Heparin inhibits human coronary artery smooth muscle cell migration

Pregnancy Outcome in Women with Obstetric and Thrombotic Antiphospholipid Syndrome-A Retrospective Analysis and a Review of Additional Treatment in Pregnancy

Antiphospholipid syndrome (APS) is associated with pregnancy complications such as recurrent early fetal loss (RFL), fetal death, preeclampsia (PE), and intrauterine growth restriction (obstetric APS/OAPS). Other clinical manifestations are venous and/or arterial thromboses (thrombotic APS/TAPS). The data of 37 pregnancies with OAPS and 37 pregnancies with TAPS were analyzed and compared. Overall, the most frequent APS antibodies (aPl) were LA as well as "triple-positivity"; LA antibodies were significantly more frequent in women with TAPS (67.6 % TAPS vs. 29.7 % OAPS, p < 0.010), whereas "triple-positivity" was significantly more seen in women with OAPS (40.5 % OAPS vs. 13.5 % TAPS, p < 0.010). Adequate therapy has been administered in nearly all pregnancies with TAPS, whereas in 18.9 % of pregnancies with OPS, no therapy has been given at all. One woman in OAPS and four women in TAPS were treated with plasmapheresis and immunoadsorption. There was no significant association between adverse obstetric outcome and therapy. The most frequent pregnancy complications were RFL in the OAPS group (32.4 vs. 13.5 % in TAPS) and PE in the TAPS group (18.9 % in OAPS and TAPS, respectively). The data of our study showed that pregnancies with OAPS and TAPS have a similar rate of pregnancy complications. However, pregnancies with OAPS tend to have rather RFL. Although we were not able to reveal a significant association with adverse obstetric outcome, it seems that the current adequate therapy for APS in pregnancy, consisting of LDA and LMWH, might rather prevent the development of RFL. Additionally, it might be considered to divide the obstetric APS into obstetric APS with early pregnancy complications and obstetric APS with late pregnancy complications. The division into two groups of obstetric APS might facilitate the choice of additional therapy in these women.

Fibronectin promotes directional persistence in fibroblast migration through interactions with both its cell-binding and heparin-binding domains

The precise mechanisms through which insoluble, cell-adhesive ligands induce and regulate directional cell migration remain obscure. We recently demonstrated that elevated surface density of physically adsorbed plasma fibronectin (FN) promotes high directional persistence in fibroblast migration. While cell-FN association through integrins α₅β₁ and α_vβ₃ was necessary, substrates that selectively engaged these integrins did not support the phenotype. We here show that high directional persistence necessitates a combination of the cell-binding and C-terminal heparin-binding domains of FN, but does not require the engagement of syndecan-4 or integrin α₄β₁. FN treatment with various fixation agents indicated that associated changes in fibroblast motility were due to biochemical changes, rather than alterations in its physical state. The nature of the coating determined the ability of fibroblasts to assemble endogenous or exogenous FN, while FN fibrillogenesis played a minor, but significant, role in regulating directionality. Interestingly, knockdown of cellular FN abolished cell motility altogether, demonstrating a requirement for intracellular processes in enabling fibroblast migration on FN. Lastly, kinase inhibition experiments revealed that regulation of cell speed and directional persistence are decoupled. Hence, we have identified factors that render full-length FN a promoter of directional migration and discuss the possible, relevant mechanisms.

The amount of fibrinogen-positive platelets predicts the occurrence of in-stent restenosis

AIMS

To determine the value of fibrinogen-positive platelet-analysis in predicting restenosis after stent implantation in acute myocardial infarction patients.

