27 research outputs found
In-house preparation of hydrogels for batch affinity purification of glutathione <it>S</it>-transferase tagged recombinant proteins
<p>Abstract</p> <p>Background</p> <p>Many branches of biomedical research find use for pure recombinant proteins for direct application or to study other molecules and pathways. Glutathione affinity purification is commonly used to isolate and purify glutathione S-transferase (GST)-tagged fusion proteins from total cellular proteins in lysates. Although GST affinity materials are commercially available as glutathione immobilized on beaded agarose resins, few simple options for in-house production of those systems exist. Herein, we describe a novel method for the purification of GST-tagged recombinant proteins.</p> <p>Results</p> <p>Glutathione was conjugated to low molecular weight poly(ethylene glycol) diacrylate (PEGDA) via thiol-ene “click” chemistry. With our in-house prepared PEGDA:glutathione (PEGDA:GSH) homogenates, we were able to purify a glutathione S-transferase (GST) green fluorescent protein (GFP) fusion protein (GST-GFP) from the soluble fraction of <it>E. coli</it> lysate. Further, microspheres were formed from the PEGDA:GSH hydrogels and improved protein binding to a level comparable to purchased GSH-agarose beads.</p> <p>Conclusions</p> <p>GSH containing polymers might find use as in-house methods of protein purification. They exhibited similar ability to purify GST tagged proteins as purchased GSH agarose beads.</p
Decellularized Human Cornea for Reconstructing the Corneal Epithelium and Anterior Stroma
In this project, we strived to develop a decellularized human cornea to use as a scaffold for reconstructing the corneal epithelium and anterior stroma. Human cadaver corneas were decellularized by five different methods, including detergent- and nondetergent-based approaches. The success of each method on the removal of cells from the cornea was investigated. The structural integrity of decellularized corneas was compared with the native cornea by electron microscopy. The integrity of the basement membrane of the epithelium was analyzed
by histology and by the expression of collagen type IV, laminin, and fibronectin. Finally, the ability of the decellularized corneas to support the growth of human corneal epithelial cells and fibroblasts was assessed in vitro. Corneas processed using Triton X-100, liquid nitrogen, and poly(ethylene glycol) resulted in incomplete
removal of cellular material. Corneas processed with the use of sodium dodecyl sulfate (SDS) or with sodium chloride (NaCl) plus nucleases successfully removed all cellular material; however, only the NaCl plus nuclease treatment kept the epithelial basement membrane completely intact. Corneas processed with NaCl plus nuclease supported both fibroblast and epithelial cell growth in vitro, while corneas treated with SDS supported the growth of only fibroblasts and not epithelial cells. Decellularized human corneas provide a scaffold that can
support the growth of corneal epithelial cells and stromal fibroblasts. This approach may be useful for reconstructing the anterior cornea and limbus using autologous cells
Reducible Micelleplexes are Stable Systems for Anti-miRNA Delivery in Cerebrospinal Fluid
Glioblastoma
multiforme (GBM) and other central nervous system
(CNS) cancers have poor long-term prognosis, and there is a significant
need for improved treatments. GBM initiation and progression are mediated,
in part, by microRNA (miRNA), which are endogenous posttranscriptional
gene regulators. Misregulation of miRNAs is a potential target for
therapeutic intervention in GBM. In this work, a micelle-like nanoparticle
delivery system based upon the block copolymer poly(ethylene glycol-<i>b</i>-lactide-<i>b</i>-arginine) was designed with
and without a reducible linkage between the lactide and RNA-binding
peptide, R<sub>15</sub>, to assess the ability of the micelle-like
particles to disassemble. Using confocal live cell imaging, intracellular
dissociation was pronounced for the reducible micelleplexes. This
dissociation was also supported by higher efficiency in a dual luciferase
assay specific for the miRNA of interest, miR-21. Notably, micelleplexes
were found to have significantly better stability and higher anti-miRNA
activity in cerebrospinal fluid than in human plasma, suggesting an
advantage for applying micelleplexes to CNS diseases and in vivo CNS
therapeutics. The reducible delivery system was determined to be a
promising delivery platform for the treatment of CNS diseases with
miRNA therapy
High and Low Molecular Weight Hyaluronic Acid Differentially Influence Macrophage Activation
Macrophages exhibit phenotypic diversity
permitting wide-ranging
roles in maintaining physiologic homeostasis. Hyaluronic acid, a major
glycosaminoglycan of the extracellular matrix, has been shown to have
differential signaling based on its molecular weight. With this in
mind, the main objective of this study was to elucidate the role of
hyaluronic acid molecular weight on macrophage activation and reprogramming.
