Abstract
Purpose :
Visual disorders such as age-related macular degeneration or retinitis pigmentosa are major health issues of global population. In order to identify and test new treatment strategies, the development of adequate models of the human retina is required. Existing models such as animal models or static cell culture models have multiple disadvantages. Here a recent breakthrough was the discovery of human induced pluripotent stem cells (hiPSC) and their differentiation into 3-dimensional (3D) retinal organoids. Retinal organoids (RO) contain all relevant retinal cell types, arrange in the appropriate stratified layering and form functional synaptic interconnections between the different neuronal layers. However, RO exhibit certain disadvantages, such as incomplete photoreceptor maturation, lack of vascularization and a missing physiological interaction between retinal pigment epithelium (RPE) and photoreceptor cells. We aim to overcome these limitations by the development of a microfluidic retina-on-a-chip (RoC).
Methods :
Human induced pluripotent stem cells (hiPSC) were differentiated to 3D-retinal organoids, based on a protocol by Zhong et al. 2014. hiPSC-dervied RPE cells result as product from organoid differentiation. To combine RO and RPE in the RoC, the RO was embedded in hydrogel in a defined distance on top of a confluent layer of hiPSC-RPE cells. The system is supplied with medium over a microfluidic channel.
Results :
We could demonstrate successful integration and long-term cultivation for several weeks of RO and RPE in the RoC. Various endpoint and live cell methods, such as live cell microscopy based on fluorophore-driven promoter constructs, immunohistochemistry and electron microscopy allowed precise monitoring of cell survival and segment maturation within the RoC. By these means, we could monitor the photoreceptor maturation over more than one week.
Conclusions :
The combination of hiPSC-derived ROs and RPE cells in a microphysiological environment reveals a physiologically relevant model of the human retina. Due to its versatility and analysis options, the RoC fulfills the requirements for developmental studies, disease modeling, and drug testing.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.