FIG. 1.

Study design. (a) To study the pro-angiogenic capability of tumor cells in response to three-dimensional (3D) culture, oxygen (O₂) level, and cell–matrix interactions, oral squamous cell carcinoma (OSCC-3) was cultured within unmodified and RGD-modified alginate disks and vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) secretion was analyzed. Subsequently, the effects of tumor-secreted factors on endothelial cell behavior were determined using a new collagen-based 3D model of invasion. (b) Fabrication of OSCC-3-seeded alginate disks. Alginate solutions were mixed with cells, cast in a micromachined mold, and cross-linked with 60 mM CaCl₂. The resulting disks were removed from the mold and used for 3D culture. (c) Three-dimensional tumor angiogenesis models were fabricated by crosslinking of collagen/tumor cell mixtures within poly(dimethylsiloxane) (PDMS) molds that were microfabricated by conventional photolithography techniques. Human umbilical vein endothelial cells were then seeded on the top of these OSCC-3-seeded gels, followed by 3-day culture.