Functional role of vitronectin in breast cancer.

Breast Cancer is the most common form of cancer in women worldwide, impacting nearly 2.1 million women each year. Identification of new biomarkers could be key for early diagnosis and detection. Vitronectin, a glycoprotein that is abundantly found in serum, extracellular matrix, and bone, binds to integrin αvß3, and promotes cell adhesion and migration. Current studies indicate that patients with amplified vitronectin levels have lower survival rates than patients without amplified vitronectin levels. In this study, we focused on the role of vitronectin in breast cancer survival and its functional role as a non-invasive biomarker for early stage and stage specific breast cancer detection. To confirm that the expression of vitronectin is amplified in breast cancer, a total of 240 serum samples (n = 240), 200 from breast cancer patients and 40 controls were analyzed using the Reverse Phase Protein Array (RPPA) technique. Of the 240 samples, 120 samples were of African American (AA) descent, while the other 120 were of White American (WA) descent. Data indicated that there were some possible racial disparities in vitronectin levels and, differences also seen in the recurrent patient samples. Next, we tried to uncover the underlying mechanism which plays a critical role in vitronectin expression. The cellular data from four different breast cancer cell lines- MCF7, MDA-MB-231, MDA-MB-468, and HCC1599 indicated that the PI3K/AKT axis is modulating the expression of vitronectin. We believe that vitronectin concentration levels are involved and connected to the metastasis of breast cancer in certain patients, specifically based on recurrence or ethnicity, which is detrimental for poor prognosis. Therefore, in this current study we showed that the serum vitronectin levels could be an early marker for the breast cancer survival and we also determine the cellular signaling factors which modulate the expression and concentration of vitronectin.

Impact of extracellular matrix stiffness on genomic heterogeneity in MYCN-amplified neuroblastoma cell line.

BACKGROUND: Increased tissue stiffness is a common feature of malignant solid tumors, often associated with metastasis and poor patient outcomes. Vitronectin, as an extracellular matrix anchorage glycoprotein related to a stiff matrix, is present in a particularly increased quantity and specific distribution in high-risk neuroblastoma. Furthermore, as cells can sense and transform the proprieties of the extracellular matrix into chemical signals through mechanotransduction, genotypic changes related to stiffness are possible. METHODS: We applied high density SNPa and NGS techniques to in vivo and in vitro models (orthotropic xenograft vitronectin knock-out mice and 3D bioprinted hydrogels with different stiffness) using two representative neuroblastoma cell lines (the MYCN-amplified SK-N-BE(2) and the ALK-mutated SH-SY5Y), to discern how tumor genomics patterns and clonal heterogeneity of the two cell lines are affected. RESULTS: We describe a remarkable subclonal selection of genomic aberrations in SK-N-BE(2) cells grown in knock-out vitronectin xenograft mice that also emerged when cultured for long times in stiff hydrogels. In particular, we detected an enlarged subclonal cell population with chromosome 9 aberrations in both models. Similar abnormalities were found in human high-risk neuroblastoma with MYCN amplification. The genomics of the SH-SY5Y cell line remained stable when cultured in both models. CONCLUSIONS: Focus on heterogeneous intratumor segmental chromosome aberrations and mutations, as a mirror image of tumor microenvironment, is a vital area of future research.

Vitronectin deficiency attenuates hepatic fibrosis in a non-alcoholic steatohepatitis-induced mouse model.

Vitronectin (VN), an extracellular matrix protein, is a promising immune biomarker of non-alcoholic steatohepatitis (NASH); however, its precise function remains unclear. This study investigated how VN deficiency contributes to the development of NASH. Towards this aim, wild-type (WT) and VN-/- mice were fed with a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for 6 and 10 weeks to induce NASH, and the livers were isolated. In WT mice fed with CDAHFD for 6 and 10 weeks, the expression of Vn mRNA and protein was up-regulated compared with that in mice fed with the MF control diet, indicating that VN is regulated in NASH condition. VN-/- mice showed decreased picrosirius red staining in the liver area and Col1a2 mRNA expression levels, compared with WT mice, indicating that the severity of hepatic fibrosis is attenuated in the CDAHFD-fed VN-/- mice. In addition, VN deficiency did not affect the area of lipid droplets in haematoxylin-eosin staining and the mRNA expression levels of fatty acid synthases, Srebp, Acc and Fas in the CDAHFD-fed mice. Moreover, VN deficiency decreased the inflammation score and the mRNA expression levels of Cd11b and F4/80, macrophage markers, as well as Tnf-α and Il-1ß, inflammatory cytokines in the CDAHFD-fed mice. Furthermore, VN deficiency decreased the protein and mRNA expression levels of α-smooth muscle actin in the CDAHFD-fed mice, suggesting that VN deficiency inhibits the activation of hepatic stellate cells (HSCs). Our findings indicate that VN contributes to the development of fibrosis in the NASH model mice via modulation of the inflammatory reaction and activation of HSCs.

