Inhibition of CD79a/Igα or CXCR4–SDF-1 interaction ablates TCF3::PBX1⁺ leukemia cells’ engraftment into cerebral organoids. (A) shRNA-miR30 (control) or shRNA-mediated CD79a knockdown (KD) 697 cells (10 000 cells) were seeded in a coculture assay with cerebral organoids for 14 days. Both conditions were analyzed using the unpaired 2-tailed t test, 697 CD79a vs 697 shRNA-miR30 (P = .0034). (B-C) To demonstrate the expression of stromal cell-derived factor in our cerebral organoids, we stained cerebral organoids with anti-SDF-1 antibody. A single z-slice of a complete 3D stack is shown above, including a portion of the image in the ROI. Immunofluorescence staining revealed colocalization with anti-MAP2 signal in cerebral organoids and the expression of SDF-1 significantly increased in neurons. (D) 697 wild-type (10 000) cells pretreated for 12 hours with (44 nM) plerixafor or with vehicle control in a coculture assay with cerebral organoids for 14 days. Both conditions were analyzed using the unpaired 2-tailed, vehicle treated vs plerixafor treated 697 cells (P = .0155). Scale bars: 50 μm, 100 μm, and 500 μm.