A Retrospective Case-Control Study on the Diagnostic Values of Hemostatic Markers in Hypertensive Disorder of Pregnancy.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic performance of the following hemostatic markers in hypertensive disorder of pregnancy (HDP): tissue-type plasminogen activator and inhibitor-1 complex (tPAI-C), thrombomodulin, thrombin-antithrombin complex, plasmin inhibitor-plasmin complex, D-dimer, and fibrinogen degradation products. METHODS: A total of 311 individuals diagnosed with HDP and 187 healthy controls (HC) of matched gestational age were admitted, including 175 subjects with gestational hypertension, 94 with mild preeclampsia, and 42 with severe preeclampsia. RESULTS: Compared with those of the HC group, the plasma concentrations of all the hemostatic markers continuously increased with the clinical severity of the hypertensive disorder, regardless of their statistical significance. In the receiver operating characteristic analysis, tPAI-C displayed the best discrimination performance. CONCLUSION: The tPAI-C level was consistently and significantly elevated across the different HDP groups when compared with the HC group, suggesting aggravated fibrinolysis disorder increasing with the severity of the HDP.

Synthetic Fibrin-Derived Bß15-42 Peptide Delays Thrombus Resolution in a Mouse Model.

[Figure: see text].

Fibrinogen protects neutrophils from the cytotoxic effects of histones and delays neutrophil extracellular trap formation induced by ionomycin.

Neutrophils are pivotal players in immune defence which includes a process of release of histones and DNA as neutrophil extracellular traps (NETs). Histones, while toxic to invading pathogens, also kill host cells, including neutrophils. Bacteria have evolved mechanisms to escape neutrophils, including the secretion of leucocidins (e.g. ionomycin). Live cell video microscopy showed how fibrinogen and fibrin influence NETosis and neutrophil responses to extracellular histones. Histones were rapidly lethal to neutrophils after binding to cells, but formation of fibrinogen/fibrin-histone aggregates prevented cell death. Histone cytotoxicity was also reduced by citrullination by peptidyl arginine deiminase 4, or digestion by serine proteases. Ionomycin and phorbol 12-myristate 13 acetate (PMA) are used to trigger NETosis. Fibrinogen was responsible for a second distinct mechanism of neutrophil protection after treatment with ionomycin. Fibrinogen clustered on the surface of ionomycin-stimulated neutrophils to delay NETosis; and blocking the ß integrin receptor, αMß2, abolished fibrinogen protection. Fibrinogen did not bind to or protect neutrophils stimulated with PMA. Fibrinogen is an acute phase protein that will protect exposed cells from damaging circulating histones or leucocidins; but fibrinogen depletion/consumption, as in trauma or sepsis will reduce protection. It is necessary to consider the role of fibrinogen in NETosis.

Binding to carboxypeptidase M mediates protective effects of fibrinopeptide Bß15-42.

During fibrinolysis a 28-amino-acid peptide is generated besides other degradation products of fibrin. This peptide, called Bß15-42, which is cleaved by plasmin from the end of the fibrin Bß-chain, is protective in myocardial and renal ischemia/reperfusion injury and improves the outcome in experimental sepsis. Bß15-42 has been shown to mediate different beneficial effects in endothelial cells through binding to vascular endothelial-cadherin. Here, we provide in vitro and in vivo evidence that Bß15-42 has additional cell protective activity in tubular cells, which is caused by a distinct mechanism. As vascular endothelial-cadherin is not expressed by tubular cells we used ligand-receptor capture technology LRC-TriCEPS to search for tubular cell surface receptors and identified carboxypeptidase M (CBPM) as a novel binding partner of Bß15-42. Silencing CBPM with siRNA reduced the protective potential of Bß15-42 against tubular cell stress. Bß15-42 inhibited the enzymatic activity of CBPM and modified the impact of CBPM on bradykinin signaling. We conclude that beneficial properties of Bß15-42 are not restricted to endothelial cells but are also active in epithelial cells where cytoprotection depends on CBPM binding.

Fibrin-VLDL Receptor-Dependent Pathway Promotes Leukocyte Transmigration by Inhibiting Src Kinase Fyn and is a Target for Fibrin ß15-42 Peptide.

