Molecular imaging of bacterial outer membrane vesicles based on bacterial surface display

Area of Science:

• Biotechnology
• Medical Imaging
• Nanomedicine

Background:

• Bacterial outer membrane vesicles (OMVs) are increasingly recognized for their roles in disease and potential in vaccine and drug delivery.
• Accurate quantification of OMV biodistribution is essential for developing these applications.
• Existing imaging techniques lack the specificity and precision required for OMV tracking.

Purpose of the Study:

• To develop a specific and efficient radiolabeling technique for bacterial outer membrane vesicles (OMVs).
• To enable precise quantification of OMV biodistribution using positron emission tomography (PET) imaging.
• To establish a foundation for utilizing bioengineered OMVs in advanced therapeutic strategies.

Main Methods:

• Engineered a novel E. coli strain for enhanced OMV production.
• Utilized autotransporter systems to anchor SpyCatcher to the OMV surface.
• Developed and optimized a radiolabeling protocol using SpyTag-NODAGA conjugates and 64Cu.
• Validated OMV labeling efficiency, radiochemical purity, and serum stability.
• Performed in vivo biodistribution studies in mice using PET/MRI.

Main Results:

• Achieved 100% radiochemical purity and ~29% radiolabeling efficiency for 64Cu-labeled OMVs.
• Demonstrated excellent serum stability of the radiolabeled OMVs.
• PET/MRI imaging confirmed biodistribution patterns consistent with prior studies, with highest uptake in liver and spleen.
• The novel radiolabeling method proved effective for in vivo tracking.

Conclusions:

• A novel, efficient, and specific method for radiolabeling bacterial outer membrane vesicles (OMVs) with 64Cu was successfully developed.
• This technique facilitates precise in vivo biodistribution analysis of OMVs using PET/MRI.
• The developed method provides a versatile platform for advancing OMV-based vaccine and drug delivery applications.