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At least 199 records · Page 11Linked to original sources
PubMed2001

Continuous release of endostatin from microencapsulated engineered cells for tumor therapy.

Research studies suggest that tumor-related angiogenesis contributes to the phenotype of malignant gliomas. We assessed the effect of local delivery of the angiogenesis inhibitor endostatin on human glioma cell line (U-87MG) xenografts. Baby hamster kidney (BHK) cells were stably transfected with a human endostatin (hES) expression vector and were encapsulated in alginate-poly L-lysine (PLL) microcapsules for long-term delivery of hES. The release of biologically active endostatin was confirmed using assays of bovine capillary endothelial (BCE) proliferation and of tube formation. Human endostatin released from the microcapsules brought about a 67. 2% inhibition of BCE proliferation. Furthermore, secreted hES was able to inhibit tube formation in KDR/PAE cells (porcine aortic endothelial cells stably transfected with KDR, a tyrosine kinase) treated with conditioned U-87MG medium. A single local injection of encapsulated endostatin-secreting cells in a nude mouse model resulted in a 72.3% reduction in subcutaneous U87 xenografts' weight 21 days post treatment. This inhibition was achieved by only 150.8 ng/ml human endostatin secreted from 2 x 10(5) encapsulated cells. Encapsulated endostatin-secreting cells are effective for the treatment of human glioblastoma xenografts. Continuous local delivery of endostatin may offer an effective therapeutic approach to the treatment of a variety of tumor types.

Alginates↗
PubMed1994

Engineering cell shape and function.

An elastomeric stamp, containing defined features on the micrometer scale, was used to imprint gold surfaces with specific patterns of self-assembled monolayers of alkanethiols and, thereby, to create islands of defined shape and size that support extracellular matrix protein adsorption and cell attachment. Through this technique, it was possible to place cells in predetermined locations and arrays, separated by defined distances, and to dictate their shape. Limiting the degree of cell extension provided control over cell growth and protein secretion. This method is experimentally simple and highly adaptable. It should be useful for applications in biotechnology that require analysis of individual cells cultured at high density or repeated access to cells placed in specified locations.

Albumins↗
PubMed1993

Evaluation of a genetically engineered cell line and a histochemical beta-galactosidase assay to detect herpes simplex virus in clinical specimens.

A novel histochemical method was compared with a cytopathic effect (CPE) assay for the identification of herpes simplex virus (HSV) in clinical specimens. The method utilizes a stably transformed cell line (BHKICP6LacZ-5) that expresses beta-galactosidase only after infection with HSV. A total of 96 specimens submitted to our diagnostic virology laboratory were analyzed. Thirty-one specimens contained HSV as evidenced by positive CPE, and all were positive for beta-galactosidase staining. CPE were not evident for 2 or more days in 15 of the 31 positive specimens, whereas the histochemical stain was positive in all 31 positives by 16 to 24 h. This preliminary study shows that the BHKICP6LacZ-5 cell line can be used in a rapid, sensitive, and specific assay for the detection of HSV in clinical specimens.

Animals↗
PubMed1998

A luciferase-engineered cell line for study of cAMP regulation in endothelial cells.

cAREL is a cAMP-responsive endothelial cell line carrying a luciferase reporter gene introduced by stable transfection of a luciferase enhancer trap into rabbit aortic endothelial cells. Luciferase gene expression in cAREL was stimulated 233-fold by 8-BrcAMP. Treatment with the beta-adrenoceptor agonist isoproterenol induced a 7.0-fold increase in luciferase expression, which was partially blocked by either beta1- or beta2-adrenoceptor antagonists and totally blocked by propranolol and by a combination of beta1- plus beta2-adrenoceptor antagonists. Receptor stimulation was mimicked by cholera toxin, forskolin, 8-BrcAMP, and isobutylmethylxanthine but not by 8BrcGMP, dexamethasone, or phorbol 12-myristate 13-acetate. Stimulation by isoproterenol was completely blocked by H-89, a protein kinase A inhibitor. cAREL was also stimulated by A-23187, and this effect was abrogated by EGTA and H-89. cAREL is the first cAMP-sensitive endothelial cell line described, and it can be useful as a positive control, as a model for cAMP regulation, as a background to genetic introduction of receptors, as an indicator of intracellular pathway activation, and as a tool to investigate cAMP effects on other signaling pathways.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Several aspects of red blood cell engineering: potential therapeutic applications.

Erythrocytes can be used to entrap drugs, enzymes or other molecules with active properties, with various encapsulation procedures. The method of internalization we are using includes an hypotonic dialysis step. Carrier erythrocytes survival depends on the dialysis process and the carried molecule. Research has led us to perform preclinical trials on animals for several drugs and enzyme therapies and for the improvement of oxyphoric capacity of erythrocytes. There exist many potential clinical applications for each kind of internalized molecules.

Animals↗
PubMed2000

Pharmacologic suppression of target cell recognition by engineered T cells expressing chimeric T-cell receptors.

