Figure 7. In vitro effectiveness of the bsAb-releasing MSCs/cryogel system.

(a) A schematic representation of the experimental settings established for the in vitro T-cell activation and tumor cell killing assays is reported. (b) The expression of T-cell-specific activation markers was determined by flow cytometry after 48 h of incubation of T-cells and 1 × 10⁴ CD33⁺ MOLM-13 cells at an effector-to-target (E:T) ratio of 1:1 in the presence or absence of 1 × 10⁴ genetically cryogel-housed MSCs. The activation status of redirected T cells is reported as the percentage of CD25⁺/CD69⁺ cells detected on the total of CD3⁺ T-cell number. (c,d) Specific lysis of ⁵¹Cr labeled CD33⁺ MOLM-13 cells was analyzed via standard chromium release assay after 24 h or 48 h of co-cultivation with 1 × 10⁴ T-cells at an E:T ratio of 1:1 in the presence or in the absence of 1 × 10⁴ bsAb-releasing and 4-1BBL-expressing modified MSCs seeded in the cryogel matrix. Data are reported as the means ± SD for three different T-cells donors. Statistical significance was determined using one-way ANOVA with Bonferroni multiple comparison test. *p < 0.05. X = not detectable.