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Introduction: In patients with an increased bleeding tendency, extensive diagnostic blood testing is often performed. When results of tier 1 assays of primary haemostasis are normal, protocols recommend additional testing to rule out rare disorders including coagulation factor XIII (FXIII) and α2-antiplasmin (α2AP) deficiency., Aim: To evaluate the added diagnostic value of FXIII and α2AP levels in patients with a bleeding disorder of unknown cause (BDUC)., Methods: A retrospective monocentre cohort study between August 2011 and August 2023 was conducted. In all patients with bleeding tendencies and normal diagnostic tests for von Willebrand disease and platelet function, FXIII and α2AP were measured., Results: We included 158 consecutive patients; mean ISTH-BAT scores were 8.2 (SD ± 3.7) in children, 6.2 (SD ± 2.1) in men and 10.6 (SD ± 3.3) in women. Median age was 37 (range 5-79) years, 88.6% of patients were female. Patients displayed median FXIII activity of 111% (IQR = 97-131) and median α2AP activity of 112% (IQR = 103-119). Three (1.9%) patients had FXIII levels < 50%, respectively 43%, 45% and 46%. Corresponding ISTH-BAT scores were 7, 12 and 14. No α2AP levels < 60% was observed. No significant association was found between FXIII levels and ISTH-BAT scores., Conclusion: In our cohort of BDUC patients, no clinical relevant FXIII deficiencies were detected; absolute values were well above the 30% cutoff considered adequate for normal haemostasis. No α2AP deficiencies were detected. These data suggest that in BDUC patients, measuring FXIII or AP activity is of limited value., (© 2024 The Author(s). Haemophilia published by John Wiley & Sons Ltd.)

Objectives: Depression is a psychiatric disorder that affects about 10% of the world's population and is accompanied by anxiety. Depression and anxiety are often caused by various stresses. However, the etiology of depression and anxiety remains unknown. It has been reported that alpha2-antiplasmin ( α 2AP) not only inhibits plasmin but also has various functions such as cytokine production and cell growth. This study aimed to determine the roles of α 2AP on the stress-induced depression and anxiety., Methods: We investigated the mild repeated restraint stress-induced depressive and anxiety-like behavior in the α 2AP +/+ and α 2AP -/- mice using the social interaction test (SIT), sucrose preference test (SPT), and elevated plus maze (EPM)., Results: The stresses such as the mild repeated restraint stress suppressed α 2AP expression in the hippocampus of mice, and the treatment of fluoxetine (selective serotonin reuptake inhibitor [SSRI]) recovered the stress-caused α 2AP suppression. We also showed that α 2AP deficiency promoted the mild restraint stress-stimulated depression-like behavior such as social withdrawal and apathy and apoptosis in mice. In contrast, α 2AP deficiency attenuated the mild restraint stress induced the anxiety-like behavior in mice., Conclusions: α 2AP affects the pathogenesis of depression and anxiety induced by stress., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Background: The plasma serine protease inhibitor alpha 2-antiplasmin (α 2 -AP, otherwise known as α 2 -plasmin inhibitor) is a rapid-acting plasmin inhibitor recently found in human plasma, which seems to have a significant role in the regulation of in vivo fibrinolysis. Congenital deficiency of α 2 -AP is extremely uncommon., Case Presentation: We report here a case of absolute deficiency of α 2 -AP in an 11-year-old Sudanese boy, who had a lifelong intermittent hemorrhagic tendency (gum bleeding, epistaxis, and exaggerated bleeding after trauma). Coagulation tests including prothrombin time, partial thromboplastin time, thrombin time, bleeding time, platelet count, clot retraction test, antithrombin, and factor VIII levels were within normal limits. Hepatic function tests and complete blood count were also normal. The main interesting finding in this patient was that the whole blood clot lysis was extremely fast, completed within 5-8 hours. The second abnormal finding is that the euglobulin clot lysis time was short. Nevertheless, the concentration of α 2 -AP in the patient's plasma was 0.2 IU/ml (reference range is 0.80-1.20 IU/ml). The addition of pooled plasma (with normal α 2 -AP) to the patient's whole blood corrected the accelerated fibrinolysis., Conclusion: The study showed that α 2 -AP deficiency resulted in uninhibited fibrinolysis that caused the hemorrhagic tendency in this patient. Thus, this report demonstrates the significant role of α 2 -AP in coagulation.

