Bone Abstracts

Bone marrow is composed of cells developed within the marrow compartment as well as blood supplied from the general circulation. Bone tissue is affected by cytokines within the bone marrow.

We investigated if the levels of different bone acting cytokines differ between bone marrow and blood from the peripheral circulation.

Fifty-three healthy postmenopausal women participated in a study designed to evaluate the effect of rosiglitazone on bone mineral density. Blood and bone marrow were drawn at the end of the trial. Bone marrow was drawn from the iliac crest in local anesthesia into a 20 ml syringe. From the syringe 2 ml were transferred into smaller tubes and centrifuged. The serum was aspirated and transferred into cryotubes. We measured the levels of the cytokines adiponectin, leptin, OPG, TGFB, FA1, and MCP1 using ELISA.

The correlations between the levels ranged from 0.22 (OPG) to 0.98 (adiponectin). The levels of adiponectin and TGFB were 44.1 and 31.0% higher in blood compared to bone marrow, respectively (P<0.001) whereas the level of FA1 was 8.6% lower (P<0.001). There were no differences between the levels of OPG, MCP1, or leptin.

Our data show that the correlation between cytokine levels in blood and bone marrow varies greatly. Moreover, the level of some cytokines (adiponectin and TGFB) is significantly higher in blood and the level of others (FA1) significantly lower. These data suggest that the marrow is a partly independent compartment that can be investigated using the method described above. Thus, measuring cytokine levels in the bone marrow might be a better approach to evaluate the effects of cytokines on bone –especially when considering the effects on trabecular bone as this is supplied with nutrients from the bone marrow, whereas cortical bone is supplied by perforant arteries from the peripheral circulation.