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Tat-functionalized near-infrared emissive polymersomes for dendritic cell labeling
Natalie A Christian1, Michael C Milone, Shraddha S Ranka
1School of Engineering and Applied Science, Department of Bioengineering, Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Insights
Researchers developed Tat-conjugated near-infrared (NIR) polymersomes for tracking dendritic cells (DCs) in vivo. This method enables efficient cellular delivery and detection of labeled DCs for improved immune cell therapy and research.
Area of Science:
- Immunology and cellular therapy
- Biomedical imaging and nanotechnology
Background:
- Dendritic cells (DCs) are crucial for immune responses and tolerance.
- Tracking DCs in vivo is essential for cellular therapies and understanding DC function.
- Current methods for DC tracking are limited.
Purpose of the Study:
- To develop a novel method for in vivo dendritic cell tracking.
- To conjugate Tat peptide to near-infrared (NIR) emissive polymersomes for efficient intracellular delivery.
- To evaluate the efficacy and impact of these probes on DC function.
Main Methods:
- Conjugation of Tat peptide to NIR emissive polymersomes.
- Intracellular delivery and localization studies using flow cytometry and confocal microscopy.
- Assessment of DC maturation, viability, and T cell activation post-labeling.
- Determination of probe uptake and detection limits.
Main Results:
- Tat-mediated polymersome delivery to DCs was concentration and time-dependent, showing punctate intracellular localization.
- Labeling DCs with Tat-NIR polymersomes did not significantly impede cytokine-induced maturation or viability.
- A significant effect was observed on mature DC-induced naive T cell activation.
- A detection limit of 5000 labeled DCs was achieved with an uptake of ~70,000 vesicles/cell.
Conclusions:
- Tat-conjugated NIR polymersomes offer an efficient method for intracellular delivery and in vivo tracking of dendritic cells.
- These probes allow for quantitative, repetitive detection of labeled cells at depth without disrupting cellular function.
- This technology holds promise for advancing DC-based therapies and immunological research.
Abstract:
Dendritic cells (DCs) play a pivotal role in both immune tolerance and the initiation of immunological responses. The ability to track DCs in vivo is imperative for the development of DC-based cellular therapies and to advance our understanding of DC function and pathophysiology. Here, we conjugate a cell permeable peptide, Tat, to near-infrared (NIR) emissive polymersomes in order to enable efficient intracellular delivery for future DC tracking with these optical probes. NIR imaging allows quantitative, repetitive, in vivo detection of fluorophore-laden cells, at centimeter tissue depths without disturbing cellular function. Flow cytometry and confocal microscopy results indicate that Tat-mediated polymersome delivery to DCs is concentration and time dependent, resulting in punctate intracellular localization. Further, loading cells with Tat NIR emissive polymersomes does not interfere with cytokine-induced DC maturation and has modest effects on DC viability, but has a significant effect on mature DC-induced activation of naive T cells. We observe significant uptake of NIR emissive polymersomes when conjugated to the peptide, with a lower detection limit of 5000 labeled DCs. The extent of polymersome delivery is estimated as 70 000 +/- 10 000 vesicles/cell, equivalent to 0.7 +/- 0.1 fmol of NIR fluorophore. Our studies will enable future in vivo tracking of ex vivo labeled DCs by NIR fluorescence based imaging.
