Hypertrophy and/or Hyperplasia: Dynamics of Adipose Tissue Growth

• Published in: PLoS computational biology Vol. 5; no. 3; p. e1000324
• Main Authors: Jo, Junghyo, Gavrilova, Oksana, Pack, Stephanie, Jou, William, Mullen, Shawn, Sumner, Anne E, Cushman, Samuel W, Periwal, Vipul
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.03.2009; Public Library of Science (PLoS)
• Subjects: Adipocytes - pathology; Adipose Tissue - growth & development; Adipose Tissue - pathology; Adipose tissues; Animals; Biophysics; Biophysics/Theory and Simulation; Body fat; Cell Biology/Cell Growth and Division; Cell Enlargement; Cell Proliferation; Cell Size; Computational Biology; Computer Simulation; Developmental Biology/Cell Differentiation; Diabetes and Endocrinology/Obesity; Diet; Dietary Fats - metabolism; Genetic aspects; Genetics and Genomics/Complex Traits; Growth; Hyperplasia; Hyperplasia - pathology; Hyperplasia - physiopathology; Hypertrophy; Hypertrophy - pathology; Hypertrophy - physiopathology; Mice; Mice, Inbred C57BL; Models, Biological; Nutrition/Obesity; Obesity; Obesity - pathology; Obesity - physiopathology; Physiological aspects; Physiology/Integrative Physiology; Rodents; Studies; United States; Obesity; Cell Proliferation; Hyperplasia; Mice, Inbred C57BL; Cell Size; Adipocytes; Cell Enlargement; Animals; Models, Biological; Computer Simulation; Dietary Fats; Mice; Adipose Tissue; Hypertrophy
• ISSN: 1553-7358; 1553-734X; 1553-7358
• DOI: 10.1371/journal.pcbi.1000324

Adipose tissue grows by two mechanisms: hyperplasia (cell number increase) and hypertrophy (cell size increase). Genetics and diet affect the relative contributions of these two mechanisms to the growth of adipose tissue in obesity. In this study, the size distributions of epididymal adipose cells from two mouse strains, obesity-resistant FVB/N and obesity-prone C57BL/6, were measured after 2, 4, and 12 weeks under regular and high-fat feeding conditions. The total cell number in the epididymal fat pad was estimated from the fat pad mass and the normalized cell-size distribution. The cell number and volume-weighted mean cell size increase as a function of fat pad mass. To address adipose tissue growth precisely, we developed a mathematical model describing the evolution of the adipose cell-size distributions as a function of the increasing fat pad mass, instead of the increasing chronological time. Our model describes the recruitment of new adipose cells and their subsequent development in different strains, and with different diet regimens, with common mechanisms, but with diet- and genetics-dependent model parameters. Compared to the FVB/N strain, the C57BL/6 strain has greater recruitment of small adipose cells. Hyperplasia is enhanced by high-fat diet in a strain-dependent way, suggesting a synergistic interaction between genetics and diet. Moreover, high-fat feeding increases the rate of adipose cell size growth, independent of strain, reflecting the increase in calories requiring storage. Additionally, high-fat diet leads to a dramatic spreading of the size distribution of adipose cells in both strains; this implies an increase in size fluctuations of adipose cells through lipid turnover.