Tunel assay (green stain) indicated the presence of apoptotic cells (white arrows) in the total cell population (blue stain - nuclei) treated with 10−4 M pamidronate (B, H) compared to untreated controls (A, G). Corresponding bright-field images are shown for pamidronate treated (D, J) and untreated cultures (C, I). Magnification 100×. Quantitative assessments of the Tunel slides (E, K) and measurements of caspase-3 activity (F, L) indicated a significant increase in the apoptotic cells after 72h of treatment with 10−4 M pamidronate compared to lower concentrations (*, p< 0.001). A similarly increasing trend with significant increases of caspase-3 activity after 72h was found with three-times higher pamidronate concentration (#, p<0.01) (*, p< 0.001). Data represent averages ± SD of measurements (n=3–4) obtained from three alveolar bone and three BMSCs samples.