Primitive stem cells derived from bone marrow express glial and neuronal markers and support revascularization in injured retina exposed to ischemic and mechanical damage

Ischemic or mechanical injury to the optic nerve is an irreversible cause of vision loss, associated with limited regeneration and poor response to neuroprotective agents. The aim of this study was to assess the capacity of adult bone marrow cells to participate in retinal regeneration following the induction of anterior ischemic optic neuropathy (AION) and optic nerve crush (ONC) in a rodent model. The small-sized subset of cells isolated by elutriation and lineage depletion (Fr25lin ^-) was found to be negative for the neuroglial markers nestin and glial fibrillary acidic protein (GFAP). Syngeneic donor cells, identified by genomic marker in sex-mismatched transplants and green fluorescent protein, incorporated into the injured retina (AION and ONC) at a frequency of 0.35%-0.45% after intravenous infusion and 1.8%-2% after intravitreous implantation. Perivascular cells with astrocytic morphology expressing GFAP and vimentin were of the predominant lineage that engrafted after AION injury; 10%-18% of the donor cells incorporated in the retinal ganglion cell layer and expressed NeuN, Thy-1, neurofilament, and beta-tubulin III. The Fr25lin ^- cells displayed an excellent capacity to migrate to sites of tissue disruption and developed coordinated site-specific morphological and phenotypic neural and glial markers. In addition to cellular reconstitution of the injured retinal layers, these cells contributed to endothelial revascularization and apparently supported remodeling by secretion of insulin-like growth factor-1. These results suggest that elutriated autologous adult bone marrow-derived stem cells may serve as an accessible source for cellular reconstitution of the retina following injury.