METHODS AND RESULTS

Our patient population comprised 50 patients who underwent intravascular ultrasound (IVUS) guided stent implantation for acute myocardial infarction. In all cases, IVUS confirmed a deep vessel wall injury due to a ruptured plaque within the culprit lesion. Flow cytometry quantified the amount of platelets with surface-bound fibrinogen and thrombospondin before and immediately after the intervention. After 5 months, IVUS was repeated to assess the long-term results. In-stent restenosis - defined as a percent diameter stenosis of >50% - was detected in 11 of 45 patients who attended follow-up angiography. The amount of fibrinogen-positive platelets was significantly higher among patients who subsequently developed in-stent restenosis (50.5+/-6.8% fibrinogen-positive platelets immediately after intervention) than among those who did not (39.7+/-12.3% fibrinogen-positive platelets, p<0.005). Receiver operating characteristic curve revealed a 40% cut-off for fibrinogen-positive platelets immediately after the intervention to predict restenosis (p<0.05, sensitivity: 90.9%, specificity: 47.1%).

CONCLUSION

The amount of fibrinogen-positive platelets immediately after stent implantation predicts the occurrence of in-stent restenosis, as confirmed by IVUS in acute myocardial infarction patients.

Use of heparin-coated stents in neurovascular interventional procedures: preliminary experience with 10 patients

OBJECTIVE

Currently, there is minimal published data on the use of heparin-coated stents in the neurovasculature; however, these stents have a proven clinical record in the treatment of coronary disease. This article details our experience with the safety and technical aspects of stent deployment in the first 10 patients who had heparin-coated stents placed in the intracranial and cervical vasculature and the preliminary follow-up in most cases.

METHODS

We retrospectively reviewed the clinical history, intra- and periprocedural data, and imaging for the patients who received heparin-coated stents in the cervical and intracranial vasculature for cerebrovascular disease between October 2002 and October 2003.

RESULTS

Thirteen heparin-coated stents were placed in 10 patients. Seven out of the 10 patients had heparin-coated stents placed in the posterior circulation; the remaining three patients had stents placed in the anterior circulation. Four patients had stents placed intracranially. There was no acute or subacute in-stent thrombosis and no procedure-related complications. Follow-up was performed on most patients, with no clinical symptoms attributable to restenosis in any patient.

CONCLUSION

This small series suggests that heparin-coated stents are safe for use in the treatment of cervical and intracranial atherosclerotic disease. Longer-term follow-up is needed to study the heparin coating effect on in-stent restenosis rates and to assess the long-term durability and clinical efficacy of this stent. The use of drug-coated stents in the cerebrovascular circulation is an area that warrants further investigation.

Heparin Regulates Transcription of Endothelin-1 Gene in Endothelial Cells

Heparin, which is widely used as an anticoagulant, has been shown to have antiatherosclerotic and antihypertensive effects in animals and humans. These effects are mediated by the inhibition of endothelin-1 (ET-1) production in endothelial cells. To clarify the mechanism of this inhibition, we investigated the effect of heparin on transcriptional regulation of the ET-1 gene in bovine aortic endothelial cells (BAEC) cultured in fetal calf serum. ET-1 mRNA expression was significantly suppressed by heparin in a dose-dependent manner. Promoter analysis revealed that the minimum ET-1 promoter containing only the GATA and AP-1 sequences as positive cis-acting sites in the ET-1 promoter is sufficient for this suppression. Gel mobility shift assays using oligonucleotides encoding the ET-1 AP-1 and ET-1 GATA sites confirmed that both AP-1 and GATA binding activities in BAEC nuclear extract were markedly inhibited by heparin. Western blot analyses indicated that heparin completely blocked extracellular signal-regulated kinase (ERK) activation, and inhibiting ERK activity resulted in loss of heparin-dependent inhibition of the ET-1 gene. These data indicate that the ET-1 mRNA level is negatively regulated by heparin at the transcription level, through modification of AP-1 and GATA protein binding activities, which direct the ET-1 promoter in BAEC. This effect may be mediated, at least in part, through inhibition of ERK activity.

