Home About us Contact
|
Home About us Contact | ||
|
|
||
Delivery Vehicles (delivery + vehicle)
Kinds of Delivery Vehicles Selected AbstractsPotential of Fortified Fibrin/Hyaluronic Acid Composite Gel as a Cell Delivery Vehicle for ChondrocytesARTIFICIAL ORGANS, Issue 6 2009Sang-Hyug Park Abstract Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 ± 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 ± 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel. [source] Antimicrobial Nanotubes Consisting of Ag-Embedded Peptidic Lipid-Bilayer Membranes as Delivery VehiclesADVANCED MATERIALS, Issue 17 2009Yong Zhou Functional drug-delivery vehicles consisting of Ag-embedded bilayer membranes of a peptidic lipid nanotube (LNT) are synthesized. The Ag,LNTs possess antimicrobial ability against E coli, contributing to the release of Ag+ into the aqueous culture. The Ag,LNTs may be applicable to the delivery of DNA or biotechnological drugs that are usually sensitive to changes in their surroundings. [source] Innentitelbild: Monodisperse Yolk,Shell Nanoparticles with a Hierarchical Porous Structure for Delivery Vehicles and Nanoreactors (Angew. Chem.ANGEWANDTE CHEMIE, Issue 29 201029/2010) Eine ,Dotter-Schale-Struktur" mit einer klaren Kern-Hohlraum-Schale-Konfiguration wurde mithilfe einer einfachen Vesikeltemplatstrategie hergestellt. S.,Z. Qiao, G.,Q. Lu et,al. beschreiben in der Zuschrift auf S.,5101, wie die Größe von Kern und Schale gesteuert werden kann. Außerdem wurden das Beladen dieser mesoporösen Materialien mit Goldnanokatalysatoren und ihre Eignung für den Wirkstofftransport untersucht. [source] Monodisperse Yolk,Shell Nanoparticles with a Hierarchical Porous Structure for Delivery Vehicles and Nanoreactors,ANGEWANDTE CHEMIE, Issue 29 2010Jian Liu Dr. Nano-,Eier": Bei einer allgemeinen Templatstrategie für die Herstellung hohler Nanokügelchen mit beweglichen Kernen (,yolk,shell structures", rechts im Bild) aus Gold, SiO2 oder magnetischem Fe3O4 wird der Kern zunächst von einem Fluorkohlenstofftensid überzogen, das das Vesikeltemplat für die Schale darstellt. [source] Polyelectrolyte Microcapsules as Antigen Delivery Vehicles To Dendritic Cells: Uptake, Processing, and Cross-Presentation of Encapsulated Antigens,ANGEWANDTE CHEMIE, Issue 45 2009Koker Dr., Stefaan De Eingeschleuste Wirkung: Abbaubare Polyelektrolytmikrokapseln (PMs; siehe Bild) als Antigentransporter werden von dendritischen Zellen (DCs) durch Makropinocytose aufgenommen. Nach der Aufnahme bricht die Schale der Mikrokapseln auf, worauf der Cytoplasmainhalt in die hohlen PM-Kerne eindringt, sodass die DCs das eingekapselte Antigen effizient prozessieren können. [source] Effects of Drug Hydrophobicity on Liposomal StabilityCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2008David R. Khan A major obstacle in drug delivery is the inability to effectively deliver drugs to their intended biological target without deleterious side-effects. Delivery vehicles such as liposomes can minimize toxic side-effects by shielding the drug from reaction with unintended targets while in systemic circulation. Liposomes have the ability to accommodate both hydrophilic and hydrophobic drugs, either in the internal aqueous core or the lipid bilayer, respectively. In the present study, fluorescein and rhodamine have been used to model hydrophilic and hydrophobic drugs, respectively. We have compared the stabilities of liposomes encapsulating these fluorophores as a function of lipid content, time, and temperature. At 25 and 37 °C, liposomes containing distearoyl phosphatidylcholine as the major phospholipid component were found to be more stable over time than those containing dipalmitoyl phosphatidylcholine, regardless of the fluorophore encapsulated. Liposomes loaded with fluorescein were found to be more stable than those with rhodamine. Dipalmitoyl phosphatidylcholine liposomes that encapsulated rhodamine were the least stable. The results indicate that the physical properties of the drug cargo play a role in the stability, and hence drug delivery kinetics, of liposomal delivery systems, and desired drug release times can be achieved by adjusting/fine-tuning the lipid compositions. [source] Cytoprotection of beta cells: rational gene transfer strategiesDIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 3 2006Cillian McCabe Abstract Gene transfer to pancreatic islets may prove useful in preventing islet cell destruction and prolonging islet graft survival after transplantation in patients with type 1 diabetes mellitus (T1DM). Potentially, a host of therapeutically relevant transgenes may be incorporated into an appropriate gene delivery vehicle and used for islet modification. An increasing