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Brain tumor invasion model system using organotypic brain-slice culture as an alternative to in vivo model

Abstractn Purpose. The primary cause of local recurrence and therapeutic failure in the treatment of malignant gliomas is the invasion of tumor cells into the surrounding normal brain. While it is known that malignant gliomas infiltrate diffusely into regions of normal brain, it is frequently very difficult to unequivocally identify the solitary invading glioma cell in histopathological preparations, or in experimental glioma models. We have developed an experimental invasion assay system, which allows us to track the solitary invasive glioma cell, using human brain tissue obtained from routine craniotomies for seizures or trauma.n Methods. This tissue is cut into 1-mm thick slices and cultured in the upper chamber of Transwell culture dishes on top of a 0.4-µm pore size polyester membrane, which is fed on medium provided in the lower chamber. Glioma cells are stably transfected with vectors containing a green fluorescent protein (GFP) cDNA. Stable, high-level expression GFP transfectants were selected by direct visualization under fluorescence microscope. In addition, various tumor spheroids are stained with vital dye, DiI, to track the invading cells. GFP-expressing glioma cells or stained spheroids were then implanted on the center of the brain slice, and the degree of brain tumor invasion into the brain tissue was evaluated at different time points by optical sectioning using a confocal microscope.n Results. We observed that GFP-expressing glioma cells or stained spheroids could be readily tracked and followed with this model system. Individual tumor cells that exhibited green or red fluorescence could be identified and their migration path through the brain slices unequivocally followed.n Conclusion. This experimental invasion system may be of considerable utility in studying the process of brain tumor invasion and in evaluating its invasiveness in individual brain tumor because it not only provides a better representation of extracellular matrix molecules normally encountered by invading glioma cells, but also provides the fluorescent tag applied to the tumor cells.

Protective effect of diet supplemented with rice prolamin extract against DNCB-induced atopic dermatitis in BALB/c mice.

BackgroundRice prolamin has been reported to possess antioxidative, anti-inflammatory and immune-promoting properties. This study is aimed to examine the protective effects of dietary rice prolamin extract (RPE) against dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD)-like skin lesions in mice.MethodsBALB/c mice were fed diet supplemented with 0–0.1xa0% RPE for 6xa0weeks. For the last 2xa0weeks, 1xa0% or 0.2xa0% DNCB was applied repeatedly to the back skin of mice to induce AD-like lesions. Following AD induction, the severity of skin lesions was examined macroscopically and histologically. In addition, the serum levels of IgE, IgG1 and IgG2a were determined by ELISA, and the mRNA expression of IL-4 and IFN-γ in the skin was determined by real-time PCR.ResultsDietary RPE suppressed the clinical symptoms of DNCB-induced dermatitis as well as its associated histopathological changes such as epidermal hyperplasia and infiltration of mast cells and eosinophils in the dermis. RPE treatment also suppressed the DNCB-induced increase in transepidermal water loss. Dietary RPE inhibited the DNCB-induced enhancement of serum IgE and IgG1 levels, whereas it increased the serum IgG2a level in DNCB-treated mice. In addition, dietary RPE upregulated the IFN-γ mRNA expression and downregulated the IL-4 mRNA expression in the skin of DNCB-treated mice.ConclusionsThe above results suggest that dietary RPE exerts a protective effect against DNCB-induced AD in mice via upregulation of Th1 immunity and that RPE may be useful for the treatment of AD.