The yin and yang of imaging tumor associated macrophages with PET and MRI

Mukherjee, Sudip; Sonanini, Dominik; Maurer, Andreas; Daldrup‐Link, Heike E.

doi:10.7150/thno.37306

Cited by 57 publications

(60 citation statements)

References 185 publications

(200 reference statements)

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“…It is important to monitor the process in real‐time. Molecular imaging with macrophage‐targeting probes, [ 153–166 ] which binds macrophages through different biomarkers in order to image them with high spatiotemporal resolution, is promising for identifying the distribution and polarization of macrophages in tumor tissues. Second, the immune microenvironment in the tumor tissue is complicated, and macrophage‐mediated cancer immunotherapy alone is not potent enough to eradicate tumors.…”

Section: Discussionmentioning

confidence: 99%

Engineering Macrophages for Cancer Immunotherapy and Drug Delivery

et al. 2020

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was that most nanoparticles do not have a sufficiently long blood half-life and cannot realize deep penetration in tumor tissue. Thus, recent progress in the development of strategies for mimicking or modulating cells offers a highly attractive alternative to drug delivery. [10-17] As natural immune cells and antigenpresenting cells, macrophages [18] have a long blood half-life and can specifically bind to tumor tissue. Therefore, applying macrophages in chemical drug delivery would lead to a significant increase in drug accumulation in tumors. Since macrophages can engulf foreign particles in nature, they can directly phagocytose drugs and then deliver drugs to tumors. [19] Thus, live macrophages may serve as drug carriers. To further increase the tumor-targeting ability of macrophages, they can be engineered with targeting ligands. [20] In addition, learning from red blood cell (RBC) membrane coating technology, [21-23] a macrophage cell membrane coating was developed and it resulted in enhanced tumor uptake of drugs. On the other hand, macrophages play an important role in modulating the tumor immune microenvironment. M1 macrophages inhibit tumor growth, while M2 macrophages promote tumor growth. Inhibition of M2 macrophages and repolarization of M2 macrophages to M1 macrophages are common strategies to treat solid tumors. Furthermore, since these macrophages express SIRPα on their surface, their phagocytic activity against CD47-expressing tumor cells is significantly affected by the CD47-SIRPα pathway. Therefore, blocking the CD47-SIRPα pathway can further enhance the anti-tumor efficacy of macrophages. Herein, to elucidate the importance of macrophages in tumor therapy (Figure 1), we will first discuss the role of macrophages in cancer immunotherapy, including the inhibition, depletion, and repolarization of tumor-associated macrophages (TAMs) and the blocking of the CD47-SIRPα pathway to enhance phagocytosis in tumor therapy. Then, based on the tumor targeting of M1 macrophages, we will discuss the applications of macrophages, macrophage-derived exosomes, and macrophage-coated NPs for drug delivery. We will thus offer a comprehensive understanding of functionalizing macrophages for tumor therapy. Macrophages play an important role in cancer development and metastasis. Proinflammatory M1 macrophages can phagocytose tumor cells, while antiinflammatory M2 macrophages such as tumor-associated macrophages (TAMs) promote tumor growth and invasion. Modulating the tumor immune microenvironment through engineering macrophages is efficacious in tumor therapy. M1 macrophages target cancerous cells and, therefore, can be used as drug carriers for tumor therapy. Herein, the strategies to engineer macrophages for cancer immunotherapy, such as inhibition of macrophage recruitment, depletion of TAMs, reprograming of TAMs, and blocking of the CD47-SIRPα pathway, are discussed. Further, the recent advances in drug delivery using M1 macrophages, macrophage-derived exosomes, and macrophage-membrane-coated nanoparticles are ela...

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Section: Discussionmentioning

confidence: 99%

Engineering Macrophages for Cancer Immunotherapy and Drug Delivery

et al. 2020

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“…Ionizing radiation such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are based on the use of high-energy elements (radioisotopes) characterized by high-detection sensitivity (from nanomolar to picomolar) but with low spatial resolution 189 , 190 . To obtain anatomical images, ionizing radiations are combined with another high-energy approach based on X-rays, computed tomography (CT), or non-ionizing methods such as MRI 191 . To solve the different issues regarding the lack of sensitivity or spatial resolution in previous techniques, multimodal imaging was developed.…”

Section: Macrophage As Theranostic Toolsmentioning

confidence: 99%

The twin cytokines interleukin-34 and CSF-1: masterful conductors of macrophage homeostasis

Muñoz-García¹,

Cochonneau²,

Téletchéa³

et al. 2021

Theranostics

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“…A distinct design of magneto-fluorescent nanoparticles can render the particle specific for certain macrophage polarizations [ 224 ]. The application of SPIO for TAM imaging has been extensively reviewed elsewhere [ 225 ]. The advantage of the SPIO approach is that there are particles that have been clinically approved for liver MR imaging carrying a very low toxic potential.…”

Section: Tam Tracking and Imagingmentioning

confidence: 99%

Tumor-Associated Macrophages—Implications for Molecular Oncology and Imaging

et al. 2021

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Tumor-associated macrophages (TAMs) represent the largest group of leukocytes within the tumor microenvironment (TME) of solid tumors and orchestrate the composition of anti- as well as pro-tumorigenic factors. This makes TAMs an excellent target for novel cancer therapies. The plasticity of TAMs resulting in varying membrane receptors and expression of intracellular proteins allow the specific characterization of different subsets of TAMs. Those markers similarly allow tracking of TAMs by different means of molecular imaging. This review aims to provides an overview of the origin of tumor-associated macrophages, their polarization in different subtypes, and how characteristic markers of the subtypes can be used as targets for molecular imaging and theranostic approaches.

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The yin and yang of imaging tumor associated macrophages with PET and MRI

Cited by 57 publications

References 185 publications

Engineering Macrophages for Cancer Immunotherapy and Drug Delivery

Engineering Macrophages for Cancer Immunotherapy and Drug Delivery

The twin cytokines interleukin-34 and CSF-1: masterful conductors of macrophage homeostasis

Tumor-Associated Macrophages—Implications for Molecular Oncology and Imaging

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