A novel endothelial cell-based gene therapy platform for the in vivo delivery of apolipoprotein E.

A major focus in gene therapy has been the use of recombinant viruses to deliver genes in vivo. Although this approach shows much promise, there are many safety concerns associated with the use of viral materials in the treatment of human diseases. Our alternative cell-based gene therapy approach utilizes endothelial cells (Pro 175) isolated from the murine embryonic yolk sac.

Tetracycline-regulatable expression vectors tightly regulate in vitro gene expression of secreted proteins.

The regulation of gene expression by the tetracycline system has attracted a high level of interest in the recent past. However, expression of secreted proteins has not been evaluated precisely. In this study, we constructed two versions of a one-plasmid system containing the elements necessary for the regulation of gene expression.

Cancer gene therapy by direct tumor injections of a nonviral T7 vector encoding a thymidine kinase gene.

Previously, we described a nonviral cytoplasmic gene therapy vector system based on the T7 autogene concept. This system has been shown to achieve rapid and high levels of gene expression in a variety of animal cells and tissues. To test the utility of the system in vivo tumor ablation, a T7 cancer gene therapy plasmid vector, pT7T7/T7TK, was constructed.

Cloning and characterization of developmental endothelial locus-1: an embryonic endothelial cell protein that binds the alphavbeta3 integrin receptor.

We have taken advantage of an enhancer trap event in a line of transgenic mice to identify a unique developmentally regulated endothelial cell locus (Del1). The protein encoded in this locus contains three EGF-like repeats homologous to those in Notch and related proteins, including an EGF-like repeat that contains an RGD motif, and two discoidin I-like domains. Del1 is shown to be a matrix protein and to promote adhesion of endothelial cells through interaction with the alphavbeta3 integrin receptor.

Variable efficiency of the thymidine kinase/ganciclovir system in human glioblastoma cell lines: implications for gene therapy.

The gene therapy strategy using the hsvl-thymidine kinase gene (TK) and ganciclovir (GCV) injections that has been used for treating human glioblastomas has not been as effective as expected after the first animal experiments. A better understanding of the different steps involved in this treatment, like gene transfer, gene expression, and sensitivity of the recipient cells, is needed. After proposing sensitivity criteria for the TK/GCV system and for the bystander effect, based on the levels of GCV that can be reached in vivo, we studied seven human glioblastoma cell lines (U87, U118, U251, SNB19, SNB75, SF295, SF539) for their sensitivity to the TK/GCV system.

The therapeutic potential of inducing molecules.

Many fundamental developmental mechanisms that result in the generation and formation of specific cells and organ systems are not limited to embryogenesis. Regenerative processes in the adult serve to help regulate cellular turnover in systems where specific cell numbers or balance is crucial. In addition, these processes can be re-activated to replace cell populations which are lost due to damage or disease.

Parameters influencing the efficiency of the thymidine kinase/ganciclovir strategy in human glioblastoma cell lines.

The gene therapy strategy using the hsv1-thymidine kinase gene (TK) and ganciclovir (GCV) injections that has been used for treating human glioblastomas has not been as effective as expected after the first animal experiments. A better understanding of the different steps involved in this treatment, like gene transfer, gene expression, and sensitivity of the recipient cells is needed. Therefore, we studied 7 human glioblastoma cell lines (U87, U118, U251, SNB19, SNB75, SF295, SF539) for their sensitivity to the TK/GCV system.

Novel B219/OB receptor isoforms: possible role of leptin in hematopoiesis and reproduction.

Hematopoietic development is a complex process that involves a large number of growth factors and cytokines. Many cytokines are known to act on more mature, lineage-restricted cells of the hematopoietic system. However, no specific factors have yet been identified that induce the expansion of the most primitive hematopoietic cells without also inducing differentiation.

A novel nonviral cytoplasmic gene expression system and its implications in cancer gene therapy.

We recently have developed a unique cytoplasmic transient gene expression system based on cotransfection of target cells with bacteriophage T7 RNA polymerase (RNAP) and plasmid DNA vectors containing a T7 autogene. Because this T7 system is self-initiating, self-maintaining, and requires no cellular factors for transcription, it is therefore likely to function in any mammalian cell with any gene both in vitro and, more importantly, in vivo. In this study we demonstrate that the T7 DNA vector and T7 RNAP could be efficiently codelivered to cultured cells by lipofection.

Selective killing of glioma cells in culture and in vivo by retrovirus transfer of the herpes simplex virus thymidine kinase gene.

The thymidine kinase gene (tk) of herpes simplex type 1 virus (HSV-1) was inserted into a retroviral vector under the transcriptional control of the enhancer-promoter element of the Moloney murine leukemia virus long terminal repeat. Replication-defective viral particles were obtained by transfection of vector DNA into the packaging cell line psi2 and were used to infect C6 rat glioma-derived cell lines in culture. The sensitivity of these cells to the toxic effects of the nucleoside analog ganciclovir was found to be significantly increased by transfer of the HSV-1 tk gene.

Neuronal traits of clonal cell lines derived by fusion of dorsal root ganglia neurons with neuroblastoma cells.

In an attempt to immortalize the gene products of single neurons, somatic cell hybrids were produced by fusion of embryonic rat dorsal root ganglion (DRG) neurons with mouse neuroblastoma cells. Embryonic day 13 rat DRGs were fused with mouse neuroblastoma cells deficient in hypoxanthine phosphoribosyltransferase (HPRT; IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.

Oxygen chemoreception by carotid body cells in culture.

Chemoreceptors for oxygen reside within the carotid body, but it is not known which cells actually sense hypoxia and by what mechanisms they transduce this information into afferent signals in the carotid sinus nerve. We have developed systems for the growth of glomus cells of the carotid body in dissociated cell culture. Here we demonstrate that, as in vivo, these cells contain the putative neurotransmitters dopamine, serotonin, and norepinephrine.

Jejunal diverticulosis with perforation as a complication of Fabry's disease.

This study presents the case of a patient who had jejunal diverticulosis with perforation and abscess formation as a complication of Fabry's disease. Light microscopy disclosed glycolipid deposition in the neurons and nerve fibers of the intestinal nerve plexuses and smooth muscle. Silver stains of the myenteric plexus in the involved segment of the bowel showed enlarged, granular argyrophobic neurons and a marked decrease in the number of argyrophilic neurons, with those remaining being enlarged and distorted by the cytoplasmic glycolipid accumulation.