SEARCH · Search PubMed

Results for “Cellular engineering”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources

PubMed2003

Posttransplant lymphoproliferative disease: pathogenesis, monitoring, and therapy.

The spectrum of transplant-related lymphoproliferative diseases is expanding to include a variety of neoplasias that typically occur late after transplant including Epstein-Barr virus (EBV)-negative B- and T-cell lymphomas, EBV-positive T-cell lymphoma, myeloma, plasmacytoma, and Hodgkin's disease. New approaches to diagnosis and monitoring based on quantitative polymerase chain reaction for EBV DNA are being explored. What exactly is being measured (the source and character of the viral DNA) remains to be determined, as does the compartment that should be assayed (whole blood, serum, plasma, or lymphocytes). These questions not withstanding, there is an emerging consensus that these technologies will facilitate rapid diagnosis and therapeutic monitoring in the future. A myriad of therapeutic interventions are or will become available. Rituximab, alone or in addition to other therapies, promises a profound change in the landscape with regard to the treatment and perhaps the prevention of posttransplant lymphoproliferative disease. New approaches to adoptive cellular immunotherapy, including use of EBV-specific products from unrelated donors, nonspecifically activated autologous products, and genetically engineered T cells, are all being explored.

Adoptive Transfer↗

PubMed1994

Humoral and cell-mediated immunity in rabbits immunized with live non-replicating avipox recombinants expressing the HIV-1SF2 env gene.

The canarypox (CP) and fowlpox (FP) viruses, which are unable to replicate productively in non-avian species, have been utilized as live vectors carrying the HIV-1SF2 env gene with the putative immunosuppressive (IS) region complete (CPIS+ and FPIS+) or deleted (CPIS- and FPIS-). To determine if these avipox-env recombinants could be utilized to elicit a specific immune response against HIV-1, six groups of rabbits were immunized with CPIS+, CPIS-, FPIS+, FPIS- constructs or their non-engineered wild-type CPwt or FPwt counterparts. After a primary inoculation and successive boosters, env-specific humoral and cell-mediated immunity were demonstrated by ELISA, immunoblots and lymphoproliferation assays. Antibody titres and neutralization activities were higher in CP- than FP-inoculated rabbits, the CPIS+ always showing a similar immunogenic capacity to CPIS-. Evidence is also presented indicating that rabbit sera possess group-specific antibodies, which were, however, unable to cross-neutralize divergent HIV-1 strains. Although the protective capacity against HIV-1 experimental infection has not yet been determined in these animals, our results suggest that these recombinants might represent promising and safer candidate vaccines against HIV-1.

AIDS Vaccines↗

PubMed2005

Cyclic strain-mediated regulation of vascular endothelial cell migration and tube formation.

UNLABELLED: Hemodynamic forces exerted by blood flow (cyclic strain, shear stress) affect the initiation and progression of angiogenesis; however, the precise signaling mechanism(s) involved are unknown. In this study, we examine the role of cyclic strain in regulating bovine aortic endothelial cell (BAEC) migration and tube formation, indices of angiogenesis. Considering their well-documented mechanosensitivity, functional inter-dependence, and involvement in angiogenesis, we hypothesized roles for matrix metalloproteinases (MMP-2/9), RGD-dependent integrins, and urokinase plasminogen activator (uPA) in this process. BAECs were exposed to equibiaxial cyclic strain (5% strain, 1Hz for 24h) before their migration and tube formation was assessed by transwell migration and collagen gel tube formation assays, respectively. In response to strain, both migration and tube formation were increased by 1.83+/-0.1- and 1.84+/-0.1-fold, respectively. Pertussis toxin, a Gi-protein inhibitor, decreased strain-induced migration by 45.7+/-32% and tube formation by 69.8+/-13%, whilst protein tyrosine kinase (PTK) inhibition with genistein had no effect. siRNA-directed attenuation of endothelial MMP-9 (but not MMP-2) expression/activity decreased strain-induced migration and tube formation by 98.6+/-41% and 40.7+/-31%, respectively. Finally, integrin blockade with cRGD peptide and siRNA-directed attenuation of uPA expression reduced strain-induced tube formation by 85.7+/-15% and 84.7+/-31%, respectively, whilst having no effect on migration. CONCLUSIONS: Cyclic strain promotes BAEC migration and tube formation in a Gi-protein-dependent PTK-independent manner. Moreover, we demonstrate for the first time a putative role for MMP-9 in both strain-induced events, whilst RGD-dependent integrins and uPA appear only to be involved in strain-induced tube formation.

