Increased angiogenic differentiation of HUVECs treated with pre-conditioned media from Lipedema adipocytes in vitro

Purpose: Lipedema is a connective tissue disorder characterized by an increased number of dilated blood vessels (angiogenesis), fibrosis, inflammation and accumulation of interstitial fluid in the subcutaneous adipose tissue. This project aims to gain insights into the lipedema vasculature using human umbilical vein endothelial cells (HUVECs) as an in vitro model of angiogenesis. Methods: HUVECs were cultured in conditioned media (CM) collected from lipedema adipocytes differentiated in vitro. The effects on the expression of the endothelial and angiogenic markers [CD31, von Willebrand Factor (vWF), Angiopoietin 2 (Ang2), Hepatocyte Growth Factor (HGF), Vascular endothelial growth factor (VEGF), Matrix Metalloproteinase (MMPs)] in HUVECs, as well as tube formation, were investigated. Real-time polymerase chain reaction (RT-PCR), tube formation and Western blot assays were used to assess the expression of endothelial and angiogenic markers in HUVECs. In addition, the ability of HUVECs to form capillary-like tubular structures (tubes) when seeded on reconstituted basement membrane (Matrigel) was determined by phase-contrast microscopy and the number of tubes formed (number of nodes and branches) was quantified using NIH ImageJ software. Results: The expression of CD31 and Ang2 were increased at both the gene and protein levels, while vWF expression was significantly decreased in HUVECs treated with CM from lipedema adipocytes. In addition, the gene expression of HGF and MMP9 and the number of nodes and branches were increased in treated HUVECs. No changes in VEGF gene expression were detected. Conclusion: These results indicate that lipedema adipocyte-CM promotes the vascular tube formation of endothelial cells through paracrine mechanisms. The expression of multiple factors that stimulate the process of angiogenesis was upregulated after exposure to conditioned media from lipedema adipocytes. Definition of the pathways that enhance angiogenesis in lipedema tissues will help researchers develop new therapeutic approaches to treat this disease.