Single-Cell Landscapes of Adipose-Derived Mesenchymal Stem Cells: From Homeostatic Regulators to Obesity-Driven...

The prevalence of obesity is steadily increasing worldwide. Obesity profoundly alters the composition, structure, and function of adipose tissue (AT), the largest endocrine organ in the body. Adipose-derived mesenchymal stem cells (ASCs) are central to AT plasticity and become dysfunctional in obesity. In this review, we outline the molecular regulation of ASCs in self-renewal and differentiation, and their roles in regulating AT expansion, modulating immune and inflammatory response, and remodeling the extracellular matrix (ECM), positioning ASCs as decisive homeostatic regulators of AT. By integrating recent findings from cutting-edge studies and performing extensive bioinformatic analyses, we delineate ASC differentiation trajectories and propose a fundamentally revised view of ASCs with a heterogeneous hierarchy of functionally distinct subpopulations. Obesity impairs ASC subsets in their self-renewal and differentiation, driving fibro-inflammatory phenotypes that promote maladaptive immune response, ECM stiffening and fibrosis, and premature cellular senescence, acting as central hubs of obesity-associated tissue dysfunction. These alterations likely arise from reprogrammed ASC epigenomic landscapes and obesogenic niches characterized by an inflammatory milieu, toxic metabolites, and oxidative stress. Interestingly, substantial weight loss attenuates fibro-inflammatory stromal states and partially restores ASC pools, whereas fibrosis-associated transcriptional programs and niche memory persist, indicating incomplete reversal of obesity-induced stromal remodeling. Drawing on human, mouse, and experimental single-cell datasets, we provide mechanistic insights into the ASC-immune cell-ECM regulatory network, highlighting how obesity reshapes ASC identity, lineage trajectories, and niche signaling. Finally, we propose that therapeutic restoration of ASC plasticity may represent a promising strategy to reestablish AT homeostasis and limit the progression of metabolic disease.