understanding of the molecular pathogenesis of immune-mediated beta cell death has served to highlight molecules which have become suitable candidates for promoting islet cell survival in the face of oxidative stress. This review aims to give an overview of some conventional gene transfer strategies aimed at promoting islet cell survival in the face of cytokine onslaught. These strategies target three aspects of islet cell physiology: redox status and antioxidant defence, anti-apoptotic gene expression and mediators of cytokine signal transduction pathways. Copyright © 2006 John Wiley & Sons, Ltd. [source] Photopolymerizable Hydrogels Made from Polymer-Conjugated Albumin for Affinity-Based Drug Delivery,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Liat Oss-Ronen As a drug delivery vehicle, biodegradable albumin hydrogels can combine the high binding capacity of albumin with the structural stability of a polymeric hydrogel network to enable controlled release of small molecules based on both binding affinity and physical interactions. In the present study, we report on the development of a hybrid hydrogel composed of albumin conjugated to poly(ethylene glycol) (PEG) for drug delivery applications where controlled release is accomplished using the natural affinity of the drugs to the serum albumin. Bovine serum albumin was conjugated to PEG-diacrylate having a molecular weight of 1.5, 4, or 10,kDa to form a PEGylated albumin macromolecule (mono-PEGylated or multi-PEGylated). Biodegradable hydrogels were formed from the PEGylated albumin using photopolymerization. Two model drugs, Warfarin and Naproxen, were used for equilibrium dialysis and release experiments from the hydrogels, both having relatively low molecular weights and a known high affinity for albumin. Equilibrium dialysis experiments showed that multi-PEGylation of albumin significantly decreased the drug affinity to the protein compared to non-PEGylated controls, irrespective of the PEG molecular weight. However, the results from drug release experiments showed that mono-PEGylation of albumin did not change its natural affinity to the drug. Comparing the release profiles with a Fickian diffusion model provided strong evidence that hydrogels containing mono-PEGylated albumin exhibited sub-diffusive drug release properties based on the affinity of the drug to the tethered protein. [source] Doxorubicin-Conjugated Immuno-Nanoparticles for Intracellular Anticancer Drug DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Meng Shi Abstract A polymeric nanoparticle comprised of surface furan groups is used to bind, by Diels,Alder (DA) coupling chemistry, both targeting anti-human epidermal growth factor receptor 2 (anti-HER2) antibodies and chemotherapeutic doxorubicin (DOX) for targeted, intracellular delivery of DOX. In this new approach for delivery, where both chemotherapeutic and targeting ligand are attached, for the first time, to the surface of the delivery vehicle, the nuclear localization of DOX in HER2-overexpressing breast cancer SKBR-3 cells is demonstrated, as determined by confocal laser scanning microscopy. Flow cytometric analysis shows that the conjugated DOX maintains its biological function and induces similar apoptotic progression in SKBR-3 cells as free DOX. The viable cell counts of SKBR-3 cancer cells following incubation with different nanoparticle formulations demonstrates that the combined DOX and anti-HER2 nanoparticle is more efficacious than the nanoparticle formulation with either DOX or anti-HER2 alone. While free DOX shows similar cytotoxicity against both cancerous SKBR-3 cells and healthy HMEC-1 cells, the combined DOX-anti-HER2 nanoparticle is significantly more cytotoxic against SKBR-3 cells than HMEC-1 cells, suggesting the benefit of nanoparticle-conjugated DOX for cell type-specific targeting. The DOX-conjugated immuno-nanoparticle represents an entirely new method for localized co-delivery of chemotherapeutics and antibodies. [source] Accelerated repair of cortical bone defects using a synthetic extracellular matrix to deliver human demineralized bone matrixJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 7 2006Yanchun Liu Abstract Injectable hydrogel and porous sponge formulations of CarbylanÔ-GSX, a crosslinked synthetic extracellular matrix (ECM), were used to deliver human demineralized bone matrix (DBM) in a rat femoral defect model. A cortical, full-thickness 5-mm defect was created in two femurs of each rat. Six rats were assigned to each of five experimental groups (thus, 12 defects per group). The defects were either untreated or filled with CarbylanÔ-GSX hydrogel or sponges with or without 20% (w/v) DBM. Radiographs were obtained on