Bone marrow adipogenesis and nutrition: Impact of metabolic stress on bone marrow adipocyte - niche crosstalk

Bone marrow adipose tissue (BMAT) is a specialized fat depot located within the medullary cavities of long bones, accounting for over 10% of total body fat in humans. Once considered a passive filler, BMAT is now recognized as a metabolically active endocrine organ that influences bone homeostasis and systemic metabolism. Unlike white or brown adipose tissue, BMAT derives from bone marrow mesenchymal stromal cells and resides in close proximity to hematopoietic and stromal niche cells. Notably, BMAT expands in both obesity and under caloric restriction, highlighting its distinct regulatory mechanisms. Emerging evidence suggests that BMAT undergoes context-specific remodeling during metabolic stress, with obesity-associated BMAT acquiring inflammatory and metabolically dysfunctional features, whereas formation of energy deficit-associated BMAT may reflect adaptive stress responses within the bone marrow niche. This review synthesizes recent advances in BMAT heterogeneity, metabolic programming, and BMAT-hematopoietic interactions across states of nutrient excess and energy deficit.