Ultrasmall superparamagnetic iron oxide ( USPIO) particles are very useful for cellular magnetic resonance imaging (MRI ), which plays a key role in developing successful stem cell therapies. However, their low intracellular labeling efficiency, and biosafety concerns associated with their use , have limited their potential usage. In this study we develop a novel system composed of RBC-derived vesicles ( RDVs) for efficient delivery of USPIO particles into human bone marrow mesenchymal stem cells (MSCs) for cellular MRI in vitro and in vivo. RDVs are highly biosafe to their autologous MSCs as manifested by cell viability, differentiation, and gene microarray assays. The data demonstrate the potential of RDVs as intracellular delivery vehicles for biomedical applications. ; 附設醫院影像醫學部 ; 醫學院附設醫院 ; 期刊論文