Abstract P120: Increased [ca2+]e Enhances Adipocyte Development In Bone Marrow Stroma
Background: Bone marrow stroma contains adipocytes, osteoblasts, and lymphohematopoietic donor cells. With age, fatty marrow gradually predominates in bone marrow stroma and is a factor underlying age-related fracture and anemia. Thus, it is important to understand the mechanism of adipocyte development in bone marrow stroma. Bone marrow Ca2+ levels can reach high concentrations of 8 to 40 mM, while circulating plasma Ca2+ levels normally range from 2.3 to 2.6 mM. However, the effects of a high extracellular calcium concentration ([Ca2+]e) on adipocyte development in bone marrow stroma remain largely unknown.
Methods and Results: We studied the effects of high [Ca2+]e on adipocyte development in bone marrow stroma. First, we used the fura-2 method to examine whether a change in [Ca2+]e alters [Ca2+]i levels in bone marrow stromal cells. Changes of [Ca2+]e from 1.8 mM to 5.4 mM and 10.8 mM significantly increased [Ca2+]i by 1.1 and 1.3 times, respectively. Next, bone marrow stromal cells were cultured for 14 days in high [Ca2+]e (5.4 mM and 10.8 mM) and normal [Ca2+]e (1.8 mM) conditions. Adipocyte development was monitored by Oil Red O staining of cytoplasmic lipids and by the activity of glycerol-3-phosphate dehydrogenase (GPDH). In 5.4 mM and 10.8 mM [Ca2+]e, Oil Red O-stained cells increased significantly by 1.4 and 2.3 times, respectively, and GPDH activity increased significantly by 1.7 and 2.3 times, respectively, compared with the respective values in 1.8 mM [Ca2+]e.
Conclusions: These results indicate that high [Ca2+]e induces an increase of [Ca2+]i, which enhances adipocyte development in bone marrow stroma. Further studies are required to determine the influx pathway of Ca2+, since prevention of Ca2+ influx into bone marrow stromal cells might suppress development of fatty marrow and reduce age-related fracture and anemia.
- © 2011 by American Heart Association, Inc.