Vitronectin Regulates the Fibrinolytic System during the Repair of Cerebral Cortex in Stab-Wounded Mice.

Vitronectin (VN), one of the serum proteins, is known to be involved in the regulation of blood coagulation, fibrinolysis, and cell migration. It has been proposed that the regulation of fibrinolysis by VN promotes the blood-brain barrier (BBB) recovery from brain injuries such as traumatic injury and subarachnoid hemorrhage. The effects of VN on fibrinolysis in the injured brain remain unclear, however. We examined the effects of VN on the fibrinolytic system in the stab-wounded cerebral cortex of VN-knockout (KO) mice. First, hemorrhage and recovery from BBB breakdown in the wounded regions were assessed by serum immunoglobulin G (IgG) extravasation. The level of IgG extravasation increased 3-7 days after the stab wound (D3-7) in the cortex of VN-KO mice, compared with that in wild type mice, indicating that VN deficiency inhibited the recovery from BBB breakdown. The VN deficiency decreased fibrin fiber deposition at D1-3, suggesting that VN deficiency tilts the balance between fibrinogenesis and fibrinolysis toward fibrinolysis. Next, the effects of VN deficiency on the fibrinolytic factors were analyzed in the stab-wounded cortex. The VN deficiency impaired the activity of plasminogen activator inhibitor-1, an inhibitor of the fibrinolytic system, at D3-5. Further, VN deficiency up-regulated the mRNA and protein expression levels of tissue-type plasminogen activator, and urokinase-type plasminogen activator. These results demonstrate that VN contributes to the regulation of the fibrinolytic system and recovery from BBB breakdown in the wounded brain.

Evidence that vitronectin is a potent migration-enhancing factor for cancer cells chaperoned by fibrinogen: a novel view of the metastasis of cancer cells to low-fibrinogen lymphatics and body cavities.

Diluted (1%) plasma induces migration of malignant cell lines much more strongly than potent pro-metastatic factors. To characterize the factor(s) present in diluted plasma responsible for this phenomenon we performed i) heat inactivation, ii) dialysis, iii) proteinase K treatment, and iv) molecular size filtration studies. We found that this remarkable pro-migratory activity of diluted normal plasma is associated with a ~50-100-kD protein that interacts with GαI protein-coupled receptors and activates p42/44 MAPK and AKT signaling in target cells. Since this pro-migratory activity of 1% plasma decreases at higher plasma concentrations (> 20%), but is retained in serum, we hypothesized that fibrinogen may be involved as a chaperone of the protein(s). To identify the pro-migratory protein(s) present in diluted plasma and fibrinogen-depleted serum, we performed gel filtration and hydrophobic interaction chromatography followed by mass spectrometry analysis. We identified several putative protein candidates that were further tested in in vitro experiments. We found that this pro-migratory factor chaperoned by fibrinogen is vitronectin, which activates uPAR, and that this effect can be inhibited by fibrinogen. These results provide a novel mechanism for the metastasis of cancer cells to lymphatics and body cavities, in which the concentration of fibrinogen is low, and thus suggests that free vitronectin stimulates migration of tumor cells.

The vitronectin RGD motif regulates TGF-ß-induced alveolar epithelial cell apoptosis.

