Abstract
Purpose:
Evaluation of the safety and efficacy of a new methodology of retinal and choroidal dynamic angiography using human erythrocytes preloaded with indocyanine green dye.
Methods:
A group of 5 patients with different retinal diseases (3 affected by diabetic retinopathy, 1 affected by central serous chorioretinopathy and 1 with exudative age related maculopathy) and a control group from our team of 3 healthy people with no history of eye diseases underwent to an SLO dynamic ICG angiography, using Heidelberg HRA Spectralis (Heidelberg Engineering).<br /> After a withdrawn of 50 ml of autologous blood, red blood cells (RBCs) were processed in a sterile manner using a specific medical device: the Red Cell Loader (EryDel)® with the CE approval. The procedure consisted in the dialysis of erythrocytes at a high hematocrit (about 70-80%) against a hypotonic saline solution (dialysis buffer) to allow the opening of membrane pores of the RBCs; subsequently RBCs were incubated in the presence of the substance to be encapsulated (ICG). The final step of our loading phase was the resealing process by the restoration of physiological isotonicity. The processing time was about 2 hours.<br /> After the preparation of the RBC loaded with ICG, a bolus of these cells was then reinjected in the antecubital vein of the same withdrawn patient. Different concentrations (from 1 ml to 5 ml) of our RBCs loaded were randomly injected before in the healthy controls in order to explore the best quantity for a good angiography.<br /> Before and after the angiography with RBCs loaded, the following parameters were measured: blood pressure, hematocrit.
Results:
High-speed ICG angiography showed the movement of individual and clusters of ICG-loaded erythrocytes in the retinal and the choroidal vessels. The signal was more visible in the early frames than in the late frames. None of the patients involved in the study showed any ophthalmic or general adverse events after the intravenous injection of ICG-loaded erythrocytes.
Conclusions:
This pilot trial suggests that the angiography with the ICG-loaded RBCs is safe and well tollerated, meanwhile is very easy to perform. The methodology should be improved on a higher sample of patients in order to verify the rationality and any future clinical applications.