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At least 325 records · Page 18Linked to original sources
PubMed2005

Adenovirus-mediated transgene-engineered dendritic cell vaccine of cancer.

Dendritic cells (DCs) are the most effective antigen presenting cells (APCs) to elicit both primary and secondary T-cell response that is critical for antitumor immunity and elimination of intracellular pathogens. Therefore, DCs pulsed ex vivo with antigens have the potential used as cell-based vaccines against tumors. Viral vectors derived from adenoviruses have been extensively used to pulse DCs ex vivo by delivering genes encoding immunomodulatory molecules and tumor antigens to DCs since these vectors are relatively safe, effective in inducing the maturation of DCs, and can accommodate large expression cassettes encoding antigens. One of the hurdles for gene delivery to DCs by adenovirus (Ad) vectors, however, is low transfection efficiency of DCs due to the paucity of Ad receptor on DCs. To overcome this obstacle, targeted Ad vectors have been made by modifying viral capsid proteins. These targeted Ad vectors not only enhance the gene delivery to DCs, but also allow in vivo gene delivery to DCs, thus avoiding ex vivo manipulation of DCs.

Adenoviridae↗
PubMed1999

Frontiers in transplantation of insulin-secreting tissue for diabetes mellitus.

Transplantation of insulin-secreting tissue represents a physiologic approach to reverse diabetes mellitus. Pancreas transplants yield a remarkable enhancement in quality of life and appear to modify the devastating neurovascular complications of diabetes. A more attractive approach is transplantation of insulin-secreting cells, a procedure of low invasiveness with the exciting prospect of modulating graft immunogenicity before transplantation, so as to minimize requirements for toxic immunosuppressive drugs. The Surgical-Medical Research Institute at the University of Alberta in Edmonton, and several others centres throughout the world, has demonstrated that islet cell transplants can reverse insulin dependence and induce remarkable glycemic stability for several years. However, widespread success has been denied because of insufficient donor tissue, early failures to reverse insulin dependence and the loss of graft function with time. Promising new research approaches to these problems are reviewed, including xenogeneic sources of cells, engineering islet cells with genes that induce expression of immunoprotective molecules, and neogenesis factors that may sustain populations of transplanted beta cells.

Alberta↗
PubMed2005

Polyesterurethane foam scaffold for smooth muscle cell tissue engineering.

Reconstruction of the genitourinary tract, using engineered urological tissues, requires a mechanically stable biodegradable and biocompatible scaffold and cultured cells. Such engineered autologous tissue would have many clinical implications. In this study a highly porous biodegradable polyesterurethane-foam, DegraPol was evaluated with tissue engineered human primary bladder smooth muscle cells. The cell-polymer constructs were characterized by histology, scanning electron microscopy, immunohistochemistry and proliferation assays. Smooth muscle cells grown on DegraPol showed the same morphology as when grown on control polystyrene surface. Positive immunostaining with alpha smooth muscle actin indicated the preservation of the specific cell phenotype. Micrographs from scanning electron microscopy showed that the cells grew on the foam surface as well as inside the pores. In addition they grew as cell aggregates within the foam. The smooth muscle cells proliferated on the Degrapol; however, proliferation rate decreased due to apoptosis with time in culture. This study showed that Degrapol has the potential to be used as a scaffold.

Apoptosis↗
PubMed1999

Heterogeneity of multiorgan metastases of human lung cancer cells genetically engineered to produce cytokines and reversal using chimeric monoclonal antibodies in natural killer cell-depleted severe combined immunodeficient mice.

Lung cancer is a major cause of cancer deaths, most of which can be attributed to distant multiorgan metastases. To examine the cellular and molecular mechanisms of lung cancer metastasis to distant organs, we have established novel models of human lung cancer (small cell and non-small cell lung cancer) metastasis in natural killer cell-depleted severe combined immunodeficient (SCID) mice. We investigated whether local production of the cytokines responsible for regulation of macrophage function at tumor growth sites affects the pattern of lung cancer metastasis in distant organs. Several lung cancer cell lines were genetically engineered to produce human macrophage colony-stimulating factor (M-CSF) and monocyte chemoattractant protein-1 (MCP-1), and their metastatic potentials were assessed. Interestingly, M-CSF gene transduction had an antimetastatic effect for the liver and lymph nodes, but not the kidneys. In contrast, MCP-1 gene-modified lung cancer cells and their parent cells had identical metastatic potentials. These findings indicate a possible role for cytokines and suggest that lung cancer has metastatic heterogeneity. Examining ways of controlling human lung cancer metastases, we investigated the antimetastatic effect of chimeric monoclonal antibodies (MAbs) against P-glycoprotein and ganglioside GM2 (MH162 and KM966, respectively). Both MAbs, when given on days 2 and 7, inhibited the development of distant metastases of lung cancer in a dose-dependent fashion. Combined use of anti-P-glycoprotein MAb with M-CSF or MCP-1 gene transduction caused complete inhibition of metastasis of H69/VP cells. The antimetastatic effect of these MAbs in vivo was mainly due to an antibody-dependent cell-mediated cytotoxicity reaction mediated by mouse macrophages. These findings suggest that the mouse-human chimeric MAb in combination with cytokine gene transduction may be useful for the eradication of lung cancer metastases in humans.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Effects of sugar concentration on recombinant human alpha(1)-antitrypsin production by genetically engineered rice cell.

