Identification of six cell surface proteins for specific liver targeting

Purpose: Cell surface proteins are the primary means for a cell to sense and interact with its environment and their dysregulation has been linked to numerous diseases. In particular, the identification of proteins specific to a single tissue type or to a given disease phenotype may enable the characterization of novel therapeutic targets. We tested here the feasibility of a cell surface proteomics approach to identify pertinent markers directly in a clinically relevant tissue. Experimental design: We analyzed the cell surface proteome of freshly isolated primary heptatocytes using a glycocapture-specific approach combined with a robust bioinformatics filtering. Results: Using primary lung epithelial cell cultures as negative controls, we identified 32 hepatocyte-specific cell surface proteins candidates. We used mRNA expression to select six markers that may provide adequate specificity for targeting therapeutics to the liver. Conclusions and clinical relevance: We demonstrate the feasibility and the importance of conducting such studies directly in a clinically relevant tissue. In particular, the cell surface proteome of freshly isolated hepatocytes differed substantially from cultured cell lines.