This method provides a direct link between the selectable phenotype and reproducible genotype encoding for that phenotype. By selection with the target of interest, a phage pool that has increasing specific binding ability to the target can be obtained efficiently. Phage display serves as a valuable tool for selection of the new biomarkers for wide range of biomaterials,. Among all biomaterials targeted for phage display selection, directly using whole cells as selection target has many advantages: 1) it needs no further information about cell surface molecules or purification of these molecules; 2) the surface molecules are most likely in their original state; 3) the selection stimulates the native binding environment where other macromolecules coexist. In this way, antibodies and peptides could be directly and quickly generated from cell screening, which are promising in the applications of cell labeling, gene delivery and ligand stimulation. Retinal astrocytes play an important role in the development of the mammalian retinal vasculature. They invade the retina from the optic nerve head as a proliferating population of cells and spread across the inner surface of the retina, creating a template for the developing retinal vasculature which follows in their wake. There is a tight correlation between the presence of retinal astrocytes and the retinal vasculature. In animals with only partially vascularized retinas, such as rabbit and horse, retinal astrocytes are absent from the avascular regions of the retina. Furthermore, in primates, retinal astrocytes are absent from the foveal avascular zone. Numerous studies have shown that during retinal vascularization retinal astrocytes produce high levels of Vegf mRNA in the not yet vascularized peripheral portion of the retina. This part of the retina is experiencing physiological hypoxia during development, increasing VEGF transcription possibly via hypoxia inducible factors or Vegf mRNA stabilization. The Oxidation Resistance 1 gene is present in all eukaryote genomes sequenced so far and is known to protect yeast and human cells from oxidative damage, through an unknown mechanism. When human OXR1 is expressed in Escherichia coli mutants that are unable to repair oxidative damage, it has a protective effect, reducing the accumulation of mutations in the SAR131675 bacterial genome. The OXR1 protein is localized in the mitochondria in yeast and human cells, but nuclear localization has also been reported in mouse and rat cell lines. The most highly conserved region of the gene is the carboxylterminal TLDc domain, which has been shown to be sufficient to reduce the mutation rate in E. coli. This differential expression of VEGF – high in the periphery and low in the centre might lead to a gradient providing a directional stimulus for retinal vascularization.