Background: Congenital alpha-2 antiplasmin deficiency is a rare, often misdiagnosed coagulopathy that may result in severe hemorrhage. Homozygous patients develop symptomatology in early childhood, while heterozygous individuals may be asymptomatic or bleed profusely following invasive dental procedures, surgery or trauma late in life. Due to the rarity of this entity, we performed an analysis of reported cases of congenital alpha-2 antiplasmin deficiency to share uncommon cases with the medical community, to raise awareness of the condition among clinicians, and to promote better patient management., Methods: To identify relevant studies, PubMed and Science Direct were searched using controlled vocabulary and keywords based on medical subject headings (MeSH). Data of all reported cases of congenital alpha-2 antiplasmin deficiency were extracted and summarized for study setting, patient characteristics, and types of treatments., Results: Thirty-three publications were identified encompassing one hundred twenty-three patients. This manuscript presents many important clinical conditions that are uncommon and may go undetected by medical personnel. It illustrates the importance of considering alpha-2 antiplasmin deficiency in the work-up of patients who present with a severe bleeding phenotype and may have normal coagulation screening tests. Management of such patients may be challenging especially when the diagnosis of alpha-2 antiplasmin deficiency is not known., Conclusions: Improved awareness and access to diagnostic tools will contribute to better management of rare co-agulopathies.

α2-Antiplasmin (α2AP), a principal physiological plasmin inhibitor, is mainly produced by the liver and kidneys, but it is also expressed in several parts of the brain, including the hippocampus and cerebral cortex. Our previous study demonstrated that α2AP knockout mice exhibit spatial memory impairment in comparison to wild-type mice, suggesting that α2AP is necessary for the fetal and/or neonatal development of the neural network for spatial memory. However, it is still unclear whether α2AP plays a role in the memory process. The present study demonstrated that adult hippocampal neurogenesis and remote spatial memory were enhanced by the injection of an anti-α2AP neutralizing antibody in WT mice, while the injection of α2AP reduced hippocampal neurogenesis and impaired remote spatial memory, suggesting that α2AP is a negative regulator in memory processing. The present study also found that the levels of α2AP in the brains of old mice were higher than those in young mice, and a negative correlation between the α2AP level and spatial working memory. In addition, aging-dependent brain oxidative stress and hippocampal inflammation were attenuated by α2AP deficiency. Thus, an age-related increase in α2AP might cause cognitive decline accompanied by brain oxidative stress and neuroinflammation. Taken together, our findings suggest that α2AP is a key regulator of the spatial memory process, and that it may represent a promising target to effectively regulate healthy brain aging.

Deficiencies or excessive activation of the  fibrinolytic system can result in severe, lifelong bleeding disorders. The most severe clinical phenotype is caused by α2-Antiplasmin (α2-AP) deficiency which results in excess fibrinolysis due to the inability to inhibit plasmin. Another bleeding disorder due to a defect in the fibrinolytic pathway results from Plasminogen activator inhibitor-1 (PAI-1) deficiency causing enhanced fibrinolysis due to the decreased inhibition of plasminogen activators resulting in increased conversion of plasminogen to plasmin. Both these disorders are rare and have an autosomal recessive pattern of inheritance. They can remain undetected as routine coagulation and platelet function tests are normal. A unique gain-of-function defect in fibrinolysis causes the Quebec platelet disorder (QPD) which is characterized by profibrinolytic platelets containing increased urokinase-type plasminogen activator (uPA) in the α-granules. A high index of suspicion based on clinical phenotype along with the availability of specialized hemostasis testing is required for timely and accurate diagnosis. Antifibrinolytic agents, such as tranexamic acid or ε-aminocaproic acid, are the mainstays of treatment which inhibit fibrinolysis by preventing the binding of plasminogen to fibrin and thereby stabilizing the fibrin clot. The purpose of this review is to summarize the pathogenesis, clinical phenotype, approaches to diagnosis and treatment for these three major disorders of fibrinolysis., (Copyright © 2019. Published by Elsevier Ltd.)

