Mechanoresponsive reprogramming of tumor-associated macrophages during cancer progression

Source: Frontiers in Cell and Developmental Biology, by Dayeon Kim; Yeonjae Kim; Jihye Lee; Saumendra Kumar Bajpai; Dong-Hwee Kim (September 17, 2026). AI-generated summary by biochip.com, published October 4, 2026. Not independently reviewed.

A review led by Dayeon Kim and colleagues at Korea University examines how the physical makeup of a tumor can reshape the immune cells living inside it. The team focuses on tumor-associated macrophages, or TAMs, which can either support immune attack or, more commonly in many tumors, help cancer grow and spread. Crucially for biochip research, the review assesses hydrogels, spheroids, organoids, and microfluidic organ-on-a-chip systems that model these mechanical conditions in the laboratory. The work argues that reproducing a tumor's stiffness, density, and structure is essential for studying how macrophages become tumor-supportive.

Tumors Are Physical Environments

A tumor is not simply a cluster of abnormal cells. It includes immune cells, blood vessel-associated cells, supportive stromal cells, and the extracellular matrix, the protein-rich scaffold surrounding cells. During cancer progression, this matrix can become denser and stiffer as collagen and fibronectin accumulate.

The review describes these mechanical changes as active signals, not passive consequences of disease. A useful analogy is walking across different surfaces: loose sand, packed soil, and concrete each change how a person moves. Similarly, macrophages sense the resistance and architecture of the matrix around them, which can influence their migration, infiltration, and functional state.

Why Macrophage Origin Matters

TAMs are a diverse population, and their developmental origins help explain that diversity. Some arise from circulating monocytes, immune cells produced in bone marrow that enter a tumor after being recruited by chemical signals. Others are tissue-resident macrophages, cells already established in an organ before cancer develops.

For monocyte-derived TAMs, the review highlights the CCL2-CCR2 signaling axis, in which tumor and stromal cells release CCL2 to attract monocytes carrying the CCR2 receptor. It also discusses CSF-1 and its receptor, CSF-1R, which influence monocyte recruitment, macrophage survival, maturation, and differentiation within tumors.

Once inside the tumor microenvironment, macrophages often acquire an M2-like state associated with immune suppression and tumor-promoting activity. This framework is a simplification of a broader spectrum of macrophage states, but it remains useful for explaining efforts to shift TAMs toward more inflammatory, antitumor behavior.

Modeling Mechanical Niches in 3D

Conventional two-dimensional cell culture places cells on a flat surface, which cannot fully recreate the cell-to-cell contacts, matrix interactions, or spatial structure found in a solid tumor. Kim and colleagues identify three-dimensional models as more suitable tools for studying how physical conditions affect TAM behavior.

Hydrogels, water-rich polymer networks, can be tuned to mimic aspects of the extracellular matrix and help researchers examine cell-matrix interactions. Spheroids and organoids build more realistic three-dimensional cellular arrangements. Microfluidic organ-on-a-chip models add controlled fluid flow and small channels, making them particularly useful for observing monocyte and macrophage infiltration and migration.

These approaches matter because different regions of one tumor can present different mechanical conditions. A stiff, dense zone may recruit or shape macrophages differently from a softer region, helping create the heterogeneous TAM populations observed in solid tumors.

Therapeutic Questions

The review outlines two broad approaches to targeting TAMs. One is depletion: blocking pathways such as CCL2-CCR2 or CSF-1-CSF-1R to reduce monocyte recruitment and TAM accumulation. The other is reprogramming, which aims to move M2-like, immunosuppressive macrophages toward M1-like states associated with inflammatory antitumor responses.

Mechanical regulation could add another dimension to these strategies. Instead of targeting macrophages alone, researchers may need to consider the physical niches that help sustain their tumor-supportive behavior, including matrix stiffening and interactions with cancer-associated fibroblasts.

Why This Matters

Microfluidic and other 3D biomimetic platforms provide a way to test immune behavior under conditions that more closely resemble a tumor than flat cell cultures do. They could help separate the effects of chemical signals from the effects of matrix stiffness, density, architecture, and spatial variation. The review also emphasizes that current models still have limits in reproducing the full mechanical complexity of living tumors.

Future cancer models will need to integrate multiple cell types and carefully controlled mechanical features if they are to capture TAM plasticity more faithfully. That could make organ-on-a-chip systems valuable not only for observing macrophage migration, but also for testing whether interventions can disrupt the physical conditions that push these cells toward tumor-supportive roles.

Topics: Microfluidics · Organ-on-a-chip · Cancer

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