Angiogenesis associated with visceral and subcutaneous adipose tissue in severe human obesity

The expansion of adipose tissue is linked to the development of its vasculature. However, the regulation of adipose tissue angiogenesis in humans has not been extensively studied. Our aim was to compare the angiogenesis associated with subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) from the same obese patients in an in vivo model.

Adipose tissue samples from visceral (VAT) and subcutaneous (SAT) sites, obtained from 36 obese patients (mean BMI 46.5 kg/m(2)) during bariatric surgery, were layered on chick chorioallantoïc membrane (CAM).

Both SAT and VAT expressed angiogenic factors without significant difference for vascular endothelial growth factor (VEGF) expression. Adipose tissue layered on CAM stimulated angiogenesis. Angiogenic stimulation was macroscopically detectable, with engulfment of the samples, in 39% and was evidenced by angiography in 59% of the samples. A connection between CAM and adipose tissue vessels was evidenced by immunohistochemistry, with recruitment of both avian and human endothelial cells. The angiogenic potency of adipose tissue was not related to its localization (with an angiogenic stimulation in 60% of SAT samples and 61% of VAT samples) or to adipocyte size or inflammatory infiltrate assessed in adipose samples before the graft on CAM. Stimulation of angiogenesis by adipose tissue was nearly abolished by bevacizumab, which specifically targets human VEGF.

We have established a model to study the regulation of angiogenesis by human adipose tissue. This model highlighted the role of VEGF in angiogenesis in both SAT and VAT.