According to the current view, binding of fibrin degradation product E1 fragment to endothelial VE-cadherin promotes transendothelial migration of leukocytes and thereby inflammation, and fibrin-derived ß15-42 peptide reduces leukocyte transmigration by competing with E1 for binding to VE-cadherin and, in addition, by signaling through Src kinase Fyn. However, the very low affinity of ß15-42 to VE-cadherin raised a question about its ability to inhibit E1-VE-cadherin interaction. Further, our previous study revealed that fibrin promotes leukocyte transmigration through the very-low-density lipoprotein (VLDL) receptor (VLDLR)-dependent pathway and suggested a possible link between the inhibitory properties of ß15-42 and this pathway. To test such a link and the proposed inhibitory mechanisms for ß15-42, we performed in vitro experiments using surface plasmon resonance, enzyme-linked immunosorbent assay, and leukocyte transendothelial migration assay, and in vivo studies with wild-type and VLDLR-deficient mice using mouse model of peritonitis. The experiments revealed that ß15-42 cannot inhibit E1-VE-cadherin interaction at the concentrations used in the previous in vivo studies leaving the proposed Fyn-dependent signaling mechanism as a viable explanation for the inhibitory effect of ß15-42. While testing this mechanism, we confirmed that Fyn plays a critical role in controlling fibrin-induced transendothelial migration of leukocytes and found that signaling through the VLDLR-dependent pathway results in inhibition of Fyn, thereby increasing leukocyte transmigration. Furthermore, our in vivo experiments revealed that ß15-42 inhibits this pathway, thereby preventing inhibition of Fyn and reducing leukocyte transmigration. Thus, this study clarifies the molecular mechanism underlying the VLDLR-dependent pathway of leukocyte transmigration and reveals that this pathway is a target for ß15-42.

The Fibrin-Derived Peptide Bß15-42 (FX06) Ameliorates Vascular Leakage and Improves Survival and Neurocognitive Recovery: Implications From Two Animal Models of Cardiopulmonary Resuscitation.

OBJECTIVES: The fibrin-derived peptide Bß15-42 (FX06) has been proven to attenuate ischemia/reperfusion injury. We tested the hypothesis that Bß15-42 improves survival rate and neurocognitive recovery after cardiopulmonary resuscitation. DESIGN: Pig and mouse model of cardiopulmonary resuscitation. SETTING: Two university hospitals. SUBJECTS: Pigs and mice. INTERVENTIONS: Pigs (n = 16) were subjected to 8-minute cardiac arrest. Successful resuscitated pigs (n = 12) were randomized either to 3 mg/kg Bß15-42 followed by a continuous infusion of 1 mg/kg/hr for 5 hours (pFX06; n = 6) or the control group (pCONTROL; n = 6). Cardiac damage, function, and hemodynamics were recorded up to 8 hours. Mice (n = 52) were subjected to 4-minute cardiac arrest followed by cardiopulmonary resuscitation, and randomized either to two boli of 2.4 mg/kg Bß15-42 (mFX06; n = 26) or the control group (mCONTROL; n = 26). Fourteen-day survival rate, neurocognitive function, and endothelial integrity (additional experiment with n = 26 mice) were evaluated. MEASUREMENTS AND MAIN RESULTS: Bß15-42 reduced cumulative fluid intake (3,500 [2,600-4,200] vs 6,800 [5,700-7,400] mL; p = 0.004) within 8 hours in pigs. In mice, Bß15-42 improved 14-day survival rate (mFX06 vs mCONTROL; 11/26 vs 6/26; p < 0.05) and fastened neurocognitive recovery in the Water-Maze test (15/26 vs 9/26 mice with competence to perform test; p < 0.05). Bß15-42-treated mice showed a significant higher length of intact pulmonary endothelium and reduced pulmonary leukocyte infiltration. CONCLUSIONS: This study confirms the new concept of an important role of fibrin derivatives in global ischemia/reperfusion injury, which can be attenuated by the fibrin-derived peptide Bß15-42.

[Safety and efficacy of rivaroxaban for prevention of deep vein thrombosis in patients with preoperative abnormal D-dimer after total knee arthroplasty].

