Macrophage In Vitro and In Vivo Tracking via Anchored Microcapsules

Abstract

A new promising trend in personalized medicine is the use of autologous cells (macrophages or stem cells) for cellbased therapy and also as a "Trojan horse" for targeted delivery of a drug carrier. The natural ability of macrophages for chemotaxis allows them to deliver cargo to the damaged area, significantly reducing side effects on healthy organ tissues. Therefore, it is important to develop tools to track their behavior in the organism. While labeled containers can serve as anchored tags for imaging macrophages in vivo, they can affect the properties and functions of macrophages. This work demonstrates that 3 μm sized capsules based on biocompatible polyelectrolytes and fluorescently labeled with both Cy7 and RITC dyes do not affect cell functionalization in vitro, such as viability, proliferation, and movement of transformed monocyte/macrophage-like cells (RAW 264.7) and primary bone marrow derived macrophages (BMDM) at maximal loading of five capsules per cell. In addition, capsules allowed fluorescent detection of ex vivo loaded cells 24 h after the tail vein injection in vivo and visualization of microcapsule-laden macrophages ex vivo using confocal microscopy. We have delivered about 62.5% of injected BMDM containing 12.5 million capsules with 3.75 μg of highmolecular-weight cargo (0.3 pg/capsule) to the liver. Our results demonstrate that 3 μm polyelectrolyte fluorescently labeled microcapsules can be used for safe macrophage loading, allowing cell tracking and drug delivery, which will facilitate development of macrophage-based cell therapy protocols.

Fluorescent polymer markers photoconvertible with a 532 nm laser for individual cell labeling

“…The optimal capsule‐to‐cell ratio that provides the desired internalization degree was found to be 5 capsules to the cell. Such capsule‐to‐cell ratio also was found to be optimal for RAW 264.7 cell line in previous article [44]. The number of internalized capsules depended on the overall capsule‐to‐cell ratio (Figure 5A, pink line).…”

“…It is known that macrophages are capable of chemotaxis, performing pinocytosis and phagocytosis, and affecting inflammation and regeneration processes in situ. Also, these cells can be used as a model for cell-based therapy and as vehicles in drug delivery [42][43][44].…”

Macrophage based drug delivery: Key challenges and strategies

“…Therefore, mechanical entrapment in the lungs occurs often via systemic circulation. Previous studies have documented that after intravenous injection, drug-loaded macrophages are distributed and accumulate in the three major organs of the liver, lung and spleen [ 60 , 143 , 144 ]. In a clinical trial on the biological distribution of autologous activated macrophages (AAM) in patients with metastatic renal cell carcinoma (RCC), results showed a transient retention of AAM in the lungs, where they predominated in the first hour after intravenous infusion.…”

Impact of Macrophages on the Interaction of Cetuximab-Functionalized Polyelectrolyte Capsules with EGFR-Expressing Cancer Cells

“…The efficiency of targeting cancer cells also depends on the tumor microenvironment, a complex dynamic structure containing immune cells, stromal cells, blood vessels, and extracellular matrix. , During transport within the tumor stroma, the capsules can be internalized by both macrophages and cancer cells. The uptake of capsules leads to the formation of phagocytic cups (vesicles) and engulfment of the capsules by both cancer cells and macrophages. , Tumor-associated macrophages can remodel the tumor microenvironment due to polarization upon interaction with functionalized particles and render the tumor microenvironment immunosuppressive, which protects cancer cells from specific immune responses …”