In vivo subretinal arpe-19 cell tracking using indocyanine green contrast-enhanced multimodality photoacoustic microscopy, optical coherence tomography, and fluorescence imaging for regenerative medicine

Purpose: Cell-based regenerative therapies are being investigated as a novel treatment method to treat currently incurable eye diseases, such as geographic atrophy in macular degeneration. Photoacoustic imaging is a promising technology which can visualize transplanted stem cells in vivo longitudinally over time in the retina. In this study, a US Food and Drug Administration (FDA)-approved indocyanine green (ICG) contrast agent is used for labeling and tracking cell distribution and viability using multimodal photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence imaging. Methods: Twelve rabbits (2.4–3.4 kg weight, 2–4 months old) were used in the study. Human retinal pigment epithelial cells (ARPE-19) were labeled with ICG dye and transplanted in the subretinal space in the rabbits. Longitudinal PAM, OCT, and fluorescence imaging was performed for up to 28 days following subretinal administration of ARPE-19 cells. Results: Cell migration location, viability, and cell layer thickness were clearly recog-nized and determined from the fluorescence, OCT, and PAM signal. The in vivo results demonstrated that fluorescence signal increased 37-fold and PAM signal enhanced 20-fold post transplantation. Conclusions: This study demonstrates that ICG-assisted PAM, OCT, and fluorescence imaging can provide a unique platform for tracking ARPE-19 cells longitudinally with high resolution and high image contrast. Translational Relevance: Multimodal PAM, OCT, and fluorescence in vivo imaging with ICG can improve our understanding of the fate, distribution, and function of regenerative cell therapies over time nondestructively.