OBJECTIVE: To evaluate the safety and efficacy of rivaroxaban for prevention of deep vein thrombosis (DVT) in patients with preoperative abnormal D-dimer after total knee arthroplasty (TKA). METHODS: Between August and September 2013, 60 consecutive patients with varus knee osteoarthritis undergoing unilateral TKA were enrolled in the study. According to the preoperative D-dimer level, the patients were divided into 2 groups: D-dimer normal group (control group, n = 41) and D-dimer abnormal group (test group, n = 19). No significant difference was found in gender, age, body mass index, and preoperative knee range of motion between 2 groups (P > 0.05). All patients underwent conventional primary TKA and anticoagulation therapy with rivaroxaban to prevent DVT. The tourniquet use time, postoperative hospitalization time, and total hospitalization time were compared between 2 groups. At 1, 3, and 5 days after operation, prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB), and D-dimer were measured. Wound complications and DVT were observed. RESULTS: The postoperative hospitalization time of the test group was significantly longer than that of the control group (t = 2.327, P = 0.031), while the tourniquet use time and total hospitalization time showed no significant difference between 2 groups (P > 0.05). All the patients were followed up 6-8 months (mean, 7.2 months). Wound complications occurred in 3 cases (7.3%) of the control group and in 2 cases (10.5%) of the test group, showing no significant difference (χ2 = 0.175, P = 0.676). Color ultrasonography showed no pulmonary embolism and DVT at 6 weeks after TKA. There were significant differences in PT, TT, and FIB between at pre- and post-TKA in the same group, but no significant difference was found between 2 groups. The APTT and D-dimer had significant differences between at pre- and post-TKA in the same group, and between groups. There was no significant interaction effect between time and group for each index. CONCLUSION: Preoperative abnormal D-dimer level should not be regarded as a contraindication for TKA. The risks of DVT and wound complications in patients with abnormal D-dimer level are similar to patients with normal D-dimer level using rivaroxaban administration after TKA. It is unnecessary to conventional monitor D-dimer and other coagulation and hemorrhage laboratory tests in the patients after TKA.

The small fibrinopeptide Bß15-42 as renoprotective agent preserving the endothelial and vascular integrity in early ischemia reperfusion injury in the mouse kidney.

Disruption of the renal endothelial integrity is pivotal for the development of a vascular leak, tissue edema and consequently acute kidney injury. Kidney ischemia amplifies endothelial activation and up-regulation of pro-inflammatory mechanisms. After restoring a sufficient blood flow, the kidney is damaged through complex pathomechanisms that are classically referred to as ischemia and reperfusion injury, where the disruption of the inter-endothelial connections seems to be a crucial step in this pathomechanism. Focusing on the molecular cell-cell interaction, the fibrinopeptide Bß15-42 prevents vascular leakage by stabilizing these inter-endothelial junctions. The peptide associates with vascular endothelial-cadherin, thus preventing early kidney dysfunction by preserving blood perfusion efficacy, edema formation and thus organ dysfunction. We intended to demonstrate the early therapeutic benefit of intravenously administered Bß15-42 in a mouse model of renal ischemia and reperfusion. After 30 minutes of ischemia, the fibrinopeptide Bß15-42 was administered intravenously before reperfusion was commenced for 1 and 3 hours. We show that Bß15-42 alleviates early functional and morphological kidney damage as soon as 1 h and 3 h after ischemia and reperfusion. Mice treated with Bß15-42 displayed a significantly reduced loss of VE-cadherin, indicating a conserved endothelial barrier leading to less neutrophil infiltration which in turn resulted in significantly reduced structural renal damage. The significant reduction in tissue and serum neutrophil gelatinase-associated lipocalin levels reinforced our findings. Moreover, renal perfusion analysis by color duplex sonography revealed that Bß15-42 treatment preserved resistive indices and even improved blood velocity. Our data demonstrate the efficacy of early therapeutic intervention using the fibrinopeptide Bß15-42 in the treatment of acute kidney injury resulting from ischemia and reperfusion. In this context Bß15-42 may act as a potent renoprotective agent by preserving the endothelial and vascular integrity.

Effects of FX06 in vitro on platelet, coagulation, and fibrinolytic biomarkers in volunteers and patients with documented coronary artery disease.

