The relationship between adipose tissue and bone metabolism.

ABSTRACT

OBJECTIVES: The authors have set out to evaluate the literature relevant to the dynamic regulation of adipogenesis and osteogenesis. DESIGN AND METHODS: A detailed search of the past and recent literature was conducted on Pubmed using a combination of keywords including adipogenesis, bone marrow, hematopoiesis, mesenchymal stromal/stem cell, and osteogenesis. RESULTS: Throughout one's lifespan, the bone marrow microenvironment provides a unique niche for mesenchymal stromal/stem cells (BMSCs) and hematopoietic stem cells (HSCs). The marrow changes as a function of biological age and pathophysiology. Historically, clinical biochemistry has observed these changes from an HSC and hematological perspective. Nevertheless, these changes also reflect the balance between BMSC adipogenic and osteogenic processes which can display an inverse or reciprocal relationship. Multiple hormonal factors and nuclear hormone receptor ligands and drugs are responsible for BMSC lineage selection. Data from a number of laboratories now implicates endocrine feedback loops between extramedullary adipose depots and the central nervous system. CONCLUSIONS: This concise review provides a perspective on the mechanisms regulating BMSC differentiation in the context of biological aging, obesity, and osteoporosis.