Thrombospondins (TSPs) are matricellular glycoproteins expressed in response to vascular injury. TSP-1 and TSP-2 are promotors of arterial remodeling while TSP-5 is believed to be protective. The current study assessed the differential effect of TSPs on protein expression in vascular smooth muscle cells (VSMCs). We hypothesized that TSP-1, TSP-2 and TSP-5 would regulate VSMC proteins involved in arterial remodeling. Human VSMCs were exposed to TSP-1, -2, -5 or serum free media (24 hours). Cell lysates were used to assess the targets TSP-1, TSP-2, TSP-5 and CD44), while the culture media was used to detect TGF-β1, PDGF-BB, ANGPTL-4 and IL-8. Statistical analysis was performed by t-test and p< 0.05 was considered significant. All TSPs increased their own expression and TSP-5 increased TSP-2. TSP-1 and TSP-2 increased production of ANGPTL-4 and PDGF-BB, while TSP-5 only increased ANGPTL-4. TSP-1 increased exclusively TGF-β1 and CD44 production. TSP-2 increased TSP-1 expression. All TSPs decreased IL-8. The findings suggest that TSP-1 and TSP-2 may promote vascular remodeling, in part, by increasing ANGPTL-4, PDGF-BB and their own expression. TSP-5 did not upregulate the inflammatory mediators TSP-1, PDGF-BB or TGF-β1, but upregulated its own expression, which could be a protective mechanism against the response to vascular injury.

Lower extremity peripheral arterial disease (PAD) is the atherosclerotic obstruction of the lower extremity arteries that can lead to walking impairment, non-healing open wounds, gangrene or limb loss. It is estimated that PAD affects greater than 200 million people worldwide and is associated with advanced age, tobacco use, diabetes, hypertension, and hypercholesterolemia. Initial management of PAD involves risk factor modification and pharmacologic strategies, including the implementation of statin therapy. Statins, the most commonly used cholesterol lowering medications, also have beneficial pleiotropic (cholesterol independent) effects including improved patency rates from vascular reconstruction, decreased risk of stroke, myocardial infarction and improved survival. In this chapter, we will discuss the relevant clinical trials, prospective observation and retrospective studies that exemplify the effect of statins on PAD. We will then focus on statin’s cellular effects on endothelial and vascular smooth muscle cell function by examining effects on plaque progression, intimal hyperplasia, re-endothelialization, and angiogenesis/arteriogenesis.

Cardiovascular disease remains the leading cause of morbidity and mortality worldwide, with atherosclerosis and maladaptive vascular remodeling serving as central drivers of clinical events. Mechanistic investigation of arterial disease processes relies heavily on experimental animal models that permit precise control of vascular injury, hemodynamic forces, and ischemic stress. Over the past several decades, murine and rat models have become indispensable tools for studying endothelial dysfunction, intimal hyperplasia, flow-mediated remodeling, and ischemia–reperfusion injury. Each model reproduces distinct aspects of human vascular pathology while offering unique technical and biological advantages. This review summarizes commonly used murine and rat models of arterial disease, emphasizing the biological mechanisms they study, the surgical techniques used, pathophysiology, experimental endpoints, advantages, and limitations.

Peripheral arterial disease progression to critical limb ischemia remains a significant burden in the aged, necessitating revascularization. Therapies to enhance neovascularization, such as angiogenesis or arteriogenesis, may provide an option for patients not suitable for surgery. The thrombospondins (TSPs) are secreted matricellular glycoproteins, with TSP‐1, TSP‐2, and TSP‐5 implicated in neovascularization. Currently, there is little data regarding the effects of TSP‐2, TSP‐5, sex, and aging on angiogenesis and arteriogenesis. In vitro, the effect of TSP‐2 or TSP‐5 on early or late passage endothelial cell (EC) tubule formation or disruption was assessed. In vivo, angiogenesis, and arteriogenesis in male and female, young (14–16 weeks) and old (105–110 weeks) wild‐type, TSP‐2 and TSP‐5 knockout mice were compared. To assess the effect of sex hormones, neovascularization was assessed in ovariectomized young female mice. After 14 days, angiogenesis and arteriogenesis were quantified using immunohistochemistry. Laser Doppler was used to confirm > 50% decrease in blood flow. In vitro: TSP‐2 inhibited angiogenesis in early passage ECs and disrupted tubules in late passage ECs. TSP‐5 prevented early passage tubule disruption. Late passage cells showed greater disruption than early passage. In vivo: TSP‐2 was anti‐angiogenic in young mice and anti‐arteriogenic in old mice; TSP‐5 had no effect on angiogenesis but largely negatively impacted arteriogenesis. Females showed reduced angiogenesis/arteriogenesis versus males, aging blunted both responses, and TSP‐2/TSP‐5 knockouts altered sex‐ and age‐specific ischemic responses. In conclusion, we broadly elucidate the differential effects of TSP‐2, TSP‐5, sex and aging on neovascularization after inducing limb ischemia.

Background: Statins have beneficial pleiotropic effects, including reducing intimal hyperplasia (IH), but off-target effects remain a concern. Here, we tested the hypothesis that chitosan-functionalized polymeric nanoparticles (NPs) loaded with simvastatin (SL-cNPs) would (1) readily associate with endothelial cells (ECs) and vascular smooth muscle cells (VSMCs); (2) affect EC and VSMC function; and (3) reduce IH compared to systemic simvastatin. Methods: Human aortic ECs and VSMCs were cultured with fluorescently labeled SL-cNPs. The association of SL-cNPs was assessed by immunostaining and flow cytometry. The effect of SL-cNPs, empty cNPs (E-cNPs), and free simvastatin on cells was determined using qRT-PCR for RhoA and RhoB. Carotid artery balloon-injured rats were treated intraoperatively with intraluminal saline, E-cNPs, low- or high-dose SL-cNPs, periadventitial high-dose SL-cNPs, or with pre- and post-operative oral simvastatin plus intraoperative intraluminal saline or low-dose SL-cNPs. Rats were euthanized (day 14) and IH was quantified. Results: SL-cNPs readily associated with ECs and VSMCs. Low- and high-dose SL-cNPs induced significant increases in EC and VSMC RhoA gene expression. High-dose SL-cNPs induced a significant increase in EC RhoB expression, while free simvastatin and low- and high-dose SL-cNPs significantly increased RhoB expression in VSMCs. In vivo, oral simvastatin plus intraluminal SL-cNPs significantly reduced IH compared to controls. Conclusions: cNPs can be used as a vehicle to locally deliver statins to vascular cells. However, other NP formulations may be preferential for IH reduction given only the combination of oral simvastatin and SL-cNPs effectively reduced IH.