA sequences, at least 10,000 cells were necessary to induce sufficient contrast. Labeling was stable and had no adverse effects on labeled cells. Silica is a biocompatible material that has been approved for clinical use. sMPIOs could therefore be suitable for future clinical applications in cellular MRI, especially in settings that require strong cellular contrast. Moreover, the particle surface provides the opportunity to create multifunctional particles for targeted delivery and diagnostics.

RVG peptide as transfection reagent for specific cdk4 gene silencing in vitro and in vivo.

The rabies virus glycoprotein (RVG) peptide is known as a transfection reagent for systemic delivery of small interfering RNA (siRNA) into the brain. However, selective transfection of neuronal cells or specific brain regions remains a problem. In the present study, we show that the RVG peptide can efficiently be used as shuttle system to transfect neuronal cells with cdk4 siRNA leading to selective knockdown of cdk4 expression in vitro and in vivo. After transfection, cdk4 expression was reduced up to 75% in Neuro2A cells. Stereotactically injected RVG peptide delivered cdk4 siRNA specifically to neurons in the hippocampus, resulting in a specific knockdown of cdk4 expression up to 400 µm from the injection site. Further complexation studies of RVG peptide with larger molecules such as plasmid vectors or DNA fragments were also successfully performed and improved in vitro. Therefore, the peptide is not only a highly promising drug delivery system for siRNA and potentially other therapeutic molecules, but also a powerful tool to systematically analyze gene function in the brain under experimental settings in correlation to neurodegenerative disorders.

Transcriptional control of cell cycle-dependent kinase 4 by Smad proteins--implications for Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by deregulation of neuronal cell cycle and differentiation control eventually resulting in cell death. During brain development, neuronal differentiation is regulated by Smad proteins, which are elements of the canonical transforming growth factor ß (TGF-ß) signaling pathway, linking receptor activation to gene expression. In the normal adult brain, Smad proteins are constitutively phosphorylated and predominantly localized in neuronal nuclei. Under neurodegenerative conditions such as AD, the subcellular localization of their phosphorylated forms is heavily disturbed, raising the question of whether a nuclear Smad deficiency in neurons might contribute to a loss of neuronal differentiation control and subsequent cell cycle re-entry. Here, we show by luciferase reporter assays, electromobility shift, and RNA interference (RNAi) technique a direct binding of Smad proteins to the CDK4 promoter inducing transcriptional inhibition of cell cycle-dependent kinase 4 (Cdk4). Mimicking the neuronal deficiency of Smad proteins observed in AD in cell culture by RNAi results in elevation of Cdk4 and retardation of neurite outgrowth. The results identify Smad proteins as direct transcriptional regulators of Cdk4 and add further evidence to a Smad-dependent deregulation of Cdk4 in AD, giving rise to neuronal dedifferentiation and cell death.

An operational concept for long-term cinemicrography of cells in mono- and co-culture under highly controlled conditions--the SlideObserver.

Cell morphology, proliferation and motility, as well as mono- and heterotypic cell-to-cell interactions, are of increasing interest for in vitro experiments. However, tightly controlling culture conditions whilst simultaneously monitoring the same set of cells is complicated. Moreover, video-microscopy of distinct cells or areas of cells over a prolonged period of time represents a technical challenge. The SlideObserver was designed for cinemicrography of cells in co-and monoculture. The core elements of the system are the SlideReactors, miniaturised hollow fibre-based bioreactors operated in closed perfusion loops. Within the SlideReactors, cells can be cultured under adaptable conditions as well as in direct- and indirect co-culture. The independent perfusion loops enable controlled variation of parameters such as medium, pH, and oxygenation. A combined automated microscope stage and camera set-up allows for micrograph acquisition of multiple user-defined regions of interest within the bioreactor units. For proof of concept, primary cells (HUVEC, human hepatocytes) and cell lines (HuH7, THP-1) were cultured under stable and varying culture conditions, as well as in mono- and co-culture. The operational system enabled non-stop imaging and automated control of process parameters as well as elective manipulation of either reactor. As opposed to non-perfused culture systems or comparable devices for cinemicrographic analysis, the SlideObserver allows simultaneous morphological monitoring of an entire culture of cells in multiple bioreactors.

Neuroprotection against iron-induced cell death by perineuronal nets - an in vivo analysis of oxidative stress.

Perineuronal nets (PNs) are a specialized form of extracellular matrix, surrounding different types of neurons and mainly consist of chondroitin sulfate proteoglycans connected to hyaluronan, stabilized by link protein and cross-linked via tenascin-R. Due to their polyanionic character, caused by the highly charged chondroitin sulfate glycosaminoglycan and hyaluronan components, PNs might be involved in local ion homeostasis. They are able to scavenge and bind redox-active ions and thus reduce the local oxidative potential. We investigated whether netenwrapped neurons are less vulnerable against iron-induced oxidative processes. Oxidative stress is a key factor in the development and progression of neurodegenerative diseases like Alzheimer's and Parkinson's disease. Iron is believed to contribute to oxidative stress in Alzheimer brains by catalyzing the generation of free radicals. For examining potential neuroprotective effects of PNs, mice were microinjected with 0.2µl of a 20mM solution of FeCl3 into the barrel field while the control group received an equal volume of 0.9% NaCl. Brains were analyzed after time intervals of 24h and 72h. Neuronal degeneration was visualized using Fluoro-Jade B staining. The presence of PNs was assessed by Wisteria floribunda agglutinin histochemistry or aggrecan immunocytochemistry. The analysis showed a significant lower degeneration rate of net-ensheathed neurons in comparison to neurons without PNs. The results suggest a neuroprotective mechanism associated with the presence of PNs against iron-induced cell death.