Magnetic resonance imaging methods to track Treg distribution and homing for clinical applications

PROJECT SUMMARY Regulatory T cell (Treg) infusion, alongside solid organ transplantation, is an emerging strategy which focuses on rebalancing the Treg ratio in the transplanted organ to prevent rejection or loss. However, developing effective therapeutics using live cells necessitates means to determine their in vivo biodistribution, persistence, and

efficacy after administration. Clinicians do not know the fate of injected cells, thus, interpreting cases of non- responding patients remains a barrier to wider use. Magnetic resonance imaging (MRI) is the only technique that is radiation-free, clinically translatable, and enables direct visualization of labeled cells in vivo. Due to the clinical translation potential, MRI applications and

contrast agent development continue to see remarkable growth, especially in the cell tracking sphere. Through this diversity supplement, our goal is to design, synthesize and characterize a novel click functional dextran coated superparamagnetic Fe3O4 nanoparticles for in-vivo T cell tracking by 1H MRI.. We will

develop a novel Fe3O4 nanoparticle platform containing T cell directing functionalities for enhanced cell uptake and improved contrast in MR imaging. Synthesis and derivatization of dextran coated Fe3O4 nanoparticles with CD4, CD8 or CD25 click chemistry functionality will provide a platform to be used for T cell labeling and tracking.

Decorated nanoparticles will be optimized and tested in cell culture assays including uptake and viability measurements. T cell tracking and homing will be evaluated in vivo in a murine models. If successful, this platform will allow for more precise and personalized treatment approaches, potentially increasing the overall

response rates to cell therapy. This will give clinicians adequate tools through imaging to improve patient management and overall outcomes. The logical extension of this Aim would be to test longitudinal tracking capability of the cells labeled with this new in-house probe. The rationale for developing our own platform with the CD25 target is two-fold. First, it

would minimize dependance on a patented product from Miltenyi. Second, the goal is to develop a universal platform that would enable clicking of any target moiety of interest, such as CD4, CD8 and beyond for a multitude of disease models, which corresponds to Brock’s comprehensive PhD thesis plan. This protected training

and research time will also provide necessary experience and education critical for Brock’s PhD trajectory and future career as an independent scientist in academia.