Modeling Reversible In Vivo-like Insulin Resistance Using Long-Term Adipocyte Spheroid Culture

Human adipose biology is strongly influenced by three-dimensional (3D) architecture, cell–cell interactions, and local oxygen availability maintained over a long-term culture period, features that are not reproduced in traditional two-dimensional (2D) culture systems. To address this gap, we established a long-term human adipose-derived stem cell (hASC) spheroid model using elastin-like polypeptide–polyethyleneimine (ELP-PEI) coating. The ELP-PEI coating facilitated stable spheroid formation and sustained adipogenic differentiation over 56 days. As spheroids enlarged and matured, they exhibited hallmark features of adipocytes, including lipid accumulation, morphological compaction, and transition out of the proliferative state. Glucose uptake increased during maturation and declined as spheroids became larger. This reduction coincided with a marked rise in hypoxia-inducible factor-1α (HIF-1α) expression, indicating the emergence of a hypoxic microenvironment within larger spheroids. Notably, inhibiting HIF-1α restored insulin-stimulated glucose uptake, demonstrating that hypoxia was the primary driver of impaired insulin responsiveness in late-stage spheroids. These findings position ELP-PEI-supported hASC spheroids as a practical and physiologically relevant platform for studying human adipocyte biology, particularly the development and reversibility of hypoxia-associated metabolic dysfunction. This model offers new opportunities for mechanistic studies and for evaluating therapeutic strategies targeting insulin resistance and adipose tissue pathology.