No abstract

Extracellular vesicles (EVs) are emerging as a promising alternative approach to cell‐therapies. However, to realize the potential of these nanoparticles as new regenerative tools, healthcare materials that address the current limitations of systemic administration need to be developed. Here, two technologies for controlling the structure of alginate based microgel suspensions are used to develop sustained local release of EVs, in vitro. Microparticles formed using a shearing technique are compared to those manufactured using vibrational technology, resulting in either anisotropic sheet‐like or spheroid particles, respectively. EVs harvested from preosteoblasts are isolated using differential ultracentrifugation and successfully loaded into the two systems, while maintaining their structures. Promisingly, in addition to exhibiting even EV distribution and high stability, controlled release of vesicles from both structures is exhibited, in vitro, over the 12 days studied. Interestingly, a significantly greater number of EVs are released from the suspensions formed by shearing (69.9 ± 10.5%), compared to the spheroids (35.1 ± 7.6%). Ultimately, alterations to the hydrogel physical structures have shown to tailor nanoparticle release while simultaneously providing ideal material characteristics for clinical injection. Thus, the sustained release mechanisms achieved through manipulating the formation of such biomaterials provide a key to unlocking the therapeutic potential held within EVs.

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Type I diabetics are dependent on daily insulin injections. A therapy capable of immunoisolating pancreatic beta-cells and providing normoglycaemia is an alternative since it would avoid the late complications associated with insulin use. Here, 3D-concave agarose micro-wells were used to culture robust pancreatic MIN-6 cell spheroids within 24 hours that were shown to exhibit cell-cell contact and uniform size (201 ± 2 μm). A polyelectrolyte multilayer (PEM) approach using alginate and poly-l-lysine was employed to coat cell spheroids. In comparison to conventional PEM, use of a novel Ca2+ pre-coating step enhanced beta-cells viability (89 ± 6%) and metabolic activity since it reduced the toxic effect of the cationic polymer. Pre-coating was achieved by treating MIN-6 spheroids with calcium chloride, which enabled the adhesion of anionic polymer to the cells surface. Pre-coated cells coated with four bilayers of polymers were successfully immunoisolated from FITC-mouse antibody and pro-inflammatory cytokines. Novel PEM coated cells were shown to secret significantly (P < 0.05) different amounts of insulin in response to changes in glucose concentration (2 vs. 20 mM). This work presents a 3D culture model and novel PEM coating procedure that enhances viability, maintains functionality and immunoisolates beta-cells, which is a promising step towards an alternative therapy to insulin.

Nanomedicines are promising therapeutic compounds allowing the development of new treatment approaches. However, important factors affecting the behavior of nanoparticles in vivo cannot be simulated in conventional static models. Dynamic cell cultures, where cells are cultivated in the presence of shear stress, have the potential to bridge this gap by mimicking critical features of physiological conditions. Iron-carbohydrate nanoparticles are a dominant treatment for iron deficiency unresponsive to oral iron supplements. Compared to the data available from clinical studies, little is known about the interaction of these particles with endothelial cells. Our approach implements and compares a microchannel-based dynamic human endothelium model to the static culture to explore potential differences in cells response after exposure to iron nanoparticles. Differences in cellular uptake are observable using Prussian blue assay. There is a noticeable increase on VCAM-1 and ICAM-1 gene expression on endothelial cells activated by inflammatory responses, in cells exposed to nanoparticles under static condition. Results show that cytotoxicity caused by iron particles is significantly lower under dynamic condition compared to static cultures. We demonstrate that inclusion of dynamic flow and biological fluids are positive steps towards nanoparticle evaluation in a physiologically relevant in vitro model.