Figure 5.

LICs are protected from chemotherapy within PDLS. (A) B-ALL PDLS were incubated with daunorubicin (75 ng/ml) for 1 h and enzymatically disrupted; red fluorescence was determined in CD45⁺ (B-ALL) and MSCs by FACS (n = 5). (B) Primary B-ALL blasts were cultured in SF, 2D and PDLS and CD45⁺ cell viability evaluated upon 24-h treatment with daunorubicin, prednisolone, and vincristine (n = 3), or (C) combined chemotherapy: daunorubicin [75 ng/ml], prednisolone [10 ng/ml], vincristine [50 ng/ml], and methotrexate [5 mM] (P-V-D-M). (D) Viable leukemic cells recovered from PDLS-in untreated or 24-h P-V-D-M-treated were re-exposed to the drugs for 24 h and their viability was measured by FACS (n = 5). (E) PDLS P-V-D-M-treated were replated; upon 120 h, PDLS-out leukemia re-emerging was recorded (n = 7). B-ALL, B-cell acute lymphoblastic leukemia; PDLS, patient-derived leukemia spheroids; MSCs, mesenchymal stromal cells; FACS, Fluorescence-activated cell sorting; NS, non-significant. *P < 0.05; **P < 0.01; ***P < 0.001, ***P < 0.0001. Error bars represent SD.