Acquired factor XIII (FXIII) deficiency is a rare and life-threatening condition that is often misdiagnosed or missed completely. A 72-year-old woman presented with symptoms of major unprovoked bleeding but routine coagulation screening tests and platelet count were normal. Low activated FXIII (FXIIIa) activity levels and abnormal urea clot stability led to diagnosis of acquired FXIII deficiency. A modified Bethesda inhibitor titre of 1.6 Bethesda units/ml indicated the presence of a FXIII inhibitor. Bleeding responded to a single dose of FXIII concentrate and immunosuppression with prednisolone induced remission. A subsequent relapse was treated with combined prednisolone and Rituximab resulting in a prolonged, ongoing remission. Here we analyse the mechanisms underlying this idiopathic case of acquired FXIII deficiency. Prospective analysis of patient plasma revealed minimal FXIIIa activity and antigen in presentation and relapse samples. Thrombi formed from these samples lysed rapidly and showed an absence of cross-linked α 2 AP. Western blotting revealed the presence of FXIII-B, indicating only FXIII-A and FXIII-A 2 B 2 were affected. FXIII activity and antigen levels normalised on remission. Our data suggest the presence of inhibitor-induced clearance of FXIII from plasma. As a consequence, reduced thrombus stability was evident due to defective α 2 AP cross-linking, thereby explaining symptoms of excessive bleeding., (© 2017 John Wiley & Sons Ltd.)

Background: In patients with hemodynamically significant pulmonary embolism, physiological fibrinolysis fails to dissolve thrombi acutely and r-tPA (recombinant tissue-type plasminogen activator) therapy may be required, despite its bleeding risk. To examine potential mechanisms, we analyzed the expression of key fibrinolytic molecules in experimental pulmonary emboli, assessed the contribution of α2-antiplasmin to fibrinolytic failure, and compared the effects of plasminogen activation and α2-antiplasmin inactivation on experimental thrombus dissolution and bleeding., Methods: Pulmonary embolism was induced by jugular vein infusion of 125 I-fibrin or fluorescein isothiocyanate-fibrin labeled emboli in anesthetized mice. Thrombus site expression of key fibrinolytic molecules was determined by immunofluorescence staining. The effects of r-tPA and α2-antiplasmin inactivation on fibrinolysis and bleeding were examined in a humanized model of pulmonary embolism., Results: The plasminogen activation and plasmin inhibition system assembled at the site of acute pulmonary emboli in vivo. Thrombus dissolution was markedly accelerated in mice with normal α2-antiplasmin levels treated with an α2-antiplasmin-inactivating antibody ( P <0.0001). Dissolution of pulmonary emboli by α2-antiplasmin inactivation alone was comparable to 3 mg/kg r-tPA. Low-dose r-tPA alone did not dissolve emboli, but was synergistic with α2-antiplasmin inactivation, causing more embolus dissolution than clinical-dose r-tPA alone ( P <0.001) or α2-antiplasmin inactivation alone ( P <0.001). Despite greater thrombus dissolution, α2-antiplasmin inactivation alone, or in combination with low-dose r-tPA, did not lead to fibrinogen degradation, did not cause bleeding (versus controls), and caused less bleeding than clinical-dose r-tPA ( P <0.001)., Conclusions: Although the fibrinolytic system assembles at the site of pulmonary emboli, thrombus dissolution is halted by α2-antiplasmin. Inactivation of α2-antiplasmin was comparable to pharmacological r-tPA for dissolving thrombi. However, α2-antiplasmin inactivation showed a unique pattern of thrombus specificity, because unlike r-tPA, it did not degrade fibrinogen or enhance experimental bleeding. This suggests that modifying the activity of a key regulator of the fibrinolytic system, like α2-antiplasmin, may have unique therapeutic value in pulmonary embolism., (© 2016 American Heart Association, Inc.)