Changes in macrophage activation were assessed by activation state
selective marker measurement, specifically quantitative real time
polymerase chain reaction, and cytokine enzyme-linked immunoassays,
after macrophage treatment with differing molecular weights of hyaluronic
acid under four conditions: the resting state, concurrent with classical
activation, and following inflammation involving either classically
or alternatively activated macrophages. Regardless of initial polarization
state, low molecular weight hyaluronic acid induced a classically
activated-like state, confirmed by up-regulation of pro-inflammatory
genes, including <i>nos2</i>, <i>tnf</i>, <i>il12b</i>, and <i>cd80,</i> and enhanced secretion
of nitric oxide and TNF-α. High molecular weight hyaluronic
acid promoted an alternatively activated-like state, confirmed by
up regulation of pro-resolving gene transcription, including <i>arg1</i>, <i>il10</i>, and <i>mrc1,</i> and
enhanced arginase activity. Overall, our observations suggest that
macrophages undergo phenotypic changes dependent on molecular weight
of hyaluronan that correspond to either (1) pro-inflammatory response
for low molecular weight HA or (2) pro-resolving response for high
molecular weight HA. These observations bring significant further
understanding of the influence of extracellular matrix polymers, hyaluronic
acid in particular, on regulating the inflammatory response of macrophages.
This knowledge can be used to guide the design of HA-containing biomaterials
to better utilize the natural response to HAs
Toroidal-Spiral Particles for Codelivery of Anti-VEGFR‑2 Antibody and Irinotecan: A Potential Implant to Hinder Recurrence of Glioblastoma Multiforme
Heterogeneous
toroidal-spiral particles (TSPs) were generated by
polymer droplet sedimentation, interaction, and cross-linking. TSPs
provide a platform for encapsulation and release of multiple compounds
of different sizes and physicochemical properties. As a model system,
we demonstrate the encapsulation and independently controlled release
of an anti-VEGFR-2 antibody and irinotecan for the treatment of glioblastoma
multiforme. The anti-VEGFR-2 antibody was released from the TS channels
and its binding to HUVECs was confirmed by confocal microscopy and
flow cytometry, suggesting active antibody encapsulation and release.
Irinotecan, a small molecule drug, was released from the dense polymer
matrix of poly(ethylene glycol) diacrylate (MW ∼ 700 g/mol;
PEGDA 700). Released irinotecan inhibited the proliferation of U251
malignant glioma cells. Since the therapeutic compounds are released
through different pathways, specifically diffusion through the polymer
matrix versus TS channels, the release rate can be controlled independently
through the design of the structure and material of particle components
In Vitro Evaluation of Macroporous Hydrogels to Facilitate Stem Cell Infiltration, Growth, and Mineralization
Hydrogels have gained acceptance as biomaterials in a wide range of applications, including pharmaceutical formulations, drug delivery, and tissue sealants. However, exploiting the potential of hydrogels as scaffolds for cell transplantation, tissue engineering, and regenerative medicine still remains a challenge due to, in part, scaffold design limitations. Here, we describe a highly interconnected, macroporous poly(ethylene glycol) diacrylate hydrogel scaffold, with pores ranging from 100 to 600 μm. The scaffold exhibits rapid cell uptake and cell seeding without the need of any external force or device with high incorporation efficiency. When human mesenchymal stem cells are seeded within the porous scaffolds, the scaffolds were found to promote long-term stem cell viability, and on exposure to osteogenic medium, elicit an mineralization response as evaluated by an increased alkaline phosphatase activity (per cell) and calcium and phosphate content within the constructs. The atomic composition of the mineralized matrix was further determined by energy dispersive spectroscopy and found to be similar to calcium-deficient hydroxyapatite, the amorphous biological precursor of bone. The macroporous design of the hydrogel appears advantageous over similar porous hydrogel scaffolds with respect to ease of synthesis, ease of stem cell seeding, and its ability to support long-term stem cell survival and possible differentiation
Decellularized Human Cornea for Reconstructing the Corneal Epithelium and Anterior Stroma
In this project, we strived to develop a decellularized human cornea to use as a scaffold for reconstructing the corneal epithelium and anterior stroma. Human cadaver corneas were decellularized by five different methods, including detergent- and nondetergent-based approaches. The success of each method on the removal of cells from the cornea was investigated. The structural integrity of decellularized corneas was compared with the native cornea by electron microscopy. The integrity of the basement membrane of the epithelium was analyzed by histology and by the expression of collagen type IV, laminin, and fibronectin. Finally, the ability of the decellularized corneas to support the growth of human corneal epithelial cells and fibroblasts was assessed in vitro. Corneas processed using Triton X-100, liquid nitrogen, and poly(ethylene glycol) resulted in incomplete removal of cellular material. Corneas processed with the use of sodium dodecyl sulfate (SDS) or with sodium chloride (NaCl) plus nucleases successfully removed all cellular material; however, only the NaCl plus nuclease treatment kept the epithelial basement membrane completely intact. Corneas processed with NaCl plus nuclease supported both fibroblast and epithelial cell growth in vitro, while corneas treated with SDS supported the growth of only fibroblasts and not epithelial cells. Decellularized human corneas provide a scaffold that can support the growth of corneal epithelial cells and stromal fibroblasts. This approach may be useful for reconstructing the anterior cornea and limbus using autologous cells