In vivo Bioluminescence Imaging Monitoring of Stem Cells' Participation in Choroidal Neovascularization

Abstract

Background: Choroidal neovascularization (CNV) is common in various retinal diseases and is one of the most common causes of severe and irreversible visual loss. Our previous works suggested that bone marrow-derived cells (BMCs) participate in CNV, but little is known about stem cells' dynamic change when injected into mouse CNV. In vivo optical bioluminescence imaging (BLI) is a newly developing technology for dynamically observing biological behavior. Using this technology, we can observe the stem cells' dynamic behavior in CNV, in vivo. Methods: Two types of BMCs were used: bone marrow mononuclear cells (BMMNCs) and bone mesenchymal stem cells (MSCs). Cells were characterized using flow cytometry and BLI. C57BL/6J mice (n = 6/group) underwent CNV followed by caudal vein injection of 4 × 10⁶ BMMNCs, MSCs or phosphate buffer. Cell survival was measured: (1) in vivo using BLI during 2 weeks, and (2) in vitro using firefly luciferase (Fluc) assays and histology. Results: BMMNCs and MSCs expressed a similar Fluc reporter enzyme, as confirmed by luminometry. After injection into CNV mouse models, the two cell types showed dynamic behavior in CNV using BLI. The in vitro Fluc assay and histology results provided further proof for the above results. Conclusion: This is the first study comparing the behavior of stem cells in CNV using BLI, in vivo. BMMNCs and MSCs could contribute to CNV and could serve as delivery vehicles for CNV treatments. Meanwhile, BLI could lay a foundation for CNV mechanism research in a prospective manner.