Dual targeted extracellular vesicles regulate oncogenic genes in advanced pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) tumours carry multiple gene mutations and respond poorly to treatments. There is currently an unmet need for drug carriers that can deliver multiple gene cargoes to target high solid tumour burden like PDAC. Here, we report a dual targeted extracellular vesicle (dtEV) carrying high loads of therapeutic RNA that effectively suppresses large PDAC tumours in mice. The EV surface contains a CD64 protein that has a tissue targeting peptide and a humanized monoclonal antibody. Cells sequentially transfected with plasmid DNAs encoding for the RNA and protein of interest by Transwell®-based asymmetric cell electroporation release abundant targeted EVs with high RNA loading. Together with a low dose chemotherapy drug, Gemcitabine, dtEVs suppress large orthotopic PANC-1 and patient derived xenograft tumours and metastasis in mice and extended animal survival. Our work presents a clinically accessible and scalable way to produce abundant EVs for delivering multiple gene cargoes to large solid tumours.

Cell-cell proximity effects in multi-cell electroporation.

We report a fundamental study of how the electropermeabilization of a cell is affected by nearby cells. Previous researchers studying electroporation of dense suspensions of cells have observed, both theoretically and experimentally, that such samples cannot be treated simply as collections of independent cells. However, the complexity of those systems makes quantitative modeling difficult. We studied the change in the minimum applied electric field, the threshold field, required to affect electropermeabilization of a cell due to the presence of a second cell. Experimentally, we used optical tweezers to accurately position two cells in a custom fluidic electroporation device and measured the threshold field for electropermeabilization. We also captured video of the process. In parallel, finite element simulations of the electrostatic potential distributions in our systems were generated using the 3-layer model and the contact resistance methods. Reasonably good agreement with measurements was found assuming a model in which changes in a cell's threshold field were predicted from the calculated changes in the maximum voltage across the cell's membrane induced by the presence of a second cell. The threshold field required to electroporate a cell is changed ∼5%-10% by a nearby, nearly touching second cell. Cells aligned parallel to the porating field shield one another. Those oriented perpendicular to the field enhance the applied field's effect. In addition, we found that the dynamics of the electropermeabilization process are important in explaining observations for even our simple two-cell system.

Increased anti-leukemic activity of decitabine via AR-42-induced upregulation of miR-29b: a novel epigenetic-targeting approach in acute myeloid leukemia.

Histone deacetylase (HDAC) inhibitors either alone or in combination with hypomethylating agents have limited clinical effect in acute myeloid leukemia (AML). Previously, we demonstrated that AML patients with higher miR (microRNA)-29b expression had better response to the hypomethylating agent decitabine. Therefore, an increase in miR-29b expression preceding decitabine treatment may provide a therapeutic advantage. We previously showed that miR-29b expression is suppressed by a repressor complex that includes HDACs. Thus, HDAC inhibition may increase miR-29b expression. We hypothesized that priming AML cells with the novel HDAC inhibitor (HDACI) AR-42 would result in increased response to decitabine treatment via upregulation of miR-29b. Here, we show that AR-42 is a potent HDACI in AML, increasing miR-29b levels and leading to downregulation of known miR-29b targets (that is, SP1, DNMT1, DNMT3A and DNMT3B). We then demonstrated that the sequential administration of AR-42 followed by decitabine resulted in a stronger anti-leukemic activity in vitro and in vivo than decitabine followed by AR-42 or either drug alone. These preclinical results with AR-42 priming before decitabine administration represent a promising, novel treatment approach and a paradigm shift with regard to the combination of epigenetic-targeting compounds in AML, where decitabine has been traditionally given before HDACIs.

Simulation of single DNA molecule stretching and immobilization in a de-wetting two-phase flow over micropillar-patterned surface.

We investigate single DNA stretching dynamics in a de-wetting flow over micropillars using Brownian dynamics simulation. The Brownian dynamics simulation is coupled with transient flow field computation through a numerical particle tracking algorithm. The droplet formation on the top of the micropillar during the de-wetting process creates a flow pattern that allows DNA to stretch across the micropillars. It is found that DNA nanowire forms if DNA molecules could extend across the stagnation point inside the connecting water filament before its breakup. It also shows that DNA locates closer to the top wall of the micropillar has higher chance to enter the flow pattern of droplet formation and thus has higher chance to be stretched across the micropillars. Our simulation tool has the potential to become a design tool for DNA manipulation in complex biomicrofluidic devices.

A novel 3-D model for cell culture and tissue engineering.

A novel method of making microcapsules in a macrocapsule is demonstrated as a 3-D culture system in this article. Mouse embryonic stem (mES) cells as model cells were used in the 3-D culture space, and the cell viability and histological observation were conducted. Furthermore, Oct4 gene expression was evaluated for the undifferentiated status of mES cells in this 3-D model. The results showed that mES cells can grow in this 3-D model and retain their normal viability and morphology. This 3-D model allows mES cells to stay in the undifferentiated state better than 2-D culture systems. This work demonstrates a new 3-D tissue model which can provide an in vivo like microenvironment for non-differentiated mES cells with good immunoisolation. This approach may bridge the gap between traditional 2-D cell culture and animal models.

Adipogenesis of murine embryonic stem cells in a three-dimensional culture system using electrospun polymer scaffolds.

A mechanistic understanding of adipose tissue differentiation is critical for the treatment and prevention of obesity and type 2 diabetes. Conventional in vitro models of adipogenesis are preadipocytes or freshly isolated adipocytes grown in two-dimensional (2D) cultures. Optimal results using in vitro tissue culture models can be expected only when adipocyte models closely resemble adipose tissue in vivo. Thus the design of an in vitro three-dimensional (3D) model which faithfully mimics the in vivo environment is needed to effectively study adipogenesis. Pluripotent embryonic stem (ES) cells are a self-renewing cell type that can readily be differentiated into adipocytes. In this study, a 3D culture system was developed to mimic the geometry of adipose tissue in vivo. Murine ES cells were seeded into electrospun polycaprolactone scaffolds and differentiated into adipocytes in situ by hormone induction as demonstrated using a battery of gene and protein expression markers along with the accumulation of neutral lipid droplets. Insulin-responsive Akt phosphorylation, and beta-adrenergic stimulation of cyclic AMP synthesis were demonstrated in ES cell-derived adipocytes. Morphologically, ES cell-derived adipocytes resembled native fat cells by scanning electron and phase contrast microscopy. This tissue engineered ES cell-matrix model has potential uses in drug screening and other therapeutic developments.

Fabrication of polymeric microparticles for drug delivery by soft lithography.

Soft lithographic techniques were used to fabricate polymeric microparticles for drug delivery applications. The microparticles were made of thermoplastics and thermosets from different types of precursors including reactive resin and polymer solutions in organic solvents or water. The microparticles produced using these methods were made of widely used polymers for drug delivery with highly uniform sizes, plate-like morphology, and well-defined lateral sizes and shapes, making them potentially useful for drug delivery applications and as platform for the construction of multi-functional drug delivery devices.