day 1 and at weeks 2, 4, 6, and 8 postsurgery of each femur. Animals were sacrificed at week 8 postsurgery and each femur was fixed, embedded, sectioned, and processed for Masson's Trichrome staining. The bone defects were measured from radiographs and the fraction of bone healing was calculated. The average fractions of bone healing for each group were statistically different among all groups, and all treatment groups were significantly better than the control group. The CarbylanÔ-GSX sponge with DBM was superior to the sponge without DBM and to the hydrogel with DBM. Histology showed that defects treated with the CarbylanÔ-GSX sponge plus DBM were completely filled with newly generated bone tissue with a thickness comparable to native bone. CarbylanÔ-GSX sponge was an optimal delivery vehicle for human DBM to accelerate bone healing. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:1454,1462, 2006 [source] Repair of rabbit segmental defects with the thrombin peptide, TP508JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2004Michael R. Sheller Abstract The synthetic peptide, TP508 (Chrysalin®), was delivered to rabbit segmental bone defects in biodegradable controlled-release PLGA microspheres to determine its potential efficacy for enhancing healing of non-critically and critically sized segmental defects. Non-critically sized radial defects were created in the forelimbs of New Zealand White rabbits, which were randomized into three treatment groups receiving 10, 50 and 100 ,g doses of TP508 in the right radius and control microspheres (without TP508) in the left radius. Torsional testing of the radii at six weeks showed a significant increase in ultimate torque, failure torque, ultimate energy, failure energy, and stiffness when treated with TP508 compared to controls (p < 0.01 for all measures). Thus, TP508 appeared to enhance or accelerate bone growth in these defects. In a second set of experiments, critically sized ulnar defects were created in the forelimbs of New Zealand White rabbits, which were randomized into two groups with each rabbit receiving microspheres with 100 or 200 ,g of TP508 into the right ulnar defect and control microspheres (without TP508) alone into the left ulnar defect. Bone healing was evaluated with plain radiographs, synchrotron-based microtomography, and mechanical testing. Radiographs of the rabbit limbs scored by three blinded, independent reviewers demonstrated a significantly higher degree of healing when treated with TP508 than their untreated control limbs (p < 0.05). Three-dimensional synchrotron tomography of a limited number of samples showed that the new bone in TP508-treated samples had a less porous surface appearance and open marrow spaces, suggesting progression of bone remodeling. Torsional testing of the ulnae at nine weeks showed a significant increase in maximum torque and failure energy when treated with TP508 compared to controls (p < 0.01 for both measures). These results suggest that TP508 in a controlled release delivery vehicle has the potential to enhance healing of segmental defects in both critically and non-critically sized defects. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Poly(glycoamidoamine)s: Cationic glycopolymers for DNA deliveryJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2006Theresa M. Reineke Abstract Polymer science is playing an exciting role in inspiring and advancing novel discoveries in the area of genetic drug delivery. Polymeric materials can be synthesized and chemically tailored to bind and compact nucleic acids into viral-like nanoparticles termed polyplexes that can deliver genetic materials into cells. This article highlights our work in this area to synthesize and study a novel class of cationic glycopolymers that we have termed poly(glycoamidoamine)s (PGAAs). The design of these materials has been inspired by many previous works in the literature. Carbohydrate comonomers have been incorporated into these structures to lower the toxicity of the delivery vehicle, and oligoamine moieties have been added to yield a cationic backbone that facilitates strong DNA binding, compaction, cellular uptake, and delivery of genetic material. PGAAs have been designed to vary in the carbohydrate size, the hydroxyl number and stereochemistry, the amine number, and the presence or absence of heterocyclic groups. Through structure,bioactivity studies, we have discovered that these materials are highly biocompatible, and each specific feature plays a large role in the observed delivery efficacy. Such structure,property studies are important for increasing our understanding of how the polymer chemistry affects the biological activity for the clinical development of polymer-based therapeutics. