Human Bone Marrow Adipose Tissue is a Metabolically Active and Insulin-Sensitive Distinct Fat Depot

Area of Science:

• Endocrinology
• Metabolism
• Adipose Tissue Biology

Background:

• Bone marrow adipose tissue (BMAT) is abundant in adult long bones, yet its metabolic functions remain largely uncharacterized.
• Understanding BMAT's role is crucial, especially concerning its potential involvement in metabolic diseases like obesity and type 2 diabetes (T2DM).

Purpose of the Study:

• To investigate the metabolic and molecular characteristics of human BMAT.
• To determine if BMAT is insulin-sensitive and how this sensitivity is affected by obesity and T2DM.

Main Methods:

• Positron emission tomography (PET) imaging with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) was used to assess glucose uptake (GU) in BMAT.
• Molecular profiling of BMAT was conducted using quantitative RT-PCR.
• Studies included morbidly obese individuals (with and without T2DM) and healthy controls, with assessments before and after bariatric surgery for obese subjects.

Main Results:

• Insulin administration significantly enhanced glucose uptake in human BMAT.
• Femoral BMAT exhibited impaired insulin sensitivity in obese patients with T2DM compared to controls.
• Bariatric surgery led to improved insulin sensitivity in femoral BMAT of obese patients.
• Gene expression analysis indicated that BMAT possesses a molecular profile distinct from both white and brown adipose tissues.

Conclusions:

• Human BMAT is a metabolically active and insulin-sensitive fat depot.
• BMAT's distinct molecular characteristics suggest a unique role in whole-body energy metabolism.
• Dysregulation of BMAT insulin sensitivity in obesity and T2DM highlights its potential contribution to metabolic disorders.