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.

Biomimetic tissue engineering aspires to develop bioinspired implantable devices that would positively interact with the host. Given that glycosaminoglycans are involved in many physiological processes, whereas their deprivation is associated with pathophysiologies, functionalization of implantable devices with natural and/or synthetic carbohydrate moieties is at the forefront of scientific research and industrial innovation. Herein, we venture to assess the influence of various concentrations (0.01%, 0.1%, 1%) of hyaluronic acid and Ficoll on the structural, thermal, biomechanical and biological (human osteoblasts) properties of electrospun poly(lactic-co-glycolic acid) fibers. The addition of hyaluronic acid and Ficoll reduced the fiber diameter, with the 1% hyaluronic acid exhibiting the smallest fibers diameter (p < 0.001). Neither the addition of hyaluronic acid nor the addition Ficoll significantly affected the onset and peak temperatures (p > 0.05). All hyaluronic acid and Ficoll treatments significantly reduced stress at break, strain at break and elastic modulus values (p < 0.001). Hyaluronic acid and Ficoll did not affect osteoblast viability and metabolic activity temperatures (p > 0.05); the 1% hyaluronic acid and Ficoll significantly increased (p < 0.001) osteoblast proliferation at day 21. By day 21, the 1% hyaluronic acid and 1% Ficoll fibers showed the highest alkaline phosphatase activity and calcium deposition. At day 21, osteocalcin was not detected, whereas osteopontin was detected on all samples. Collectively, our data clearly illustrate the biological benefit of nonsulfated polysaccharides as functionalization molecules.

Telephone: +44(0)1782 733875Acknowledgments: We would like to thank Prof. Glenn E Morris for his invaluable insights into the growth of the Py clones, and the production of antibodies for immunofluorescence.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. AbstractAlmost 30 years ago, the monoclonal antibody Py was developed to detect pyramidal neurons in the CA3 region of the rat hippocampus. The utility of this antibody quickly expanded when several groups discovered that it could be used to identify very specific populations of neurons in the normal, developing, and diseased or injured central nervous system. Despite this body of literature, the identity of the antigen that the Py antibody recognizes remained elusive. Here, immunoprecipitation experiments from the adult rat cortex identified the Py antigen as neurofilament heavy chain (NF-H). Double immunolabelling of sections through the rat brain using Py and NF-H antibodies confirmed the identity of the Py antigen, and reveal that Py/NF-H+ neurons appear to share the feature of being particularly large in diameter. These include the neurons of the gigantocellular reticular formation, pyramidal neurons of layers II/III and V of the cortex, cerebellar Purkinje neurons as well as CA3 pyramidal neurons. Taken together, this finding gives clarity to past work using the monoclonal Py antibody, and immediately expands our understanding of the importance of NF-H in neural development, functioning, and disease.