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6895,6908, 2006 [source] Spatiotemporal control of vascular endothelial growth factor delivery from injectable hydrogels enhances angiogenesisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 3 2007E. A. SILVA Summary. Therapeutic angiogenesis with vascular endothelial growth factor (VEGF) delivery may provide a new approach for the treatment of ischemic diseases, but current strategies to deliver VEGF rely on either bolus delivery or systemic administration, resulting in limited clinical utility, because of the short half-life of VEGF in vivo and its resultant low and transient levels at sites of ischemia. We hypothesize that an injectable hydrogel system can be utilized to provide temporal control and appropriate spatial biodistribution of VEGF in ischemic hindlimbs. A sustained local delivery of relatively low amounts of bioactive VEGF (3 ,g) with this system led to physiologic levels of bioactive VEGF in ischemic murine (ApoE,/,) hindlimbs for 15 days after injection of the gel, as contrasted with complete VEGF deprivation after 72 h with bolus injection. The gel delivery system resulted in significantly greater angiogenesis in these limbs as compared to bolus (266 vs. 161 blood vessels mm,2). Laser Doppler perfusion imaging showed return of tissue perfusion to normal levels by day 28 with the gel system, whereas normal levels of perfusion were never achieved with saline delivery of VEGF or in control mice. The system described in this article could represent an attractive new generation of therapeutic delivery vehicle for treatment of cardiovascular diseases, as it combines long-term in vivo therapeutic benefit (localized bioactive VEGF for 1,2 weeks) with minimally invasive delivery. [source] Biodegradable Nanogels Prepared by Self-Assembly of Poly(L- lactide)-Grafted Dextran: Entrapment and Release of ProteinsMACROMOLECULAR BIOSCIENCE, Issue 11 2008Koji Nagahama Abstract We showed previously that poly(L- lactide)-grafted dextran could form biodegradable nanogels in water. In this paper, various properties of Dex -g- PLLA nanogels were compared with Dex-Chol (dextran-cholesterol conjugate) nanogels to investigate the effects of hydrophobic units. Dex -g- PLLA nanogels exhibited significantly lower CAC and higher colloidal stability, indicating a strong tendency to form nanogels. We prepared lysozyme-loaded Dex -g- PLLA nanogels, and they exhibited a sustained release of lysozyme for 1 week without denaturation in PBS at 37,°C. The Dex -g- PLLA nanogels therefore have great potential as a delivery vehicle for therapeutic protein. [source] Cell-mediated Delivery and Targeted Erosion of Vascular Endothelial Growth Factor-Crosslinked HydrogelsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 14 2010Sung Hye Kim Abstract We have previously reported a novel polymeric delivery vehicle that is assembled via interaction between heparin and the vascular endothelial growth factor (VEGF). Here, the cell-responsiveness of this hydrogel,including the delivery of VEGF in response to VEGFR-2 overexpressing PAE/KDR cells (porcine aortic endothelial cells (PAE) equipped with the transcript for the kinase insert domain receptor (KDR)), consequent erosion of the hydrogel matrix, and cellular response,are highlighted. The release of VEGF and hydrogel erosion reached 100% only in the presence of PAE/KDR. The [PEG-LMWH/VEGF] hydrogel (PEG,=,poly(ethylene glycol), LMWH,=,low molecular weight heparin) correspondingly prompted increases in VEGFR-2 phosphorylation and proliferation of PAE/KDR cells. This study proves that growth factor-crosslinked hydrogels can liberate VEGF in response to specific receptors, causing gel erosion and desired cell responses. The promise of these approaches in therapeutic applications, including targeted delivery, is suggested. [source] Hereditary inclusion body myopathy: single patient response to GNE gene Lipoplex therapyTHE JOURNAL OF GENE MEDICINE, Issue 5 2010Gregory Nemunaitis Abstract Background Hereditary inclusion body myopathy (HIBM) is an autosomal recessive adult onset myopathy. It is characterized by mutations of the GNE (UDP- N -acetylglucosamine 2-epimerase/N -acetylmannosamine kinase) gene. Afflicted patients have no therapeutic options. In preclinical testing, we have previously demonstrated the ability to correct GNE gene function and the safety of delivery of wild type GNE gene using a liposomal delivery vehicle. Methods A single patient (subject #001) with severe HIBM treated by compassionate investigational new drug received four doses of GNE gene Lipoplex via intramuscular injection. GNE transgene expression, downstream induction of