Figure 6. Expression of key OC factors in MKs from young and aged mice. (A–D) MKs were prepared from the bone marrow of young and aged, male and female mice using a BSA gradient and used for mRNA expression analyses by real-time PCR. (A) M-CSF mRNA (Ct cycle range was 25.2–30.12). (B) OPG mRNA (Ct range 35.09–39.53). (C) RANKL mRNA (Ct range 28.6–35.5). (D) The RANKL/OPG ratio was calculated for young and aged, male and female MKs (N=4-5/group). (E) RANKL concentrations in MK CM was quantified by ELISA. MK CM from aged females was significantly higher than MK CM from young females. P-values were calculated by one-way ANOVA followed by Tukey’s post-hoc test and the data are presented as mean ± SD. (*p<0.05, **p<0.01, ***p<0.001, ****p<0.0001).