FX06 is a naturally occurring fibrin-derived peptide demonstrated to confer cytoprotection in the setting of primary percutaneous coronary intervention. Because the effect of FX06 on human platelet, coagulation, and fibrinolysis biomarkers (PCFB) is unknown but is important for further clinical development, we evaluated how FX06 affects PCFB. The in vitro effects of the whole-blood pre-incubation with escalating concentrations of FX06 (4, 25, and 75 µg/mL) were assessed in aspirin-naïve healthy volunteers (n = 10), those with multiple risk factors for vascular disease (n = 10), and patients with documented coronary artery disease (n = 10). The last two groups were treated with aspirin (81 mg/daily). Thirty-two variables of PCFB were measured with the vehicle and for each chosen FX06 dose. Pretreatment of blood samples with FX06 resulted in a moderate but significant and mostly dose-dependent increases of platelet aggregation induced by adenosine diphosphate and collagen. Similarly, the closure time was reduced, suggesting share-induced activation, PECAM-1, GP Ib, GP IIb/IIIa activity, and vitronectin receptors, which were also up-regulated. In contrast, P-selectin and GPIIb antigen expression were reduced after FX06. All other PCFB were predominantly unaffected by FX06, with the exception of the increased plasminogen, decreased protein C activity, and activated von Willebrand factor. We conclude that in the therapeutic range, FX06 in vitro mildly affects hemostasis by way of mostly activating platelets. Applying moderate concomitant antiplatelet strategies should be considered for the adequate protection from vascular thrombotic events in patients treated with FX06. Similar ex vivo study in patients receiving aspirin and clopidogrel is warranted.

The NF-κB pathway: regulation of the instability of atherosclerotic plaques activated by Fg, Fb, and FDPs.

Recently, the molecular mechanism responsible for the instability of atherosclerotic plaques has gradually become a hot topic among researchers and clinicians. Matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) play an important role in the processes of formation and development of atherosclerosis. In this study, we established and employed the transwell co-culture system of rabbit aortic endothelial cells and smooth muscle cells to explore the relationship between fibrin (Fb), fibrinogen (Fg), and/or their degradation products (FDPs) in relation to the instability of atherosclerotic plaques; meanwhile, we observed the effects of Fg, Fb, and FDPs on the mRNA levels of MMPs and VEGF as well as on the activation of nuclear factor-kappa B (NF-κB). We concluded that Fb, Fg, and FDPs are involved in the progression of the instability of atherosclerotic plaques via increasing the expression of MMPs and VEGF. This effect might be mediated by the NF-кB pathway.

The fibrin-derived peptide bß15-42 attenuates liver damage in a rat model of liver ischemia/reperfusion injury.

The inflammatory response after liver ischemia/reperfusion (I/R) contributes to increased risk of liver failure after liver surgery. Strategies aimed to preventing inflammation could be beneficial in reducing liver I/R injury. Recent studies have demonstrated that peptide Bß15-42 is able to decrease the injury of I/R in heart and kidney by inhibition of leukocyte migration and preserving endothelial barrier function. Prompted by these results, we hypothesized that Bß15-42 could also possess anti-inflammatory abilities to protect from or reduce hepatic I/R injury. Therefore, in this study, we aimed to evaluate the effects of Bß15-42 in a model of liver I/R injury in rats. Rats were treated with Bß15-42 at initiation of reperfusion and 2 h thereafter. Rats were killed at 0.5, 6, 24, and 48 h after reperfusion. Hepatic mRNA levels of fibrinogen-α (Fgα), Fgß, Fgγ were significantly increased after I/R. Treatment with Fg-derived Bß15-42 ameliorated liver I/R injury, as indicated by lower serum aminotransferase levels and fewer I/R-associated histopathologic changes. Bß15-42 treatment decreased leukocyte infiltration and expression of hepatic inflammatory cytokines. Moreover, Bß15-42 significantly reduced high-mobility group box 1 release and altered mitogen-activated protein kinase activation. In conclusion, Bß15-42 treatment protected against liver warm I/R injury. The mechanism of protective action of Bß15-42 seemed to involve its ability to reduce hepatic inflammatory response through preventing high-mobility group box 1 release and altering mitogen-activated protein kinase activation.

The fibrinopeptide bß15-42 reduces inflammation in mice subjected to polymicrobial sepsis.

Sepsis is still a leading cause of death on intensive care units. Despite intensive research, only few new therapies have been developed and used in the clinical setting. The fibrin fragment Bß15-42 was already shown to preserve endothelial barrier function by binding to VE-cadherin and thus stabilize the interendothelial junctions. This was accompanied by reduced inflammation. Now we show that treatment with Bß15-42 reduces inflammation in a murine polymicrobial sepsis model. Administration of Bß15-42 reduced proinflammatory cytokine levels in the lung, liver, and blood and decreased neutrophil infiltration into the lung. Analysis alanine aminotransferase and aspartate aminotransferase further indicated reduced liver damage following polymicrobial sepsis. In vitro experiments using endothelial cells and macrophages further revealed that Bß15-42 had no direct effect on Toll-like receptor-mediated inflammation. Therefore, we assume that attenuated inflammation is rather due to sustained vascular integrity and thus suppresses vascular leakage and subsequently leukocyte infiltration during sepsis.

