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Magnetization transfer contrast MRI in GFP‑tagged live bacteria
Valeria Righi1, Melissa Starkey2, George Dai3
1NMR Surgical Laboratory, Department of Surgery, Massachusetts General Hospital and Shriners Burns Hospital, Harvard Medical School, Boston, MA 02114, USA.
Abstract:
Green fluorescent protein (GFP) is a widely utilized molecular reporter of gene expression. However, its use in in vivo imaging has been restricted to transparent tissue mainly due to the tissue penetrance limitation of optical imaging. Magnetization transfer contrast (MTC) is a magnetic resonance imaging (MRI) methodology currently utilized to detect macromolecule changes such as decrease in myelin and increase in collagen content. MTC MRI imaging was performed to detect GFP in both in vitro cells and in an in vivo mouse model to determine if MTC imaging could be used to detect infection from Pseudomonas aeruginosa in murine tissues. It was demonstrated that the approach produces values that are protein specific and concentration dependent. This method provides a valuable, non‑invasive imaging tool to study the impact of novel antibacterial therapeutics on bacterial proliferation and perhaps viability within the host system, and could potentially suggest the modulation of bacterial gene expression within the host when exposed to such compounds.
Insights
Magnetization transfer contrast MRI can detect green fluorescent protein (GFP) in vivo, overcoming optical imaging limitations. This non-invasive method tracks bacterial infection and therapeutic responses in mouse models.
Area of Science:
- Biomedical Imaging
- Molecular Biology
- Infectious Disease Research
Background:
- Green fluorescent protein (GFP) is a common reporter for gene expression but limited for in vivo imaging due to poor tissue penetration.
- Optical imaging techniques struggle to visualize GFP in deeper or opaque tissues.
Purpose of the Study:
- To evaluate Magnetization Transfer Contrast (MTC) MRI as a method for detecting green fluorescent protein (GFP) in vitro and in vivo.
- To assess MTC MRI's capability to detect Pseudomonas aeruginosa infection in murine tissues.
Main Methods:
- MTC MRI was performed on GFP-expressing cells in vitro.
- MTC MRI was applied to an in vivo mouse model to detect GFP and P. aeruginosa infection.
- Protein specificity and concentration dependency of the MTC signal were analyzed.
Main Results:
- MTC MRI successfully detected GFP in both in vitro and in vivo settings.
- The MTC signal was demonstrated to be protein-specific and concentration-dependent.
- MTC MRI showed potential for detecting bacterial infection in murine tissues.
Conclusions:
- MTC MRI offers a non-invasive imaging approach to detect GFP, overcoming limitations of optical methods.
- This technique can serve as a valuable tool for studying bacterial proliferation and viability in vivo.
- MTC MRI may enable monitoring the impact of antibacterial therapeutics and bacterial gene expression modulation within a host system.
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