TSP-1, TSP-2, and TSP-5 demonstrate sexual dimorphism in intimal hyperplasia in rats and mice.

Thrombospondins (TSPs) are matricellular proteins involved in intimal hyperplasia (IH). We hypothesized that 1) TSP-1, TSP-2, and TSP-5 are interdependent regarding their effects on vascular smooth muscle (VSMC) physiology; 2) local or systemic knockout of THBS1 or THBS2 reduces IH, with its combination (THBS1/2) being most effective; 3) local or systemic knockout of THBS5 increases IH; and 4) the effects of TSPs differ between males and females. In vitro, VSMCs were transfected with siRNA against THBS1, THBS2, THBS5, or THBS1/2. VSMC proliferation by TSP-1, TSP-2, or PDGF-BB was tested, and chemotaxis to TSP-1, TSP-2, TSP-5, or PDGF-BB was assessed. Sprague-Dawley male and female rats underwent carotid artery balloon injury with intraluminal treatment of saline or adeno-associated virus containing siRNA against THBS1, THBS2, THBS1/2, THBS5, or scrambled siRNA. Wild-type, THBS1, THBS2, or THBS5 null male or female mice underwent carotid artery ligation. After 14 days (rat) or 28 days (mice), animals were perfusion-fixed, euthanized, and IH measured. In vitro, siRNA to THBS1, THBS2, THBS1/2, or THBS5 decreased VSMC response to exogenous TSPs. The novel combined siRNA THBS1/2 demonstrated the most robust decrease in proliferation and migration. In vivo, only male rats and mice had reduced IH with local or systemic knock down of THBS1 or THBS2 (P < 0.05), with combined siRNA to THBS1/2 having the most robust effect. Knockdown of THBS5 increased IH only in female mice (P < 0.05). In conclusion, TSPs affect one another and demonstrate a sexual dimorphism that may explain differences between male and female IH.NEW & NOTEWORTHY Thrombospondins (TSPs) are matricellular proteins involved in intimal hyperplasia (IH). We demonstrate in vitro, TSP-1, TSP-2, and TSP-5 affect one another and influence vascular smooth muscle cell proliferation and migration. In vivo, using a rat and mouse model of IH, we show that TSPs demonstrate a sexual dimorphism that may explain differences between male and female IH. Particularly, TSP-1 and TSP-2 appear to be strong mediators of IH in males only.