Figure 3. Changes in TPO levels in young and aged mice. (A) TPO concentration was measured by ELISA in serum from young and aged, male and female C57BL/6J mice. Serum TPO was significantly reduced in aged female and male mice compared to sex-matched young mice. The data are presented as mean ± SD (*p<0.05, **p<0.01, N=9-10/group). (B) Bone marrow supernatant was collected from young and aged femur and tibia (male and female mice were combined) and used to determine TPO concentrations by ELISA. The data are presented as mean ± SD (*p<0.05; N=5/group).