sialic acid, safety and muscle function were evaluated. Results Significant durable improvement in locoregional skeletal muscle function was observed in the injected left extensor carpi radialis longus of #001 in correlation with GNE transgene upregulation and local induction of sialic acid. Other than transient low grade fever and pain at the injection site, no significant toxicity was observed. Conclusions Proof of principle for manufacturing of ,clinical grade' GNE gene Lipoplex, clinical safety and activity are demonstrated with GNE gene Lipoplex. Further assessment will involve intravenous administration and subsequent phase I trial involving additional but less severely afflicted HIBM patients. Copyright © 2010 John Wiley & Sons, Ltd. [source] In vitro targeted photodynamic therapy with a pyropheophorbide-a conjugated inhibitor of prostate-specific membrane antigenTHE PROSTATE, Issue 6 2009Tiancheng Liu Abstract BACKGROUND The lack of specific delivery of photosensitizers (PSs), represents a significant limitation of photodynamic therapy (PDT) of cancer. The biomarker prostate-specific membrane antigen (PSMA) has attracted considerable attention as a target for imaging and therapeutic applications for prostate cancer. Although recent efforts have been made to conjugate inhibitors of PSMA with imaging agents, there have been no reports on PS-conjugated PSMA inhibitors for targeted PDT of prostate cancer. The present study focuses on the use of a PSMA inhibitor-conjugate of pyropheophorbide-a (Ppa-conjugate 2) for targeted PDT to achieve apoptosis in PSMA+ LNCaP cells. METHODS Confocal laser scanning microscopy with a combination of nuclear staining and immunofluorescence methods were employed to monitor the specific imaging and PDT-mediated apoptotic effects on PSMA-positive LNCaP and PSMA-negative (PC-3) cells. RESULTS Our results demonstrated that PDT-mediated effects by Ppa-conjugate 2 were specific to LNCaP cells, but not PC-3 cells. Cell permeability was detected as early as 2 hr by HOE33342/PI double staining, becoming more intense by 4 hr. Evidence for the apoptotic caspase cascade being activated was based on the appearance of poly-ADP-ribose polymerase (PARP) p85 fragment. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay detected DNA fragmentation 16 hr post-PDT, confirming apoptotic events. CONCLUSIONS Cell permeability by HOE33342/PI double staining as well as PARP p85 fragment and TUNEL assays confirm cellular apoptosis in PSMA+ cells when treated with PS-inhibitor conjugate 2 and subsequently irradiated. It is expected that the PSMA targeting small-molecule of this conjugate can serve as a delivery vehicle for PDT and other therapeutic applications for prostate cancer. Prostate 69:585,594, 2009. © 2009 Wiley-Liss, Inc. [source] Cartilage Tissue Engineering With Demineralized Bone Matrix Gelatin and Fibrin Glue Hybrid Scaffold: An In Vitro StudyARTIFICIAL ORGANS, Issue 2 2010Zheng-Hui Wang Abstract To develop a cartilage-like tissue with hybrid scaffolds of demineralized bone matrix gelatin (BMG) and fibrin, rabbit chondrocytes were cultured on hybrid fibrin/BMG scaffolds in vitro. BMG scaffolds were carefully soaked in a chondrocyte,fibrin suspension, which was polymerized by submerging the constructs into thrombin,calcium chloride solution. Engineered cartilage-like tissue grown on the scaffolds was characterized by histology, immunolocalization, scanning electron microscopy, biochemical assays, and analysis of gene expression at different time points of the in vitro culture. The presence of proteoglycan in the fibrin/BMG hybrid constructs was confirmed by positive toluidine blue and alcian blue staining. Collagen type II exhibited intense immunopositivity at the pericellular matrices. Chondrogenic properties were further demonstrated by the expression of gene-encoded cartilage-specific markers, collagen type II, and aggrecan core protein. The glycosaminoglycan production and hydroxyproline content of tissue grown on the fibrin/BMG hybrid scaffolds were higher than that of the BMG group. In conclusion, the fibrin/BMG hybrid scaffolds may serve as a potential cell delivery vehicle and a structural basis for cartilage tissue engineering. [source] Potential of Fortified Fibrin/Hyaluronic Acid Composite Gel as a Cell Delivery Vehicle for ChondrocytesARTIFICIAL ORGANS, Issue 6 2009Sang-Hyug Park Abstract Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 ± 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 ± 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel. [source] Encapsulation of adult human mesenchymal stem cells within collagen-agarose microenvironments,BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Anna Batorsky