DNA-coated gold nanoparticles for tracking hepatocyte growth factor secreted by transplanted mesenchymal stem cells in pulmonary fibrosis therapy

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.

Ferroptotic MSCs protect mice against sepsis via promoting macrophage efferocytosis

The therapeutic effect of mesenchymal stem cells (MSCs) on sepsis has been well-known. However, a comprehensive understanding of the relationship between MSCs and macrophages remains elusive. Superparamagnetic iron oxide (SPIO) is one of the most commonly used tracers for MSCs. Our previous study has shown that SPIO enhanced the therapeutic effect of MSCs in a macrophage-dependent manner. However, the fate of SPIO-labeled MSCs (MSC^SPIO) after infusion remains unknown and the direct interaction between MSC^SPIO and macrophages remains unclear. Mice were injected intravenously with MSC^SPIO at 2 h after Escherichia coli infection and sacrificed at different times to investigate their distribution and therapeutic effect. We found that MSC^SPIO homed to lungs rapidly after infusion and then trapped in livers for more than 10 days. Only a few MSC^SPIO homed to the spleen and there was no MSC^SPIO detectable in the brain, heart, kidney, colon, and uterus. MSC^SPIO tended to stay longer in injured organs compared with healthy organs and played a long-term protective role in sepsis. The mRNA expression profiles between MSCs and MSC^SPIO were rather different, genes related to lipid metabolism, inflammation, and oxidative stress were changed. The levels of ROS and lipid peroxide were elevated in MSC^SPIO, which confirmed that SPIO-induced ferroptosis in MSC^SPIO. Ferroptosis of MSC^SPIO induced by SPIO enhanced the efferocytosis of macrophages and thus enhanced the protective effect on septic mice, while the benefits were impaired after MSC^SPIO were treated with Ferrostatin-1 (Fer-1) or Liproxtatin-1 (Lip-1), the inhibitors of ferroptosis. SPIO-induced ferroptosis in MSCs contributes to better therapeutic effects in sepsis by enhancing the efferocytosis of macrophages. Our data showed the efficacy and advantage of MSC^SPIO as a therapeutic tool and the cell states exert different curative effects on sepsis.