Generation of a monoclonal human single chain antibody fragment to hepatic stellate cells – a potential mechanism for targeting liver anti-fibrotic therapeutics

Hepatic stellate cells are pivotal to fibrogenesis in the liver and many potential anti-fibrotic therapeutics are required to act on targets within hepatic stellate cells. The aim of this study was to generate a human antibody fragment to hepatic stellate cells. Phage display was used to generate a human monoclonal antibody fragment to a peptide sequence present on an extracellular domain of synaptophysin, a protein expressed on the surface of hepatic stellate cells. An antibody fragment was isolated (termed C1-3), expressed in bacteria and purified. Fluorescently-labelled C1-3 antibody associated with human hepatic stellate cells but not hepatocytes in culture. Binding of fluorescently labelled C1-3 to hepatic stellate cells was blocked by the extracellular synaptophysin peptide sequence and uptake of the antibody intracellularly was inhibited by monensin. The toxin tributyl tin—when conjugated to C1-3—retained the ability to kill hepatic stellate cells confirming that C1-3 is sequestered intracellularly. This antibody fragment may be an effective means to target therapeutics to human hepatic stellate cells.