Background: Although increased levels of neutrophils and matrix metalloproteinase-9 (MMP-9) in the ischemic brain are reported in patients and experimental stroke studies the effects of neutrophils and MMP-9 on thromboembolic ischemic stroke are poorly understood. Objectives: To define the contribution of MMP-9 and neutrophils to brain injury. Blood-brain barrier breakdown (BBB) and hemorrhage after middle cerebral artery thromboembolism. Methods: Thromboembolic stroke was induced in mice to determine the contribution of neutrophils and MMP-9 to acute stroke outcomes. The effects of MMP-9 gene deletion, specific MMP-9 inhibition, and antibody-mediated neutrophil depletion were examined. Ischemic brain injury, hemorrhage, swelling, neutrophil recruitment, MMP-9 expression, BBB breakdown, and fibrin(ogen) deposition were quantified. Results and Conclusions: During thromboembolic stroke, neutrophil recruitment and MMP-9 expression significantly increased in the ischemic brain hemisphere and were localized to the intravascular, perivascular, and brain parenchymal tissue. Neutrophil depletion significantly reduced brain swelling (P < .001) and cerebral infarction (P < .0001). Neutrophils colocalized with MMP-9, and nonneutrophilic expression of MMP-9 appeared vascular. MMP-9 deficiency significantly reduced neutrophil infiltration in the infarcted brain tissue (P < .01). MMP-9 deficiency (MMP-9-/- mice) and inhibition (anti-MMP-9 antibody) significantly decreased brain swelling (P < .001 and P < .05, respectively) and infarct volume (P < .05), but the effects were neutralized when the MMP-9-/- mice were supplemented with purified MMP-9 protein. MMP-9 deficiency/inhibition or neutrophil depletion caused comparable reductions in BBB breakdown and fibrin(ogen) deposition. However, even after stroke onset, intravenous treatment of MMP-9+/+ mice with an MMP-9-specific antibody significantly reduced brain infarction (P < .05). These data show that neutrophils and MMP-9 increase ischemic brain injury and BBB breakdown and that intravascular inhibition of MMP-9 may be a potential therapeutic strategy for ischemic stroke.

BACKGROUND:Saddle pulmonary embolism (SPE) is defined as large emboli located at the bifurcation of the main pulmonary artery. The prevalence and optimal intervention for SPE remain unclear. Herein, we focus on contemporary epidemiology and reperfusion strategies for SPE with acute cor pulmonale (SPE-ACP). METHODS:The National Inpatient Sample of the USA (2016-2022) was analyzed. Diagnoses and procedures were identified by International Classification of Diseases, Tenth Revision (ICD-10) codes. Therapies were classified as conventional therapy (CT), systemic fibrinolysis (SF), catheter-directed thrombolysis (CDTL), and catheter-directed mechanical thrombectomy (CDMT). Outcomes evaluated were bleeding, transfusion, discharge to home, and in-hospital mortality. Statistical analyses included chi-squared tests, Wilcoxon rank-sum tests, propensity score matching, and logistic regression. RESULTS:SPE-ACP constituted 1.7% of all PEs (frequency-trend, 2016-2022, ptrend < 0.001); 49.2% of patients received CT. Among advanced reperfusion therapies (ARTs), SF was associated with higher risks of major bleeding and mortality (vs CDTL/CDMT, p < 0.05). CDTL was associated with lower transfusion risk (vs SF/CDMT, p < 0.01) and higher rates of discharge to home (vs SF, p = 0.009). Notably, CDMT showed increasing trends in utilization and discharge to home, and decreasing trends in transfusion and mortality (2016-2022, all ptrend < 0.05). Except for transfusion (p = 0.013), the outcomes became comparable between CDTL and CDMT (2020-2022, all p > 0.10). SPE-ACP with acute popliteal/femoral deep vein thrombosis (DVT) was associated with lower mortality risk (vs no femoropopliteal DVT, all p < 0.05). CONCLUSION:SPE-ACP, an uncommon condition, showed a substantially increased prevalence over time. Among ARTs, favorable outcomes were observed with CDTL during 2016-2022; CDMT may be evolving into an alternative strategy given its relatively comparable outcomes during 2020 to 2022. SPE-ACP with concomitant acute femoral/popliteal DVT may be associated with lower mortality risk.

