Organoids: Unlocking the 3D 'miniature battlefield' for tumor immune research

I. Introduction

II. Core Characteristics of Organoids and Their Adaptability to Tumor Research

(I) Biological Properties of Organoids

Structural and functional mimicry: They can replicate the typical architecture of the original organ (e.g., the crypt-villus structure of intestinal organoids), retain functional cell types (e.g., absorptive cells, immune cells), and exhibit partial physiological functions (e.g., cytokine secretion, expression of specific surface markers);

Microenvironment compatibility: They can integrate non-epithelial components such as immune cells and stromal cells to construct a "tumor-immune" microenvironment that closely resembles in vivo conditions;

Stability and accessibility: They can be cultured in vitro for long periods (some can be passaged over 20 times) and directly derived from patient tumor tissues, preserving the genetic characteristics and heterogeneity of tumors.

(II) Types of Organoids in Tumor Immunology Research

Colorectal tumor organoids (retaining mutations such as APC and KRAS);

Lung tumor organoids (covering subtypes like non-small cell lung cancer);

Breast tumor organoids (replicating the structure of ductal carcinoma);

Gastric tumor organoids (suitable for studying Helicobacter pylori-related tumors).

III. Two Core Application Strategies of Organoids in Tumor Immunology Research

(I) Holistic Culture Strategy: "Native Microenvironment" Models Retaining Endogenous Immune Cells

Interaction between breast tumor organoids and Vδ2+ T cells: A 2016 study constructed breast organoids retaining intraepithelial lymphocytes. After treatment with aminobisphosphonates, Vδ2+ T cells within the organoids were activated to secrete IFN-γ, efficiently killing breast tumor cells. This study was the first to confirm that organoids can dissect the anti-tumor mechanism of γδ T cells;

MDOTS/PDOTS models in microfluidic chips: A 2018 study developed mouse-derived organotypic tumor spheres (MDOTS) and patient-derived organotypic tumor spheres (PDOTS). MDOTS could replicate in vivo responses or resistance to PD-1 inhibitors, while PDOTS (e.g., derived from melanoma) allowed the detection of resistance-related cytokines such as CCL19 and CXCL13 after anti-PD-1 treatment, providing a basis for marker screening;

Complex organoids cultured at the air-liquid interface: Recent technologies enable the construction of organoids from colorectal and lung tumors, stably maintaining various immune cells (CTLs, TH cells, NK cells, etc.) and TCR heterogeneity for 30 days in vitro. After immune checkpoint blockade, proliferation of tumor antigen-specific T cells and tumor killing were observed, perfectly simulating in vivo immune responses.

(II) Simplified Co-Culture Strategy: "Assembled Models" for Precise Analysis of Immune Cell-Tumor Interactions

Triple co-culture of gastric tumor organoids with DCs and CTLs: Gastric tumor organoids were constructed from transgenic mice and co-cultured with DCs and CTLs in the presence of PD-L1 inhibitors. Significant cell death was only observed in the tumor organoid group, confirming the synergistic effect of DC antigen presentation and CTL killing;

Co-culture of high-mutational-burden organoids with PBMCs: Colorectal cancer and non-small cell lung cancer organoids (with high mutational burden) were co-cultured with autologous peripheral blood mononuclear cells (PBMCs). Tumor organoids activated T cells by presenting neoantigens, and expanded CTLs specifically killed tumor organoids without affecting normal organoids;

Validation of CAR-NK cell activity: CAR-NK cells targeting HER2 and EGFRvIII were constructed and co-cultured with tumor organoids positive for the corresponding antigens. EGFRvIII-specific CAR-NK cells efficiently killed tumor organoids, while CAR-NK cells targeting FZD also damaged normal organoids, providing a basis for evaluating the safety of therapeutic targets.

IV. Conclusion and Outlook