Targeted Inactivation of the Mouse Locus Encoding Coagulation Factor XIII-A: Hemostatic Abnormalities in Mutant Mice and Characterization of the Coagulation Deficit

Abstract

SummaryBlood coagulation factor XIII (FXIII) promotes cross-linking of fibrin during blood coagulation; impaired clot stabilization in human genetic deficiency is associated with marked pathologies of major clinical impact, including bleeding symptoms and deficient wound healing. To investigate the role of FXIII we employed homologous recombination to generate a targeted deletion of the inferred exon 7 of the FXIII-A gene. FXIII transglutaminase activity in plasma was reduced to about 50% in mice heterozygous for the mutant allele, and was abolished in homozygous null mice. Plasma fibrin γ-dimerization was also indetectable in the homozygous deficient animals, confirming the absence of activatable FXIII. Homozygous mutant mice were fertile, although reproduction was impaired. Bleeding episodes, hematothorax, hematoperitoneum and subcutaneous hemorrhage in mutant mice were associated with reduced survival. Arrest of tail-tip bleeding in FXIII-A deficient mice was markedly and significantly delayed; replacement of mutant mice with human plasma FXIII (Fibrogammin® P) restored bleeding time to within the normal range. Thrombelastography (TEG) experiments demonstrated impaired clot stabilization in FXIII-A mutant mice, replacement with human FXIII led to dose-dependent TEG normalization. The mutant mice thus reiterate some key features of the human genetic disorder: they will be valuable in assessing the role of FXIII in other associated pathologies and the development of new therapies.

Critical Role of Factor XIII in the Initial Stages of Carbon Tetrachloride–Induced Adult Liver Remodeling

“…Because FXIIIA deficiency is often associated with impaired wound healing, 13,14 we examined whether the lack of FXIIIA affects hepatocyte apoptosis and/or proliferation in response to acute liver damage. There was a significantly increased number of cleaved caspase 3 (a marker for apoptosis)-positive cells in the FXIIIA-null liver at 24 hours after injury (P Ͻ 0.05), whereas no significant differences were noted at 3 days after injury ( Figure 5A).…”

“…14 Although FXIII mediates covalent cross-linking in several ECM proteins, 4 we focused here on the plasma fibronectinfibrin(ogen) provisional matrix and its roles in response to tissue damage. This study provides evidence demonstrating that FXIII-mediated covalent cross-linking of fibronectin and fibrin is not essential for collagen fibrillogenesis after acute liver injury; we suggest that FXIII mediates covalently cross-linked matrix survival signals for hepatocytes.…”

Coated platelets function in platelet-dependent fibrin formation via integrin α IIb β 3 and transglutaminase factor XIII

“…Mice deficient in factor XIII A1 subunit (F13a1 tm1Gdi , abbreviated as F13a1 -/-) 17 were bred on a mixed 129Sv/CBA background and were compared to F13a1 +/+ mice of the same background (Harlan Laboratories). Murine blood was taken on trisodium citrate for whole-blood flow experiments; other blood samples were taken on acid-citrate-dextrose anticoagulant to isolate washed platelets, as previously described.…”

Roles of transglutaminases in cardiac and vascular diseases

“…Human Factor XIII deficiency is characterized by a life-long severe bleeding disorder, with intracranial hemorrhage (2) and recurrent abortions (3) being a significant risk. Factor XIII subunit A−/− mice have a similar phenotype with impaired clot formation and reduced clot stability (4), and also suffer from spontaneous miscarriages due to uterine bleeding (5).…”

“…Platelets that are activated by thrombin release thymosin beta 4 which is cross-linked by factor XIIIa to collagen and fibrin (158). Thymosin beta 4 has roles in promoting angiogenesis by supporting endothelial cell attachment, spreading and migration (158). Furthermore, FXIIIa downregulates thrombospondin-1, an inhibitor of angiogenesis (159).…”