Transforming growth factor-ß (TGF-ß) is a critical driver of acute lung injury and fibrosis. Injury leads to activation of TGF-ß, which regulates changes in the cellular and matrix makeup of the lung during the repair and fibrosis phase. TGF-ß can also initiate alveolar epithelial cell (AEC) apoptosis. Injury leads to destruction of the laminin-rich basement membrane, which is replaced by a provisional matrix composed of arginine-glycine-aspartate (RGD) motif-containing plasma matrix proteins, including vitronectin and fibronectin. To determine the role of specific matrix proteins on TGF-ß-induced apoptosis, we studied primary AECs cultured on different matrix conditions and utilized mice with deletion of vitronectin (Vtn(-/-)) or mice in which the vitronectin RGD motif is mutated to nonintegrin-binding arginine-glycine-glutamate (RGE) (Vtn(RGE/RGE)). We found that AECs cultured on fibronectin and vitronectin or in wild-type mouse serum are resistant to TGF-ß-induced apoptosis. In contrast, AECs cultured on laminin or in serum from Vtn(-/-) or Vtn(RGE/RGE) mice undergo robust TGF-ß-induced apoptosis. Plasminogen activator inhibitor-1 (PAI-1) sensitizes AECs to greater apoptosis by disrupting AEC engagement to vitronectin. Inhibition of integrin-associated signaling proteins augments AEC apoptosis. Mice with transgenic deletion of PAI-1 have less apoptosis after bleomycin, but deletion of vitronectin or disruption of the vitronectin RGD motif reverses this protection, suggesting that the proapoptotic function of PAI-1 is mediated through vitronectin inhibition. Collectively, these data suggest that integrin-matrix signaling is an important regulator of TGF-ß-mediated AEC apoptosis and that PAI-1 functions as a natural regulator of this interaction.

Haemophilus influenzae P4 Interacts With Extracellular Matrix Proteins Promoting Adhesion and Serum Resistance.

Interaction with the extracellular matrix (ECM) is one of the successful colonization strategies employed by nontypeable Haemophilus influenzae (NTHi). Here we identified Haemophilus lipoprotein e (P4) as a receptor for ECM proteins. Purified recombinant P4 displayed a high binding affinity for laminin (Kd = 9.26 nM) and fibronectin (Kd = 10.19 nM), but slightly less to vitronectin (Kd = 16.51 nM). A P4-deficient NTHi mutant showed a significantly decreased binding to these ECM components. Vitronectin acquisition conferred serum resistance to both P4-expressing NTHi and Escherichia coli transformants. P4-mediated bacterial adherence to pharynx, type II alveolar, and bronchial epithelial cells was mainly attributed to fibronectin. Importantly, a significantly reduced bacterial infection was observed in the middle ear of the Junbo mouse model when NTHi was devoid of P4. In conclusion, our data provide new insight into the role of P4 as an important factor for Haemophilus colonization and subsequent respiratory tract infection.

Notch increased vitronection adhesion protects myeloma cells from drug induced apoptosis.

Notch signaling activation was found in many human cancers including multiple myeloma. It was previously reported that notch contributes to drug resistant of myeloma cells upon chemotherapy treatment, inhibition of notch by inhibitors helped to overcome drug resistance. However, the mechanism of notch developed drug resistance is remained to be fully illustrated. In the current study, we reported that Notch signaling activation up-regulated expression of integrin αvß5 in myeloma cells companied with enhanced cells adhesion on vitronectin. Silencing Notch-1 receptor with siRNA or blocking cells with integrin αvß5 antibody reduced myeloma cells adhesion on vitronectin, importantly, vitronectin mediated adhesion confers protection of myeloma cells from drug induced apoptosis. Thus, we revealed a novel mechanism of myeloma cells resistance to drug induced apoptosis. This study first connected Notch signaling, VTN adhesion and drug resistance together. Therefore, blocking αvß5 receptor with antibody or knock down approach would be a novel promising strategy to treat MM.

Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

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Age-related macular degeneration and Alzheimer disease.

This review highlight the similarities in the pathogenesis between Alzheimer disease and age-related macular degeneration. All studies published between 1990 and 2014 were reviewed to identify the common pathological pathways. Alzheimer disease and age-related macular degeneration share common features such as vitronectin and amyloid-ß accumulation, increased oxidative stress, and apolipoprotein and complement activation pathways, which are reviewed as histologic and immunologic common features.

The ADAM15 ectodomain is shed from secretory exosomes.

