Endogenously produced SDF-1α is a trigger for BM contribution to sites of postnatal neovasculogenesis. (A) Eyes were harvested and embedded in paraffin at different time points after retinal injury. Tissues were sectioned (5 μm) and staining was performed for SDF-1α and DAPI (4,6 diamidino-2-phenylindole). As expected, consistent expression of SDF-1α in the PRL was observed. Nontreated left eyes served as controls. SDF-1α expression is observed in the GCL at 1 and 12 hours after laser injury (n = 5; scale bar represents 100 μm). (B-C) SDF-1α ELISA of samples from the vitreous and blood serum after retinal ischemic injury. Vitreous fluid and blood serum were obtained from mice at different time points after retinal injury. ELISA analysis showed a direct correlation to the staining results with significant increases in SDF-1α levels observed at 1 hour and 12 hours in the vitreous (B) and blood serum (C), respectively (n = 5; *P < .05). (D-E) SDF-1α expression was also observed in LLC tumors (D) with nondetectable levels seen in B16 tumors (E). Tumors are outlined by dashed lines (n = 8; scale bars represent 100 μm). (F) ELISA analysis of SDF-1α in the serum of mice inoculated with both LLC and B16 tumors showed a significant increase in serum levels 7 days after tumor inoculation, with levels returning to background by day 13 (n = 5; *P < .05).