Human Stem Cell Derived Retinal Spheroids Characterized Non-Invasively for Structure and Function by Multimodal Imaging

Abstract

Purpose : To employ non-invasive advanced imaging modalities to characterize stem cell derived retinal spheroid structure and metabolic function, and create a correlative database of multimodal imaging.

Methods : Retinal Spheroids created from differentiation of human embryonic stem cells were subjected to a pallet of imaging modalities: Broad field microscopy, Fluorescence Lifetime Imaging Microscopy (FLIM), Hyperspectral Imaging (HSpec), Clinical Optical Coherence Tomography (OCT), radiographic micro Computerized Tomography (microCT), immunofluorescence, and standard haematoxalin and eosin histology. Retinal spheroids at different stages of development were imaged with each of these modalities and analyzed for structural and functional features. Retinal development features observed with different modalities were correlated.

Results : Each imaging technique enabled detection of structural changes in developing retinal spheroids. FLIM enabled detection of changes in metabolic activity and HSpec demonstrated retinol concentrations as spheroids matured into organized lamellae. OCT enabled rapid and non-lethal imaging of spheroid structures. MicroCT enabled micron resolution of retinal spheroids and provided intricate details of 3-dimensional structure at the cost of fixing living tissue. Each of these imaging modalities correlated with standard histologic structures and provide insights into photoreceptor organization and metabolic activity.

Conclusions : Non-invasive imaging facilitates real-time and non-destructive imaging of retinal spheroids in vitro as they organize into sophisticated lamellar structures. FLIM and HSpec demonstrate organizational and functional features resembling the mature human retina in vivo. Employing these imaging modalities provides more structural and functional information than histology and brightfield microscopy alone. As retinal spheroid tissue engineering technology matures to clinical utility in retinal degenerative disorders and drug screening, non-invasive imaging modalities will be critical to optimizing manufacturing practices and quality control.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.