Brains Of Immunodeficient Mice Research Articles

Genetic alterations and in vivo tumorigenicity of neurospheres derived from an adult glioblastoma

Pediatric brain tumors may originate from cells endowed with neural stem/precursor cell properties, growing in vitro as neurospheres. We have found that these cells can also be present in adult brain tumors and form highly infiltrating gliomas in the brain of immunodeficient mice. Neurospheres were grown from three adult brain tumors and two pediatric gliomas. Differentiation of the neurospheres from one adult glioblastoma decreased nestin expression and increased that of glial and neuronal markers. Loss of heterozygosity of 10q and 9p was present in the original glioblastoma, in the neurospheres and in tumors grown into mice, suggesting that PTEN and CDKN2A alterations are key genetic events in tumor initiating cells with neural precursor properties.

Anti-invasive effect of an anti-matrix metalloproteinase agent in a murine brain slice model using the serial monitoring of green fluorescent protein-labeled glioma cells.

We aimed to analyze the anti-invasive effect of the anti-matrix metalloproteinase (anti-MMP) agent SI-27 by quantitative tracking of enhanced green fluorescent protein (EGFP)-labeled human malignant glioma cell lines in a brain slice model. Persistent expression of EGFP in human malignant glioma cell clones (U87MG, U251MG, and U373MG) was established with the use of the pEGFP-C1 vector. Tumor spheroid in 1 microl Matrigel was implanted into the caudate nucleus-putamen of a severe combined immunodeficient mouse brain slice. To allow the quantitative assessment of tumor cell invasion, the invasion area index was measured on Days 1, 3, 5, and 7 with a fluorescence stereomicroscope and an image analyzer in the presence of various concentrations of SI-27 (0, 1, 10, 50, or 100 microg/ml). In the control group (0 microg/ml), all glioma cell lines invaded in a fingerlike fashion and reached the contralateral hemisphere through the corpus callosum. SI-27 at concentrations of 10, 50, and 100 microg/ml significantly suppressed the invasion area index on Days 5 and 7 in a dose-dependent manner, whereas 1 microg/ml had no effect. Transmission electron microscopy and laser confocal microscopy indicated that the tumor cells had penetrated the brain slice and that the normal structural integrity of the brain was maintained until Day 7. This model enabled unequivocal periodic tracking of individual invading tumor cells in normal brain. The significant suppression of glioma cell invasion by noncytotoxic concentrations of SI-27 indicates that anti-MMP treatment may represent an important future therapeutic strategy for malignant cerebral neoplasms.

Neurovirulent strains of Alphavirus induce apoptosis in bcl-2-expressing cells: role of a single amino acid change in the E2 glycoprotein.

The isolation and sequence comparison of avirulent and neurovirulent strains of polio virus, alpha virus, herpes virus, immunodeficiency virus, and other viruses have identified genetic changes that are required to cause disease in the nervous system. The molecular mechanisms by which these genetic changes result in neurovirulence are unknown. An avirulent laboratory strain of the Alphavirus Sindbis kills most cultured cell lines not by lethal parasitism, but by inducing apoptosis or programmed cell death. Transfection of cultured cells with the human bcl-2 oncogene can block Sindbis virus-induced apoptosis, resulting in a persistent viral infection resembling that observed in brains of immunodeficient mice. We investigated the possibility that neurovirulent strains of Sindbis virus could overcome the protective effects of bcl-2--a potential mechanism to explain the ability of these strains to cause fatal disease. Strains of Sindbis virus that were lethal for 2- to 4-week-old mice induced apoptotic death in cultured cells despite the presence of bcl-2. Using recombinant viruses, we show that a single amino acid change in the E2 glycoprotein of Sindbis virus confers both neurovirulence and the ability to kill cells expressing bcl-2.