Need of Multimodal SPECT/MRI for Tracking of 111 In-Labeled Human Mesenchymal Stem Cells in Neuroblastoma Tumor-Bearing Mice

Tumor-homing is a complex, multistep process used by many cells, like mesenchymal stem cells (MSCs), to travel from a distant location to a tumor. The purpose of this study is to investigate the applicability of 111In-oxine for tracking human MSCs in vivo with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). 111In labeled hMSCs (106 cells) were infused intraperitoneally in neuroblastoma tumor-bearing mice, and SPECT/MRI images were performed 24 and 48 hour afterwards. High initial hMSC localization occurred in the abdomen cavity and 48 hour later hMSC-injected animals showed tumor uptake. MRI information was essential to properly define Regions of Interest on the images. Tracking 111In labeled hMSC combining SPECT and MRI is feasible and may be transferable to human studies.