Productivity of recombinant human alpha(1)-antitrypsin (rAAT) with a genetically engineered rice cell using an inducible promoter has been studied by batch-wise and continuous production. A simple model explained the effect of proteases released from the disrupted cells on the rAAT degradation. Glucose concentration in the medium significantly affected the rAAT productivity in the continuous production, because the rAAT was induced by sugar depletion. When the fresh medium containing 5mM glucose was supplied to the continuous bioreactor, induction time was long and the productivity was low, indicating that the glucose concentration in the cells was high enough as to repress the promoter. When the glucose concentration in the fresh medium was reduced to 0.5mM, total amount of rAAT produced in 70h cultivation reached 6.7-7.6mg/g-dry cell, which was two times larger than the control medium without glucose.

Journal Article↗
PubMed2002

[Differentiation potential of human stem cells--approaches to tissue engineering and to cell transplantation].

The prospect of future clinical applications of human stem cells is one of the major arguments for the use of embryonic stem cells. Scientists are currently developing methods to culture and isolate different somatic cell types. The enormous capacity for proliferation of embryonic and certain adult stem cells combined with suitable protocols to differentiate these cells may allow the production of sufficient amounts even of those cell types which cannot be expanded in the terminal differentiated state. The ability to generate large quantities of certain somatic cells in vitro has led to the first cell transplantation-based therapeutic concepts and clinical studies. Even today comparatively simply structured in vitro-engineered tissues are applied clinically. However, to grow larger and more complex structures, a variety of problems including their vascularisation and the development of suitable matrices have to be resolved. In the long term, tissue engineering offers an as yet incalculable potential for future medical applications and may finally allow the development and clinical transplantation of complex tissues or even whole organs.

Cell Culture Techniques↗
PubMed2000

Regression of engineered tumor cells secreting cytokines is related to a shift in host cytokine profile from type 2 to type 1.

The precise role of the endogenous immune response in modulating cancer development remains unclear. In this study, three mouse tumor cell lines were used to elucidate the immune mechanisms for tumor regression versus tumor growth. These cell lines were (1) the poorly immunogenic VKCK cell line and (2) its two derived cell lines VKCK/RM4-tumor necrosis factor-alpha (TNF-alpha) and VKCK/RM4-interferon-gamma (IFN-gamma) engineered to secrete TNF-alpha and IFN-gamma, respectively. Our data showed that VKCK tumors grew aggressively in syngeneic BALB/c mice, and vaccination of irradiated VKCK cells failed to protect the mice from a subsequent challenge with the same tumor. In contrast, engineered VKCK tumor cells lost their tumorigenicity, and vaccination of engineered VKCK cells induced a protective immunity against VKCK cells that was mediated with VKCK-specific CD8+T cells. Susceptible mice developed a Th2-dominant response, whereas resistant mice developed a Th1-dominant response to VKCK. The T cell proliferative response and cytolytic activity against VKCK developed in both resistant and susceptible mice, but in the susceptible mice, these responses were much weaker compared with those in the resistant mice. Our results indicate that regression of tumor cells engineered to secrete cytokines TNF-alpha and IFN-gamma is related to a shift from a host type 2 to a type 1 cytokine profile. Our results further suggest that the failure of unmodified VKCK to generate efficacious T cells is not due to an inability to recognize tumor antigens but, rather, to the nature and magnitude of the antitumor immune response that develops. A better understanding of the mechanisms by which tumor cells modulate the host immune system may result in newer approaches for manipulating host-tumor interactions that favor the development of a protective antitumor immune response.

Animals↗
PubMed2005

Tuning the cell-cycle engine for improved plant performance.

Cell-cycle regulation plays a crucial role in organogenesis, morphogenesis, growth and differentiation and conceptually offers a means to design a next generation of crop plants that outperform traditionally bred ones. However, cell-cycle regulation involves a large, highly redundant, set of genes, which complicates unravelling of function in the context of a higher plant. Nevertheless, ten years of molecular cell-cycle research, primarily in the model plant Arabidopsis, have demonstrated its potential for altering plant development.

