Single-nuclei Transcriptome of Human AT Reveals Metabolically Distinct Depot-Specific Adipose Progenitor Subpopulations

Single-cell and single-nuclei RNA sequencing data (scRNAseq and snRNAseq, respectively) have revealed substantial heterogeneity in the AT (AT) cellular landscape in rodents and humans depending on depot and disease status. We used snRNAseq to characterize the cellular landscape of human visceral (VAT) and subcutaneous AT (SAT) samples from lean subjects and subjects with obesity. We identified multiple cell types in the AT cellular repertoire, including three major AT stromal cell (ASC) subpopulations, multiple types of adipocyte (ADIPO) populations that retain properties similar to ASC, endothelial cell (EC), T-cell, and macrophage (MAC) populations that are in concordance and expand upon other published datasets. ADIP and EC are more prominent in SAT compared to VAT which has a higher proportion of ASC. Of two dominant ASC subpopulations, one (inflammatory-mesothelial, IM- ASC) is present in VAT, but absent in SAT, while the other (fibroadipogenic, FA-ASC) is present in both VAT and SAT. Both populations retain their properties in in vitro culture and have adipogenic capacity with different metabolic features. Informatic and in situ studies support ADIP derived from IM- and FA- ASC are found in human VAT. We also identified a wide range of EC subtypes in human AT with features of lymphatic, venous, and arterial EC, with identification of a PRDM16 expression EC population with features of an EC progenitor. Immune cell populations match recent experimental validation of lipid activated macrophage (LAM) phenotypes, TIM4 macrophages, and a prominent population of MRC1/CD206+ resident AT macrophages with gene expression signatures related to glucocorticoid activation. Overall, our study demonstrates depot-specific cellular diversity in human VAT and SAT in which distinct ASC subpopulations may differently contribute to AT dysfunction in obesity. Also, our results highlight an unprecedented EC heterogeneity suggesting AT EC as highly specialized cells and potentially important regulators of depot-specific functions. METHODS STATEMENT Human subjects provided informed consent and were enrolled with approval from Institutional Review Boards at the University of Michigan and Veterans Affairs Ann Arbor Healthcare System. Enrollment, consent, and all aspects of human subject research were carried out in accordance with the Belmont Report from the National Research Act of 1974, and the Declaration of Helsinki set forth by the World Medical Association. This manuscript contains no human participants’ names or other HIPAA identifiers. ### Competing Interest Statement The authors have declared no competing interest.