Adoptive therapy with autologous T cells expressing chimeric T-cell receptors (chTCRs) is of potential interest for the treatment of malignancy. To limit possible T-cell-mediated damage to normal tissues that weakly express the targeted tumor antigen (Ag), we have tested a strategy for the suppression of target cell recognition by engineered T cells. Jurkat T cells were transduced with an anti-hapten chTCR tinder the control of a tetracycline-suppressible promoter and were shown to respond to Ag-positive (hapten-coated) but not to Ag-negative target cells. The engineered T cells were then reacted with hapten-coated target cells at different effector to target cell ratios before and after exposure to tetracycline. When the engineered T cells were treated with tetracycline, expression of the chTCR was greatly decreased and recognition of the hapten-coated target cells was completely suppressed. Tetracycline-mediated suppression of target cell recognition by engineered T cells may be a useful strategy to limit the toxicity of the approach to cancer gene therapy.

Flow Cytometry↗
PubMed2005

Genetically engineered myeloma cell vaccine.

Tumor cells engineered to express immunogenes have been used for cancer vaccines to induce antitumor immunity and to study the antitumor immune mechanisms derived from immunogene expression. In this chapter, we describe the design and methods for cloning a cDNA gene coding for the mouse CD40L molecule and for construction of the expression vector pcDNA-CD40L, as well as the methods for generation of engineered myeloma cells J558/CD40L expressing CD40 ligand. We also demonstrate that the engineered J558/CD40L tumor cells lose their tumorigenicity in syngeneic mice, and that the inoculation of J558/CD40L tumor cells further leads to protective immunity against wild-type J558 tumors.

Animals↗
PubMed2000

NIH 3T3 cells or engineered NIH 3T3 cells stably expressing GDNF can protect primary dopaminergic neurons.

Glial cell line-derived neurotrophic factor (GDNF) shows potent and relatively specific protective effects on dopaminergic neurons. However, the size of the GDNF protein (MW 32-42 kDa) precludes the clinical use of GDNF via parenteral administration. It would thus be useful to have a cell line that stably secretes GDNF with full biological activities. The present study shows that NIH 3T3 cells express a considerable amount of GDNF. After co-culturing with primary E14-E16 midbrain neurons, such cells protected primary rat midbrain TH-immunopositive neurons from degeneration and MPP+ toxicity. In order to enhance endogenous GDNF expression, NIH 3T3 cells were stably transfected with GDNF cDNA with the Kozak sequence. The clones with the highest GDNF expression level were selected. The protective effects of engineered cells increased as the GDNF expression level increased. These cell lines may merit clinical investigation.

3T3 Cells↗
PubMed2003

Biochemical engineering: cues from cells.

Engineering principles are used in the exploitation of biocatalysts derived from cells. The purity of reagents, catalysts and maintenance of operation variables are extremely important for bioengineering systems. Any change in the purity of reagents or in operation variables usually leads to a dramatic decrease in productivity. Cellular systems, however, are able to work with relatively high impure conditions and increase their productivity in response to external signals. Thus the seemingly disordered 'bag of juice' or cytoplasm has more order and much higher order of integration than first appears. Learning the semantics of this paradoxical ability of order and integration would help bioengineers to understand and enhance productivity even using impure reagents.

Biomedical Engineering↗
PubMed1997

Regulation of insulin secretion from novel engineered insulinoma cell lines.

In the accompanying article, we describe the creation of novel cell lines derived from RIN 1046-38 rat insulinoma cells by stable transfection with combinations of genes encoding human insulin, GLUT2, and glucokinase. Herein we describe the regulation of insulin secretion and glucose metabolism in these new cell lines. A cell line (betaG I/17) expressing only the human proinsulin transgene exhibits a clear increase in basal insulin production (measured in the absence of secretagogues) relative to parental RIN 1046-38 cells. betaG I/17 cells engineered for high levels of GLUT2 expression and a twofold increase in glucokinase activity (betaG 49/206) or engineered for a 10-fold increase in glucokinase activity alone (betaG 40/110) exhibit a 66% and 80% suppression in basal insulin secretion relative to betaG I/17 cells, respectively. As a result, betaG 49/206 and betaG 40/110 cells exhibit potent insulin-secretory responses to glucose alone (6.1- and 7.6-fold, respectively) or to glucose plus isobutylmethylxanthine (10.8- and 15.1-fold, respectively) that are clearly larger than the corresponding responses of betaG I/17 or parental RIN 1046-38 cells. betaG 49/206 and betaG 40/110 cells also exhibit a rapid and sustained response to glucose plus isobutyl-methylxanthine in perifusion studies that is clearly larger in magnitude than that of the two control lines. Glucose dose-response studies show that both engineered and non-engineered lines respond maximally to submillimolar concentrations of glucose and that betaG 49/206 cells are the most sensitive to low concentrations of the hexose, consistent with their clearly elevated rate of [5-3H]glucose usage. Finally, 5-thioglucose, a potent inhibitor of low-K(m) hexokinases, most effectively normalizes glucose concentration dependence for insulin secretion in the cell line with highest glucokinase expression (betaG 40/110). We conclude that GLUT2 and/or glucokinase expression imposes tight regulation of basal insulin secretion in cell lines that overexpress human proinsulin, allowing a marked improvement in the range of secretagogue responsiveness in such cells.

1-Methyl-3-isobutylxanthine↗