Background Although increased levels of neutrophils and MMP-9 in the ischemic brain are reported in patients and experimental stroke studies, the effects of neutrophils and MMP-9 on thromboembolic ischemic stroke are poorly understood. Methods Thromboembolic stroke was induced in mice to determine the contribution of neutrophils and MMP-9 to acute stroke outcomes. The effects of MMP-9 gene deletion, specific MMP-9 inhibition, and antibody-mediated neutrophil depletion were examined. Ischemic brain injury, hemorrhage, swelling, neutrophil recruitment, MMP-9 expression, blood-brain barrier breakdown (BBB), and fibrin(ogen) deposition were quantified. Results and Conclusions During thromboembolic stroke, neutrophil recruitment and MMP-9 expression significantly increased in the ischemic brain hemisphere and were localized to the intravascular, perivascular, and brain parenchymal tissue. Neutrophil depletion significantly reduced brain swelling (p<0.001) and cerebral infarction (p<0.0001). Neutrophils colocalized with MMP-9, and non-neutrophilic expression of MMP-9 appeared vascular. MMP-9 deficiency significantly reduced neutrophil infiltration in the infarcted brain tissue (p<0.01). MMP-9 deficiency (MMP-9-/- mice) and inhibition (anti-MMP-9 antibody) significantly decreased brain swelling (p<0.001, p<0.05) and infarct volume (p<0.05), but the effects were neutralized when the MMP-9-/- mice were supplemented with purified MMP-9 protein. MMP-9 deficiency/inhibition or neutrophil depletion caused comparable reductions in BBB breakdown and fibrin(ogen) deposition. However, even after stroke onset intravenous treatment of MMP-9+/+ mice with an MMP-9-specific antibody significantly reduced brain infarction (p<0.05). These data show that neutrophils and MMP-9 increase ischemic brain injury and BBB breakdown, and that intravascular inhibition of MMP-9 may be a potential therapeutic strategy for ischemic stroke.

A bioengineered version of recombinant tissue plasminogen activator, i.e., tenecteplase (TNK-tPA), was designed to have a longer half-life, resistance to plasminogen activator inhibitor-1, and fibrin-targeted plasminogen activation. By comparison to tPA, clinical trials suggest that TNK-tPA may be less susceptible to the effects of alpha2-antiplasmin (α2AP), the primary inhibitor of thrombus dissolution. However, preclinical studies are limited, and whether α2AP affects TNK-tPA's fibrinolytic activity or efficacy in experimental ischemic stroke is unknown. We examined the effects of TNK-tPA and α2AP on the dissolution of human plasma clots (in vitro) and experimental ischemic brain injury from stroke induced by transient middle cerebral artery ischemia. TNK-tPA induced a dose-dependent increase in plasma clot dissolution; inhibition of α2AP with a specific monoclonal antibody caused a synergistic increase in TNK-tPA-mediated clot dissolution. In experimental ischemic stroke with ischemia and reperfusion, TNK-tPA treatment of α2AP-/- mice significantly reduced ischemic infarct volume, brain swelling, brain hemorrhage, and neurobehavioral disability vs. TNK-tPA-treated α2AP+/+ (C57BL/6 background) mice with normal α2AP levels (p < 0.05 to p < 0.0001). α2AP impairs the dissolution of human clots in vitro by TNK-tPA and significantly exacerbates ischemic brain injury, swelling, hemorrhage, and neurobehavioral disability after experimental stroke, even with reperfusion. Targeting α2AP may improve the efficacy of TNK-tPA and reduce hemorrhagic complications.

