Speaker
Description
Background and Aims:
Vascular adhesion protein-1 (VAP-1) is an endothelial glycoprotein present on the endothelial surface of tissues affected by infection/inflammation that recruit lymphocytes from blood. VAP-P1 is a VAP-1 selective peptide (sequence GGGGKGGGG) which, according to previous studies, conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and labelled with Ga-68, could be used as imaging agent capable to differentiate between normal bone healing and bone infection.
The aim of this paper is to study the potential of 1,4,7-triazacyclononane-triacetic acid (NOTA)-conjugated and Cu-64 labelled VAP-P1 peptide for possible clinical applications.
Methods:
Synthesized peptide VAP-P1 was conjugated with NOTA-SCN, purified using semi-prep HPLC and lyophilized. The conjugate was then labelled with Cu-64. In vitro plasma protein binding and stability in human serum in time were determined using transfected Chinese Hamster Ovary cells (CHO) that express human VAP-1 and HT-29 (negative control). Each experiment was performed in octaplicate, and the data were reported as percentage of total added activity.
Results:
The peptide was conjugated with NOTA chelator and labelled with 68Ga and 64Cu with radiochemical purity ≥ 95 %. Radiolabelled analogue [Cu-64]NOTA-VAP-P1 presented here was rapidly internalized into CHO cells versus negative control HT-29. The internalization of the surface bound peptide was time-dependent. It sharply increased during the first 30 min reaching internalization levels of 80–90 %.
Conclusions:
In vitro studies showed that NOTA-VAP-P1 labelled with Cu-64 may provide a faster and a simpler method of diagnostics of inflammation/infection compared to the method of labelled leucocytes. The concept deserves to be tested in vivo.
Key words: Cu-64, NOTA-VAP-P1, VAP-P1, VAP-1, labelling, conjugation, PET, CHO cells, plasma protein binding, human serum stability
