THP-1 osteoclasts, hMSC osteoblasts, or a co-culture of the two cell types were maintained on silk-HA films or silk-HA films loaded with clodronate or alendronate for 7 days, and metabolic activity was measured by Alamar Blue. Metabolic activity of cells grown on drug-loaded films is normalized to metabolic activity of the same cell type(s) grown on control silk-HA films and is expressed as mean ± SD. Top left: Osteoclasts cultured on clodronate-loaded films. Top right: Osteoclasts cultured on alendronate-loaded films. Middle left: Osteoblasts cultured on clodronate-loaded films. Middle right: Osteoblasts cultured on alendronate-loaded films. Bottom left: Co-cultures cultured on clodronate-loaded films. Bottom right: Co-cultures cultured on alendronate-loaded films. *p<0.05, **p<0.01, ***p<0.001.