BACKGROUND:Recent randomized trials showed no benefit of mechanical thrombectomy (MT) for ischemic stroke due to distal medium vessel occlusion (DMVO). We sought to understand the use of MT for DMVO stroke treatment before and after the publication of these trials. METHODS:We conducted an email survey of 47 comprehensive stroke centers across the United States, which are participating in a National Institutes of Health-funded randomized controlled trial (RCT; Unique identifier: NCT05948566). The questionnaire was developed and modified with expert feedback. Site principal investigators were asked to discuss the DMVO RCT results with their local clinical teams and to subsequently respond to survey questions in a manner that reflected team-based decision-making regarding MT for DMVO before and after the publication of the RCTs, considering the location of the vessel occlusion (nondominant M2 versus M3/M4/A1/A2). If the site principal investigator was responsible for >1 site with the same stroke team, only 1 survey response was tallied. RESULTS:Of the 43 site principal investigators surveyed representing 47 unique sites, 40 (93%) representing 44 unique sites completed the survey. Before the DMVO RCTs, 95% of respondents were treating nondominant M2 occlusions with MT. Only 15% will continue to be treated with MT, while 57.5% said that treatment was dependent on at least ≥1 variable following presentation of the DMVO RCTs. For all other anterior circulation DMVOs, 50% were treating DMVOs with MT before RCT results' presentation. Only 7.5% will continue to treat with MT, while 32.5% said that treatment was dependent on at least 1 other variable following presentation of the DMVO RCTs. The most common variable named by survey respondents as important to treatment decision was symptom severity. CONCLUSIONS:In this survey of comprehensive stroke centers, the DMVO RCT results created a significant practice change in how stroke teams approach anterior circulation DMVO stroke with MT.

Background: Acetylsalicylic acid (ASA) has been shown to reduce recurrent deep venous thrombosis (DVT) rates. However, limited mechanistic data is available regarding the efficacy of ASA on DVT resolution and measures of post-thrombotic syndrome (PTS), particularly in female subjects. Furthermore, real-world sex-specific data on ASA prescription and withdrawal rates in secondary DVT prevention patients are sparse. Methods: First the effects of ASA pretreatment on thrombogenesis were assessed in both female and male C57BL/6 mice (n=149) utilizing serial intravital microscopy in an extended murine DVT model. Next the effects of ASA on DVT resolution and vein wall inflammation were evaluated in male mice with IVC stasis DVT using histopathological and scanning electron microscopy analyses. Next, in a single-center clinical study, secondary DVT prevention patients with a history of unprovoked lower extremity DVT were assessed for ASA and anticoagulant prescription and withdrawal rates over 24 months. Results: In murine stasis DVT, utilizing serial IVM for 24 hours (n=82), ASA pretreatment (3 mg/kg/day) significantly reduced thrombogenesis and accelerated DVT resolution in males (Fig 1A p<0.05), with a higher ASA dose (15 mg/kg/day) required in females for efficacy (Fig 1B p>0.05 all, Fig 1C p<0.05 all). In complete-stasis DVT (n=67), ASA pretreatment reduced day 8 thrombus (Fig 1D-E, p<0.001), fibrin-rich area and fibrin fibril density, and increased plasminogen expression. ASA further reduced vein wall fibrosis and fibroblasts (Fig 1F-H, p<0.05), as well as vein wall MMP activity. Next, in a cohort of 131 patients with unprovoked DVT followed over 24 months, 13.3% of patients discontinued anticoagulation therapy (Fig 1I-J, p trend <0.001). Discontinuation occurred more often in females (19.5% vs. 9.7% in males, p interaction =0.047). ASA was infrequently prescribed in patients who stopped anticoagulation (3/7 males, 0/8 females). Conclusions: Preventative ASA treatment reduced murine thrombogenesis and improved DVT resolution, with females requiring a higher ASA dose to achieve efficacy. ASA further reduced vein wall injury and inflammation. Clinically, patients with unprovoked DVT showed increasing rates of anticoagulant withdrawal over 24 months, especially in female patients. Such patients further infrequently receive ASA. These results may motivate reconsideration of preventative ASA to reduce recurrent DVT and PTS in patients ineligible for anticoagulant therapy.

Venous thromboembolism, defined as deep vein thrombosis and pulmonary embolism, is the third leading cause of cardiovascular deaths globally. Long-term complications of unresolved venous thrombi include post-thrombotic syndrome in the legs and chronic thromboembolic pulmonary hypertension. As the venous thrombus ages, the acute, fibrin, and red blood cell-rich composition changes to a chronic cellular, fibrotic mass that does not respond to presently available therapeutic approaches. Standard anticoagulation treatment does not fully prevent recurrent thrombosis and may cause serious bleeding. Thrombolytic therapy may resolve thrombi but it has unacceptable bleeding risks. Recent drug discovery for acute venous thromboembolism has focused on novel targets that may provide enhanced safety and efficacy. Additional therapeutic strategies have focused on the transition phase of acute-to-chronic venous thromboembolism with anti-inflammatory agents, statins, and vasodilator drugs. In this review, we discuss the mechanisms of venous thrombus aging, its clinical implications, and the latest developments in pharmacotherapeutic approaches for venous thromboembolism.

