Abstract
Purpose :
In adult newts lens regeneration is especially fascinating as the regenerated lens originates from a completely different tissue through reprogramming of the iris pigmented epithelium. However, this process has never been visualized in real time or 3D. Our goal was to establish optical coherence tomography (OCT) as an in vivo imaging platform to characterize the process of lens regeneration.
Methods :
Two separate studies were performed in adult red spotted newts, Notophthalmus viridescens. In the first study, the lens was surgically removed from 39 newts. Over the course of 80 days 3 newts were taken per time point, imaged by OCT, then immediately sacrificed and the eyes processed for histology. The second study consisted of acquiring OCT images over 60 days from a single newt. At the 60th day, the newt eye was collected and processed for histology. OCT images were acquired at 800nm with ~8µm lateral resolution and ~3µm axial resolution.
Results :
OCT captured key morphological changes associated with lens regeneration in live newts such as corneal wound healing, accumulation of ECM, migratory cells, lens vesicle formation and its differentiation into a lens with clear lens epithelium and lens fibers as well as dilation of blood vessels. These OCT images were validated with corresponding histological images collected from the same newt eye. The 3D view provided by OCT demonstrated the regenerating lens vesicle adopts an elliptical form extending along the dorsal iris tip. The lens vesicle became spherical in shape around 4 weeks post lentectomy. From the 3D reconstructions, we calculated the changes in volume size enabling a quantitative measure to monitor the progression of the lens regeneration process with time.
Conclusions :
This is the 1st report describing both in vivo and 3D imaging of the newt lens regeneration process using OCT. As verified by histological analysis, OCT is a reliable imaging tool to monitor the regenerating lens and the dynamic changes that occur in the eye during this process. Detecting the lens vesicle in as little as two weeks after lentectomy highlights the power of OCT. Future work includes characterizing the identity and function of the migrating cells detected by OCT, and to establish OCT as a semi-high throughput quantitative platform to screen inhibitors and activators of lens regenerative potential in the newt eye.
This is a 2021 ARVO Annual Meeting abstract.