Fig. 3.

Cellular viability and stress/damage induced by extrinsic cytotoxicity under serum-free or FBS-containing culture condition. a Morphological alteration of the serum-free (SFM)- and FBS-containing (FCM)-cultured PDLSCs before (Control) and after cytotoxic treatments with staurosporine (ST), hydrogen peroxide (H₂O₂), and ultraviolet radiation (UV). All the cytotoxic stimuli-treated SFM cells showed damaged appearance with degenerative changes relative to the treated FCM cells; scale bars 100 µm. b The MTT assay revealed that viability of FCM cells was significantly higher than that of SFM cells after the cytotoxic treatments (*P < 0.01). c Flow cytometric analysis by Annexin V-FITC/PI staining showed that a greater amount of damaged cells, which were fractionated as both Annexin V-positive/PI-negative (early apoptotic cells) and Annexin V/PI-double positive (late apoptotic cells), were detected in SFM cultures compared with FCM cultures, following cytotoxic treatment. d Quantification of the flow cytometric analysis for damaged cells (*P < 0.01)