The Bone Marrow-Derived Stromal Cells: Commitment and Regulation of Adipogenesis

Abstract

Bone marrow (BM) microenvironment represents an important compartment of bone that regulates bone homeostasis and the balance between bone formation and bone resorption depending on the physiological needs of the organism. Abnormalities of BM microenvironmental dynamics can lead to metabolic bone diseases. BM stromal cells (also known as skeletal or mesenchymal stem cells) [bone marrow stromal stem cell (BMSC)] are multipotent stem cells located within BM stroma and give rise to osteoblasts and adipocytes. However, cellular and molecular mechanisms of BMSC lineage commitment to adipocytic lineage and regulation of BM adipocyte formation are not fully understood. In this review, we will discuss recent findings pertaining to identification and characterization of adipocyte progenitor cells in BM and the regulation of differentiation into mature adipocytes. We have also emphasized the clinical relevance of these findings.

Keywords: adipogenesis; bone marrow microenvironment; bone marrow stem cell subpopulations; bone marrow stem cells; secreted factors.

Figure 1

Regulation of bone marrow stem cells differentiation into adipocytes or osteoblasts. Bone marrow is a heterogeneous organ, which consists of different cell types participating in bone homeostasis. Among them, most abundant are hematopoietic stem cells (bone resorptive osteoclasts) and mesenchymal stem cells giving rise into bone forming osteoblasts or adipocytes. This process is regulated via several transcription factors and secreted molecules (e.g., PPARs, Wnt, adiponectin, leptin), which are produced locally or released from peripheral tissues, including BAT, WAT, skeletal muscle, liver, or CNS and affecting bone marrow niche through circulation. This multiorgan crosstalk between bone and peripheral tissues plays an important role in the regulation of bone and energy metabolism. Abbreviations: CNS, central nervous system; BAT, brown adipose tissue; WAT, white adipose tissue. Adapted from SERVIER Medical Art; http://www.servier.com/Powerpoint-image-bank