Figure 4. TPO stimulates OC formation. (A) FACS sorted CD45+F4/80+ macrophages from young and aged mice were subject to real-time PCR to assess the relative mRNA expression of Mpl. The Ct cycle range was 34.06–35.15. The data shown are mean ± SD (*p<0.05). (B, C) FACS sorted CD45+F4/80+ macrophages were cultured with 20 ng/ml M-CSF and 80 ng/ml RANKL in the presence or absence of recombinant human TPO (100 ng/ml). Growth media was changed every second day for 5–7 days until mature, multinucleated OCs (>3 nuclei) were formed. Mature OCs were fixed and TRAP+ OCs were counted. The data are presented as mean ± SD of four (female) and two (male) independent experiments (*p<0.05, ***p<0.001; N=3/group).