The interruption of the blood flow to the heart causes the death of cardiac cells. A promising therapy for this pathological condition consists on injecting mesenchymal stem cells in the damaged heart areas as these specialized cells are able to originate and, thus, repair cardiac tissues. The lack of contrast agents to guide and monitor their intracardiac implant, however, limits the efficacy of this approach.

This problem prompted Jesse Jokerst and colleagues, University of Standford, USA, to develop novel stem cells imagining tools. To this end, the scientists produced nanoparticles consisting of three components: SiO₂, to perform ultrasounds-based imaging, fluorescein isothiocyanate fluorophores to carry out fluorescent imaging, and free Gd³⁺, a magnetic resonance contrast agent. Once loaded into mensenchymal stem cells, these nanoparticles enabled the researchers to safely and stably monitor the delivery of stem cells to damaged cardiac tissues using optical, magnetic or ultrasound-based systems.

• Intracellular Aggregation of Multimodal Silica Nanoparticles for Ultrasound-Guided Stem Cell Implantation,
  J. V. Jokerst, C. Khademi, S. S. Gambhir,
  Sci. Transl. Med. 2013, 5(177), 177ra35.
  DOI: 10.1126/scitranslmed.3005228