Many pathogens usurp the host hemostatic system during infection to promote pathogenesis. Yersinia pestis, the causative agent of plague, expresses the plasminogen activator protease Pla, which has been shown in vitro to target and cleave multiple proteins within the fibrinolytic pathway, including the plasmin inhibitor α2-antiplasmin (A2AP). It is not known, however, if Pla inactivates A2AP in vivo; the role of A2AP during respiratory Y. pestis infection is not known either. Here, we show that Y. pestis does not appreciably cleave A2AP in a Pla-dependent manner in the lungs during experimental pneumonic plague. Furthermore, following intranasal infection with Y. pestis, A2AP-deficient mice exhibit no difference in survival time, bacterial burden in the lungs, or dissemination from wild-type mice. Instead, we found that in the absence of Pla, A2AP contributes to the control of the pulmonary inflammatory response during infection by reducing neutrophil recruitment and cytokine production, resulting in altered immunopathology of the lungs compared to A2AP-deficient mice. Thus, our data demonstrate that A2AP is not significantly affected by the Pla protease during pneumonic plague, and although A2AP participates in immune modulation in the lungs, it has limited impact on the course or ultimate outcome of the infection., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

Factor XIII(a) [FXIII(a)] stabilizes clots and increases resistance to fibrinolysis and mechanical disruption. FXIIIa also mediates red blood cell (RBC) retention in contracting clots and determines venous thrombus size, suggesting FXIII(a) is a potential target for reducing thrombosis. However, the mechanism by which FXIIIa retains RBCs in clots is unknown. We determined the effect of FXIII(a) on human and murine clot weight and composition. Real-time microscopy revealed extensive RBC loss from clots formed in the absence of FXIIIa activity, and RBCs exhibited transient deformation as they exited the clots. Fibrin band-shift assays and flow cytometry did not reveal crosslinking of fibrin or FXIIIa substrates to RBCs, suggesting FXIIIa does not crosslink RBCs directly to the clot. RBCs were retained in clots from mice deficient in α2-antiplasmin, thrombin-activatable fibrinolysis inhibitor, or fibronectin, indicating RBC retention does not depend on these FXIIIa substrates. RBC retention in clots was positively correlated with fibrin network density; however, FXIIIa inhibition reduced RBC retention at all network densities. FXIIIa inhibition reduced RBC retention in clots formed with fibrinogen that lacks γ-chain crosslinking sites, but not in clots that lack α-chain crosslinking sites. Moreover, FXIIIa inhibitor concentrations that primarily block α-, but not γ-, chain crosslinking decreased RBC retention in clots. These data indicate FXIIIa-dependent retention of RBCs in clots is mediated by fibrin α-chain crosslinking. These findings expose a newly recognized, essential role for fibrin crosslinking during whole blood clot formation and consolidation and establish FXIIIa activity as a key determinant of thrombus composition and size., (© 2015 by The American Society of Hematology.)

As the development of a hypercoagulable state in the setting of disseminated intravascular coagulation (DIC) induces localized infection, therapy for DIC should be evaluated according to the findings of examinations for both severe sepsis and DIC. DIC is classified into the following types: "bleeding type," "organ failure type," "asymptomatic type," and "complication type." The "bleeding type" and "organ failure type" are considered to reflect the "plasmin inhibitor (PI) deficiency type" and "antithrombin (AT) deficiency type," respectively. In order to improve the diagnosis of DIC, in particular limitations in global coagulation tests, the Japanese Society of Thrombosis and Hemostasis recently proposed tentative diagnostic criteria for DIC using hemostatic molecular markers and AT. The recommendations for treatment of DIC, especially the use of AT concentrates, recombinant activated protein C and thrombomodulin, vary among several guidelines for the management of DIC. These agents inhibit the effects of key proteases in activating coagulation and consequently exert an anti-inflammatory effect on DIC. Hence, it is necessary to extensively evaluate these agents in well-conducted clinical trials.

