Bioengineered three-dimensional transparent eggshell as a chicken embryo experimentation platform for biomedical research

Abstract

The chicken embryo is widely used as an experimental model in the areas of regenerative medicine, tumor biology, and angiogenesis. Eggshell opacity and rigidity present restricted three-dimensional (3D) viewing and accessibility to the embryo and its circulatory network despite egg windowing. The ability to engineer an eggshell, which eliminates the opacity yet provides 3D access for manipulation is beneficial and would potentially make it enticing for the use of chicken embryo as a cheaper alternative vertebrate model. Here, we present the feasibility of fabricating a morphologically analogous transparent chicken eggshell made of polydimethylsiloxane using a biaxial rotation computer-controlled bioreactor to achieve uniform thickness. By culturing chicken embryo in the bioengineered eggshell, we demonstrated success in meeting developmental milestones and its practicality as an experimental platform by visualizing both embryo and vasculature development using common laboratory imaging tools. Although the viability of the embryo in the bioengineered eggshell was lower than in the normal egg, this was attributed to the absence of calcium source. The bioengineered eggshell, in its initial stage of development, provides a platform to be used to investigate beyond gross observations of the embryo and vascular network in 3D optical clarity and its imaging capabilities has the potential to be extended to other imaging modalities. We have developed a transparent ex ovo eggshell, biomimicking the elliptical geometry to address the lack of 3D optical clarity contributed by the eggshell opacity. This retains the natural shape that may support the development of the chicken embryo and allows easy access to the embryo, its circulatory system and respective organ development in far reaching applications.