Cold Quad-Modal Nanocomplex for Precise and Quantitative In Vivo Stem Cell Tracking

Current single imaging modalities typically lack the ability to simultaneously offer detailed anatomical visualization and quantitative cellular information, which is crucial for evaluating and improving therapeutic efficacy. This work develops a cold (non-radioactive) quad-modal imaging nanocomplex for magnetic resonance imaging (MRI), magnetic particle imaging (MPI), computed tomography (CT), and multispectral optoacoustic tomography (MSOT) within a single nanoplatform, that is, Albumin-Bismuth-Superparamagnetic iron oxide or ABS. The chemically engineered complex is composed of bovine serum albumin as biocompatible matrix, superparamagnetic iron oxide as MRI and MPI agents, and optoradiopaque bismuth sulfide as CT and MSOT agents. This work demonstrates here its first use for high-resolution, real-time, and quantitative in vivo imaging of mesenchymal stem cells transplanted in mouse brain. This versatile nanocomplex may find applications for non-invasive monitoring cell transfer and cell transplantation in vivo using multiple imaging approaches.