Vascular and Glial Repair Is Facilitated by Injection of Human Cord Blood CD14+ Cells in Oxygen Induced Retinopathy (OIR): Control of Metabolite Production

Abstract

Purpose: : To use metabolomic analysis, immunohistochemistry and confocal microscopy to assess the trophic rescue effect of human umbilical cord blood (HCB)-derived myeloid progenitor cells in a model of OIR.

Methods: : Monocytic CD14⁺ cells were isolated from HCB, characterized by flow cytometry and incubated on fibronectin-coated dishes to induce endothelial cell (EC) differentiation. Formation of tubes and networks by CD14⁺ cells was tested using a matrigel assay. CD14⁺ cells infected with Adenovirus 5-GFP were injected intravitreally and visualized by confocal microscopy. Rescue was evaluated on p17 by quantifying areas of vaso-obliteration and neovascularization (NV). Cytokine production in total retinal lysates was analyzed on p11 using an angiogenesis arrays. Metabolites were extracted and identified in OIR and normal retinas at p12, p15 and p18 and evaluated for the ability to induce toxicity and apoptosis of astrocytes and EC in vitro and in vivo.

Results: : On day 0, CD14⁺ cells express both myeloid progenitor (CD33 and CD44) and endothelial (VEGFR-2) cell specific antigens as well as form cord- and tube-like structures in vitro. Using the mouse OIR model, we show that Ad5-GFP CD14⁺ cells: (1) target sites of retinal NV and significantly enhance vascular repair; (2) induce expression of mouse angiogenic cytokines such as IL-1, FGF a and b, IL-6 and TGF in OIR retinas; (3) significantly reduce levels of toxic metabolites such as β-epoxycholesterol and 7-ketocholesterol to levels observed in control, non-OIR retinas; and (4) maintain normal levels of photoreceptor-specific molecules.

Conclusions: : We have characterized human CB CD14⁺ cells that target retinal vasculature and provide trophic rescue in a model of OIR. Metabolomic analysis demonstrates metabolites toxic for EC and glia cells in OIR retinas, the production of which can be controlled by CD14⁺ cells. These cells are visualized in the retina using Ad5-GFP vectors; use of Ad vectors encoding trophic factors could enhance efficacy of CB derived CD14⁺ cells.

Keywords: retinopathy of prematurity • differentiation • hypoxia