Endocrine Abstracts

Previous studies demonstrate unexpectly high human fat cell turnover. About 10% of the total peripheral fat cell pool is renewed every year. In relative terms this turnover is two-fold increased in obesity but reduced in subjects with pernicious adipose morphology (few but large fat cells). High turnover necessitates a renewable source of adipocyte precursors. Two independent studies, using bone marrow transplanted patients as model, demonstrated important contribution of bone marrow precursors to peripheral generation of fat cells. This input occurs throughout the human life span from infancy and onwards. Itis markedly increased among obese subjects where up to 40% of the peripheral fat cells are generated by the bone marrow. Recent studies using advanced FACS sorting and single cell gene expression measures suggest that there is a uniform pool of fat cell precursors in peripheral adipose tissue, indicating that local and bone marrow derived precursors are of the same origin. Thus, cross-talk between bone marrow and peripheral adipose tissue in the generation of fat cells is an important regulatory factor behind formation of human adipose tissue mass and morphology.