Estimation of SPIO Nanoparticles Uptakes by Macrophages Using Transmission Electron Microscopy

Area of Science:

• Nanomedicine
• Biomaterials Science
• Cell Biology

Background:

• Superparamagnetic iron oxide (SPIO) nanoparticles offer biocompatibility and unique magnetic properties, making them valuable for biomedical applications like cell tracking and drug delivery.
• Understanding nanoparticle-macrophage interactions is critical for effective nanomedicine development and safety assessment.

Purpose of the Study:

• To investigate the interaction and uptake mechanisms of SPIO nanoparticles by M1 and M2 polarized macrophages.
• To develop and apply an image processing technique for accurate quantification of SPIO nanoparticle uptake within macrophages.

Main Methods:

• Mouse monocytes were differentiated into M1 and M2 macrophages.
• Transmission electron microscopy (TEM) was used to visualize SPIO nanoparticle uptake.
• A novel image processing technique with 1 nm resolution, utilizing Otsu thresholding, was developed to segment and quantify SPIO nanoparticles within lysosomes.

Main Results:

• Lysosomes were identified as primary sites of SPIO nanoparticle accumulation within macrophages.
• Both M1 and M2 macrophages exhibited significant uptake of SPIO nanoparticles across various sizes.
• The developed image processing method provided an accurate estimation of SPIO nanoparticle quantities within macrophages.

Conclusions:

• The study provides quantitative insights into SPIO nanoparticle uptake by different macrophage subtypes.
• Findings are essential for optimizing targeted drug delivery systems utilizing SPIO nanoparticles.
• Results contribute to assessing the safety profile of SPIO nanoparticles in nanomedicine applications for human health.