Arabidopsis↗
PubMed2002

Enhanced phagemid particle gene transfer in camptothecin-treated carcinoma cells.

Engineered phage-based vectors are an attractive alternative strategy for gene delivery because they possess no natural mammalian cell tropism and can be genetically modified for specific applications. Genotoxic treatments that increase the transduction efficiency of single-stranded adeno-associated virus were tested on cells transfected by single-stranded phage. Indeed, green fluorescent protein transgene expression by epidermal growth factor-targeted phagemid particles increased with heat shock, UV irradiation, and camptothecin (CPT) treatment. CPT resulted in transduction efficiencies of 30-45% in certain human carcinoma cell lines and reduced the minimal dose needed to detect green fluorescent protein-expressing cells to as low as 1-10 particles/cell. Targeted phage transduction was effective in many tumor cell lines and in prostate tumor xenografts with CPT treatment. Taken together, these data suggest the feasibility of using phage-based vectors for therapeutic gene delivery to cancer cells.

Animals↗
PubMed2004

Genetically engineered stem cell therapy for tissue regeneration.

Therapeutic angiogenesis/vasculogenesis represents a new approach to treat patients with ischemic disease not curable with conventional treatment. This review focuses on the rationale and preliminary results of combining stem cell and gene therapy for regenerative medicine. Under disease conditions, impaired neovascularization results from diminished vascular growth factor production and primary dysfunction of endothelial cells and their progenitors. Advances in our ability to genetically manipulate cells ex vivo has provided the technological platform to implement stem cell biology and circumvent the potential hazard of direct gene transfer. Ex vivo engineered endothelial progenitor cells have been used for the treatment of peripheral limb ischemia. The approach eliminates the drawback of immune response against viral vectors and makes feasible repeating the therapeutic procedure in case of injury recurrence. The strategy of using stem cells as vectors for curative agents proved to be of value for the treatment of pulmonary hypertension and thrombosis. Transplantation of neural stem cells genetically modified to secrete nerve growth factor was able to ameliorate the death of striatal projection neurons caused by transient focal ischemia in the adult rat. By a similar approach, engineered neural stem cells might be used for treating neurodegenerative disorders. Therefore, genetic manipulation of stem cells opens new avenues for regenerative medicine.

Animals↗
PubMed2005

Exploring and engineering the cell surface interface.

Cells are inherently sensitive to local mesoscale, microscale, and nanoscale patterns of chemistry and topography. We review current approaches to control cell behavior through the nanoscale engineering of materials surfaces. Far-reaching implications are emerging for applications including medical implants, cell supports, and materials that can be used as instructive three-dimensional environments for tissue regeneration.

Animals↗
PubMed2005

Stable, soluble, high-affinity, engineered T cell receptors: novel antibody-like proteins for specific targeting of peptide antigens.

The recent development of T cell receptor phage display opens up the possibility of engineering human T cell receptors with antibody-like binding properties for cell-surface peptide antigens. In this review we briefly discuss recent developments in molecular targeting of peptide antigens. We then discuss potential clinical applications of engineered high-affinity T cell receptors in autoimmunity and cancer.

Antibodies↗
PubMed2003

Cell sheet engineering for myocardial tissue reconstruction.

Myocardial tissue engineering has now emerged as one of the most promising treatments for the patients suffering from severe heart failure. Tissue engineering has currently been based on the technology using three-dimensional (3-D) biodegradable scaffolds as alternatives for extracellular matrix. According to this most popular technique, several types of 3-D myocardial tissues have been successfully engineered by seeding cardiomyocytes into poly(glycolic acid), gelatin, alginate or collagen scaffolds. However, insufficient cell migration into the scaffolds and inflammatory reaction due to scaffold biodegradation remain problems to be solved. In contrast to these technologies, we now propose novel tissue engineering methodology layering cell sheets to construct 3-D functional tissues without any artificial scaffolds. Confluent cells on temperature-responsive culture surfaces can be harvested as a viable contiguous cell sheet only by lowering temperature without any enzymatic digestions. Electrical communications are established between layered cardiomyocyte sheets, resulting in simultaneous beating 3-D myocardial tissues. Layered cardiomyocyte sheets in vivo present long survival, macroscopic pulsation and characteristic structures of native heart tissue. Cell sheet engineering should have enormous potential for fabricating clinically applicable myocardial tissues and should promote tissue engineering research fields.

Animals↗
PubMed2001

Human dendritic cells genetically engineered to express a melanoma polyepitope DNA vaccine induce multiple cytotoxic T-cell responses.

