The functional identification of short peptide binding specifically to osteosarcoma-associated vascular endothelial cells in-vivo

Objective To identify the binging specification of the short peptide(TKPDKGY)specifi-cally binding to osteosarcoma-associated vascular endothelial cells(OAVECs)by using BALB/c-nu mice with osteosarcoma.Methods The TKPDKGY was synthesized with the N-terminal marked with fluorescein isoth-iocyanate(FITC).After purification,the peptide was injected into the vessel of nude mice.Whole-body optical imaging system was used to investigate the peptide distribution in mice.Four hours after injection,the nude mice were sacrificed.The vital organs and tumor of mice were used to make frozen slice.Confocal micro-scope was used to detect the in-vivo binding activity of the short peptide.Results Whole-body optical imaging system showed that fluorescence at tumor site was weak at 10 min after injection,and gradually in-creased at 30 min,reached the peak at 1 h,then subsidised 4 h later,and no residual fluorescence at 24 h.Confocal microscope also to shown that the short peptide homed to vascular endothelium in osteosarcoma but was not detectable in the heart,brain,lung and liver.The fluorescence at glomerular and tubular was detect-ed by confocal microscope but not renal vascular endothelium which means that the kidney is metabolism or-gan of TKPDKGY.Conclusion The TKPDKGY peptide has the specifically binding activity to vascular en-dothelium in osteosarcoma.It may be used as good targeting vector for selective delivery of therapeutics and as a diagnostic probe for the detection of osteosarcoma. Key words: Osteosarcoma;  Endothelial cells;  C-peptide