Prognosis analysis and risk factors related to progressive intracranial haemorrhage in patients with acute traumatic brain injury.

BACKGROUND: Since progressive intracranial haemorrhage (PIH) was introduced in neurosurgical literatures, several studies have been performed. PIH has been shown to be associated with a high increase in the risk of clinical worsening and related to morbidity and mortality as well. So, early detection and prediction of PIH is practically important in a clinical situation. OBJECTIVES: To investigate the risk factors related to PIH in patients with acute traumatic brain injury (TBI) and analyse their clinical significances. METHODS: PIH was confirmed by comparing the first and repeated CT scans. Data compared included gender, age, mechanism of injury, Glasgow Coma Score (GCS) at admission, timing from injury to the first CT, the signs of the initial CT scan, prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (Fg), thrombin time (TT), platelet (PLT) and D-dimer (D-D) values. Logistic regression analysis was used to show the risk factors related to PIH. RESULTS: A cohort of 498 patients with TBI was evaluated, and there were 139 (27.91%) patients who suffered from PIH. The differences between PIHs and non-PIHs were significant in age, GCS at admission, the signs of the initial CT scan (fracture, subarachnoid haemorrhage, brain contusion and primary haematoma), PT, Fg and D-D values (p < 0.001). Logistic regression analysis was used to identify that CT scans (subarachnoid haemorrhage, brain contusion and primary haematoma) and plasma D-D values as the most important predictors of PIH (p < 0.001). CONCLUSIONS: For patients with the initial CT scan showing subarachnoid haemorrhage, brain contusion and primary haematoma with abnormal D-D levels, an earlier and dynamic CT scan should be performed, for the detection of PIH as early as possible and the medical intervention would be enforced in time.

Pravastatin inhibits C-reactive protein generation induced by fibrinogen, fibrin and FDP in isolated rat vascular smooth muscle cells.

OBJECTIVE: The available evidence indicates that C-reactive protein (CRP) participates directly in atherosclerosis formation as an inflammatory molecule. Our previous investigation suggested that fibrinogen, fibrin and fibrinogen degradation products (FDP) produce a pro-inflammatory effect on vascular smooth muscle cells (VSMCs) through inducing CRP generation. In the present study, we observed the effect of pravastatin on CRP generation induced by fibrinogen, fibrin and FDP in rat VSMCs. METHODS: VSMCs from Sprague-Dawley rats were cultured. Fibrinogen, fibrin and FDP were used as stimulants for CRP generation. VSMCs were preincubated with pravastatin at 10, 30, 100 µM for 30 min prior to stimulation. CRP mRNA expression was studied by reverse transcription polymerase chain reaction (RT-PCR). CRP levels in the supernatant of VSMCs were measured by enzyme-linked immunosorbent assay (ELISA). CRP expression in VSMCs was examined with immunocytochemical staining. RESULTS: ELISA analysis showed that the pravastatin concentration-dependently reduced fibrinogen-, fibrin- and FDP-stimulated generation of CRP in VSMCs, with maximal inhibition of 56.6, 55.7 and 62.3%, respectively. Immunocytochemical staining and RT-PCR revealed that pravastatin inhibited protein and mRNA expression of CRP in VSMCs significantly. CONCLUSIONS: Pravastatin at the concentrations used in the present experiment has ability to relieve vascular inflammation and to restrain atherosclerotic processes via inhibiting the CRP production induced by fibrinogen, fibrin and FDP in VSMCs, which helps explain the beneficial effects of pravastatin on atherosclerosis.

Fibrinolysis is down-regulated in mouse collagen-induced arthritis, but its normalization does not alleviate the course of disease.

