To quantify the level of TNAP in BMSCs after co-culture with AML or ALL cell lines, primary AML cells, or healthy CD34+ progenitors, the adherent layer was subjected to trypsinization after washing with PBS to remove non-adherent cells. Cells were stained with TNAP-PE (clone W8B2; Biolegend) and with a fluorochrome-conjugated mAb specific to exclude residual leukemia cells. Specifically, CD33-PE-Cy7 (clone P67.6; BD Bioscience) was used to gate AML cells, CD19-PE-Cy7 (clone J3-119; Beckman Coulter) was used to gate B-ALL cells and CD34-FITC (clone 581; BD Pharmingen) was used to gate CD34+ progenitors.
The following antibodies were used for the analysis of BMSCs: CD90-PE (clone 5E10; eBioscience), CD73-PE (clone AD2; BD Pharmingen), CD105-PE (clone SN6; eBioscience), CD146-PE (clone P1H12; BD Pharmingen), CD45-FITC (clone HI30, BD Pharmingen), and CD34-FITC.
Median fluorescence intensities were calculated in co-cultured BMSCs in comparison to control with FlowJo software.