Visualization of homing of bone marrow derived human CD34+ stem cells in murine eyes with diabetic retinopathy following intravitreal injection using multimodal in vivo retinal imaging

Abstract

Purpose : Human CD34+ stem cells have been shown to home into damaged retinal vasculature following intravitreal injection using immunohistochemistry. The goal of the study is to determine whether multimodal in vivo retinal imaging can be used to study the effect of intravitreal injection of human CD34+ stem cells from bone marrow in a murine model of diabetic retinopathy.

Methods : Streptozotocin-induced diabetic mice (C57BL/6J) were used as murine model for diabetic retinopathy. Continuous systemic immunosuppression was achieved for the study duration by subcutaneous implantation of Alzet pump, loaded with Tacrolimus and Rapamycin, 5 days prior to intravitreal injection. Human CD34+ cells were isolated from the mononuclear cell fraction of the bone marrow aspirate by positive selection using magnetic beads. The isolated cells were labeled with enhanced green fluorescent protein (EGFP). The eyes of immunosuppressed diabetic mice received intravitreal injection of 50,000 EGFP-labeled CD34+ cells (n=12) or saline (n=12). The eyes were imaged at 1 and 4 weeks following intravitreal injection using simultaneous multimodal in vivo retinal imaging which combined scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), phase-variance OCT angiography and fluorescein angiography. The mice were euthanized after imaging and the eyes were harvested for immunohistochemistry.

Results : Retinal microvascular changes were observed in the retina on fluorescein and OCT angiography consistent with diabetic retinopathy in all mice. In vivo multimodal retinal imaging visualized the presence of EGFP-labeled human CD34+ stem cells in the vitreous, retinal surface, and along the retinal vasculature at 1 week following intravitreal injection. EGFP-labeled cells were also visualized in the eye at 4 weeks.

Conclusions : Multimodal in vivo imaging can be used to study the retinal vascular changes and the effect of intravitreal cell therapy in murine model of diabetic retinopathy. Consistent with prior immunohistochemical studies, some human CD34+ cells from bone marrow were seen along the retinal vasculature. However, human CD34+ cells also were visualized in the vitreous, and retinal surface using multimodal imaging in this murine model. Immunohistochemical and microarray correlation of the imaging observations are in progress.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.