Abstract Reliable control over the process of cell differentiation is a major challenge in moving stem cell-based therapies forward. The composition of the extracellular matrix (ECM) is known to play an important role in modulating differentiation. We have developed a system to encapsulate adult human mesenchymal stem cells (hMSC) within spherical three-dimensional (3D) microenvironments consisting of a defined mixture of collagen Type I and agarose polymers. These protein-based beads were produced by emulsification of liquid hMSC-matrix suspensions in a silicone fluid phase and subsequent gelation to form hydrogel beads, which were collected by centrifugation and placed in culture. Bead size and size distribution could be varied by changing the encapsulation parameters (impeller speed and blade separation), and beads in the range of 30,150 microns in diameter were reliably produced. Collagen concentrations up to 40% (wt/wt) could be incorporated into the bead matrix. Visible light and fluorescence microscopy confirmed that the collagen matrix was uniformly distributed throughout the beads. Cell viability post-encapsulation was in the range of 75,90% for all bead formulations (similar to control slab gels) and remained at this level for 8 days in culture. Fluorescent staining of the actin cytoskeleton revealed that hMSC spreading increased with increasing collagen concentration. This system of producing 3D microenvironments of defined matrix composition therefore offers a way to control cell-matrix interactions and thereby guide hMSC differentiation. The bead format allows the use of small amounts of matrix proteins, and such beads can potentially be used as a cell delivery vehicle in tissue repair applications. © 2005 Wiley Periodicals, Inc. [source] An alginate hydrogel matrix for the localised delivery of a fibroblast/keratinocyte co-cultureBIOTECHNOLOGY JOURNAL, Issue 5 2009Nicola C. Hunt Abstract There is significant interest in the development of tissue-engineered skin analogues, which replace both the dermal and the epidermal layer, without the use of animal or human derived products such as collagen or de-epidermalised dermis. In this study, we proposed that alginate hydrogel could be used to encapsulate fibroblasts and that keratinocytes could be cultured on the surface to form a bilayered structure, which could be used to deliver the co-culture to a wound bed, initially providing wound closure and eventually expediting the healing process. Encapsulation of fibroblasts in 2 and 5% w/v alginate hydrogel effectively inhibited their proliferation, whilst maintaining cell viability allowing keratinocytes to grow uninhibited by fibroblast overgrowth to produce a stratified epidermal layer. It was shown that the alginate degradation process was not influenced by the presence of fibroblasts within the hydrogel and that lowering the alginate concentration from 5 to 2% w/v increased the rate of degradation. Fibroblasts released from the scaffold were able to secrete extracellular matrix (ECM) and thus should replace the degrading scaffold with normal ECM following application to the wound site. These findings demonstrate that alginate hydrogel may be an effective delivery vehicle and scaffold for the healing of full-thickness skin wounds. [source] The use of bacterial minicells to transfer plasmid DNA to eukaryotic cellsCELLULAR MICROBIOLOGY, Issue 10 2006Matthew J. Giacalone Summary The delivery of DNA to mammalian cells is of critical importance to the development of genetic vaccines, gene replacement therapies and gene silencing. For these applications, targeting, effective DNA transfer and vector safety are the major roadblocks in furthering development. In this report, we present a novel DNA delivery vehicle that makes use of protoplasted, achromosomal bacterial minicells. Transfer of plasmid DNA as measured by green fluorescent protein expression was found to occur in as high as 25% of cultured Cos-7 cells when a novel chimeric protein containing the D2,D5 region of invasin was expressed and displayed on the surface of protoplasted minicells. Based on endoplasmic reticulum stress and other responses, protoplasted minicells were non-toxic to recipient eukaryotic cells as a consequence of the transfection process. Taken together, these results suggest that bacterial minicells may represent a novel and promising gene delivery vehicle. [source] Promoters and serotypes: targeting of adeno-associated virus vectors for gene transfer in the rat central nervous system in vitro and in vivoEXPERIMENTAL PHYSIOLOGY, Issue 1 2005Z. Shevtsova The brain parenchyma consists of several different cell types, such as neurones, astrocytes, microglia, oligodendroglia