Flow cytometric single cell analysis reveals heterogeneity between adipose depots.

Current research on adipose tissue faces limitations in analyzing mature adipocytes at the single-cell level. While bulk tissue studies provide general insights, they often overlook the diversity within individual fat depots. Prior work has established that different fat depots exhibit distinct metabolic and functional roles. However, no prior study has systematically compared live adipocytes from various depots using single-cell techniques. This gap motivated the development of a new method to isolate and analyze buoyant adipocytes. Existing methods rely on lipophilic dyes, but these may not fully distinguish adipocyte populations. The need for a precise tool to dissect adipose heterogeneity remains unmet. This study introduces a novel approach using flow cytometry to explore adipocyte diversity. By focusing on live cells, the study addresses a critical limitation in current adipose research.

The aim of this research was to develop a system for analyzing live adipocytes from different mouse fat depots at the single-cell level. The study sought to overcome the lack of methods for isolating and characterizing mature adipocytes. A key challenge is distinguishing adipocyte populations based on functional markers. The researchers aimed to compare lipophilic dyes to identify the most effective staining method. They also intended to evaluate mitochondrial membrane potential and CD36 expression across depots. The study's motivation was to reveal previously unreported heterogeneity in adipose tissue. By using flow cytometry, the team aimed to provide a new tool for adipocyte research. The ultimate goal was to improve understanding of depot-specific adipocyte biology.

The study used flow cytometry to analyze single-cell suspensions of buoyant adipocytes. Adipocytes were separated from the stromal vascular fraction using buoyancy-based isolation. Nile Red dye was compared to other lipophilic dyes for its ability to distinguish adipocyte populations. The researchers combined Nile Red with MitoTracker Deep Red to assess mitochondrial membrane potential. Fluorescent antibody labeling was used to detect CD36 surface expression. The team analyzed adipocytes from epicardial, brown, and other depots. They measured fluorescence intensity in relation to cell size and granularity. The protocol enabled high-resolution analysis of live adipocyte populations.

Nile Red uptake effectively distinguished adipocyte populations compared to other dyes. Adipocyte size and granularity correlated with Nile Red fluorescence intensity. MitoTracker Deep Red revealed depolarization differences across depots. Epicardial adipocytes had the least mitochondrial membrane depolarization. Brown adipocytes showed low CD36 surface expression, while epicardial cells had high CD36. Pregnancy altered CD36 and mitochondrial markers in brown and epicardial depots. The protocol identified unreported heterogeneity between fat depots. Flow cytometry proved useful for screening adipocytes at the single-cell level.

The study demonstrated that Nile Red staining combined with flow cytometry can reveal adipose heterogeneity. The protocol successfully distinguished adipocyte populations based on size, granularity, and fluorescence. The findings suggest that different depots have distinct metabolic and functional profiles. The results highlight the utility of flow cytometry for analyzing live adipocytes. The protocol may improve understanding of depot-specific adipocyte biology. The study supports the use of Nile Red as a superior dye for adipocyte analysis. The authors propose that this method can be used to screen adipocyte populations. The findings suggest that flow cytometry is a valuable tool for adipose research.