Abstract
Purpose::
Astrocytes are well known modulators of retinal vascularization. We investigated the effect of injecting primary astrocytes, or astrocyte-conditioned serum-free media on neovascularization in the mouse OIR model.
Methods::
Primary astrocytes from neonatal eGFP mice were isolated, cultured and purified prior to intravitreal injection of 150,000 cells/eye into post-natal day 7 (P7) mouse eyes. Non-conditioned serum-free media, or serum-free media conditioned for five days by either primary astrocytes or the C8-D1A astrocyte cell line, was concentrated and injected intravitreally into P7 (pre-hyperoxia) or P12 (post-hyperoxia) mouse eyes. Mice were subjected to hyperoxia (75% O2) from P7 to P12, followed by return to room air at P12, and analysis of the area of remaining avascularity in the central retina and the areas of pathological neovascularization at P17. MALDI/TOF mass spectrometry proteomics was used to identify astrocyte secreted factors in the conditioned media that might mediate these rescue functions.
Results::
Astrocyte conditioned media mediated growth and survival of bone marrow-derived progenitor cells that have demonstrated rescue potential in the mouse model of OIR; these cells did not survive in unconditioned control media. Injection of primary astrocytes themselves, or astrocyte-conditioned media, also resulted in rescue of the OIR phenotype as indicated by a significant reduction in pathological pre-laminar neovascularization and enhancement of physiological revascularization following oxygen-induced obliteration. Analysis of the conditioned media identified over 60 different proteins, several of which are secreted factors that may mediate the rescue effect.
Conclusions::
Astrocytes produce secreted proteins that when injected intravitreally can mediate normal revascularization of the retina in response to retinal hypoxia caused by hyperoxia induced vascular obliteration. Characterization of these secreted proteins provides mechanistic insight into hypoxic retinopathies and may eventually offer novel therapeutic options.
Keywords: retinal neovascularization • astrocyte • ischemia