Venous thromboembolism: diagnostic advances and unaddressed challenges in management.

PURPOSE OF REVIEW: This review summarizes recent advances in developing targeted diagnostics for venous thromboembolism (VTE) and unaddressed knowledge gaps in patient management. Without addressing these critical data needs, the morbidity in VTE patients will persist. RECENT FINDINGS: Recent studies investigating plasma protein profiles in VTE patients have identified key diagnostic targets to address the currently unmet need for low-cost, confirmatory, point-of-care VTE diagnostics. These studies and a growing body of evidence from animal model studies have revealed the importance of inflammatory and vascular pathology in driving VTE, which are currently unaddressed targets for VTE therapy. To enhance the translation of preclinical animal studies, clinical quantification of thrombus burden and comparative component analyses between modeled VTE and clinical VTE are necessary. SUMMARY: Lead candidates from protein profiling of VTE patients' plasma offer a promising outlook in developing low cost, confirmatory, point-of-care testing for VTE. Additionally, addressing the critical knowledge gap of quantitatively measuring clinical thrombi will allow for an array of benefits in VTE management and informing the translatability of experimental therapeutics.

The effects of in utero exposure to delta-9-tetrahydrocannabinol (THC) on cardiac extracellular matrix expression and vascular transcriptome in rhesus macaques.

Delta-9-tetrahydrocannabinol (THC), the psychoactive component of cannabis, remains a schedule I substance, thus safety data regarding the effects on the cardiovascular and prenatal health are limited. Importantly, there is evidence showing prenatal cannabis exposure can negatively impact fetal organ development, including the cardiovascular system. THC can cross the placenta and bind to cannabinoid receptors expressed in the developing fetus, including on endothelial cells. To understand the impact of prenatal THC exposure on the fetal cardiovascular system, we used our rhesus macaque model of prenatal daily edible THC consumption. Prior to conception, animals were acclimated to THC (2.5mg/7kg/day, equivalent to a heavy medical cannabis dose) and maintained on this dose daily throughout pregnancy. Fetal tissue samples were collected at gestational day 155 (full term is 168 days). Our model showed that in utero THC exposure was associated with a decreased heart to body weight ratio in offspring, warranting further mechanistic investigation. Histological examination of the fetal cardiac and vascular tissues did not reveal any significant effect of THC exposure on the maturity of collagen within the fetal heart or the aorta. Total collagen III expression and elastin production and organization were unchanged. However, bulk RNA-sequencing of vascular cells in the umbilical vein, umbilical artery, and fetal aorta demonstrated that THC alters the fetal vascular transcriptome and is associated with upregulated expression of genes involved in carbohydrate metabolism and inflammation. The long-term consequences of these findings are unknown, but suggest that prenatal THC exposure may affect cardiovascular development in offspring.

Role of platelet count in a murine stasis model of deep vein thrombosis.

Platelets are core components of thrombi but their effect on thrombus burden during deep vein thrombosis (DVT) has not been fully characterized. We examined the role of thrombopoietin-altered platelet count on thrombus burden in a murine stasis model of DVT. To modulate platelet count compared to baseline, CD1 mice were pretreated with thrombopoietin antisense oligonucleotide (THPO-ASO, 56% decrease), thrombopoietin mimetic (TPO-mimetic, 36% increase), or saline (within 1%). Thrombi and vein walls were examined on postoperative days (POD) 3 and 7. Thrombus weights on POD 3 were not different between treatment groups (p = .84). The mean thrombus weights on POD 7 were significantly increased in the TPO-mimetic cohort compared to the THPO-ASO (p = .005) and the saline (p = .012) cohorts. Histological grading at POD 3 revealed a significantly increased smooth muscle cell presence in the thrombi and CD31 positive channeling in the vein wall of the TPO-mimetic cohort compared to the saline and THPO-ASO cohorts (p < .05). No differences were observed in histology on POD 7. Thrombopoietin-induced increased platelet count increased thrombus weight on POD 7 indicating platelet count may regulate thrombus burden during early resolution of venous thrombi in this murine stasis model of DVT.

