Phage library-screening: A powerful approach for generation of targeting-agents specific for normal pancreatic islet-cells and islet-cell carcinoma in vivo

Phage display technology is a powerful approach for the generation of peptides and antibodies that target specific organ- or tumor-structures. By applying this approach to rats in vivo or freshly isolated rat islets in vitro, we have recently reported the successful isolation of internalizing single-chain antibodies (SCA-antibodies), which are highly specific for the endocrine-cells of a pancreatic islet (either beta- or alpha-cells) both in rodents and in humans. Moreover, others have reported peptides targeting specifically the vascular endothelium of normal or pre-malignant islets or advanced islet-cell tumors. The features of these antibodies and peptides are compatible with a potential use for in vivo delivery of molecular cargos (e.g. imaging agents and therapeutics). Therefore, this article reviews the principles of phage display, provides an overview about agents either specific for the endocrine-cells or the vascular endothelium of islets, discusses methododical key elements for the generation of these ligands and highlights remaining questions and potential future perspectives.