PURPOSE: To assess the therapeutic potential of a melanoma polyepitope vaccine in human cells. Polyepitope DNA vaccines encoding T-cell epitopes have been demonstrated in murine systems to generate multiple cytotoxic T-cell responses to different antigens. Here, for the first time we demonstrate the ability of a melanoma polyepitope to stimulate lymphocytes from normal human donors to simultaneously generate multiple antigen-specific responses. EXPERIMENTAL DESIGN: Human dendritic cells (DC), transduced with a melanoma-polyepitope cDNA, were used to activate autologous lymphocytes from naïve donors as an in vitro model of DNA vaccination. Lymphocytes were primed with polyepitope or mock-transduced DC, boosted with peptide, then measured for antigen-specific cytotoxicity. RESULTS: Lymphocytes primed with polyepitope-transduced DC and boosted with peptide generated multiple cytotoxic responses. By contrast lymphocytes primed with mock-transfected DCs and boosted with peptide gave no specific cytotoxicity. However, when lymphocytes were repeatedly stimulated with polyepitope-transduced DCs immunodominance was seen with CTLs being generated to only one epitope, MART(27-35). CONCLUSIONS: We show in a human system that a melanoma polyepitope primes CTL to multiple epitopes. However, repeated stimulation by the polyepitope restricts the response to only the MART1 epitope. Thus, although polyepitope vaccines are an effective way of priming multiple naïve T-cell responses, continual boosting with polyepitope vaccines may, as a result of immunodominance, restrict the CTL. These findings have important implications for the use of DNA polyepitope vaccines in cancer immunotherapy.

Animals↗
PubMed1993

Vaccinations with tumor cells genetically engineered to produce different cytokines: effectivity not superior to a classical adjuvant.

The potential of tumor cells (J558L) engineered to produce one of 5 different cytokines (interleukin 2, interleukin 4, interleukin 7, tumor necrosis factor, or gamma-interferon) to give rise to systemic immunity protective against a contralateral challenge with the parental cells was analyzed. The rejection of all cytokine-producing cells appeared to induce some systemic response capable of mediating the rejection of low numbers of subsequently contralaterally injected cells, but the effect was much less obvious with higher cell numbers. The injection of any possible combination of two of the cytokine producers did not reveal any synergistic effects. The cytokine gene-transfected tumor cells were not superior to the parental cells admixed with the adjuvant Corynebacterium parvum with respect to their potential as immunogens to induce immunity.

Animals↗
PubMedDate not supplied

Alginate encapsulation of genetically engineered mammalian cells: comparison of production devices, methods and microcapsule characteristics.

PRIMARY OBJECTIVE: Microencapsulation is a novel method for in vivo immunoprotection of genetically engineered mammalian cells. This study aimed at optimizing alginate/poly-l-lysine/alginate (APA) microencapsulation of mammalian cells in small size (< 300 microm) hollow core microcapsules and at evaluating some of the physical characteristics of APA microcapsules produced by different devices and with different alginate preparations. METHODS AND PROCEDURES: Alginate preparations with higher or lower viscosity were used with three different methods: (i) vibrating nozzle, (ii) coaxial gas flow extrusion (AirJet) and (iii) laminar jet break-up (JetCutter). Parameters and device settings for the production of microcapsules with specific characteristics were defined for all three methods. Mechanical stability of APA microcapsules and cell viability of encapsulated cells were investigated in long-term culture and in an animal model. MAIN RESULTS: Uniform spherical beads with a mean diameter < 300 microm could be produced by all three encapsulation methods. For the production of uniform microcapsules with a small diameter (< 300 microm) the vibrating nozzle technique required a relatively low viscosity of alginate (< 0.2 Pa/s), while the AirJet and JetCutter devices performed equally well with alginate of higher viscosity. In all cases, alginate with a lower molar mass was inferior to higher molar mass alginate in terms of mechanical stability of the microcapsules. Microcapsules with optimized mechanical properties were injected intravascularly in rats and shown to maintain their shape and the viability of encapsulated cells. CONCLUSIONS: The described methods and devices are able to produce APA microcapsules of small size and uniform shape which are mechanically stable in culture and may maintain the viability of the enclosed cells over extended periods of time. These microcapsules seem to be suitable for further therapeutic studies in an animal model of human disease.

Alginates↗
PubMed2007

Biopreservation of cells and engineered tissues.

The development of effective preservation and long-term storage techniques is a critical requirement for the successful clinical and commercial application of emerging cell-based technologies. Biopreservation is the process of preserving the integrity and functionality of cells, tissues and organs held outside the native environment for extended storage times. Biopreservation can be categorized into four different areas on the basis of the techniques used to achieve biological stability and to ensure a viable state following long-term storage. These include in vitro culture, hypothermic storage, cryopreservation and desiccation. In this chapter, an overview of these four techniques is presented with an emphasis on the recent developments that have been made using these technologies for the biopreservation of cells and engineered tissues.

Cell Culture Techniques↗