Deep vein thrombosis (DVT) is a pathology in which blood clots form in the deep veins of our body. Usually occurring in the legs, these clots can be dangerous if they dislodge and travel to the heart and are pumped into the lungs. Often these clots do not travel and heal where they formed. However, as the body heals the clot it may also cause damage to the vein wall and predispose the patient to future clots, i.e., the biggest risk factor for a second clot is the first clot. DVT can also cause symptoms of pain, swelling, and redness in the long-term, leading to post-thrombotic syndrome where the initial symptoms of the clot persist for a long time. All blood clots have common components of red blood cells, white blood cells, platelets, and fibrin in varying concentrations. Humans maintain a platelet count between 150 and 400 thousand platelets per microliter of our blood. However, diseases like cancer or medications like chemotherapy can cause a change in our body's platelet count. The effect of a changing platelet count on the size (clot burden) of DVT clot and how platelet count could affect DVT as the clot heals is not fully understood. Studying this might help us develop better targets and treat patients with a wide range of platelet counts who experience DVT. In this study, we intentionally decreased, left unchanged, and increased platelet counts in mice and then created a DVT to study what the effect of low, normal, and high platelet counts, respectively, would be on the clot burden. We observed that mice with higher platelet counts had a higher clot burden during the early part of the healing process of the clot. Within this study, we can conclude that higher platelet counts may lead to higher clot burden in DVT which furthers our understanding of how platelet count affects clot burden during DVT.

Temporal Changes in the Surface Chemistry and Topography of Reactive Ion Plasma-Treated Poly(vinyl alcohol) Alter Endothelialization Potential.

Synthetic small-diameter vascular grafts (<6 mm) are used in the treatment of cardiovascular diseases, including coronary artery disease, but fail much more readily than similar grafts made from autologous vascular tissue. A promising approach to improve the patency rates of synthetic vascular grafts is to promote the adhesion of endothelial cells to the luminal surface of the graft. In this study, we characterized the surface chemical and topographic changes imparted on poly(vinyl alcohol) (PVA), an emerging hydrogel vascular graft material, after exposure to various reactive ion plasma (RIP) surface treatments, how these changes dissipate after storage in a sealed environment at standard temperature and pressure, and the effect of these changes on the adhesion of endothelial colony-forming cells (ECFCs). We showed that RIP treatments including O2, N2, or Ar at two radiofrequency powers, 50 and 100 W, improved ECFC adhesion compared to untreated PVA and to different degrees for each RIP treatment, but that the topographic and chemical changes responsible for the increased cell affinity dissipate in samples treated and allowed to age for 230 days. We characterized the effect of aging on RIP-treated PVA using an assay to quantify ECFCs on RIP-treated PVA 48 h after seeding, atomic force microscopy to probe surface topography, scanning electron microscopy to visualize surface modifications, and X-ray photoelectron spectroscopy to investigate surface chemistry. Our results show that after treatment at higher RF powers, the surface exhibits increased roughness and greater levels of charged nitrogen species across all precursor gases and that these surface modifications are beneficial for the attachment of ECFCs. This study is important for our understanding of the stability of surface modifications used to promote the adhesion of vascular cells such as ECFCs.

Pharmacologic targeting of coagulation factors XII and XI by monoclonal antibodies reduces thrombosis in nitinol stents under flow.

BACKGROUND: Cardiovascular implantable devices, such as vascular stents, are critical for the treatment of cardiovascular diseases. However, their success is dependent on robust and often long-term antithrombotic therapies. Yet, the current standard-of-care therapies often pose significant bleeding risks to patients. Coagulation factor (F)XI and FXII have emerged as potentially safe and efficacious targets to safely reduce pathologic thrombin generation in medical devices. OBJECTIVES: To study the efficacy of monoclonal antibody-targeting FXII and FXI of the contact pathway in preventing vascular device-related thrombosis. METHODS: The effects of inhibition of FXII and FXI using function-blocking monoclonal antibodies were examined in a nonhuman primate model of nitinol stent-related thrombosis under arterial and venous flow conditions. RESULTS: We found that function-blocking antibodies of FXII and FXI reduced markers of stent-induced thrombosis in vitro and ex vivo. However, FXI inhibition resulted in more effective mitigation of thrombosis markers under varied flow conditions. CONCLUSION: This work provides further support for the translation of contact pathway of coagulation inhibitors for their adjunctive clinical use with cardiovascular devices.