We demonstrated previously that a disintegrin and metalloproteinase 15 (ADAM15) is released into the extracellular space as an exosomal component, and that ADAM15-rich exosomes have tumor suppressive functions. However, the suppressive mechanism of ADAM15-rich exosomes remains unclear. In this study, we show that the ADAM15 ectodomain is cleaved from released exosomes. This shedding process of the ADAM15 ectodomain was dramatically enhanced in conditioned ovarian cancer cell medium. Proteolytic cleavage was completely blocked by phenylmethylsulfonyl fluoride, indicating that a serine protease is responsible for exosomal ADAM15 shedding. Experimental evidence indicates that the ADAM15 ectodomain itself has comparable functions with those of ADAM15-rich exosomes, which effectively inhibit vitronectininduced cancer cell migration and activation of the MEK/extracellular regulated kinase signaling pathway. We present a tumor suppressive mechanism for ADAM15 exosomes and provide insight into the functional significance of exosomes that generate tumor-inhibitory factors.

Studies on primary uveal and cutaneous melanoma cell interaction with vitronectin.

We have examined the diversity between primary uveal (92-1 and Mel202) and cutaneous (FM55P and IGR-39) melanoma cells in their interaction with vitronectin, and established the effect of integrins and ß1,6-branched N-oligosaccharides on this process. The adhesion level of uveal melanoma cells to vitronectin was at least twice lower than that of cutaneous ones, but all cells tested repaired scratch wounds on vitronectin-coated surfaces with similar speed. Swainsonine treatment, by reducing the amount of ß1,6-branches, significantly decreased cell attachment in all cases, but reduction of wound healing efficiency was compromised only in cutaneous melanoma cell. Functional blocking antibodies used in adhesion and migration assays revealed that integrin αvß3 was strongly involved in adhesion and migration only in cutaneous melanoma cells, but its role here was less pronounced than that of integrin αvß5. However, in uveal melanoma the specific anti-αvß5 integrin antibody had no impact on migration speed. Therefore, the anti-α3ß1 integrin antibody was used in order to explain the nature of uveal melanoma interaction with vitronectin, which caused a mild decrease in adhesion efficiency and reduced their motility. Expression of αvß5 integrin differed between the cell lines, but there was no distinct pattern to distinguish uveal melanoma from cutaneous melanoma. In conclusion, αvß5, but not αvß3 integrin is heavily involved in uveal melanoma cell interaction with vitronectin. The role of ß1,6-branched N-glycans in the adhesion, but not during migration, of all cells to vitronectin has been confirmed.

Proregenerative properties of ECM molecules.

After traumatic injuries to the nervous system, regrowing axons encounter a complex microenvironment where mechanisms that promote regeneration compete with inhibitory processes. Sprouting and axonal regrowth are key components of functional recovery but are often counteracted by inhibitory molecules. This review covers extracellular matrix molecules that support neuron axonal outgrowth.

Direct evidence of the importance of vitronectin and its interaction with the urokinase receptor in tumor growth.

Extensive evidence implicates the urokinase plasminogen activator receptor (uPAR) in tumor growth, invasion, and metastasis. Recent studies have substantiated the importance of the interaction between uPAR and the extracellular matrix protein vitronectin (VN) for the signaling activity of the receptor in vitro, however, the possible relevance of this interaction for the activity of uPAR in tumor growth and metastasis has not been assessed. We generated a panel of HEK293 cell lines expressing mouse uPAR (muPAR(WT)), an uPAR mutant specifically deficient in VN binding (muPAR(W32A)), and a truncation variant (muPAR(ΔD1)) deficient in both VN and uPA binding. In vitro cells expressing muPAR(WT) display increased cell adhesion, spreading, migration, and proliferation associated with increased p130Cas and MAPK signaling. Disruption of VN binding or ablation of both VN and uPA binding specifically abrogates these activities of uPAR. When xenografted into SCID (severe combined immunodeficiency) mice, the expression of muPAR(WT), but not muPAR(W32A) or muPAR(ΔD1), accelerates tumor development, demonstrating that VN binding is responsible for the tumor-promoting activity of uPAR in vivo. In an orthotopic xenograft model using MDA-MB-231 cells in RAG1(-/-)/VN(-/-) mice, we document that host deficiency in VN strongly impairs tumor formation. These 2 lines of in vivo experimentation independently demonstrate an important role for VN in tumor growth even if the uPAR dependence of the effect in the MDA-MB-231 model remains to be ascertained.

