Directing the controlled differentiation and tracking of stem cells is essential to achieve successful stem cell therapy. In this work, we describe a multi-modal (MR/optical) transfection agent (MTA) for efficient gene delivery and cell tracking of human mesenchymal stem cells (hMSCs). The MTA was synthesized through a facile two-step approach with 1) ligand exchange of a catechol-functionalized polypeptide (CFP) and 2) chemical immobilization of fluorescence labelled cationic polymer via aminolysis reaction. Cationic polymer-immobilized MTAs with size of ~40 nm exhibit greatly enhanced colloidal stability in aqueous solution. In addition, the MTAs were capable of binding DNA molecules for transfection. The MTA/pDNA complex showed relatively good transfection efficiency in hMSCs (compared to the commercial transfection agent, Lipofectamine) and good biocompatibility. MTA-treated hMSCs were successfully visualized after transplantation via MR and optical imaging system over 14 days. These studies highlight the challenges associated with the potential advantages of designing multi-modal nanostructured materials as tools for genetic materials delivery and cell-tracking in stem cell therapy.
