Figure 3
From: Fibroblast-associated tumour microenvironment induces vascular structure-networked tumouroid
Vessel-like tubular structure formation in the microfluidic device. (a) The collagen matrix was stretched by tension forces between neighboring MCTSs due to fibroblasts. After stretching, the collagen matrix sheet was rolled up by a stretching force between the MCTSs. (b) The collagen matrix stretched by the MCTS fibroblasts exhibited torsion between neighboring MCTSs. (c) Stretching (yellow arrow heads) and torsion (white arrow heads) of the collagen matrix were revealed on a collagen matrix sheet stained with blood vessel-related markers (VE-cad, CD31). (d) The vessel structure connecting the MCTSs was tight and stable. (e) The collagen IV matrix formed a net structure and enclosed HUVECs. (f) The collagen IV matrix was also tightly formed at the site of the MCTS fibroblasts. (g,h) VE-cad and CD31 were expressed only on a vessel-like tubular structure distinct from the MCTS. This distinct tissue formed the lumen composed of HUVECs. (i) The spheroid morphology (with circularity ≥ 0.9) formed more quickly MCTSs with NIH3T3 (orange curve and box) than without NIH3T3 (blue curve and box). The vessel-like tubular structure was formed within 80 h after the formation of spheroids (orange bar) under the condition with NIH3T3 (purple bar) but not without. (j) The MCTSs formed a large tumour mass. (k) In the 3D image of the MCTS, collagen IV was expressed in a linear shape similar to that of a capillary vessel, from the outer layer of the spheroid to the interior space (colors indicate the depth of the tumouroid).
