Abstract
Purpose :
Physical damages but also pathologies such as glaucoma can lead to an irreversible destruction of the optic nerve and consequently to vision loss. A promising tool to study the underlying processes specific the human physiology is provided by induced pluripotent stem cell derived retinal organoids (RO). Their use for modelling the optic nerve is however hampered by a premature loss of ganglion cells and the absence of their main target neurons in the lateral geniculate nucleus of the thalamus.
Methods :
To overcome these limitations, we created an optic-nerve assembloid model (ONA) by a precise fusion of human induced pluripotent derived retinal organoids (RO) and thalamic organoids (TO). In contrast to previously described models and in order to acknowledge the importance of the nerve structure itself, we added a hydrogel-based sphere between RO and TO mimicking the optic nerve compartment. In this way, the integration of missing cell types and components as well as a direct manipulation the nerve structure is enabled. To mimic the architecture of the pathologically-relevant first millimeters of the optic nerve head, we added iPSC-derived astrocytes to the nervous compartment.
Results :
We observed an efficient outgrowth of nervous structures of the RO towards the TO and an ensheathing of the nerve bundles by the astrocytes demonstrated by clearing-assisted 3D imaging. Furthermore, we mimicked the mechanical destruction of the nerve (“Optic nerve crush”) which led to GFAP upregulation in astrocytes. In a proof-of-concept experiment, we also added iPSC-derived microglia (iMacs) creating an immune-competent model. iMacs in the ONA expressed canonical microglial markers, could be integrated more than 10 days and migrated within the nerve compartment towards RO and TO.
Conclusions :
In summary, the presetend optic nerve assembloid model is a step towards a complete optic nerve in vitro model and could provide a valuable tool for nerve regeneration and disease modelling studies.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.