Platelet-Derived Growth Factor-BB–Induced Human Smooth Muscle Cell Proliferation Depends on Basic FGF Release and FGFR-1 Activation

We have shown that the G protein–coupled receptor (GPCR) agonists, thrombin and Factor Xa, stimulate smooth muscle cell (SMC) proliferation through transactivation of the EGF receptor (EGFR) or the FGF receptor (FGFR), both of which are tyrosine kinase receptors. In the present study, we investigated whether platelet-derived growth factor (PDGF), a tyrosine kinase receptor agonist, might transactivate another tyrosine kinase receptor to induce SMC proliferation. Because heparin inhibits PDGF-mediated proliferation in human SMCs, we investigated whether the heparin-binding growth factor basic fibroblast growth factor (bFGF) and one of its receptors, FGFR-1, play a role in the response of human arterial SMCs to PDGF-BB. PDGF-BB induced the release of bFGF and sustained phosphorylation of FGFR-1 (30 minutes to 6 hours). A bFGF-neutralizing antibody inhibited PDGF-BB–mediated phosphorylation of FGFR-1, DNA synthesis, and cell proliferation. In the presence of bFGF antibody, PDGF-BB–induced early activation of ERK (0 to 60 minutes) was not affected, whereas late ERK activation (2 to 4 hours) was reduced. When FGFR-1 expression was suppressed using small interfering RNA (siRNA), ERK activation was reduced at late, but not early, time points after PDGF-BB stimulation. Addition of bFGF antibody to cells treated with siRNA to FGFR-1 had no further effect on ERK activation. Our results provide support for a novel mechanism by which PDGF-BB induces the release of bFGF and activation of FGFR-1 followed by the sustained activation of ERK and proliferation of human SMCs.

Ca(2+)/calmodulin-dependent protein kinase II inhibition by heparin in mesangial cells

Heparin exerts an antiproliferative effect in smooth muscle cells, and the Ca(2+)/calmodulin-dependent protein kinase (CaMK) signaling pathway is heparin sensitive. Here, we report that transfection with a truncated 326-amino acid fragment of CaMK-IIalpha increases basal activity of CaMK-II in mesangial cells. Ionomycin increased CaMK-II activity in both transfected and untransfected cells, with a concomitant increase in activated Ca(2+)/calmodulin. Heparin (1 microg/ml), but not chondroitin or dermatan sulfate, significantly attenuated both serum- or ionomycin-induced CaMK-II activity, and attendant c-fos mRNA expression, but did not affect upstream Ca(2+)/calmodulin. Autophosphorylation of Thr286 generates an autonomously active CaMK-II. Both serum and ionomycin increased phosphorylation at this site and increased CaMK-II activity in antiphosphothreonine immunoprecipitates. Heparin (1 microg/ml) did not inhibit phosphorylation of Thr286 (although much higher concentrations did). Replacement of Thr286 with Asp produces a constitutively active mutant that was insensitive to ionomycin but was inhibited by heparin maximally at 1 microg/ml. These results suggest that heparin at physiological concentrations acts at or downstream of CaMK-II to suppress its activity independent of an effect on autophosphorylation.

Heparin inhibits the motility and proliferation of human myometrial and leiomyoma smooth muscle cells

Uterine fibroids (leiomyomas) are a major women's health problem. Currently, the standard for treatment remains hysterectomy, because no other treatment modalities can reduce both symptoms and recurrence. As leiomyomas are a hyperproliferation of smooth muscle cells, we sought to understand the regulation of uterine smooth muscle cell mitogenesis by the glycosaminoglycan heparin, which has been extensively studied as an anti-proliferative molecule in vascular smooth muscle cells. Using matched pairs of human myometrial and leiomyoma smooth muscle cells from the same uterus, we demonstrate that the proliferation and motility of both cell types are inhibited by heparin. We report that the decrease in cell number seen in the presence of heparin is not because of cell death. Interestingly, there is significant patient-to-patient variability in the proliferation response but not in the motility response to heparin. Furthermore, nonanticoagulant and anticoagulant heparin were equally effective at inhibiting leiomyoma and myometrial smooth muscle cell proliferation. These results warrant further investigation into the possibility that heparin might be useful in the treatment of uterine fibroids.