and epithelial cells, which are morphologically and functionally intermingled in highly complex three-dimensional structures. These different cell types are also present in cultures of brain cells prepared to serve as model systems of CNS physiology. Gene transfer, either in a therapeutic attempt or in basic research, is a fascinating and promising tool to manipulate both the complex physiology of the brain and that of isolated neuronal cells. Viral vectors based on the parvovirus, adeno-associated virus (AAV), have emerged as powerful transgene delivery vehicles. Here we describe highly efficient targeting of AAV vectors to either neurones or astrocytes in cultured primary brain cell cultures. We also show that transcriptional targeting can be achieved by the use of small promoters, significantly boosting the transgene capacity of the recombinant viral genome. However, we also demonstrate that successful targeting of a vector in vitro does not necessarily imply that the same targeting works in the adult brain. Cross-packaging the AAV-2 genome in capsids of other serotypes adds additional benefits to this vector system. In the brain, the serotype-5 capsid allows for drastically increased spread of the recombinant vector as compared to the serotype-2 capsid. Finally, we emphasize the optimal targeting approach, in which the natural tropism of a vector for a specific cell type is employed. Taken together, these data demonstrate the flexibility which AAV-based vector systems offer in physiological research. [source] Cover Picture: Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 6 2005Mater. Abstract The cover shows biomineralized polysaccharide capsules with specifiable make-up, which can provide microenvironments for stabilization, growth, and differentiation of human cell types, as reported by Oreffo and co-workers on p.,917. The capsules are amenable to complexation with a range of bioactive molecules and cells, offering tremendous potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP-2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP-2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead-in-bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. [source] Biomineralized Polysaccharide Capsules for Encapsulation, Organization, and Delivery of Human Cell Types and Growth Factors,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2005W. Green Abstract The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP-2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP-2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead-in-bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. [source] A Biomolecular "Ship-in-a-Bottle": Continuous RNA Synthesis Within Hollow Polymer Hydrogel AssembliesADVANCED MATERIALS, Issue 6 2010Andrew D. Price The use of micrometer-sized, monodisperse polymer hydrogel capsules that act as both microreactors and drug carriers for de novo synthesized RNA is demonstrated (see figure). These capsules are expected to have broad impact as biophysical tools for the study of encapsulated RNA and as new biocompatible delivery vehicles for the cellular delivery of RNA therapeutics. [source] Controlled Growth Factor Delivery for Tissue EngineeringADVANCED MATERIALS, Issue 32-33 2009Prakriti Tayalia Abstract Growth factors play a crucial role in information transfer between cells and their microenvironment in tissue engineering and regeneration. They initiate their action by binding to specific receptors on the surface of target cells and the chemical identity, concentration, duration, and context of these growth factors contain information that dictates cell fate. Hence, the importance of exogenous delivery of these molecules in tissue engineering is unsurprising, considering their importance for tissue regeneration. However, the short half-lives of growth factors, their relatively large size, slow tissue penetration, and their potential toxicity at high systemic levels, suggest that conventional routes of administration are unlikely to be effective. In this review, we provide an overview of the design criteria for growth factor delivery vehicles with respect to the growth factor itself and the microenvironment for delivery. We discuss various methodologies that could be adopted to achieve this localized delivery, and strategies using polymers as delivery vehicles in particular. [source] Injectable Biomaterials for Regenerating Complex Craniofacial Tissues,ADVANCED MATERIALS, Issue 32-33 2009James D. Kretlow Abstract Engineering complex tissues requires a precisely formulated combination of cells, spatiotemporally released bioactive factors, and a specialized scaffold support system. Injectable materials, particularly those