Objective: Ischemic stroke is primarily attributable to thrombotic vascular occlusion. Elevated α2-antiplasmin (a2AP) levels correlate with increased stroke risk, but whether a2AP contributes to the pathogenesis of stroke is unknown. We examined how a2AP affects thrombosis, ischemic brain injury, and survival after experimental cerebral thromboembolism., Approach and Results: We evaluated the effects of a2AP on stroke outcomes in mice with increased, normal, or no circulating a2AP, as well as in mice given an a2AP-inactivating antibody. Higher a2AP levels were correlated with greater ischemic brain injury (rs=0.88, P<0.001), brain swelling (rs=0.82, P<0.001), and reduced middle cerebral artery thrombus dissolution (rs=-0.93, P<0.001). In contrast, a2AP deficiency enhanced thrombus dissolution, increased cerebral blood flow, reduced brain infarction, and decreased brain swelling. By comparison to tissue plasminogen activator (TPA), a2AP inactivation hours after thromboembolism still reduced brain infarction (P<0.001) and hemorrhage (P<0.05). Microvascular thrombosis, a process that enhances brain ischemia, was markedly reduced in a2AP-deficient or a2AP-inactivated mice compared with TPA-treated mice or mice with increased a2AP levels (all P<0.001). Matrix metalloproteinase-9 expression, which contributes to acute brain injury, was profoundly decreased in a2AP-deficient or a2AP-inactivated mice versus TPA-treated mice or mice with increased a2AP levels (all P<0.001). a2AP inactivation markedly reduced stroke mortality versus TPA (P<0.0001)., Conclusions: a2AP has profound, dose-related effects on ischemic brain injury, swelling, hemorrhage, and survival after cerebral thromboembolism. By comparison to TPA, the protective effects of a2AP deficiency or inactivation seem to be mediated through reductions in microvascular thrombosis and matrix metalloproteinase-9 expression., (© 2014 American Heart Association, Inc.)

Renal fibrosis is the final common pathway of a wide variety of chronic kidney diseases. Myofibroblast formation via the differentiation of from tissue-resident fibroblasts and bone marrow-derived mesenchymal stem cells (MSCs), and epithelial-to-mesenchymal transition (EMT) is known to play a pivotal role in the development of renal fibrosis. However, the detailed mechanisms underlying this disorder remain unclear. We herein investigated the role of alpha 2-antiplasmin (α2AP) in myofibroblast formation and the development of renal fibrosis. We observed the development of renal fibrosis using unilateral ureteral obstruction (UUO). α2AP had accumulated in the UUO-induced obstructed kidneys and α2AP deficiency attenuated UUO-induced renal fibrosis in mice. The degree of myofibroblast formation in the obstructed kidneys of α2AP(-/-) mice was less than that in α2AP(+/+) mice. In vitro, α2AP induced myofibroblast formation in renal tubular epithelial cells (RTECs), renal fibrosblasts, and bone marrow-derived mesenchymal stem cells (MSCs). α2AP also induced the production of TGF-β, which is known to be a key regulator of myofibroblast formation and fibrosis. α2AP-induced the TGF-β production was significantly reduced by SP600125, c-Jun N-terminal kinase (JNK) specific inhibitor. Our findings suggest that α2AP induces myofibroblast formation in the obstructed kidneys, and mediates the development of renal fibrosis.

Α 2 antiplasmin congenital deficiency is an uncommun fibrinolysis disorder that is diagnostics after a post-operative surgery. We report two brothers cases of α 2 antiplasmin deficiency diagnosed after a prostadenomectomy bleeding at two years intervals.

Objective: Familial amyloid polyneuropathy (FAP) is an autosomal dominant form of hereditary amyloidosis. Several studies reported coagulation factor X deficiency and excessive fibrinolysis in immunoglobulin light chain amyloidosis. However, few have investigated coagulation and fibrinolysis in FAP. The objective of this study was to determine abnormalities in plasma biomarkers of coagulation and fibrinolysis in FAP., Methods: We prospectively recruited eight FAP patients with transthyretin mutations and ten age-matched control patients with other neuropathies in our university. We examined plasma biomarkers of coagulation and fibrinolysis including prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin/fibrinogen degradation products, D-dimer, α2-antiplasmin, antithrombin, plasminogen, thrombin-antithrombin complex, plasmin-α2-antiplasmin complex, prothrombin fragment 1+2, and coagulation factor X. The Mann-Whitney U test was performed for statistical comparisons between FAP and control groups., Results: FAP patients exhibited significantly decreased levels of coagulation factor X, plasminogen and α2-antiplasmin, and significantly increased levels of prothrombin fragment 1+2 compared to control patients., Conclusion: Our results indicate abnormalities of coagulation and fibrinolysis in FAP patients.

