Effects of hyperinsulinemia on lipolytic function of three-dimensional adipocyte/endothelial co-cultures.

The increased incidence of both type 2 diabetes mellitus and obesity has prompted the need to develop physiologically relevant adipose tissue models for controlled study of both normal and diseased adipose functions. Insulin resistance, characteristic of both type 2 diabetes mellitus and obesity, is often preceded by hyperinsulinemia. We propose here a three-dimensional (3D) co-culture adipose tissue model to study the effects of high insulin exposure, which enabled the study of physiological cell responses to hyperinsulinemic conditions. Two-dimensional adipocyte studies were initially conducted to establish a baseline control in which insulin levels were established. Adipocytes and endothelial cells were subsequently co-cultured on 3D porous silk fibroin scaffolds in normal or high insulin concentrations, and their physiological responses were assessed with respect to lipogenesis and lipolysis. High insulin levels stimulated both an increase in triglyceride accumulation and a decrease in lipolysis levels compared to that of normal insulin conditions. In contrast, adipocyte monocultures did not exhibit any differences between insulin levels. The ability of this 3D system to elicit physiological responses to hyperinsulinemia in co-culture serves as a significant step forward in adipose tissue engineering. The development of physiologically relevant 3D in vitro adipose tissue models presents promise for the study of disease mechanisms as well as in assessing therapeutic treatments.