The relationship between adipose tissue and bone metabolism

ObjectivesThe authors have set out to evaluate the literature relevant to the dynamic regulation of adipogenesis and osteogenesis.Design and methodsA 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.ResultsThroughout 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.ConclusionsThis concise review provides a perspective on the mechanisms regulating BMSC differentiation in the context of biological aging, obesity, and osteoporosis.

► Bone marrow microenvironment reflects the activities of BMSCs and HSCs.
► BMSC adipogenic and osteogenic differentiation exhibits an inverse relationship.
► Adipose tissue exerts feedback loops modulating bone via secreted adipokine.
► BMSC differentiation pathways provide insights into diabetes and osteoporosis.
► BMSC differentiation pathways are potential drug and diagnostic targets.