Epistaxis, superficial and deep hematomas, hemarthrosis, gastrointestinal bleeding, hematuria represent the most frequent hemorrhagic events in congenital coagulation disorders. Occasionally, bleeding manifestations occur in unusual sites or are peculiar. A clotting defect may alter the clinical aspect of skin conditions or infections (hemorrhagic scabies or varicella). Hemobilia may occur as a complication of transjugular liver biopsy in hemophilia or Bernard-Soulier syndrome. Hemarthrosis of small joints of feet and hands occur in patients with hemophilia treated with protease inhibitors. Intramedullary hematomas of long bones have been described in α2-plasmin inhibitor or fibrinogen deficiencies. Spleen fracture with consequent hemoperitoneum has been reported in patients with fibrinogen deficiency. Rectus muscle sheath hematoma may occur in patients with factor VII (FVII)or FX deficiency. Acute or subacute intestinal obstruction may be caused by intramural wall hematomas in hemophilia and von Willebrand (vW)-disease. Physicians should always keep in mind that a congenital hemorrhagic disorder may cause bleeding in any tissue of the body and therefore alter the normal clinical features of a given disease.

In this brief report we present a patient with heterozygous alpha2 plasmin inhibitor (alpha2PI) deficiency who developed atherosclerosis and myocardial ischemia in the presence of multiple classical risk factors. Management was complicated by fear of bleeding complications with the use of antiplatelet agents and serious comorbidity.The role of alpha2PI in atherosclerosis and pathological clot formation is still not clear. This case shows, however, that atherosclerosis and acute cardiovascular events can develop in patients with reduced alpha2PI levels.

Bleeding diathesis and a hyper-fibrinolytic state often accompany a diagnosis of Acute Promyelocytic Leukaemia (APML). This complication can have grave effects if not successfully treated, with a 10-20% incidence of haemorrhagic death. We hypothesized that alpha-2-antiplasmin levels would correlate with the risk for bleeding, and that administration of epsilon-aminocaproic acid (EACA) would attenuate that risk. To assess this, we conducted a retrospective chart review analyzing 30 APML patients, 17 of whom were treated with EACA. Thirty patients were treated, 21 with primary induction therapy. Patients with low alpha-2-antiplasmin levels were treated with a coagulopathy protocol consisting of low-dose heparin, EACA and blood product support. Seventeen patients (57%) developed haemorrhagic complications during their treatment. The presence and grade of haemorrhage appeared to be associated with the alpha-2-antiplasmin level. There were no grade IV haemorrhages or episodes of haemorrhagic death. One episode of central venous catheter associated thromboembolism and three deaths from infection during chemotherapy were observed. alpha-2-Antiplasmin levels are a reliable surrogate for fibrinolysis and haemorrhagic risk in patients with APML. Treatment with EACA is a rational way to pharmacologically inhibit fibrinolysis, is associated with a low incidence of severe haemorrhagic events, and appears to be safe with a low risk of thrombosis. Randomized clinical trials further assessing the efficacy and potential toxicity of EACA in inhibiting fibrinolysis in patients with APML are needed., (Copyright (c) 2008 John Wiley & Sons, Ltd.)

Fibrinolysis serves an important role in the process of coagulation, ensuring that clots that are formed in response to injury resolve after the injured tissue is repaired. Fibrinolysis occurs because the protein plasminogen is converted to the active serine protease plasmin by its activating molecules (primarily tissue plasminogen activator). One of the inhibitors of fibrinolysis is alpha(2)-antiplasmin, which acts as the primary inhibitor of plasmin(ogen). Congenital deficiency of alpha(2)-antiplasmin causes a rare bleeding disorder because of increased fibrinolysis. Despite the rare nature of this disorder, understanding of the actions of alpha(2)-antiplasmin and the results of its deficiency has provided the opportunity for better understanding of the fibrinolytic system in both how it affects the risk of bleeding and its impact on other bodily systems. Here, we review the history of the discovery of alpha(2)-antiplasmin, our understanding of its genetics and function, and our current knowledge of its congenital deficiency. We also discuss some of the current avenues of investigation into its impact on other diseases and physiological states.

