Self-assembling elastin-like peptides growth factor chimeric nanoparticles for the treatment of chronic wounds.

Chronic wounds are associated with poor epidermal and dermal remodeling. Previous work has shown the efficacy of keratinocyte growth factor (KGF) in reepithelialization and elastin in dermal wound healing. Here we demonstrate the fabrication of a fusion protein comprising of elastin-like peptides and KGF.

Optically responsive gold nanorod-polypeptide assemblies.

Environmentally responsive nanoassemblies based on polypeptides and nanoparticles can have a number of promising biological/biomedical applications. We report the generation of gold nanorod (GNR)-elastin-like polypeptide (ELP) nanoassemblies whose optical response can be manipulated based on exposure to near-infrared (NIR) light. Cysteine-containing ELPs were self-assembled on GNRs mediated by gold-thiol bonds, leading to the generation of GNR-ELP nanoassemblies.

Development of an in vitro cell culture model of hepatic steatosis using hepatocyte-derived reporter cells.

Fatty liver disease is a problem of growing clinical importance due to its association with the increasingly prevalent conditions of obesity and diabetes. While steatosis represents a reversible state of excess intrahepatic lipid, it is also associated with increased susceptibility to oxidative and cytokine stresses and progression to irreversible hepatic injury characterized by steatohepatitis, cirrhosis, and malignancy. Currently, the molecular mechanisms underlying progression of this dynamic disease remain poorly understood, particularly at the level of transcriptional regulation.

Site-directed mutagenesis of the hinge peptide from the hemagglutinin protein: enhancement of the pH-responsive conformational change.

Environmentally responsive proteins and peptides are increasingly finding utility in various engineered systems due to their ability to respond to the presentation of external stimuli. A classic example of this behavior is the influenza hemagglutinin (HA) fusion protein. At neutral pH, HA exists in a non-fusogenic state, but upon exposure to low pH, the conformation of the structure changes to expose a fusogenic peptide.

A microfluidic bioreactor for increased active retrovirus output.

Retroviruses are one of the most commonly used vectors in ongoing gene therapy clinical trials. To evaluate and advance virus production on the microscale platform, we have created a novel microfluidic bioreactor for continuous retrovirus production. We investigated the growth kinetics of a retroviral packaging cell line in microfluidic bioreactors for several compartment sizes, and packaging cells perfused in the microdevices showed similar growth kinetics to those cultured in conventional static conditions.

The use of elastin-like polypeptide-polyelectrolyte complexes to control hepatocyte morphology and function in vitro.

Both tissue engineering and biological science will benefit from improved methods to control the morphology, differentiated state, and function of primary cells. In this paper, we show that surface modification of tissue culture polystyrene (TCPS) with chemically derivatized elastin-like polypeptides (ELPs) enables control over the in vitro morphology and liver-specific function of primary rat hepatocytes. The ELP (VPGVG)40 was produced in Escherichia coli and conjugated with polyacrylic acid (PAA) and polyethyleneimine (PEI) using carbodiimide activation chemistry.

Immunomodulation of activated hepatic stellate cells by mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (MSCs) have been reported to prevent the development of liver fibrosis in a number of pre-clinical studies. Marked changes in liver histopathology and serological markers of liver function have been observed without a clear understanding of the therapeutic mechanism by which stem cells act. We sought to determine if MSCs could modulate the activity of resident liver cells, specifically hepatic stellate cells (SCs) by paracrine mechanisms using indirect cocultures.

Amphipathic peptide-based fusion peptides and immunoconjugates for the targeted ablation of prostate cancer cells.

We describe the design, generation, and in vitro evaluation of targeted amphipathic fusion peptides and immunoconjugates for the ablation of prostate cancer cells. The overexpression of the prostate-specific membrane antigen (PSMA) was exploited as means to specifically deliver cytotoxic peptides to prostate cancer cells. Cationic amphipathic lytic peptides were chosen as cytotoxic agents due to their ability to depolarize mitochondrial membranes and induce apoptosis.

Engineering protein and peptide building blocks for nanotechnology.

The tremendous diversity in the structure and function of proteins has stimulated intense interest in using them for nanotechnology applications. In this review, we discuss recent developments in the engineering of proteins and peptides for the design and construction of functional and structural elements of nanodevices. We begin with a short discussion highlighting the differences between chemical and biological synthesis of proteins and peptides.

Modulation of single-chain antibody affinity with temperature-responsive elastin-like polypeptide linkers.

Single-chain antibodies are genetically engineered constructs composed of a VH and VL domain of an antibody linked by a flexible peptide linker, commonly (GGGGS)3. We asked whether replacement of this flexible linker with peptides known to undergo environmentally induced structural transitions could lead to antibodies with controlled binding and release characteristics. To this end, we genetically modified and produced a series of anti-fluorescein single-chain antibodies with the general linker sequence (VPGXG)n, where n is 1.

Genetically engineered polymers: status and prospects for controlled release.

Genetic engineering methodology has enabled the synthesis of protein-based polymers with precisely controlled structures. Protein-based polymers have well-defined molecular weights, monomer compositions, sequences and stereochemistries. The incorporation of tailor-made motifs at specified locations by recombinant techniques allows the formation of hydrogels, sensitivity to environmental stimuli, complexation with drugs and nucleic acids, biorecognition and biodegradation.

In vitro and in vivo evaluation of recombinant silk-elastinlike hydrogels for cancer gene therapy.

The objectives of this study were to evaluate: (i). the influences of hydrogel geometry, DNA molecular weight, and DNA conformation on DNA release from a silk-elastinlike protein polymer (SELP) hydrogel, (ii). the bioactivity and transfection efficiency of encapsulated DNA over time in vitro, (iii).

Genetically engineered silk-elastinlike protein polymers for controlled drug delivery.

The silk-elastinlike class of genetically engineered protein polymers is composed of tandemly repeated silk-like (Gly-Ala-Gly-Ala-Gly-Ser) and elastin-like (Gly-Val-Gly-Val-Pro) amino acid blocks. The precision with which these polymers can be synthesized, as well as the ability to incorporate motifs that allow for gel-formation, stimuli-sensitivity, biodegradation, and biorecognition have stimulated interest in their use for controlled drug and gene delivery. This review will focus on the synthesis and characterization of silk-elastinlike polymers as related to controlled drug delivery.

Controlled release of plasmid DNA from a genetically engineered silk-elastinlike hydrogel.

Purpose: The purpose of this study was to evaluate the potential of a genetically engineered silk-elastinlike polymer (SELP) as a matrix for the controlled release of plasmid DNA.

Methods: The influences of SELP concentration, DNA concentration, SELP cure time, and buffer ionic strength on the release of DNA from SELP hydrogels were investigated. To calculate the average effective diffusivity of DNA within the hydrogels, the release data were fitted to a known equation.