Bone marrow adipocytes

Abstract

Adipocytes were identified in human bone marrow more than a century ago, yet until recently little has been known about their origin, development, function or interactions with other cells in the bone marrow. Little functional significance has been attributed to these cells, a paradigm that still persists today. However, we now know that marrow adipose tissue increases with age and in response to a variety of physiologic induction signals. Bone marrow adipocytes have recently been shown to influence other cell populations within the marrow and can affect whole body metabolism by the secretion of a defined set of adipokines. Recent research shows that marrow adipocytes are distinct from white, brown and beige adipocytes, indicating that the bone marrow is a distinct adipose depot. This review will highlight recent data regarding these areas and the interactions of marrow adipose tissue (MAT) with cells within and outside of the bone marrow.

Keywords: adipocyte progenitors; lineage tracing; marrow adipocyte differentiation; marrow adipose tissue; marrow fat.

Figure 1.

FVB mice were fed a rosiglitazone or control diet for 8 weeks. Tibias were fixed in 10% buffered formalin overnight, washed in tap water, decalcified for 20 d in EDTA and stained with osmium tetroxide. The bones were then washed and imaged by micro-CT. Micro-CT images show the tibia on control diet (Ctrl Diet) and on rosiglitazone (rosi Diet).

Figure 2.

Meox1-cre:mT/mG mice were fed a rosiglitazone diet for 8 weeks. (A) BM plugs were collected from the femurs using a 20 guage needle, placed on a microscope slide and covered with Fluoromount-G. (B) The most proximal tail vertebrae were fixed in paraformaldehyde overnight, washed, decalcified in EDTA for 20 d and then processed for frozen sections. Fluorescence was observed using confocal microscopy.