Human adipocyte differentiation and characterization in a perfusion-based cell culture device.

Adipocytes have gained significant attention recently, because they are not only functioning as energy storage but also as endocrine cells. Adipocytes secret various signaling molecules, including adiponectin, MCP-1, and IL-6, termed collectively as "adipokines". Adipokines regulate glucose metabolism, thereby play an important role in obesity, diabetes type 2, and other metabolic disorders. Conventionally, to study the secretory function, adipocytes are cultured in vitro in static conditions. However, static culturing condition falls short of mimicking the interstitial fluid flows in living systems. Here, we developed a perfusion device which allows dynamic culture of adipocytes under constant and mild flow using a double-layered fluidic structure. Adipocytes were cultured in the bottom layer while the culture media were constantly flown in the upper layer and perfused through a porous membrane that separate the two chambers. The porous membrane between the two chambers physically separates the cells from the flow stream while maintain a fluidic connection by diffusion. This setting not only provides continuous nutrient supply to adipocytes but also maintains a steady and mild shear stress on the cell membrane. It was found the perfusion-based culture conditions promoted faster growth of primary preadipocytes and stimulated greater adipogenesis compared to static culture condition. Adipocytes cultured under perfusion systems produced more MCP-1 and IL-6, but less adiponectin. When stimulated with TNF-α, adipocytes expressed higher level of MCP-1 and IL-6, but lower level of adiponectin. No significant glucose uptake regulation was observed after treating the adipocytes with insulin in both static and perfusion-based culture. Our results demonstrate that perfusion-base culture has played a role in the adipocyte function particularly the secretion of adipokines. More future studies are required to unveil the mechanisms behind perfusion's impact on adipocytes.