CD8A and glioblastoma: Under time-lapsed imaging (Figure 2D), we monitored, on ‘GBM-on-a-Chip’, a single CD8+ T-cell’s extravasation in three stages: transmigration (0–1 hr) through the patterned brain microvessel, penetration (1–4 hr) into the brain-mimicking tissue construct, and interactions with GBM tumors (4–6 hr) at a single-cell level (Figure 2E).