Plasmin is an essential enzyme located in the pericellular microenvironment of liver cells during liver regeneration. Previously, we reported that liver regeneration ability was significantly increased in alpha2-antiplasmin gene knockout mice as compared to wild-type mice, but it was significantly decreased in plasminogen knockout mice, or Plg/alpha2-antiplasmin gene knockout mice. The present study aimed to demonstrate direct interaction between plasminogen and mouse hepatocytes in the process of liver regeneration. Using the isolated hepatocytes from mice we analyzed following subjects: binding capacity of plasminogen to hepatocytes, plasminogen activation in the presence of hepatocytes, and proliferation ability of hepatocytes cocultured with liver nonparenchymal cells. The isolated hepatocytes from plasminogen wild-type mice bound to immobilized plasminogen. The mouse hepatocytes enhanced plasminogen activation, and impaired the inhibitory effect of alpha2-antiplasmin. The proliferation ability of hepatocytes after liver injury was studied. In plasminogen wild-type and plasminogen knockout mice, the hepatocytes cocultured with nonparenchymal cells, which were obtained from mice without CCl4 injection, showed similar proliferation abilities. On the contrary, the proliferation ability of hepatocytes cocultured with nonparenchymal cells, which were obtained from CCl4-treated plasminogen knockout mice, was significantly impaired as compared to wild-type mice. These results indicate that the plasminogen-plasmin system on the surface of mouse hepatocytes plays an important role in liver regeneration.

Background: Fibrotic disease occurs in most tissues. Transforming growth factor (TGF)-beta is the major inducer of fibrosis. The fibrinolytic system is considered to play an important role in the degradation of extracellular matrices. However, the detailed mechanism of how this system affects fibrosis remains unclear., Methods and Results: We examined experimental fibrosis in mice with a deficiency of alpha(2)-antiplasmin (alpha2AP), which is a potent and specific plasmin inhibitor. We found that the lack of alpha2AP attenuated bleomycin-induced TGF-beta(1) synthesis and fibrosis. In addition, the production of TGF-beta(1) from the explanted fibroblasts of alpha2AP(-/-) mice decreased dramatically as compared to that in wild-type mice. Moreover, we found that alpha2AP specifically induces the production of TGF-beta(1) in fibroblasts., Conclusion: The lack of alpha2AP attenuated TGF-beta(1) synthesis, thereby resulting in attenuated fibrosis. This is the first report to describe the crucial role that alpha2AP plays in TGF-beta(1) synthesis during the process of fibrosis. Our results provide new insights into the role of alpha2AP in fibrosis.

Intracranial hemorrhage in a term neonate is a rare event in the absence of an identifiable precipitating factor such as severe thrombocytopenia, mechanical trauma, asphyxia, infections, or congenital vascular malformations. Congenital disorders of glycosylation are a genetically and clinically heterogeneous group of multisystem disorders characterized by the abnormal glycosylation of a number of glycoproteins. Although bleeding caused by abnormal glycosylation of various coagulation factors is a well-known clinical complication of several types of congenital disorders of glycosylation, intracranial hemorrhage has not been reported as an initial manifestation of this entity. Here we report the detailed history of a family with 2 consecutive male infants, both born at term with intracranial hemorrhage diagnosed within the first 24 hours of life. The diagnosis of a congenital disorder of glycosylation was established in the second infant by an abnormal glycosylation of serum transferrin detected by electrospray-ionization mass spectrometry. Both infants showed significant neurologic deterioration during the first month of life, and both died at 5 months of age. Intracranial hemorrhage in a term neonate without a potential precipitating factor represents yet another clinical feature that should raise the suspicion for a congenital disorder of glycosylation.

