Completely serum-free and chemically defined adipocyte development and maintenance

Background aims. In vitro engineered adipose tissue is in great demand to treat lost or damaged soft tissue or to screen for new drugs, among other applications. However, today most attempts depend on the use of animal-derived sera. To pave the way for the application of adipose tissue-engineered products in clinical trials or as reliable and robust in vitro test systems, sera should be completely excluded from the production process. In this study, we aimed to develop an in vitro adipose tissue model in the absence of sera and maintain its function long-term. Methods. Human adipose tissue-derived stem cells were expanded and characterized in a xeno-and serum-free environment. Adipogenic differentiation was induced using a completely defined medium. Developed adipocytes were maintained in a completely defined maturation medium for additional 28 days. In addition to cell viability and adherence, adipocyte-specific markers such as perilipin A expression or leptin release were evaluated. Results. The defined differentiation medium enhanced cell adherence and lipid accumulation at a significant level compared with the corresponding negative control. The defined maturation medium also significantly supported cell adherence and functional adipocyte maturation during the long-term culture period. Conclusions. The process described here enables functional adipocyte generation and maintenance without the addition of unknown or animalderived constituents, achieving an important milestone in the introduction of adipose tissue-engineered products into clinical trials or in vitro screening.