Adaptation, Physiological↗

PubMed2003

Controlling skin morphogenesis: hope and despair.

To master tissue and organ morphogenesis necessitates a thorough understanding of the cellular and molecular events involved in development, renewal, repair and regeneration. Skin reconstruction is the paradigm of tissue engineering. The transplantation of autologous adult epidermal stem cells is a life-saving procedure as it regenerates the indispensable barrier function of the skin, but the reconstruction of fully functional skin has been hampered by the complexity of the process. The recent identification of multipotent epithelial stem cells in adult hair follicles and of multipotent stem cells in dermis raises new hopes.

Animals↗

PubMed2004

Potential stem cell therapy and application in neurotrauma.

Traumatic brain injury results from a sudden and external physical insult to the head, which is often accompanied by motor and cognitive impairment. Neurotrauma is characterized not only by focal abnormalities, but rather by multifocal, or even global structural and functional disturbances of the brain network. The impact initially causes necrotic cell death in the underlying tissue, followed by apoptotic cell death in the surrounding tissue due to multiple subsequent events, such as ischemia, excitotoxicity and altered gene expression. These pathological conditions are associated with high morbidity and mortality. Despite the high medical and economical relevance of neurotrauma there are currently no sufficient treatments. Supplementary therapeutic strategies have to be established. Many types of stem cells have the ability to engraft diffusely and become integral members of structures throughout the host CNS. Intrinsic factors appear to derive spontaneously from stem cells and seem to be capable of neuroprotective and/or neuroregenerative functions. Furthermore stem cells can be readily engineered to express specific genes. Such observations suggest that stem cells might participate in reconstructing the molecular and cellular milieu of traumatized brains. In this paper, the state of stem cell research is reviewed and its possible application in neurotrauma will be discussed.

Animals↗

PubMed2005

Simulation and experiment conspire to reveal cryptic intermediates and a slide from the nucleation-condensation to framework mechanism of folding.

There is a change from three-state to two-state kinetics of folding across the homeodomain superfamily of proteins as the mechanism slides from framework to nucleation-condensation. The tendency for framework folding in this family correlates with inherent helical propensity. The cellular myeloblastis protein (c-Myb) falls in the mechanistic transition region. An earlier, preliminary report of protein engineering experiments and molecular dynamics simulations (MD) showed that the folding mechanism for this protein has aspects of both the nucleation-condensation and framework models. In the more in-depth analysis of the MD trajectories presented here, we find that folding may be attributed to both of these mechanisms in different regions of the protein. The folding of the loop, middle helix, and turn is best described by nucleation-condensation, whereas folding of the N and C-terminal helices may be described by the framework model. Experimentally, c-Myb folds by apparent two-state kinetics, but the MD simulations predict that the kinetics hide a high-energy intermediate. We stabilized this hypothetical folding intermediate by deleting a residue (P174) in the loop between its second and third helices, and the mutant intermediate is long-lived in the simulations. Equilibrium and kinetic experiments demonstrate that folding of the DeltaP174 mutant is indeed three-state. The presence and shape of the intermediate observed in the simulations were confirmed by small angle X-ray scattering experiments.

Computer Simulation↗

PubMed2005

Development of transplantable nervous tissue constructs comprised of stretch-grown axons.

Pursuing a new approach to nervous system repair, fasciculated axon tracts grown in vitro were developed into nervous tissue constructs designed to span peripheral nerve or spinal cord lesions. We optimized the newfound process of extreme axon stretch growth to maximize the number and length of axon tracts, reach an unprecedented axon growth-rate of 1cm/day, and create 5cm long axon tracts in 8 days to serve as the core component of a living nervous tissue construct. Immunocytochemical analysis confirmed that elongating fibers were axons, and that all major cytoskeletal constituents were present across the stretch-growth regions. We formed a transplantable nervous tissue construct by encasing the elongated cells in an 80% collagen hydrogel, removing them from culture, and inserting them into a synthetic conduit. Alternatively, we induced axon stretch growth directly on a surgical membrane that could be removed from the elongation device, and formed into a cylindrical construct suitable for transplant. The ability to rapidly create living nervous tissue constructs that recapitulates the uniaxial orientations of the original nerve offers an unexplored and potentially complimentary direction in nerve repair. Ideally, bridging nerve damage with living axon tracts may serve to establish or promote new functional connections.

