Modeling Tumor-Associated Macrophages <em>In Vitro</em>: The Role of Secreted Factors in Tumor Microenvironment Dynamics

Macrophages exhibit remarkable plasticity, enabling them to acquire distinct functional states in response to a variety of environmental cues. In solid tumors, they frequently constitute the most abundant immune cell population within the tumor microenvironment, where they are referred to as tumor-associated macrophages (TAMs). TAMs closely interact with malignant cells, actively promoting tumor progression, angiogenesis, and immune evasion. Tumor cells can reprogram macrophages through direct cell-cell contact and a wide array of secreted factors, shaping their polarization toward pro-tumoral phenotypes. To study these TAM polarization mechanisms in vitro, we propose a method that exposes human monocytes to soluble factors present in tumor cell line-conditioned media. This protocol enables the generation of TAM-like macrophages under controlled conditions, facilitating the analysis of phenotypic and functional changes induced by tumor-derived signals. Our approach offers a reproducible and physiologically relevant model to investigate tumor-macrophage interactions, deepens our understanding of macrophage reprogramming, and supports research into novel therapeutic strategies in cancer immunology and immunotherapy.