Abstract

Adult bone marrow (BM) contains cells capable of differentiating along hematopoietic (Lin⁺) or non-hematopoietic (Lin^-) lineages. Lin^- hematopoietic stem cells (HSCs) have recently been shown to contain a population of endothelial precursor cells (EPCs) capable of forming blood vessels. Here we show that intravitreally injected Lin^- BM cells selectively target retinal astrocytes, cells that serve as a template for both developmental and injury-associated retinal angiogenesis. When Lin^- BM cells were injected into neonatal mouse eyes, they extensively and stably incorporated into forming retinal vasculature. When EPC-enriched HSCs were injected into the eyes of neonatal rd/rd mice, whose vasculature ordinarily degenerates with age, they rescued and maintained a normal vasculature. In contrast, normal retinal angiogenesis was inhibited when EPCs expressing a potent angiostatic protein were injected. We have demonstrated that Lin^- BM cells and astrocytes specifically interact with one another during normal angiogenesis and pathological vascular degeneration in the retina. Selective targeting with Lin^- HSC may be a useful therapeutic approach for the treatment of many ocular diseases.