Animals↗

PubMed2006

Cell type and distribution in the porcine temporomandibular joint disc.

PURPOSE: Surprisingly little is known about the cellular composition of the temporomandibular joint (TMJ) disc, which is a crucial piece of the puzzle in tissue engineering efforts. Toward this end, cell types were identified and quantified regionally in the TMJ disc. MATERIALS AND METHODS: Porcine TMJ discs were examined by histology, electron microscopy, and immunohistochemistry. Histology consisted of hematoxylin and eosin staining to identify regional variation of cell type and cell numbers. Transmission electron microscopy was used to elucidate differences in organelle content and pericellular matrix between TMJ disc cells and chondrocytes from hyaline cartilage. Immunohistochemistry was used to assess the presence of smooth and skeletal muscle character in the TMJ disc. RESULTS: The overall ratio of fibroblasts to chondrocyte-like cells in the TMJ disc was approximately 2.35 to 1, with the highest relative number of chondrocyte-like cells in the intermediate zone. Electron microscopy revealed distinct differences between TMJ disc chondrocyte-like cells and chondrocytes from hyaline cartilage with respect to organelles and the pericellular region. Immunostaining identified smooth muscle in the form of vessels, which were most prominent in the anterior band. Skeletal muscle was not observed. CONCLUSION: The cells of the TMJ disc are distinctly different from cells of hyaline cartilage, and consequently should not be referred to as chondrocytes. TMJ disc cells are comprised of heterogeneously distributed subpopulations, with fibroblasts predominating over fibrochondrocytes.

Animals↗

PubMed2001

The Virtual Cell: a software environment for computational cell biology.

The newly emerging field of computational cell biology requires software tools that address the needs of a broad community of scientists. Cell biological processes are controlled by an interacting set of biochemical and electrophysiological events that are distributed within complex cellular structures. Computational modeling is familiar to researchers in fields such as molecular structure, neurobiology and metabolic pathway engineering, and is rapidly emerging in the area of gene expression. Although some of these established modeling approaches can be adapted to address problems of interest to cell biologists, relatively few software development efforts have been directed at the field as a whole. The Virtual Cell is a computational environment designed for cell biologists as well as for mathematical biologists and bioengineers. It serves to aid the construction of cell biological models and the generation of simulations from them. The system enables the formulation of both compartmental and spatial models, the latter with either idealized or experimentally derived geometries of one, two or three dimensions.

Biology↗

PubMed2006

Functionalized surface arrays for spatial targeting of immune cell signaling.

The effect of surface topography and chemistry on cellular response is of fundamental importance, especially where living systems encounter device surfaces as in medical implants, tissue engineering, and cell-based sensors. To understand these biological processes on surfaces, there is a widespread interest in tailored surface-active materials produced by a combination of surface chemistry coupled to advanced patterning processes. We utilize self-assembled monolayers (SAMs) as molecular templates with submicrometer-scale spatial resolution to engage and cluster IgE receptors on rat basophilic leukemia (RBL) mast cells. Bioactive templates consisted of gold arrays on silicon with patterns from 1 mum down to 45 nm. These gold arrays served as molecular tethering sites, enabling covalent binding of functionalized self-assembled monolayers of alkanethiols. The free ends of the monolayers were functionalized with 2,4-dinitrophenyl(DNP)-caproate-based ligands which interact specifically with anti-DNP IgE bound to its high affinity cell surface receptor, FcepsilonRI on RBL mast cells. Present results on structures 1 mum down to 600 nm in size indicate that these ligand-immobilized patterned arrays can function as a powerful tool for visualization and systematic characterization of cell membrane involvement in IgE receptor-mediated immune cell signaling.