Terminally alkylated heparin. 2. Potent antiproliferative agent for vascular smooth muscle cells

The antiproliferative activity of alkylated heparin, in which the terminal end of heparin is derivatized with an alkyl group (butyl, octyl, lauryl, stearyl), was examined using vascular smooth muscle cells. The proliferation of cells, which were growth-arrested prior to addition of heparin, was inhibited in proportion to both increase in the chain length of the alkyl group of alkylated heparin and alkylated heparin concentration in the serum-containing medium. The antiproliferative activity of stearyl group derivatized heparin was significantly stronger than that of nonmodified heparin. Little proliferation was observed at high dose (500 microg/mL). Confocal laser scanning microscopic observation indicated that alkylated heparin was accumulated on the cell membranes at an early incubation time, followed by homogeneous distribution of intracellular space. The therapeutic potential of alkylated heparin for preventing restenosis after balloon angioplasty is discussed.

Inhibition of rat smooth muscle cell adhesion and proliferation by non-anticoagulant heparins

Heparin is a well established growth inhibitor of arterial smooth muscle cells (SMCs) both in animal models and in vitro. Even though the cellular mechanisms involved in the anti-proliferative properties of heparin are being resolved, the structural requirements for the biological effects of heparin are not known in detail. Here, we have studied the effect of chemically modified heparins of different molecular weights and anticoagulant activities on proliferation and adhesion of rat aortic SMCs in vitro. The effects of native heparin (NH) and chemically modified heparins were examined after stimulation with fetal calf serum (FCS), platelet-derived growth factor BB (PDGF BB), basic fibroblast growth factor (bFGF), and heparin-binding epidermal growth factor (hbEGF) with respect to DNA synthesis and expression of phosphorylated and activated mitogen-activated protein kinase (pERK1 and 2). In a similar manner as NH, the modified heparins were capable of inhibiting activation of ERK1 and 2 and DNA synthesis induced by FCS and hbEGF whereas the modified heparins potentiated the mitogenic effect of bFGF and no compound affected PDGF BB-induced ERK activity and SMC growth. In contrast, cell adhesion to fibronectin was inhibited by NH and modified heparins in a size-dependent manner with the lowest effect by the smallest compound. The results show that heparins with varying anticoagulant activities and molecular weights but with similar sulfate content can retain anti-proliferative properties while the effect on some other biological processes such as cell adhesion is lost. Possibly, such chemical alterations may yield useful substances for the prevention of SMC proliferation after arterial injury.

The angiogenic factor cysteine-rich 61 (CYR61, CCN1) supports vascular smooth muscle cell adhesion and stimulates chemotaxis through integrin alpha(6)beta(1) and cell surface heparan sulfate proteoglycans

Cysteine-rich 61 (CYR61, CCN1) is a heparin-binding, extracellular, matrix-associated protein of the cysteine-rich 61/nephroblastoma family, which also includes connective tissue growth factor, nephroblastoma overexpressed, Wnt-induced secreted protein-1 (WISP-1), WISP-2, and WISP-3. CYR61 induces angiogenesis in vivo and supports cell adhesion, promotes cell migration, and enhances growth factor-stimulated mitogenesis in fibroblasts and endothelial cells. Although the expression of CYR61 has been observed in arterial walls, its function in vascular smooth muscle cells (VSMCs) has not been examined to date. Here we show that purified CYR61 supports VSMC adhesion in a dose-dependent, saturable manner through integrin alpha(6)beta(1) with an absolute requirement of cell surface heparan sulfate proteoglycans. In addition, CYR61 induces VSMC chemotaxis, but not chemokinesis, through integrin alpha(6)beta(1) and heparan sulfate proteoglycans. Heparin-binding defective CYR61 mutants are unable to support VSMC adhesion but can still induce chemotaxis at a reduced level. Following balloon angioplasty in rat carotid artery, CYR61 protein level is elevated in the media and neointima of the injured vessel by d 4 post angioplasty, peaks from d 7 to 14, and remains high for at least 28 d. These data demonstrate the activities of CYR61 in VSMCs, identify the receptors that mediate its functions, and show that CYR61 is synthesized in arterial smooth muscle walls during proliferative restenosis. Together, these results implicate CYR61 as a novel factor that modulates the responses of VSMCs to vascular injury.