Background: The fibrinolytic system is supposed to play an important role in the degradation of extracellular matrices for physiological and pathological tissue remodeling; however, the detailed mechanism regarding how this system affects cutaneous wound healing remains to be clarified., Methods and Results: We performed experimental cutaneous wounding in mice with a deficiency of alpha(2)-antiplasmin (alpha(2)AP), which is a potent and specific plasmin inhibitor. We found that an accelerated wound closure was observed in alpha(2)AP-deficient (alpha(2)AP-/-) mice in comparison with wild type (WT) mice. Moreover, we observed that a greater increase of angiogenesis occurred in the process of wound healing in alpha(2)AP-/- mice than in the WT mice. Intriguingly, mRNA expression of vascular endothelial growth factor (VEGF), which is the best characterized positive regulator of angiogenesis, in wound lesions was found to show a greater increase in the early phase of the healing process in alpha(2)AP-/- mice than in WT mice. In addition, the amount of released-VEGF from the explanted fibroblasts of alpha(2)AP-/- mice increased dramatically more than in the WT mice. Finally, the intra-jugular administration of anti-VEGF antibody clearly suppressed the increased angiogenesis and accelerated wound closure in the wound lesion of alpha(2)AP-/- mice., Conclusion: The lack of alpha(2)AP markedly causes an over-release of VEGF from the fibroblasts in cutaneous wound lesions, thereby inducing angiogenesis around the area, and thus resulting in an accelerated-wound closure., Conclusions: This is the first report to describe the crucial role that alpha(2)AP plays following angiogenesis in the process of wound healing. Our results provide new insight into the role of alpha(2)AP on cutaneous wound healing.

Haemostatic management of intraoral bleeding was investigated in patients with congenital alpha2-plasmin inhibitor (alpha2-PI) deficiency or congenital plasminogen activator inhibitor- 1 (PAI-1) deficiency. When extracting teeth from patients with congenital alpha2-PI deficiency, we advocate that 7.5-10 mg kg(-1) of tranexamic acid be administered orally every 6 h, starting 3 h before surgery and continuing for about 7 days. For the treatment of continuous bleeding, such as post-extraction bleeding, 20 mg kg(-1) of tranexamic acid should be administered intravenously, and after achieving local haemostasis 7.5 mg kg(-1) of tranexamic acid should be administered orally every 6 h for several days. In addition, when treating haematoma caused by labial or gingival laceration or buccal or mandibular contusion, haemostasis should be achieved by administering 7.5-10 mg kg(-1) of tranexamic acid every 6 h. Tranexamic acid can also be used for haemostatic management of intraoral bleeding in patients with congenital PAI-1 deficiency, but is less effective when compared with use in patients with congenital alpha2-PI deficiency. Continuous infusion of 1.5 mg kg(-1) h(-1) of tranexamic acid is necessary for impacted tooth extraction requiring gingival incision or removal of local bone.

We here report that the arterial blood flow after endothelial injury in mice deficient in alpha 2-antiplasmin (alpha 2-AP-/- mice) was well maintained compared with that of wild-type mice. Moreover, the development of neointima 4 weeks after injury in alpha 2-AP-/- mice was significantly decreased. Histologic observations showed a prompt recovery of endothelial cells with a much higher proliferating index in repaired endothelium in alpha 2-AP-/- mice. The amount of secreted vascular endothelial growth factor (VEGF) by explanted vascular smooth muscle cells (SMCs) from alpha 2-AP-/- mice was significantly increased. In separate experiments using a human endothelial cell (EC) line, we could demonstrate that plasminogen binds to ECs and that this binding can be prevented by alpha 2-AP. Finally, an injection of either an anti-VEGF receptor-1 antibody or alpha 2-AP reduced the prompt endothelial healing. alpha 2-AP is the main inactivator of plasmin, which cleaves extracellular matrix-bound VEGF to release a diffusible proteolytic fragment. Lack of alpha 2-AP, therefore, could lead to a local over-release of VEGF by the continuously active plasmin in the injured area, which could result in a prompt re-endothelialization after vascular injury. Our results provide new insight into the role of alpha 2-AP and VEGF in the pathogenesis of re-endothelialization following vascular injury.