Matrix metalloproteinases (MMPs) such as MMP-9, 3, and 2 degrade the cellular matrix and are believed to play a crucial role in ischemic stroke. We examined how the duration of ischemia (up to 4 h) and treatment with recombinant tissue plasminogen activator altered the comparative expression of these MMPs in experimental ischemic stroke with reperfusion. Both prolonged ischemia and r-tPA treatment markedly increased MMP-9 expression in the ischemic hemisphere (all p < 0.0001). The duration of ischemia and r-tPA treatment also significantly increased MMP-2 expression (p < 0.01–0.001) in the ischemic hemisphere (p < 0.01) but to a lesser degree than MMP-9. In contrast, MMP-3 expression significantly decreased in the ischemic hemisphere (p < 0.001) with increasing duration of ischemia and r-tPA treatment (p < 0.05–0001). MMP-9 expression was prominent in the vascular compartment and leukocytes. MMP-2 expression was evident in the vascular compartment and MMP-3 in NeuN+ neurons. Prolonging the duration of ischemia (up to 4 h) before reperfusion increased brain hemorrhage, infarction, swelling, and neurologic disability in both saline-treated (control) and r-tPA-treated mice. MMP-9 and MMP-2 expression were significantly positively correlated with, and MMP-3 was significantly negatively correlated with, infarct volume, swelling, and brain hemorrhage. We conclude that in experimental ischemic stroke with reperfusion, the duration of ischemia and r-tPA treatment significantly altered MMP-9, 3, and 2 expression, ischemic brain injury, and neurological disability. Each MMP showed unique patterns of expression that are strongly correlated with the severity of brain infarction, swelling, and hemorrhage. In summary, in experimental ischemic stroke in male mice with reperfusion, the duration of ischemia, and r-tPA treatment significantly altered the immunofluorescent expression of MMP-9, 3, and 2, ischemic brain injury, and neurological disability. In this model, each MMP showed unique patterns of expression that were strongly correlated with the severity of brain infarction, swelling, and hemorrhage.

Symptomatic heart failure (sHF) with cardiac dysfunction, edema, and mortality are driven by overactivation of the renin-angiotensin-aldosterone system (RAAS). Renin is widely recognized as a key initiator of RAAS function, yet the mechanisms that activate renin remain a mystery. We discovered that activated coagulation factor XII generates active renin in the circulation and is directly linked to pathological activation of the systemic RAAS, development of sHF, and increased mortality. These findings suggest a new paradigm for therapeutically modulating the RAAS in sHF and other pathological conditions.

Venous thrombosis and pulmonary embolism (venous thromboembolism) are important causes of morbidity and mortality worldwide. In patients with venous thromboembolism, thrombi obstruct blood vessels and resist physiological dissolution (fibrinolysis), which can be life threatening and cause chronic complications. Plasminogen activator therapy, which was developed >50 years ago, is effective in dissolving thrombi but has unacceptable bleeding risks. Safe dissolution of thrombi in patients with venous thromboembolism has been elusive despite multiple innovations in plasminogen activator design and catheter-based therapy. Evidence now suggests that fibrinolysis is rigidly controlled by endogenous fibrinolysis inhibitors, including α2-antiplasmin, plasminogen activator inhibitor-1, and thrombin-activable fibrinolysis inhibitor. Elevated levels of these fibrinolysis inhibitors are associated with an increased risk of venous thromboembolism in humans. New therapeutic paradigms suggest that accelerated and effective fibrinolysis may be achieved safely by therapeutically targeting these fibrinolytic inhibitors in venous thromboembolism. In this article, we discuss the role of fibrinolytic components in venous thromboembolism and the current status of research and development targeting fibrinolysis inhibitors.