OBJECTIVE: Down-regulation of fibrinolysis and increased fibrin deposition in joints are hallmarks of rheumatoid arthritis (RA), and are believed to be involved in disease progression. The mouse model of collagen-induced arthritis (CIA) closely resembles RA and has been used to explore mechanism and treatments of RA, but neither the fibrinolytic system nor pro-fibrinolytic therapies were investigated in CIA. MATERIALS AND METHODS: Plasmin activity, levels of plasminogen activator inhibitor (PAI-1), D-dimer, and IL-6 were measured in plasma of CIA mice. Fibrin deposition and PAI-1 levels were also measured in inflamed joints. Mice were treated with plasminogen activators uPA (urokinase-type plasminogen activator) or tPA (tissue-type plasminogen activator). Effects of treatment on disease severity and fibrinolytic system were assessed. RESULTS: CIA caused decrease in plasmin activity, accompanied by increase in PAI-1 levels, in both blood and inflamed joints. This resulted in massive fibrin deposition in synovium. PAI-1 levels correlated negatively with plasmin activity and positively with IL-6. Treatments with uPA and tPA improved plasmin activity and removed fibrin deposits in inflamed joints. However, disease severity remained unchanged. CONCLUSIONS: Fibrinolytic changes in CIA parallel changes in RA, making CIA a suitable model to study fibrinolysis in RA. Normalization of plasmin activity in CIA after treatment with plasminogen activators had no effect on disease severity.

Interaction of fibrin with VE-cadherin and anti-inflammatory effect of fibrin-derived fragments.

BACKGROUND: The interaction of the fibrin ßN-domain with VE-cadherin on endothelial cells is implicated in transendothelial migration of leukocytes, and the ß15-42 fragment representing part of this domain has been shown to inhibit this process. However, our previous study revealed that only a dimeric (ß15-66)(2) fragment, corresponding to the full-length ßN-domain and mimicking its dimeric arrangement in fibrin, bound to VE-cadherin. OBJECTIVE: To test our hypothesis that dimerization of ß15-42-containing fragments increases their affinity for VE-cadherin and ability to inhibit transendothelial migration of leukocytes. METHODS: Interaction of ß15-42-containing fragments with VE-cadherin was characterized by ELISA and surface plasmon resonance. The inhibitory effect of such fragments was tested in vitro with a leukocyte transendothelial migration assay and in vivo with mouse models of peritonitis and myocardial ischemia-reperfusion injury. RESULTS: First, we prepared the monomeric ß15-42 and ß15-64 fragments and their dimeric forms, (ß15-44)(2) and (ß15-66)(2) , and studied their interaction with the fibrin-binding domain of VE-cadherin, VE-cad(3). The experiments revealed that both dimeric fragments bound to VE-cad(3) with high affinity, whereas the affinities of ß15-42 and ß15-64 were significantly lower. Next, we tested the ability of these fragments to inhibit leukocyte transmigration in vitro and infiltration into the inflamed peritoneum in vivo, and found that the inhibitory effects of the dimers on these processes were also superior. Furthermore, (ß15-44)(2) significantly reduced myocardial injury induced by ischemia-reperfusion. CONCLUSION: The results confirm our hypotheses and indicate that (ß15-66)(2) and (ß15-44)(2) , which exhibited much higher affinity for VE-cadherin, are highly effective in suppressing inflammation by inhibiting leukocyte transmigration.

Fibrin degradation enhances vascular smooth muscle cell proliferation and matrix deposition in fibrin-based tissue constructs fabricated in vitro.

Completely biological tissue replacements can be fabricated by entrapping cells in a molded fibrin gel. Over time, the fibrin is degraded and replaced with cell-produced extracellular matrix. However, the relationship between fibrin degradation and matrix deposition has not been elucidated. We developed techniques to quantify fibrin degradation products (FDP) and examine plasmin activity in the conditioned medium from fibrin-based constructs. Fibrin-based tissue constructs fabricated with vascular smooth muscle cells (vSMC) were cultured for 5 weeks in the presence of varied concentrations of the fibrinolysis inhibitor -aminocaproic acid and cellularity, and deposited collagen and elastin were measured weekly. These data revealed that increasing concentrations of -aminocaproic acid led to delayed and diminished FDP production, lower vSMC proliferation, and decreased collagen and elastin deposition. FDP were shown to have a direct biological effect on vSMC cultures and vSMC within the fibrin-based constructs. Supplementing construct cultures with 250 or 500µg/mL FDP led to 30% higher collagen deposition than the untreated controls. FDP concentrations as high as 250µg/mL were estimated to exist within the constructs, indicating that FDP generation during remodeling of the fibrin-based constructs exerted direct biological activity. These results help explain many of the positive outcomes reported with fibrin-based tissue constructs in the literature, as well as demonstrate the importance of regulating plasmin activity during their fabrication.