Genetically Encoded Self-Assembling Iron Oxide Nanoparticles as a Possible Platform for Cancer-Cell Tracking

Area of Science:

• Biotechnology
• Molecular Imaging
• Cell Biology

Background:

• Reliable cell labels are crucial for noninvasive imaging of tumor growth and metastasis in animal models.
• Genetically encoded reporters offer contrast selectivity for viable cells and resist dilution during cell division.
• Encapsulins, bacterial protein nanocompartments, can be genetically engineered as multimodal cell labels.

Purpose of the Study:

• To implement heterologous expression of encapsulin systems from Quasibacillus thermotolerans in HepG2 cells.
• To utilize the fluorescent reporter protein mScarlet-I and ferroxidase IMEF as cargo within encapsulins.
• To evaluate the suitability of this system for multimodal cancer cell imaging.

Main Methods:

• Heterologous expression of Quasibacillus thermotolerans encapsulin systems in HepG2 cells.
• Coexpression of encapsulin nanoshells, ferroxidase cargo (IMEF), and an iron transporter.
• Confirmation of self-assembled nanocompartment expression via fluorescence and transmission electron microscopy.
• Assessment of magnetic resonance imaging (MRI) contrast enhancement.

Main Results:

• Successful expression of self-assembled encapsulin nanocompartments with functional cargo proteins was confirmed.
• Fluorescence microscopy and transmission electron microscopy validated nanocompartment formation and cargo presence.
• Coexpression of encapsulins, ferroxidase, and iron transporter significantly increased T2-weighted contrast in MRI.
• Demonstrated potential for multimodal imaging applications.

Conclusions:

• The encapsulin cargo system from Q. thermotolerans is a promising tool for multimodal imaging of cancer cells.
• This system can enhance contrast in magnetic resonance imaging, aiding in cancer research.
• Further in vitro and in vivo studies are warranted to explore its full potential in cancer diagnostics and monitoring.