SDX-101 and SDX-308 inhibit OCL formation in a concentration-dependent manner and inhibit bone resorption. Nonadherent bone marrow cells from (A) healthy donor (1 × 105) and (B) MM patients were cultured in 100 μL α-MEM/20% horse serum, 50 ng/mL RANKL, and 10 ng/mL M-CSF for 3 weeks with either 30, 50, 75, and 100 μM SDX-101; 3, 5, 7.5, and 10 μM SDX-308; or vehicle. After 3 weeks, the cultures were stained with the 23c6 antibody. 23c6-positive OCLs containing 3 or more nuclei were scored microscopically. All experiments were performed in triplicate. Results are shown as mean ± SD. Asterisks indicate significant difference from control (P < .05). (C) Nonadherent bone marrow cells from healthy donor (1 × 105) were cultured in 100 μL α-MEM/20% horse serum, 50 ng/mL RANKL, and 10 ng/mL M-CSF for 3 weeks with 75 μM SDX-101, 7.5 μM SDX-308, or vehicle (DMSO 0.1%). After 3 weeks, dentin slices were stained with TRAP to confirm OCL formation on the slices. Resorption lacunae (arrows) were stained with hematoxylin and the images were obtained using an Olympus IX70 microscope equipped with a 20×/0.40 numeric aperture objective lens (Olympus). Images were acquired through Magnafire 4.1 software (Optronics). The pit area was quantified using the public-domain NIH Image program.