Microscopy, Confocal↗

PubMed2006

Proteomic analysis of Saccharomyces cerevisiae under high gravity fermentation conditions.

Saccharomyces cerevisiae KAY446 was utilized for ethanol production, with glucose concentrations ranging from 120 g/L (normal) to 300 g/L (high). Although grown in a high glucose environment, S. cerevisiae still retained the ability to produce ethanol with a high degree of glucose utilization. iTRAQ-mediated shotgun proteomics was applied to identify relative expression change of proteins under the different glucose conditions. A total of 413 proteins were identified from three replicate, independent LC-MS/MS runs. Unsurprisingly, many proteins in the glycolysis/gluconeogenesis pathway showed significant changes in expression level. Twenty five proteins involved in amino acid metabolism decreased their expression, while the expressions of 12 heat-shock related proteins were also identified. Under high glucose conditions, ethanol was produced as a major product. However, the assimilation of glucose as well as a number of byproducts was also enhanced. Therefore, to optimize the ethanol production under very high gravity conditions, a number of pathways will need to be deactivated, while still maintaining the correct cellular redox or osmotic state. Proteomics is demonstrated here as a tool to aid in this forward metabolic engineering.

Ethanol↗

PubMed2006

Structural basis for the nuclear protein import cycle.

Transport of macromolecules between the nuclear and cytoplasmic compartments through NPCs (nuclear pore complexes) is mediated by soluble transport factors that are commonly members of the importin-beta superfamily. In the nuclear protein import cycle, importin-beta binds cargo in the cytoplasm (usually via the importin-alpha adaptor) and transports it through NPCs with which it interacts transiently by way of NPC proteins ('nucleoporins') that contain distinctive FG (Phe-Gly) sequence repeats. In the nucleus, Ran-GTP binds to importin-beta, dissociating the import complex. The importin-beta-Ran-GTP complex recycles to the cytoplasm, whereas importin-alpha is recycled by the importin-beta family member CAS (cellular apoptosis susceptibility protein) complexed with Ran-GTP. Cytoplasmic RanGAP (Ran GTPase-activating protein) dissociates these complexes, freeing the importins for another import cycle. Crystallography and biochemical and cellular studies have enabled a molecular description of the transport cycle to be developed and tested using protein engineering and computer modelling. Importin-beta family members are elongated flexible molecules that adapt their shape to encircle their cargoes. Ran-GTP binds at three sites along importin-beta and CAS, locking the molecules into a rigid conformation that is unable to bind cargoes effectively. Interactions between transport factors and key nucleoporins (such as Nup1p, Nup2p and Nup50) accelerate the formation and dissolution of many of these complexes.

Animals↗

PubMed1985

Biomechanics of bacterial walls: studies of bacterial thread made from Bacillus subtilis.

Bacterial threads of up to 1 m in length have been produced from filaments of separation-suppressed mutants of Bacillus subtilis. Individual threads may contain 20,000 cellular filaments in parallel alignment. The tensile properties of bacterial threads have been examined by using conventional textile engineering techniques. The kinetics of elongation at constant load are indicative of a viscoelastic material. Both Young's modulus and breaking stress are highly dependent upon relative humidity. By extrapolation to 100% relative humidity, it appears that cell walls may be able to bear only internal osmotic pressures of about 2 atmospheres (2.03 X 105(5) Pa) in living cells. Similarly, the strength of wall material limits the amount of cell-surface charge permissible to only a small fraction of that known to be carried by the negatively charged wall polymers.

Bacillus subtilis↗

PubMed1998

UDP-glucose deficiency causes hypersensitivity to the cytotoxic effect of Clostridium perfringens phospholipase C.

