Lipedema is a chronic, progressive disease of adipose tissue with unknown etiology. Based on the relevance of the stromal vascular fraction (SVF) cell population in lipedema, we performed a thorough characterization of subcutaneous adipose tissue, SVF isolated thereof and the sorted populations of endothelial cells (EC), pericytes and cultured adipose-derived stromal/stem cells (ASC) of early-stage lipedema patients. We employed histological and gene expression analysis and investigated the endothelial barrier by immunofluorescence and analysis of endothelial permeability in vitro. Although there were no significant differences in histological stainings, we found altered gene expression of factors relevant for local estrogen metabolism (aromatase), preadipocyte commitment (ZNF423) and immune cell infiltration (CD11c) in lipedema on the tissue level, as well as in distinct cellular subpopulations. Machine learning analysis of immunofluorescence images of CD31 and ZO-1 revealed a morphological difference in the cellular junctions of EC cultures derived from healthy and lipedema individuals. Furthermore, the secretome of lipedema-derived SVF cells was sufficient to significantly increase leakiness of healthy human primary EC, which was also reflected by decreased mRNA expression of VE-cadherin. Here, we showed for the first time that the secretome of SVF cells creates an environment that triggers endothelial barrier dysfunction in early-stage lipedema. Moreover, since alterations in gene expression were detected on the cellular and/or tissue level, the choice of sample material is of high importance in elucidating this complex disease.

Lipedema is a chronic adipose tissue disorder characterized by disproportionate and often painful enlargement of the extremities, occurring predominantly in women. Despite increasing clinical recognition, the underlying pathophysiology remains incompletely understood and is likely multifactorial. Existing evidence suggests contributions from vascular alterations, adipose tissue remodeling, inflammatory activation, hormonal influences, and lymphatic dysfunction. This review proposes a hypothesis-generating integrative framework in which lipedema may reflect a regenerative imbalance of subcutaneous adipose tissue. Within this model, genetically and hormonally modulated endothelial permeability could promote activation of perivascular adipose-derived stromal/stem-cell niches and stromal vascular fraction signaling pathways, thereby facilitating coupled angiogenesis and adipogenesis. Progressive adipocyte hyperplasia and hypertrophy may subsequently contribute to inflammatory remodeling, pain generation, and secondary impairment of dermal and subdermal lymphatic drainage. The proposed framework attempts to integrate clinical, histological, imaging, molecular, and endocrine observations into a biologically coherent conceptual model. At the same time, the review emphasizes the current limitations of the available evidence, the heterogeneity of lipedema phenotypes, and the ongoing controversies regarding disease progression, obesity overlap, and the relative role of lymphatic dysfunction. Finally, the potential mechanistic rationale of lymphatic-sparing liposuction is discussed in the context of tissue decompression, restoration of lymphatic transport, and interruption of persistent adipose remodeling. The model presented here should be interpreted as a hypothesis-generating conceptual scaffold requiring prospective validation. Importantly, the present framework should be interpreted as a biologically plausible and hypothesis-generating conceptual model rather than a definitive mechanistic doctrine. Several proposed interactions remain associative and require prospective biological validation.

Lipedema is a painful, chronic and progressive disorder of subcutaneous adipose tissue characterized by disproportionate, symmetrical fat accumulation in the extremities—typically the legs and less often the arms—while sparing hands and feet. It is clinically distinct from obesity and lymphoedema, affects almost exclusively women, and often exacerbates during hormonal transition phases. This paper proposes a unifying pathophysiological concept in which lipedema reflects a regenerative imbalance of adipose tissue. A genetically and estrogen-modulated increase in endothelial permeability (“leaky vessels”) is suggested to activate perivascular/mural adipose-derived stem cells (ADSCs), thereby initiating coupled angiogenesis and adipogenesis. The stromal vascular fraction (SVF) is described as a central mediator, with SVF-derived extracellular vesicles and characteristic microRNAs promoting adipocyte hyperplasia and hypertrophy and leading to large, metabolically less active adipocytes. The organism attempts to counterbalance this surplus through inflammatory activation of mast cells and macrophages; however, inefficient clearance of excess adipocytes (including “crown-like” structures) sustains inflammation and pain. Progressive adipose expansion may compress lymphatic capillaries and precollectors, resulting in dermal and subdermal lymphatic congestion and contributing to oedema and symptom progression. Increased aromatase activity and local estrogen availability are discussed as additional amplifiers of adipogenesis and inflammatory remodeling. Finally, lymphatic-sparing liposuction is outlined as a mechanistically plausible intervention that can reduce tissue pressure, improve lymphatic drainage, and alleviate key symptoms.