Abstract
Purpose :
Dynamic full-field OCT (D-FFOCT) is a 3D non-invasive micrometric imaging technique which allows to differentiate cells by their metabolic activity. D-FFOCT is a new imaging tool for the purposes of developing human induced pluripotent stem cells (hiPSC)-derived therapy solutions for regenerative medicine and disease modeling.
Methods :
D-FFOCT contrast arises from intrinsic subcellular organelle movement. These signals are recorded with 0.5 µm transverse x 1.5 µm axial resolution over several hours. Different types of human induced pluripotent stem cell (hiPSC)-derived retinal samples were imaged. Two types of hiPSC-derived retinal organoids grown by the Vision Institute were imaged at different stages of their development. HiPSC-derived RPE and primary porcine RPE cell cultures, grown on polycarbonate membranes, were analyzed with D-FFOCT after performing scratch assays with a scalpel blade.
Results :
The first type of retinal organoids we imaged has its photoreceptors in its center. The second type corresponds to a recent layered variant, closer to real retinas,with the photoreceptors at the surface. We were able to image these non destructively from 27 days to 177 days, and D-FFOCT allowed us to distinguish cells such as neuroretinal cells, RPE and photoreceptors. Regarding scratch assays, the hiPSC-derived RPE closed with a speed of ~5 µm/h, while for porcine RPE, we measured ~17 µm/h. We also noticed a retractation of RPE layer, increasing the wound, after failing to close the wound, both for a damaged membrane or a too large wound (>40µm). The quantification of the changes in intracellular activity of the damaged area was also possible.
Conclusions :
D-FFOCT allowed us to image diverse retinal cell cultures samples. We were able to study the structure of retinal organoids at various stages of their development, and to document behavior of healing RPE cells (speed and metabolic activity of wound closing), showing that large wounds mimic atrophic AMD expansion by retracting rather than closing. Both results show that D-FFOCT is a convenient tool for disease modeling and therapy solutions studies.
This is a 2020 Imaging in the Eye Conference abstract.