Bifunctional magnetic silica nanoparticles for highly efficient human stem cell labeling

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Cell Biology

Background:

• Superparamagnetic iron oxide (SPIO) nanoparticles are promising for noninvasive cell tracking.
• Low intracellular labeling efficiency of SPIO nanoparticles limits their application.
• Developing improved labeling strategies is crucial for SPIO nanoparticle utility.

Purpose of the Study:

• To develop and characterize fluorescein isothiocyanate (FITC)-incorporated silica-coated SPIO nanoparticles (SPIO@SiO2(FITC)).
• To evaluate the efficiency of SPIO@SiO2(FITC) nanoparticles for labeling human mesenchymal stem cells (hMSCs).
• To assess the in vitro and in vivo MRI detectability of labeled hMSCs.

Main Methods:

• Synthesis of 50 nm SPIO@SiO2(FITC) core-shell nanoparticles.
• Labeling of hMSCs via clathrin- and actin-dependent endocytosis.
• Assessment of nanoparticle uptake kinetics (time- and dose-dependent).
• In vitro and in vivo MRI detection of labeled hMSCs using a clinical 1.5-T MRI imager.

Main Results:

• SPIO@SiO2(FITC) nanoparticles efficiently labeled hMSCs with intracellular localization in late endosomes/lysosomes.
• Effective MRI contrast was achieved at low iron concentrations (0.5 microg/mL) and low cell numbers (1x104).
• Labeled hMSCs maintained viability, proliferation, and differentiation capacities and were detectable in vivo.

Conclusions:

• This study presents the first report of efficient MRI contrast nanoparticle labeling of hMSCs.
• SPIO@SiO2(FITC) nanoparticles offer a bifunctional magnetic vector for effective cell tracking.
• The developed nanoparticles enable simultaneous MRI monitoring in vitro and in vivo under optimized conditions.