Tanshinone IIA impairs platelet function and thrombus formation

Tanshinone IIA (T-IIA) is a fat-soluble active ingredient derived from the traditional Chinese medicine Danshen and possesses cardioprotective property. However, its exact role in platelet function is unknown.

This study investigated T-IIA's role in platelet aggregation, granules release, spreading, clot retraction, as well as in vivo hemostasis and thrombus formation.

Human platelets were treated with different doses of T-IIA (10, 50, and 100 μM) to measure platelet function and activation. In addition, T-IIA was administrated into wild-type mice to evaluate hemostasis and thrombus formation.

T-IIA significantly impaired platelet aggregation, adenosine triphosphate secretion, P-selectin expression, and spreading and clot retraction dose dependently without affecting the expression profiles of α_IIbβ₃ and glycoprotein VI or Ibα. Administration of T-IIA significantly prolonged mice tail bleeding time and inhibited arterial and venous thrombosis. Further analysis showed that T-IIA dose dependently reduced platelet reactive oxygen species generation. Quantitative proteomic and phosphoproteimic assays analyzing T-IIA-treated vs vehicle-treated platelets after stimulation identified dysregulated phosphorylation of several proteins, which were enriched in platelet activation. Among the downregulated phosphoproteins, Rho-associated protein kinase (ROCK)1, integrin β₃, and talin1 exhibited the lower fold change of phosphorylation in T-IIA-treated platelets compared with those in vehicle-treated platelets. Consistently, T-IIA treatment inhibited the phosphorylation of ROCK1, p47phox, integrin β₃, and talin1 in activated platelets.

T-IIA impairs platelet function and thrombosis via inhibition of several signaling pathways including ROCK1/p47phox, β₃, and talin1, implying that T-IIA may represent a promising therapeutic candidate for treating thrombotic diseases.