Objective: To demonstrate the feasibility of the ultrasmall superparamagnetic iron oxide (USPIO) modified by cyclo (Arg-Gly-Asp-Try-Cys) peptide (c(RGDyC)-USPIO) for targeting hepatic stellate cells (HSCs).
Materials and methods: A c(RGDyC)-USPIO probe was prepared by conjugating c(RGDyC) with USPIO through a thiol-maleinide interaction. The specificity of c(RGDyC)-USPIO for HSCs was investigated in vitro. In vivo, normal and fibrosis rats were treated with either c(RGDyC)-USPIO or USPIO, and magnetic resonance imaging (MRI) of the rats performed after administration of the probes for 4 h. The T2 relaxation times changes before and after probe injection were analyzed and the locations of probes in normal or injured mice were identified histologically.
Results: The hydrodynamic size of c(RGDyC)-USPIO was 13 ± 3 nm. HSCs took up more specific probes than plain ones. The reduction of T2 relaxation times in fibrosis rat by c(RGDyC)-USPIO was much greater than that by USPIO (P < 0.05). Prussian blue staining and transmission electron microscopy of the injured rat liver treated with c(RGDyC) demonstrated that c(RGDyC)-USPIO were specifically engulfed by the activated HSCs.
Conclusion: In vivo cellular targeted imaging of activated HSCs in liver fibrosis using c(RGDyC)-USPIO targeting α(v)β(3) integrins was feasible using a clinical 1.5-Tesla MR system.