A Chinese hamster cell line with a mutation in the UDP-glucose pyrophosphorylase (UDPG:PP) gene leading to UDP-glucose deficiency as well as a revertant cell were previously isolated. We now show that the mutant cell is 10(5) times more sensitive to the cytotoxic effect of Clostridium perfringens phospholipase C (PLC) than the revertant cell. To clarify whether there is a connection between the UDP-glucose deficiency and the hypersensitivity to C. perfringens PLC, stable transfectant cells were prepared using a wild type UDPG:PP cDNA. Clones of the mutant transfected with a construct having the insert in the sense orientation had increased their UDP-glucose level, whereas those of the revertant transfected with a UDPG:PP antisense had reduced their level of UDP-glucose compared with control clones transfected with the vector. Exposure of these two types of transfectant clones to C. perfringens PLC demonstrated that a cellular UDP-glucose deficiency causes hypersensitivity to the cytotoxic effect of this phospholipase. Further experiments with genetically engineered C. perfringens PLC variants showed that the sphingomyelinase activity and the C-domain are required for its cytotoxic effect in UDP-glucose-deficient cells.

Animals↗

PubMed2001

Multilineage cells from human adipose tissue: implications for cell-based therapies.

Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.

Adipocytes↗

PubMed2005

Adeno-associated virus inverted terminal repeats improve neuronal transgene expression mediated by baculoviral vectors in rat brain.

Baculoviral vectors can transduce neurons in the CNS but mediate only transient expression of transgenes. We have developed a new baculoviral vector in which the inverted terminal repeats (ITRs) of adeno-associated virus are used to flank a luciferase reporter gene cassette harboring a neuron-specific promoter. When tested in rat brain, the new viral vector was able to provide transgene expression for at least 90 days. Immunohistological analysis demonstrated that ITR flanking did not affect the cellular preference of the neuronal promoter in the context of baculovirus. These findings establish an effective way to engineer baculoviral vectors in order to achieve sustained expression of a functional gene for gene therapy for neurodegenerative disorders and physiological studies of neurons.

Animals↗

PubMed2001

Systems biology: the reincarnation of systems theory applied in biology?

With the availability of quantitative data on the transcriptome and proteome level, there is an increasing interest in formal mathematical models of gene expression and regulation. International conferences, research institutes and research groups concerned with systems biology have appeared in recent years and systems theory, the study of organisation and behaviour per se, is indeed a natural conceptual framework for such a task. This is, however, not the first time that systems theory has been applied in modelling cellular processes. Notably in the 1960s systems theory and biology enjoyed considerable interest among eminent scientists, mathematicians and engineers. Why did these early attempts vanish from research agendas? Here we shall review the domain of systems theory, its application to biology and the lessons that can be learned from the work of Robert Rosen. Rosen emerged from the early developments in the 1960s as a main critic but also developed a new alternative perspective to living systems, a concept that deserves a fresh look in the post-genome era of bioinformatics.

Causality↗

PubMed1994

Pharmacological modulation of peptide growth factor receptor expression on tumor cells as a basis for cancer therapy.

Membrane receptors for peptide growth factor receptors (PGF-R) play a crucial role in the regulation of cancer cell proliferation and may behave as tumor associated antigens (TAA), which are currently regarded as specific targets for immunodetection and immunotherapy of human cancer. PGF-R are often more expressed by tumor cells than by normal counterparts and, by analogy to TAA, their surface expression may be regulated by cytokines. Moreover, the biological functions and specific ligands of most PGF-R are presently well elucidated as opposed to the great majority of TAA. PGF-R may, therefore, represent ideal cellular targets for at least two different therapeutic approaches: (i) naked or conjugated monoclonal antibodies and (ii) genetically engineered fusion proteins composed of PGF-R physiological ligands linked to genetically modified bacterial toxins. To date, clinical studies based on targeting of receptors for epidermal growth factor and interleukin-2 on tumor cells have been performed. Information from such studies suggests that PGF-R as well as TAA targeting strategies are clinically feasible, but that they still have to be optimized. A variety of host and tumor factors which affect targeting of neoplastic cells have been recently identified. For instance, it has been demonstrated that the antigenic density of the targeted molecule at the tumor cell surface is an important factor. In this view upregulation of PGF-R on cancer cells could be of major clinical advantage in immunotargeting. It has been reported that several cytokines and chemical compounds can induce PGF-R modulation on tumor cells. This paper reviews therapeutic opportunities related to the pharmacologic modulation of PGF-R expression. In addition a mechanistic hypothesis regarding PGF-R upregulation induced by cytostatic drugs and cytokines is proposed.

Antibodies, Monoclonal↗