[18F]-FBEM, a tracer targeting cell-surface protein thiols for cell trafficking imaging

Area of Science:

• Radiochemistry
• Molecular Imaging
• Cell Biology

Background:

• Accurate cell trafficking assessment is crucial for understanding biological processes and disease progression.
• Existing imaging agents for cell tracking may lack stability or specific targeting mechanisms.
• Positron emission tomography (PET) offers high sensitivity for in vivo imaging.

Purpose of the Study:

• To develop and evaluate [(18)F]-4-fluorobenzamido-N-ethylamino-maleimide ([(18)F]-FBEM) as a novel radiolabeling agent for ex vivo cell labeling.
• To assess the in vivo cell trafficking of radiolabeled cells using PET imaging in a mouse model.
• To investigate the stability and cell viability impact of the [(18)F]-FBEM labeling procedure.

Main Methods:

• Cells were radiolabeled ex vivo using [(18)F]-FBEM, which forms a covalent bond with cell surface thiol groups.
• The stability of [(18)F]-FBEM was tested across various pH levels.
• Cell viability post-labeling was assessed.
• PET imaging was performed on mice intravenously injected with [(18)F]-FBEM labeled T lymphocytes to track cell distribution.

Main Results:

• [(18)F]-FBEM demonstrated retained thiol-labeling efficiency up to pH 9.
• The labeling process did not significantly impact cell viability.
• PET imaging successfully visualized the homing of labeled T lymphocytes to the spleen in mice.
• Control mice injected with free label showed no specific organ accumulation.

Conclusions:

• [(18)F]-FBEM is a stable and effective radiolabeling agent for ex vivo cell labeling.
• This method allows for accurate in vivo cell trafficking assessment using PET imaging.
• The specific covalent binding of [(18)F]-FBEM ensures reliable tracking of labeled cells.