Fig 1.
Schematic diagram of cytotoxicity assay using PB-NK cells toward the 3D tumor spheroids.
Fig 2.
Evaluation of NK cell cytotoxic activity toward 3D tumor spheroids.
(A) Flow cytometric analysis of the NK cell-related markers (CD45, CD3, and CD56) of the post-sorted PB-NK cells. (B) Proliferation and flow cytometric analysis of the PB-NK cells in the presence of the genetically modified mIL-21-K562 cell line and hIL-2 (PB-NK cells were isolated from 2 donors, n = 2). (C) Fluorescent and phase-contrast images of the CFSE-labeled KKU213A tumor spheroids in the culture medium containing 2.5% Matrigel® matrix on day 2. Green = tumor cells (CFSE), Red = dead cells (PI), scale bar = 20 μm. (D) Representative fluorescent images of the PB-NK cells and the 3D tumor spheroids at different effector to target ratios (E: T) (1:1, 2.5:1, 5:1, and 10:1). Green = tumor cells (CFSE). Red = dead cells (PI), scale bar = 20 μm. (E) Cytotoxic activity of the PB-NK cells against 3D tumor spheroids at 1:1, 2.5:1, 5:1, and 10:1. The PB-NK cells were obtained from 2 donors. Data are presented as mean ± SEM (n = 2).