3D is not enough: Building up a cell instructive microenvironment for tumoral stroma microtissues

Area of Science:

• Biomedical Engineering
• Cancer Biology
• Tissue Engineering

Background:

• In vitro tumor models are crucial for studying cancer progression and drug efficacy.
• Current models like spheroids fail to replicate tumor stroma remodeling.
• The tumor microenvironment, including stromal cells, significantly influences cancer progression.

Purpose of the Study:

• To engineer novel three-dimensional (3D) microtissues that accurately replicate the tumor microenvironment's composition and function.
• To compare the suitability of microtissues versus spheroids in modeling normal and cancer-activated fibroblasts (CAF).
• To establish a more physiologically relevant in vitro system for studying stromal contributions to cancer.

Main Methods:

• Fabrication of 3D microtissues using porous gelatin microscaffolds and cell aggregation (spheroids).
• Culturing of normal fibroblasts (NF) and cancer-activated fibroblasts (CAF) in both configurations.
• Analysis of biophysical properties: cell growth, metabolic activity, extracellular matrix (ECM) composition (collagen, fibronectin, hyaluronic acid), and mechanical properties via multiphoton imaging and particle tracking microrheology.

Main Results:

• Spheroid models showed consistent biophysical properties regardless of fibroblast type.
• Microtissues fabricated with CAF exhibited higher proliferation rates and contraction capabilities compared to NF-microtissues.
• CAF-microtissues developed an ECM richer in collagen, fibronectin, and hyaluronic acid, with distinct collagen network architecture.
• Microtissues, unlike spheroids, demonstrated significant differences reflecting in vivo stromal variations.

Conclusions:

• 3D microtissues, particularly those incorporating CAF, provide a superior in vitro model of the tumor microenvironment compared to spheroids.
• Microtissues effectively recapitulate functional and compositional differences between normal and cancer-associated stroma.
• This novel microtissue system offers a more accurate platform for studying tumor-stroma interactions and validating cancer therapies.