Figure 2
From: Fibroblast-associated tumour microenvironment induces vascular structure-networked tumouroid
Fibroblast-associated microenvironment during formation of an in vitro tumouroid. (a,b) Cellular constituents and collagen type I matrix of the in vitro tumour microenvironment developed a spherical structure of cancer cells in the microwell of the microfluidic device. On days 1 and 2, the collagen matrix was aligned by contraction forces due to the transformation of fibroblasts on the collagen matrix (see Movie 1). Fibroblasts attached to the aligned collagen matrix during tumour formation could be distinguished from cancer cells. During days 2–4, multicellular tumour spheroids (MCTSs) formed rapidly with the alignment of the collagen matrix. The morphology of these MCTSs persisted during tumourigenesis. Microvilli for cell-to-cell interactions of cellular constituents were activated on the MCTSs. (c) Alignment of the collagen matrix by fibroblasts in the microwell was observed during tumouroid formation. (d) TGFβ was highly expressed during tumour formation under the condition of fibroblasts. (e) During tumour formation, MMP1 was expressed on fibroblasts attached to the collagen matrix, and MMP9 was expressed on aggregated cancer cells. (f) Cell-to-cell interactions were observed in activated microvilli rather than in fibroblast-free MCTSs in the tumour formed by fibroblasts.