Introduction: Patients with iliofemoral deep vein thrombosis (IFDVT) may preferentially benefit from catheter-directed thrombolysis/thrombectomy (CDT) to reduce the post-thrombotic syndrome (PTS). Our prior analysis of the full NIH ATTRACT trial cohort demonstrated that the maximal benefit of CDT occurs at the day (D) 4-8 symptom-onset-to-randomization (SOR) timeframe (Circulation 2021; 143:1224-1238). However, the optimal time window for CDT benefit specifically for IFDVT patients has not been determined. Hypothesis: IFDVT patients may have a broader time window and greater magnitude for CDT benefit compared to all-comer DVT patients. Methods: We analyzed the IFDVT subgroup (N=391) of the NIH ATTRACT trial to assess optimal SOR timeframes for improved PTS outcomes (Villalta and VEINES-QoL scores). In a series of sensitivity analyses, IFDVT patients were non-prespecified divided into two (early, late) or three (early, intermediate, late) SOR groups. Mean scores were estimated by a piecewise linear-regression growth-curve model, with adjustment for strata including clinical center and baseline covariates (age, sex, BMI) by intention-to-treat analysis. Results: In the IFDVT patients, sensitivity analyses revealed that CDT significantly and maximally improved PTS outcomes in the intermediate D4-9 SOR [CDT +anticoagulation (AC) vs. AC alone; between-group difference= -2.54 (Villalta), +13.13 (VEINES-QoL), p<0.0001 for each]. However, CDT did not provide a benefit at early SOR ≤D3 and later SOR ≥D10 (p>0.05). Moreover, CDT effects differed across SOR 0-3, 4-9 and 10+ days (Villalta: -0.77, -2.54, -1.98; p=0.027), (VEINES-QoL: -1.89, +13.13, +1.92; p=0.022). Conclusions: CDT maximally improves PTS outcomes for IFDVT patients in the D4-9 timeframe, which is a more selective time window and of greater magnitude of PTS benefit than the full ATTRACT trial cohort. However, CDT does not improve outcomes beyond AC at early D0-3 and late D10+ timeframes. These findings may have practice implications to consider symptom duration to optimize AC and CDT therapies in IFDVT patients. Mechanisms underlying the benefit of AC and CDT on PTS outcomes need further study.

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Introduction: Despite anticoagulation (AC), up to 50% of proximal deep vein thrombosis (DVT) patients will develop the post-thrombotic syndrome (PTS). In a substudy of the ATTRACT DVT trial, catheter-directedthrombectomy/thrombolysis (CDT) in addition to AC improved PTS outcomes for patients presenting at an intermediate day (D) 4-8 symptom-onset-to-randomization (SOR) timeframe, but not at an early D0-3 or late D9+ SOR timeframe. Mechanisms underlying the role of early AC and CDT are unknown, particularly iliofemoral DVT (IFDVT) patients that preferentially benefit from CDT. Methods: First, we assessed the temporal impact of AC on Villalta and VEINES-QoL PTS scores in a post-hoc analysis of the IFDVT ATTRACT patients (N=391). Mean scores were estimated by a piecewise linear-regression growth-curve model. Next, to mechanistically explore the effects of AC on PTS measures, C57/BL6 mice (N=76) underwent inferior vena cava (IVC) ligation to produce stasis DVT. Mice then underwent true or sham de-ligation at D2 to spur restoration of blood flow (RBF). Last, enoxaparin AC was initiated at D2 and given daily until D8, at either 0, 10, or 30 mg/kg/d SQ. D4 RBF rates in the IVC, and D8 thrombus burden were assessed. Results: In IFDVT ATTRACT patients, CDT+AC improved PTS scores in the intermediate D4-8 SOR timeframe (p<0.001 vs. AC alone). However, in the early D0-3 SOR timeframe, CDT+AC did not improve PTS scores (p>0.05 vs. AC alone). In the AC alone groups, early AC D0-3 significantly improved PTS scores over delayed AC (p<0.05). In sham de-ligated mice with IVC DVT, D2 enoxaparin improved D4 RBF rates (sham, 11.1%; low-dose, 33.3%; high-dose, 40.0%). D2 enoxaparin also significantly reduced D8 thrombus weight (p<0.05, both doses vs. saline). However, in true de-ligation mice, D2 enoxaparin only mildly increased D4 RBF rates (sham, 50%; low-dose, 61.5%; high-dose, 60%), and did not decrease D8 thrombus weight (p>0.05). Conclusions: In ATTRACT patients presenting with IFDVT at an early D0-3 SOR timeframe, PTS outcomes were improved by AC but not further improved by CDT. Experimentally, early D2 AC initiation can improve RBF rates and DVT resolution. These findings suggest that achieving early RBF may reduce the risk of PTS.