Heparin and coumadin versus acetylsalicylic acid for prevention of restenosis after coronary angioplasty

The purpose of the present study was to determine whether postprocedural antithrombotic therapy with prolonged heparin infusion followed by 6 months of oral anticoagulation in addition to acetylsalicylic acid (ASA) reduces the incidence of angiographic restenosis after successful PTCA. One hundred ninety-one patients with uncomplicated PTCA were randomized into two groups: one group was discharged with ASA 100 mg only (G1) and the other group was additionally treated with 12-24 hr of heparin infusion and overlapping oral anticoagulation with coumadin for 6 months (G2). The two groups were comparable with respect to age, gender, coronary risk profile, clinical presentation, and angiographic lesion characteristics. Stents were implanted in 33% and 36% of the G1 and G2 patients, respectively. In-hospital myocardial infarction occurred in 4% of the G1 and 3% of the G2 patients. One patient in G1 died of subacute stent thrombosis (day 3). Six-month angiographic follow-up was obtained in 90% of G1 patients and 94% of G2 patients. Restenosis occurred in 30% and 33% of the patients and mean diameter stenoses at follow-up were 40% +/- 28% and 39% +/- 24%, respectively. Thrombin inhibition with heparin infusion followed by 6 months of oral anticoagulation did not reduce angiographic restenosis among patients undergoing PTCA with or without stent implantation. The occurrence of acute ischemic complications was also comparable in the two groups.

Fucoidan inhibits smooth muscle cell proliferation and reduces mitogen-activated protein kinase activity

OBJECTIVES AND DESIGN

fucoidan has previously been shown to inhibit the proliferation of arterial smooth muscle cells both in animal models and in vitro. However, the mechanisms behind the anti-proliferative effects of this polysulfated polysaccharide are not known in detail. Here, the inhibitory effect of fucoidan on rat aortic smooth muscle cell proliferation was examined and compared with the effects of heparin after stimulation with fetal calf serum, platelet-derived growth factor BB, basic fibroblast growth factor, heparin-binding epidermal growth factor, and angiotensin II.

MATERIALS AND METHODS

the cultures were analysed with respect to cell proliferation and DNA synthesis by cell counting and measurement of(3)H-thymidine incorporation. Phosphorylation of mitogen-activated protein kinase and nuclear translocation of phosphorylated mitogen-activated protein kinase were studied by immunoblotting and immunocytochemistry.

RESULTS

fucoidan was shown to be a more potent inhibitor of smooth muscle cell proliferation than heparin. Fucoidan also reduced growth factor-induced activation of mitogen-activated protein kinase and prevented nuclear translocation of phosphorylated mitogen-activated protein kinase.

CONCLUSION

fucoidan is a more potent anti-proliferative polysulphated polysaccharide than heparin and may mediate its effects through inhibition of the mitogen-activated protein kinase pathway in a similar manner as heparin.

Cultured porcine coronary artery smooth muscle cells. A new model with advanced differentiation

Arterial intimal thickening after endothelial injury induced in rodents has proven to be a relatively unreliable model of restenosis for testing clinically useful compounds. The same has been found for cultured rat or rabbit vascular smooth muscle cells (SMCs). To test alternative possibilities, we have studied several differentiation features of porcine coronary artery SMCs, cultured up to the 5th passage after enzymatic digestion of the media. The effects of heparin, transforming growth factor (TGF)-beta1 or TGF-beta2, and all-trans-retinoic acid (tRA) on proliferation, migration, and differentiation of these cells also were examined. Porcine arterial SMCs in culture not only express high levels of alpha-smooth muscle (SM) actin but, contrary to rodent SMCs, also maintain an appreciable expression of SM myosin heavy chain isoforms 1 and 2, desmin, and smoothelin, a recently described late differentiation marker of vascular SMCs. We demonstrate for the first time that smoothelin is colocalized with alpha-SM actin in these cells. Finally, we show that in the porcine model, heparin is more potent than TGF-beta1 or TGF-beta2 and tRA in terms of inhibition of proliferation and migration and of increasing the expression of differentiation markers. This model should be a useful complement to in vivo studies of SMC differentiation and of pathological situations such as restenosis and atheromatosis.