delivered in aqueous solution, are considered ideal delivery vehicles for cells and bioactive factors and can also be delivered through minimally invasive methods and fill complex 3D shapes. In this review, we examine injectable materials that form scaffolds or networks capable of both replacing tissue function early after delivery and supporting tissue regeneration over a time period of weeks to months. The use of these materials for tissue engineering within the craniofacial complex is challenging but ideal as many highly specialized and functional tissues reside within a small volume in the craniofacial structures and the need for minimally invasive interventions is desirable due to aesthetic considerations. Current biomaterials and strategies used to treat craniofacial defects are examined, followed by a review of craniofacial tissue engineering, and finally an examination of current technologies used for injectable scaffold development and drug and cell delivery using these materials. [source] Acute oral toxicity of colchicine in rats: effects of gender, vehicle matrix and pre-exposure to lipopolysaccharideJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2007Paddy L. Wiesenfeld Abstract The oral toxicity of a single administration by gavage (10, 20 or 30 mg kg,1 body weight) of colchicine (COL) was determined in young, mature male and female Sprague-Dawley rats. The effect of COL was evaluated in the presence or absence of additional treatment variables that included vehicle and lipopolysaccharide (LPS) pre-exposure. The vehicle for COL was either Half and Half cream (H & H) or saline, and each group included pretreatment with either saline or a low, minimally toxic dose (83 µg kg,1 body weight) of LPS. Colchicine toxicity in both male and female age-matched rats was characterized by progressively more severe dose-related clinical signs of toxicity. These included mortality, decreased body weight and feed intake during the first several days after dosing, with recovery thereafter in surviving animals. There were differences in the severity of the toxic response to COL between male and female rats. The most notable sex-related difference was in COL lethality. Female rats were two times more susceptible to the lethal effects of COL than male rats. Saline or H & H delivery vehicles did not result in any apparent qualitative or quantitative differences in COL toxicity. LPS pretreatment significantly potentiated COL lethality in both males and females, although the potentiation in males was greater than in females. LPS pretreatment modestly increased the COL induced anorexic effect in surviving males, but not in surviving female animals. LPS did not appear to modulate either the body weights or clinical signs of COL induced toxicity in surviving males or females. Copyright © 2007 John Wiley & Sons, Ltd. [source] Adult-derived stem cells and their potential for use in tissue repair and molecular medicineJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2005Henry E. Young Abstract This report reviews three categories of precursor cells present within adults. The first category of precursor cell, the epiblast-like stem cell, has the potential of forming cells from all three embryonic germ layer lineages, e.g., ectoderm, mesoderm, and endoderm. The second category of precursor cell, the germ layer lineage stem cell, consists of three separate cells. Each of the three cells is committed to form cells limited to a specific embryonic germ layer lineage. Thus the second category consists of germ layer lineage ectodermal stem cells, germ layer lineage mesodermal stem cells, and germ layer lineage endodermal stem cells. The third category of precursor cells, progenitor cells, contains a multitude of cells. These cells are committed to form specific cell and tissue types and are the immediate precursors to the differentiated cells and tissues of the adult. The three categories of precursor cells can be readily isolated from adult tissues. They can be distinguished from each other based on their size, growth in cell culture, expressed genes, cell surface markers, and potential for differentiation. This report also discusses new findings. These findings include the karyotypic analysis of germ layer lineage stem cells; the appearance of dopaminergic neurons after implantation of naive adult pluripotent stem cells into a 6-hydroxydopamine-lesioned Parkinson's model; and the use of adult stem cells as transport mechanisms for exogenous genetic material. We conclude by discussing the potential roles of adult-derived precursor cells as building blocks for tissue repair and as delivery vehicles for molecular medicine. [source] | |||||||||||||||||||||||||||||||