Symptomatic heart failure with reduced ejection fraction (HFrEF) is characterized by edema and chronic pathological activation of the classical renin–angiotensin–aldosterone system (RAAS). The soluble (pro)renin receptor (s(P)RR) is released into circulation by proteolytic cleavage of tissue expressed (P)RR and is a candidate biomarker of RAAS activation. However, previous studies linked elevated levels of s(P)RR in patients with HFrEF to renal dysfunction. Utilizing prospectively enrolled patients with comparable rEF, we show that increased plasma levels of s(P)RR are associated with symptomatic HF (characterized by edema), independent of chronic renal dysfunction. We also found that s(P)RR levels were positively correlated with patient plasma renin activity (PRA). Normotensive mice with dilated cardiomyopathy (DCM) and HFrEF, without renal dysfunction, showed plasma s(P)RR and PRA patterns similar to human HFrEF patients. Plasma s(P)RR levels positively correlated with PRA and systemic edema, but not with EF, resembling findings in patients with HFrEF without chronic kidney dysfunction. In female DCM mice with elevated PRA levels and plasma s(P)RR levels, a randomized, blinded trial comparing the direct renin inhibitor, aliskiren vs. vehicle control, showed that direct renin inhibition normalized PRA, lowered s(P)RR, and prevented symptomatic HFrEF. Considered in light of previous findings, these data suggest that, in HFrEF, in the absence of renal dysfunction, elevation of plasma s(P)RR levels is caused by increased PRA and associated with the development of systemic edema.

Pathological sodium-water retention or edema/congestion is a primary cause of heart failure (HF) decompensation, clinical symptoms, hospitalization, reduced quality of life, and premature mortality. Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) based therapies reduce hospitalization due to HF, improve functional status, quality, and duration of life in patients with HF with reduced ejection fraction (HFrEF) independently of their glycemic status. The pathophysiologic mechanisms and molecular pathways responsible for the benefits of SGLT-2i in HFrEF remain inconclusive, but SGLT-2i may help HFrEF by normalizing salt-water homeostasis to prevent clinical edema/congestion. In HFrEF, edema and congestion are related to compromised cardiac function. Edema and congestion are further aggravated by renal and pulmonary abnormalities. Treatment of HFrEF patients with SGLT-2i enhances natriuresis/diuresis, improves cardiac function, and reduces natriuretic peptide plasma levels. In this review, we summarize current clinical research studies related to outcomes of SGLT-2i treatment in HFrEF with a specific focus on their contribution to relieving or preventing edema and congestion, slowing HF progression, and decreasing the rate of rehospitalization and cardiovascular mortality.

In heart failure with reduced ejection fraction (HFrEF), cardiogenic edema develops from impaired cardiac function, pathological remodeling, chronic inflammation, endothelial dysfunction, neurohormonal activation, and altered nitric oxide-related pathways. Pre-clinical HFrEF studies have shown that treatment with sodium–glucose cotransporter-2 inhibitors (SGLT-2i) stimulates natriuretic and osmotic/diuretic effects, improves overall cardiac function, attenuates maladaptive cardiac remodeling, and reduces chronic inflammation, oxidative stress, and endothelial dysfunction. Here, we review the mechanisms and effects of SGLT-2i therapy on cardiogenic edema in various models of HFrEF. Overall, the data presented suggest a high translational importance of these studies, and pre-clinical studies show that SGLT-2i therapy has a marked effect on suppressing the progression of HFrEF through multiple mechanisms, including those that affect the development of cardiogenic edema.