Effects of in utero delta-9-tetrahydrocannabinol (THC) exposure on fetal and infant musculoskeletal development in a preclinical nonhuman primate model.

The endocannabinoid system (ECS) plays a major role in the maintenance of bodily homeostasis and adaptive response to external insults. It has been shown to regulate crucial physiological processes and behaviors, spanning nervous functions, anxiety, cognition, and pain sensation. Due to this broad activity, the ECS has been explored as a potential therapeutic target in the treatment of select diseases. However, until there is a more comprehensive understanding of how ECS activation by exogenous and endogenous ligands manifests across disparate tissues and cells, discretion should be exercised. Previous work has investigated how endogenous cannabinoid signaling impacts skeletal muscle development and differentiation. However, the effects of activation of the ECS by delta-9-tetrahydrocannabinol (THC, the most psychoactive component of cannabis) on skeletal muscle development, particularly in utero, remain unclear. To address this research gap, we used a highly translational non-human primate model to examine the potential impact of chronic prenatal THC exposure on fetal and infant musculoskeletal development. RNA was isolated from the skeletal muscle and analyzed for differential gene expression using a Nanostring nCounter neuroinflammatory panel comprised of 770 genes. Histomorphological evaluation of muscle morphology and composition was also performed. Our findings suggest that while prenatal THC exposure had narrow overall effects on fetal and infant muscle development, the greatest impacts were observed within pathways related to inflammation and cytokine signaling, which suggest the potential for tissue damage and atrophy. This pilot study establishes feasibility to evaluate neuroinflammation due to prenatal THC exposure and provides rationale for follow-on studies that explore the longer-term implications and functional consequences encountered by offspring as they continue to mature.

Activation of coagulation FXI promotes endothelial inflammation and amplifies platelet activation in a nonhuman primate model of hyperlipidemia.

Background: Hyperlipidemia is associated with chronic inflammation and thromboinflammation. This is an underlying cause of several cardiovascular diseases, including atherosclerosis. In diseased blood vessels, rampant thrombin generation results in the initiation of the coagulation cascade, activation of platelets, and endothelial cell dysfunction. Coagulation factor (F) XI represents a promising therapeutic target to reduce thromboinflammation, as it is uniquely positioned at an intersection between inflammation and thrombin generation. Objectives: This study aimed to investigate the role of FXI in promoting platelet and endothelial cell activation in a model of hyperlipidemia. Methods: Nonhuman primates (NHPs) were fed a standard chow diet (lean, n = 6) or a high-fat diet (obese, n = 8) to establish a model of hyperlipidemia. Obese NHPs were intravenously administered a FXI blocking antibody (2 mg/kg) and studied at baseline and at 1, 7, 14, 21, and 28 days after drug administration. Platelet activation and inflammatory markers were measured using fluorescence-activated cell sorting or enzyme-linked immunosorbent assay. Molecular imaging was used to quantify vascular cell adhesion molecule 1 (VCAM-1) expression at the carotid bifurcation. Results: Obese NHPs demonstrated increased sensitivity for platelet P-selectin expression and phosphatidylserine exposure in response to platelet GPVI or PAR agonists compared with lean NHPs. Obese NHPs exhibited elevated levels of C-reactive protein, cathepsin D, and myeloperoxidase compared with lean NHPs. Following pharmacological inhibition of FIX activation by FXIa, platelet priming for activation by GPVI or PAR agonists, C-reactive protein levels, and endothelial VCAM-1 levels were reduced in obese NHPs. Conclusion: FXI activation promotes the proinflammatory phenotype of hyperlipidemia by priming platelet activation and inciting endothelial cell dysfunction.