Development of a Screening Platform for Angiogenic Drug Delivery Systems Using Zebrafish Embryos
The development of an angiogenic drug delivery system requires in vitro and in vivo testing before the system can used to treat a disease or condition. The zebrafish embryo is a promising animal model for screening potential angiogenic drug delivery systems due to their optical transparency, which allows for the live imaging of tissues and biological responses. Following establishment of injection protocols, the trunk and yolk sac of 2 - 3 day post-fertilization (dpf) embryos were investigated as potential implant sites for evaluating angiogenic responses due to the highly ordered and easily visualized vasculature at these locations. Bolus injections of vascular endothelial growth factor A(VEGF-A) was carried out into the yolk sac of Tg[fli1a:DsRED] zebrafish embryos and the survival rate and angiogenic response in the neighboring gut vasculature was evaluated, and microparticle retention rates within the trunk and yolk sac were analyzed. Embryos that received the VEGF-A bolus injections had a survival rate of 100%, and the survival rate of embryos that received a vehicle only injection was also 100%. No angiogenic response was detected in the surrounding vasculature. The microparticle retention rate of 25 μm PE microparticles injected into the yolk sac was poor, where only 7% of injected microparticles were retained in the yolk sac after 2 days. The trunk injection model was evaluated for microparticle retention rates using 10 μm polystyrene microparticles and 3 dpf Tg[fli1a:DsRED] embryos. At 2 days post-injection (dpi), 56% of the injected microparticles remained within the injection sites. A simple VEGF-A delivery system was made by adsorbing the protein to the surface of 15 μm PLGA microparticles. In vitro release studies showed that this system released 0.042 μg VEGF-A/mg microparticle/hr and that 100% of the loaded protein was released after 48 hours. The VEGF-A-loaded microparticles were injected into the trunk of 3 dpf (Tg[fli1a:DsRED]) embryos. Qualitative and quantitative analysis of the intersegmental vessels in proximity to the injection site showed no change in the vasculature between the VEGF-A injection groups and the two control groups injected with either 15 μm PLGA particles and a solution of PBS.
URI for this recordhttp://hdl.handle.net/1974/27580
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