Perivascular CLICK-gelatin delivery of thrombospondin-2 small interfering RNA decreases development of intimal hyperplasia after arterial injury.

Bypass graft failure occurs in 20%-50% of coronary and lower extremity bypasses within the first-year due to intimal hyperplasia (IH). TSP-2 is a key regulatory protein that has been implicated in the development of IH following vessel injury. In this study, we developed a biodegradable CLICK-chemistry gelatin-based hydrogel to achieve sustained perivascular delivery of TSP-2 siRNA to rat carotid arteries following endothelial denudation injury. At 21 days, perivascular application of TSP-2 siRNA embedded hydrogels significantly downregulated TSP-2 gene expression, cellular proliferation, as well as other associated mediators of IH including MMP-9 and VEGF-R2, ultimately resulting in a significant decrease in IH. Our data illustrates the ability of perivascular CLICK-gelatin delivery of TSP-2 siRNA to mitigate IH following arterial injury.

The impact of heparin and direct thrombin inhibitors on cell-penetrating polymer siRNA transfection.

Gene therapy using siRNA has become a promising strategy to achieve targeted gene knockdown for treatment of cardiovascular pathologies. However, efficient siRNA transfection often relies on cationic delivery vectors such as synthetic cell-penetrating polymers which are susceptible to interference by negatively charged molecules. Anticoagulants such as heparin, which is negatively charged and widely used in cardiovascular applications, may pose a significant barrier to effective siRNA delivery. We therefore conducted in vitro studies utilizing human smooth muscle and endothelial cells transfected with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and ß2-microglobulin (B2M) siRNA in the presence of heparin, argatroban, and bivalirudin in order to determine which anticoagulant therapy is most compatible for siRNA delivery. We observed that while heparin, at clinical doses, decreases the efficiency of siRNA targeted mRNA knockdown, mRNA knockdown is not inhibited in the presence of either argatroban or bivalirudin. Our data suggests that heparin should be avoided during siRNA therapy with cationic transfection agents, and argatroban and bivalirudin should be used in its stead.

Management and Outcomes of Venous Thoracic Outlet Decompression: A Transition to the Infraclavicular Approach.

OBJECTIVE: Venous thoracic outlet syndrome (vTOS) is caused by compression of the subclavian vein at the costoclavicular space, which may lead to vein thrombosis. Current treatment includes thoracic outlet decompression with or without venolysis. However, given its relatively low prevalence, the existing literature is limited. Here, we report our single institution experience in the treatment of vTOS. METHODS: We performed a retrospective review of all patients who underwent rib resection for vTOS at our institution from 2007 to 2022. Demographic, procedural details, perioperative and long-term outcomes were reviewed. RESULTS: A total of 76 patients were identified. The mean age was 36 years. Swelling was the most common symptom (93%), followed by pain (6.6%). 90% of patients had associated DVT, with 99% of these patients starting anticoagulation preoperatively. 91% of patients underwent rib resection via infraclavicular approach, 2% via paraclavicular approach (due to neurogenic component), and 7% via the transaxillary approach. Eighty-three percent of patients had endovascular intervention prior or at the time of the rib resection, with catheter-directed-thrombolysis (87%), followed by angioplasty (71%), and rheolytic thrombectomy (57%) being the most common interventions. Median time from endovascular intervention to rib resection was 14 days, with 25% at same admission. Median postoperative stay was 3 days (2-5). There was no perioperative mortality or nerve injury. Fourteen percent of patients had postoperative complications, with bleeding complications (12%) being the most common. Waiting more than 30 days between initial endovascular intervention and rib resection was not associated with decreased risk of bleeding complications. Patients were seen postoperatively at 1-month (physical exam) and 6-month (duplex) intervals or for any new or recurrent symptoms. Twenty-two percent of our overall patient population underwent reintervention, most commonly angioplasty (21%). At last follow-up, 97% of subclavian veins were patent, and 93% of patients were symptom-free. CONCLUSION: Over the last decade we have transitioned to an infraclavicular approach for isolated vTOS, with low perioperative morbidity and good patency rates. These results support the adoption of the infraclavicular approach with adjunct endovascular techniques as a safe and efficacious treatment of vTOS.