Vitronectin induces phosphorylation of ezrin/radixin/moesin actin-binding proteins through binding to its novel neuronal receptor telencephalin.

Vitronectin (VN) is an extracellular matrix protein abundantly present in blood and a wide variety of tissues and plays important roles in a number of biological phenomena mainly through its binding to αV integrins. However, its definite function in the brain remains largely unknown. Here we report the identification of telencephalin (TLCN/ICAM-5) as a novel VN receptor on neuronal dendrites. VN strongly binds to TLCN, a unique neuronal member of the ICAM family, which is specifically expressed on dendrites of spiny neurons in the mammalian telencephalon. VN-coated microbeads induce the formation of phagocytic cup-like plasma membrane protrusions on dendrites of cultured hippocampal neurons and trigger the activation of TLCN-dependent intracellular signaling cascade including the phosphorylation of ezrin/radixin/moesin actin-binding proteins and recruitment of F-actin and phosphatidylinositol 4,5-bisphosphate for morphological transformation of the dendritic protrusions. These results suggest that the extracellular matrix molecule VN and its neuronal receptor TLCN play a pivotal role in the phosphorylation of ezrin/radixin/moesin proteins and the formation of phagocytic cup-like structures on neuronal dendrites.

Thrombin stimulates integrin ß1-dependent adhesion of human pancreatic cancer cells to vitronectin through protease-activated receptor (PAR)-1.

BACKGROUND/AIMS: The aim of this study was to investigate the effect of thrombin and the thrombin receptor protease-activated receptor (PAR)-1 on adhesion of human pancreatic cancer cell lines to extracellular matrices (ECMs) and to identify related integrins with these effects. METHODOLOGY: Human pancreatic cancer cell lines SUIT-2 and its four sublines, and Panc- 1, AsPC-1 and MiaPaCa-2 were treated with thrombin, PAR-1 agonist TRAP-6, PAR-1 antagonist SCH79797, or anti-integrin ±vß3, ±vß5 and ß1 monoclonal antibodies. Cells were incubated for 45 minutes on micro titer plates that were pre-coated with ECMs (fibronectin, laminin, vitronectin, type IV collagen). The number of adherent cells was measured by the MTT method. RESULTS: Eight human pancreatic cancer cell lines expressed PAR-1. Thrombin significantly enhanced adhesion of SUIT-2 and its sublines and MiaPaCa-2 to vitronectin, especially in the SUIT-2 subline S2-007. We obtained similar results on S2-007 cells through treatment with TRAP-6. However, SCH79797 inhibited the effect of thrombin. Furthermore, anti-integrin ß1 antibody conspicuously inhibited 1U/mL thrombin-induced enhancement of adhesion to vitronectin. CONCLUSIONS: Thrombin significantly enhanced adhesion of pancreatic cancer cells to vitronectin through PAR- 1 depending on the presence of integrin ß1. Suppression of thrombin action by anti-integrin ß1 antibody will become a useful therapy against pancreatic cancer.

Vitronectin inhibits neutrophil apoptosis through activation of integrin-associated signaling pathways.

Vitronectin is present in large concentrations in serum and the extracellular matrix. Although vitronectin is known to modulate neutrophil adhesion and chemotaxis, and to contribute to neutrophil-associated proinflammatory processes, a role in apoptosis has not been demonstrated. In the present studies, we found that neutrophils demonstrated more rapid progression to spontaneous or TNF-related apoptosis-inducing ligand-induced apoptosis when incubated under vitronectin-free conditions than when vitronectin was present. The ability of native vitronectin to delay neutrophil apoptosis was not recapitulated by the vitronectin somatomedin B domain. In contrast, inclusion of the cyclo[Arg-Gly-Asp-D-Phe-Val] peptide in cultures containing vitronectin resulted in enhanced neutrophil apoptosis, showing that the vitronectin RGD motif (Arg-Gly-Asp motif) was responsible for the antiapoptotic effects of vitronectin. Addition of antibodies to ß(1), ß(3), or ß(5), but not to ß(2) or ß(4) integrins, reversed the ability of vitronectin to diminish neutrophil apoptosis. The ability of vitronectin to enhance neutrophil viability was dependent on activation of phosphatidylinositol 3-kinase and extracellular signal-regulated kinase 1/2 kinases, but not on the p38 kinase. Increased numbers of apoptotic neutrophils were present in the lungs of LPS-treated transgenic vitronectin-deficient mice, as compared with control mice. These results demonstrate a novel antiapoptotic function for vitronectin.

