Adipose tissue biology has been attracting ever-increasing attention because of the growing prevalence of obesity and type 2 diabetes globally1. Adipocytes store excess energy in the form of lipid droplets, which are released upon starvation. Moreover, adipose tissue maintains systemic energy homeostasis by serving as an endocrine organ and communicating with other tissues2,3. Intriguingly, both excess adipose tissue (obesity) and adipose loss (lipodystrophy) are linked to insulin resistance and diabetes1. Adipocytes are divided into three types: white, brown, and beige1. White adipocytes mainly store excess energy as lipids, whereas brown and beige adipocytes dissipate energy in the form of heat via mitochondrial uncoupling protein-1 (Ucp1)1,4. Notably, beige adipocytes (also called "inducible" brown adipocytes) appear in white adipose tissue in response to cold or sympathetic stimulation and exhibit gene expression patterns that overlap with but are distinct from those of "classical" brown adipocytes5. Recently, brown and beige adipocytes have been anticipated as potential targets of anti-obesity and anti-diabetes treatments aimed at "enhancing energy dissipation" rather than "suppressing energy intake"4. Supportively, the risk allele of the FTO obesity variant rs1421085 in humans, which exhibits the strongest association with higher body mass index (BMI) among common variants6,7 and exhibits various gene-environment interactions8,9, is reported to negatively regulate beige adipocyte differentiation and function10. Peroxisome proliferator-activated receptor γ (PPARγ) is known as a master transcriptional regulator of adipogenesis and is necessary and sufficient for adipocyte differentiation11. Transcriptional regulators, such as PRD1-BF1-RIZ1 homologous domain containing 16 (PRDM16), early b cell factor 2 (EBF2), and nuclear factor I-A (NFIA), are crucial for brown and beige adipocyte differentiation and function12,13,14,15,16,17,18. On the other hand, white adipocyte gene programming requires transcriptional regulators, such as transducin-like enhancer protein 3 (TLE3) and zinc finger protein 423 (ZFP423)19,20,21.
In vitro model systems enable molecular studies to be performed that aim to improve the understanding of the mechanism(s) underlying the functions and dysfunctions of adipocytes. Although publicly available and immortalized preadipocyte cell lines such as 3T3-L1 and 3T3-F442A exist22,23,24, the culture of primary preadipocytes and differentiation into adipocytes would be a more suitable model for studying in vivo adipogenesis. Isolation of the stromal vascular fraction (SVF) from murine adipose tissue is a well-known method for obtaining primary preadipocytes25,26. However, collagenase digestion of adipose tissue, which is commonly performed using a bacterial shaker with a tube rack, can result in experimental variation and is prone to contamination27,28. Here, we describe an alternative protocol that uses a gentle magnetic-activated cell sorting (MACS) tissue dissociator for collagenase digestion to achieve easier isolation of the SVF.