Supplementary Material for: Emodin inhibits the indoxyl sulfate-induced trans-differentiation of vascular smooth muscle cells through up-regulating TSP-1

Indoxyl sulfate (IS) is a protein-bound uremic toxin with vascular toxicity. The primary cause of death in uremic patients on maintenance hemodialysis is vascular disease, and it had been reported that vascular smooth muscle cells (VSMCs) trans-differentiation (VT) plays a vital role in the context of vascular diseases, but the underlying mechanisms remain obscure. Thrombospondin-1 (TSP-1) participates in vascular calcification by keeping the balance of extracellular matrix, but its role in IS-induced VT is unclear. In this study, clinical specimens, animal models and in vitro VSMCs were used to investigate the role of TSP-1 in IS induced VT, and the potential therapeutic methods. We found that TSP-1 was significantly decreased in arterial samples from uremic patients, animal models, and in VSMCs after IS-treatment. Down-regulation of TSP-1 sufficiently induced the trans-differentiation genotypes of VSMCs. Emodin, the main monomer extracted from rhubarb, could alleviate IS-induced VT in vitro by up-regulating TSP-1. Taken together, IS induces VT by down-regulating TSP-1. Emodin might be a candidate drug to alleviate VT under IS treatment.