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. 2015 Dec 22;34(3):756–767. doi: 10.1002/stem.2255

Figure 2.

Figure 2

Zoledronate (ZOL) enhances DNA repair in human mesenchymal stem cell (hMSC) following irradiation and rescues their function. (A): Number of γH2AX foci enumerated in hMSC following irradiation (3Gy) in the presence or absence of ZOL (1 µM) and assessed at 0, 4, 12, 24, and 48 hours post irradiation (scored 25 cells from hMSC cultures from three independent donors). (B): Percentage of cells in different comet categories (CC) calculated based on increasing tail moments (CC1‐CC5) to determine cellular DNA damage (n = 3) 20×. (C): Number of colony forming unit fibroblast (CFU‐F) obtained from hMSC cultures exposed to irradiation (3 Gy) in the presence or absence of ZOL (n = 3). (D): Representative example of hMSC growth curve showing number of cumulative population doublings. Cultures were either left nonirradiated or irradiated at 3 Gy and grown in the presence or absence of ZOL for 3 days, and 12 hours later cultures were washed free from ZOL and expanded in hMSC medium (n = 3). (E, F): hMSC treated as described in (D): and at passage 9 exposed to osteogenic and adipogenic differentiation supplements, respectively. Cultures were assessed for the expression of osteogenic differentiation markers core‐binding factor subunit alpha, osteopontin, alkaline phosphatase, osteocalcin, and adipogenic differentiation markers lipoprotein lipase and peroxisome proliferator‐activated receptor γ. All markers were normalized to ribosomal protein L‐32 (n = 3). Data expressed as mean ± SD and analyzed by one way analysis of variance (ANOVA) and Bonferroni post hoc test for multiple comparisons, with the exception of data in panel A which was analyzed by two way ANOVA and Sidak's post‐test for multiple comparisons *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001. Abbreviations: ALP, alkaline phosphatase; CBFA, core‐binding factor subunit alpha; CFU, colony forming unit; IR, irradiation; LPL, lipoprotein lipase; OC, osteocalcin; OPN, osteopontin; PBS, phosphate buffer saline; PD, population doubling; PPAR γ, peroxisome proliferator‐activated receptor γ; UI, not irradiated; ZOL, zoledronate.