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CellDrop_glycerol_v5.2.pdf (5.24 MB)

Rapid Lipolytic Oscillations in Ex-Vivo Adipose Tissue Explants Revealed Through Microfluidic Droplet Sampling at High Temporal Resolution

submitted on 02.10.2019, 13:43 and posted on 03.10.2019, 21:06 by Juan Hu, xiangpeng li, Robert L. Judd, Christopher Easley
Our understanding of adipose tissue biology has steadily evolved. While structural and energy storage functionalities have been in the forefront, a key endocrine role for adipocytes was revealed only over the last few decades. In contrast to the wealth of information on dynamic function of other endocrine tissues, few studies have focused on dynamic adipose tissue function or on tool development toward that end. Here, we apply our unique droplet-based microfluidic devices to culture, perfuse, and sample secretions from primary murine epididymal white adipose tissue (eWAT), and from predifferentiated clusters of 3T3-L1 adipocytes. Through automated control, oil-segmented aqueous droplets (~2.6 nL) were sampled from tissue or cells at 3.5-second temporal resolution, with integrated enzyme assays enabling real-time quantification of glycerol (down to 1.9 fmol droplet-1). This high resolution revealed previously unreported oscillations in secreted glycerol at frequencies of 0.2 to 2.0 min-1 (~30-300 s periods) present in the primary tissue but not in clustered cells. Low-level bursts (~50 fmol) released in basal conditions were contrasted with larger bursts (~300 fmol) during stimulation. Further, both fold changes and burst magnitudes were decreased in eWAT of aged and obese mice. These results, combined with immunostaining and photobleaching analyses, suggest that gap-junctional coupling or nerve cell innervation within the intact ex-vivo tissue explants play important roles in this apparent tissue-level, lipolytic synchronization. High-resolution, quantitative sampling by droplet microfluidics thus permitted unique biological information to be observed, giving an analytical framework poised for future studies of dynamic oscillatory function of adipose and other tissues.


NIH R01 DK093810


Email Address of Submitting Author


Auburn University


United States

ORCID For Submitting Author


Declaration of Conflict of Interest


Version Notes

Version 5.2, submitted for peer-review