The Manufacturing Conditions for the Direct and Reproducible Formation of Electrospun PCL/Gelatine 3D Structures for Tissue Regeneration

Electrospinning is a versatile technique for fabricating nanofibrous scaffolds for tissue engineering applications. However, the direct formation of 3D sponges through electrospinning has previously not been reproducible. We used a Taguchi experimental design approach to optimise the electrospinning parameters for forming PCL and PCL/gelatine 3D sponges. The following parameters were investigated to improve sponge formation: solution concentration, humidity, and solution conductivity. Pure PCL sponges were achievable. However, a much fluffier sponge formed by increasing the solution conductivity with gelatine. The optimal conditions for sponge formation 24 w/v% 80:20 PCL:gelatine on aluminium foil at ≥70% humidity, 15 cm, 22 kV and 1500 µL/h. The resulting sponge had a highly porous structure with a fibre diameter of ~1 µm. They also supported significantly higher cell viability than 2D electrospun mats, dropcast films of the same material and even the TCP positive control. Our study demonstrates that the direct formation of PCL/gelatine 3D sponges through electrospinning is feasible and promising for tissue engineering applications. The sponges have a highly porous structure and support cell viability, which are essential properties for tissue engineering scaffolds. Further studies are needed to optimise the manufacturing process and evaluate the sponges' long-term performance in vivo.

Serotype-specific microvascular changes in the liver due to dengue virus (DENV) non-structural protein-1 (NS1)

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): University of Surrey

Dengue virus is the most common arbovirus in humans worldwide, with a minor proportion developing severe dengue, which includes the cardiovascular complications of vascular leakage, haemorrhage, organ failure and shock, all of which could prove fatal. The mechanisms that lead to microvascular leakage remain incompletely understood. While DENV-2 NS1 has been shown by our group to disrupt endothelial-pericyte interactions leading to enhanced endothelial cell permeability in vitro, it is unclear whether this is true across all four serotypes of DENV and to what degree. It is also unclear whether DENV NS1 similarly affects all types of pericytes across the body. Our previous work was performed in saphenous venous pericytes, which we here extend to include hepatic stellate cells (HSCs), since the liver is a major site of dengue pathology. In this project, transendothelial electrical resistance readings of co-cultures of endothelial cells with either SVPs or HSCs both revealed the DENV serotypes to significantly lower endothelial membrane function, most notably at DENV-2. Additionally, preliminary data from the 3D Matrigel angiogenesis assay revealed the DENV serotypes to alter the ability of endothelial cells and SVPs to form vascular structures. Interestingly, our alamar blue proliferation assay utilising hepatic stellate cells (HSCs) showed that liver pericytes display increased proliferation in response to the various DENV serotypes, with immunostaining of HSCs also revealing an increase in myofibroblast protein alpha-smooth muscle actin. These results collectively show the ability to disrupt endothelial-pericyte interactions is shared across the DENV serotypes and suggest a potential loss of endothelial-pericyte interaction due to pericyte differentiation in the liver. This information gives further insight to the mechanisms related with DENV interactions with the vasculature, which could aid in establishing a diagnostic test or treatment for those affected with severe dengue fever.