Cell apoptosis assays

Quantification of apoptosis was determined by the Annexin-V apoptosis detection kit (BD Pharmingen) following the instructions of the manufacturer protocol. Annexin-V-positive and propidium iodide-negative cells were considered to be in the early apoptotic phase, whereas the cells that exerted positive staining for Annexin-V and propidium iodide were considered to be in the late apoptotic and/or necrotic stage. All data were collected, stored, and analyzed by LYSIS II software (BD Biosciences, San Diego, CA, USA). For primary myeloma samples, cells were selected from MNCs using EasyStep CD138+ magnetic nanoparticles and stained with Annexin-V-FITC, and propidium iodide at room temperature for 30 min. The cells were washed with 1 × binding buffer twice, and analyzed using a LSR II flow cytometer (BD biosciences).