An ultrasound-guided biopsy technique for obtaining supraclavicular brown fat biopsies and preadipocytes

Studying activated human brown adipose tissue (BAT) in vivo poses challenges due to its intricate anatomical positioning. Through the implementation of an ultrasound-guided biopsy technique, we successfully collected BAT samples from the supraclavicular region of 27 healthy individuals. As a comparative control, subcutaneous white adipose tissue (WAT) was similarly extracted from the same participants. Furthermore, we isolated progenitor cells from four tissue biopsies in both regions, subsequently subjecting them to a 12-day in vitro differentiation protocol following stimulation with 10 µM norepinephrine. To assess the mRNA expression of thermogenic genes within these small tissue samples, we employed a targeted cDNA amplification procedure, followed by conventional quantitative PCR (qPCR). Our study demonstrated that, with further refinement, this biopsy methodology can be used to obtain thermogenic adipose tissue. However, the expression data exhibited considerable diversity, and no statistically significant overall trends emerged for any of the five BAT marker genes (UCP1, PPARGC1A, PRDM16, CIDEA, CITED1), nor for the WAT marker HOXC8. The differentiation capacity of the progenitor cells revealed irregularities, with only three adipocyte cultures (two WAT and one BAT) displaying satisfactory differentiation potential. Remarkably, the differentiated BAT culture displayed a significantly elevated basal UCP mRNA expression level, further induced by 1.7-fold upon stimulation with norepinephrine. In summary, based on the in vitro data, brown adipose samples can be obtained using our ultrasound-guided biopsy technique approach. However, significant refinements are necessary before robust in vivo data can be generated in future intervention studies. ### Competing Interest Statement The authors have declared no competing interest.