Matrix metalloproteinase-9 (MMP-9) degrades collagen and other cellular matrix proteins. After acute ischemic stroke, increased MMP-9 levels are correlated with hemorrhage, lack of reperfusion and stroke severity. Nevertheless, definitive data that MMP-9 itself causes poor outcomes in ischemic stroke are limited. In a model of experimental ischemic stroke with reperfusion, we examined whether ischemia and recombinant tissue plasminogen activator (r-tPA) therapy affected MMP-9 expression, and we used specific inhibitors to test if MMP-9 affects brain injury and recovery. After stroke, MMP-9 expression increased significantly in the ischemic vs. nonischemic hemisphere of the brain (p < 0.001). MMP-9 expression in the ischemic, but not the non-ischemic hemisphere, was further increased by r-tPA treatment (p < 0.001). To determine whether MMP-9 expression contributed to stroke outcomes after r-tPA treatment, we tested three different antibody MMP-9 inhibitors. When compared to treatment with r-tPA and saline, treatment with r-tPA and MMP-9 antibody inhibitors significantly reduced brain hemorrhage by 11.3 to 38.6-fold (p < 0.01), brain swelling by 2.8 to 4.3-fold (p < 0.001) and brain infarction by 2.5 to 3.9-fold (p < 0.0001). Similarly, when compared to treatment with r-tPA and saline, treatment with r-tPA and an MMP-9 antibody inhibitor significantly improved neurobehavioral outcomes (p < 0.001), decreased weight loss (p < 0.001) and prolonged survival (p < 0.01). In summary, both prolonged ischemia and r-tPA selectively enhanced MMP-9 expression in the ischemic hemisphere. When administered with r-tPA, specific MMP-9 inhibitors markedly reduced brain hemorrhage, swelling, infarction, disability and death, which suggests that blocking the deleterious effects of MMP-9 may improve outcomes after ischemic stroke. (C) 2021 Published by Elsevier Ltd on behalf of IBRO.

BACKGROUND:Up to 50% of patients with proximal deep vein thrombosis (DVT) will develop the postthrombotic syndrome characterized by limb swelling and discomfort, hyperpigmentation, skin ulcers, and impaired quality of life. Although catheter-based interventions enabling the restoration of blood flow (RBF) have demonstrated little benefit on postthrombotic syndrome, the impact on the acuity of the thrombus and mechanisms underlying this finding remain obscure. In experimental and clinical studies, we examined whether RBF has a restricted time window for improving DVT resolution. METHODS:First, experimental stasis DVT was generated in C57/BL6 mice (n=291) by inferior vena cava ligation. To promote RBF, mice underwent mechanical deligation with or without intravenous recombinant tissue plasminogen activator administered 2 days after deligation. RBF was assessed over time by ultrasonography and intravital microscopy. Resected thrombosed inferior vena cava specimens underwent thrombus and vein wall histological and gene expression assays. Next, in a clinical study, we conducted a post hoc analysis of the ATTRACT (Acute Venous Thrombosis: Thrombus Removal with Adjunctive Catheter-Directed Thrombolysis) pharmacomechanical catheter-directed thrombolysis (PCDT) trial (NCT00790335) to assess the effects of PCDT on Venous Insufficiency Epidemiological and Economic Study quality-of-life and Villalta scores for specific symptom-onset-to-randomization timeframes. RESULTS:Mice that developed RBF by day 4, but not later, exhibited reduced day 8 thrombus burden parameters and reduced day 8 vein wall fibrosis and inflammation, compared with controls. In mice without RBF, recombinant tissue plasminogen activator administered at day 4, but not later, reduced day 8 thrombus burden and vein wall fibrosis. It is notable that, in mice already exhibiting RBF by day 4, recombinant tissue plasminogen activator administration did not further reduce thrombus burden or vein wall fibrosis. In the ATTRACT trial, patients receiving PCDT in an intermediate symptom-onset-to-randomization timeframe of 4 to 8 days demonstrated maximal benefits in Venous Insufficiency Epidemiological and Economic Study quality-of-life and Villalta scores (between-group difference=8.41 and 1.68, respectively, P<0.001 versus patients not receiving PCDT). PCDT did not improve postthrombotic syndrome scores for patients having a symptom-onset-to-randomization time of <4 days or >8 days. CONCLUSIONS:Taken together, these data illustrate that, within a restricted therapeutic window, RBF improves DVT resolution, and PCDT may improve clinical outcomes. Further studies are warranted to examine the value of time-restricted RBF strategies to reduce postthrombotic syndrome in patients with DVT.