Carbon ion irradiation inhibits glioma cell migration through downregulation of integrin expression.

PURPOSE: To investigate the effect of carbon ion irradiation on glioma cell migration. METHODS AND MATERIALS: U87 and Ln229 glioma cells were irradiated with photons and carbon ions. Migration was analyzed 24 h after irradiation. Fluorescence-activated cell sorting analysis was performed in order to quantify surface expression of integrins. RESULTS: Single photon doses of 2 Gy and 10 Gy enhanced α(ν)ß(3) and α(ν)ß(5) integrin expression and caused tumor cell hypermigration on both vitronectin (Vn) and fibronectin (Fn). Compared to integrin expression in unirradiated cells, carbon ion irradiation caused decreased integrin expression and inhibited cell migration on both Vn and Fn. CONCLUSION: Photon radiotherapy (RT) enhances the risk of tumor cell migration and subsequently promotes locoregional spread via photon induction of integrin expression. In contrast to photon RT, carbon ion RT causes decreased integrin expression and suppresses glioma cell migration on both Vn and Fn, thus promising improved local control.

Vitronectin: a matrix support factor for human limbal epithelial progenitor cells.

PURPOSE: The authors recently developed a therapeutic technique for patients with limbal stem cell deficiency by harvesting ocular surface stem cells (SCs), expanding them on therapeutic contact lenses (CLs), and applying them to diseased corneas. The present study determined the proteins that bind to CLs and whether such factors, along with transplanted cells, are critical determinants for corneal rehabilitation using this method. METHODS: Therapeutic CLs were exposed to human serum, and adherent proteins were analyzed by proteomics. The distribution of vitronectin (VN) on the ocular surface was determined with specific antibodies. Cadaveric human corneas were chemically wounded, and cell transfer by CLs was assessed in organ culture. RESULTS: VN was identified as a serum factor that binds and desorbs from CLs. VN localized to the limbal and basement membranes (BM) of other SC-harboring organs. Clonogenic assays demonstrated higher colony-forming efficiency on VN compared with uncoated surfaces. Cell transfer from CLs was achieved through in vitro models and was abrogated by RGD peptides and inhibitory antibodies to VN and its receptor. CONCLUSIONS: Identification of VN within the limbal BM, its effect on limbal SC activity, and the discovery of this factor on serum-exposed CL polymers implies a role in supporting progenitor cells and facilitating corneal regeneration.

Vitronectin in vascular context: facets of a multitalented matricellular protein.

Vitronectin is an abundant adhesive glycoprotein in blood plasma and is found associated with different extracellular matrix sites, the vessel wall, and tumor cells, particularly upon tissue remodeling, injury/repair, or under disease conditions. Plasma vitronectin is a structurally labile molecule that may be converted into a multimeric/multivalent form by interaction with various (hemostatic) factors or through surface binding. Several distinct binding domains along the vitronectin sequence for integrin-type cell adhesion receptors, for urokinase receptor or proteoglycans as well as for growth factors, endow vascular matrix- or fibrin-associated vitronectin with differentiated cell attachment and aggregatory properties. These were found to be relevant for modulation of the cell-matrix interface in angiogenesis, hemostasis and thrombus formation, or wound repair, respectively. Other vitronectin ligands include plasminogen activator inhibitor (PAI)-1 or high molecular weight kininogen that confer strong antiadhesive functions upon integrin- or urokinase receptor-mediated cell interactions with vitronectin. Together, vitronectin acts as a potent matricellular factor, coordinating cell migration with pericellular proteolysis and growth factor signaling at sites of tissue remodeling or in tumors. Structure-function studies of such vitronectin-related ligands and receptors lead to the characterization of their mode of action, also stimulating the search for new antagonists in tumor angiogenesis, platelet aggregation, or atherosclerosis. This review focuses on new developments in vitronectin biology, with particular emphasis on regulatory mechanisms of the protein in the context of cell adhesion/migration/proliferation and cell-dependent proteolysis, relevant for our understanding of hemostasis, thrombosis, tissue repair, and vascular diseases.