Glioblastoma Therapy with Cytotoxic Mesenchymal Stromal Cells Optimized by Bioluminescence Imaging of Tumor and Therapeutic Cell Response

Genetically modified adipose tissue derived mesenchymal stromal cells (hAMSCs) with tumor homing capacity have been proposed for localized therapy of chemo- and radiotherapy resistant glioblastomas. We demonstrate an effective procedure to optimize glioblastoma therapy based on the use of genetically modified hAMSCs and in vivo non invasive monitoring of tumor and therapeutic cells. Glioblastoma U87 cells expressing Photinus pyralis luciferase (Pluc) were implanted in combination with hAMSCs expressing a trifunctional Renilla reniformis luciferase-red fluorescent protein-thymidine kinase reporter in the brains of SCID mice that were subsequently treated with ganciclovir (GCV). The resulting optimized therapy was effective and monitoring of tumor cells by bioluminescence imaging (BLI) showed that after 49 days GCV treatment reduced significantly the hAMSC treated tumors; by a factor of 104 relative to controls. Using a Pluc reporter regulated by an endothelial specific promoter and in vivo BLI to image hAMSC differentiation we gained insight on the therapeutic mechanism. Implanted hAMSCs homed to tumor vessels, where they differentiated to endothelial cells. We propose that the tumor killing efficiency of genetically modified hAMSCs results from their association with the tumor vascular system and should be useful vehicles to deliver localized therapy to glioblastoma surgical borders following tumor resection

Human mesenchymal stem cell-derived iron oxide exosomes allow targeted ablation of tumor cells via magnetic hyperthermia

U Altanerova,1 M Babincova,2 P Babinec,2 K Benejova,1 J Jakubechova,1 V Altanerova,1 M Zduriencikova,3 V Repiska,4 C Altaner1,3 1Stem Cell Preparation Department, St Elisabeth Cancer Institute, Bratislava, Slovakia; 2Department of Nuclear Physics and Biophysics, Comenius University, Bratislava, Slovakia; 3Cancer Research Institute, Biomedical Center, Slovak Academy of Sciences, Bratislava, Slovakia; 4Institute of Medical Biology, Genetics and Clinical Genetics, Faculty of Medicine, Comenius University in Bratislava, Slovakia Abstract: Magnetic hyperthermia, or the heating of tissues using magnetic materials, is a promising approach for treating cancer. We found that human mesenchymal stem cells (MSCs) isolated from various tissues and MSCs expressing the yeast cytosine deaminase::uracil phosphoribosyl transferase suicide fusion gene (yCD::UPRT) can be labeled with Venofer, an iron oxide carbohydrate nanoparticle. Venofer labeling did not affect cell proliferation or the ability to home to tumors. All Venofer-labeled MSCs released exosomes that contained iron oxide. Furthermore, these exosomes were efficiently endocytosed by tumor cells. Exosomes from Venofer-labeled MSCs expressing the yCD::UPRT gene in the presence of the prodrug 5-fluorocytosine inhibited tumor growth in a dose-dependent fashion. The treated tumor cells were also effectively ablated following induction of hyperthermia using an external alternating magnetic field. Cumulatively, we found that magnetic nanoparticles packaged into MSC exosomes are efficiently endocytosed by tumor cells, facilitating targeted tumor cell ablation via magnetically induced hyperthermia. Keywords: mesenchymal stem cells, iron oxide labeling, Venofer, yCD::UPRT-exosomes, yCD::UPRT-MSCs/Fe exosomes, magnetic hyperthermi

Magnetoliposome Mediated Local Electromagnetic Tumor Hyperthermia

Magnetoliposomes prepared by enwrapping 8 nm sized superparamagnetic magnetite grains with phospholipid bilayer were evaluated as possible new material for local electromagnetic hyperthermia both in vitro and in vivo after their injection into implanted BP-6 tumor in rats. As has been found the center of tumor is heated in 10 minutes from 35°C to 44.1°C using magnetic field with induction 1.5 mT and frequency 3.5 MHz

Characterization of the RNA dependent DNA polymerase of bovine leukemia virus

The reverse transcriptase - RNA dependent DNA polymerase of Bovine Leukemia Virus (BLV) was isolated and characterized. The enzyme has a molecular weight of about 80kd and the isoelectric point is 7.6. The enzyme prefers magnesium, as a divalent cation using synthetic homopolymeric template primer poly (C) oligo (dG). Monoclonal antibodies directed against reverse transcriptase of human immunodeficiency virus type I (HIV-I) did not crossreact with the isolated polymerase