Sustained inhibition of intimal thickening. In vitro and in vivo effects of polymeric beta-cyclodextrin sulfate

A multifunctional surface for blood contact with fibrinolytic activity, ability to promote endothelial cell adhesion and inhibit smooth muscle cell adhesion

A multifunctional surface with fibrinolytic activity, the ability to promote endothelial cell and inhibit smooth muscle cell adhesion was realized.

The antiangiogenic properties of sulfated β-cyclodextrins in anticancer formulations incorporating 5-fluorouracil

Sulfated β-cyclodextrins (S-β-CDs) are useful excipients for improving the solubility of drugs. One such formulation incorporating 5-fluorouracil (5-FU), termed FD(S), showed improved efficacy over 5-FU alone in orthotopic carcinoma xenograft models. S-β-CDs have heparin-like anticoagulant properties, which may have contributed toward the improved antitumor effect of FD(S). S-β-CDs have also been reported to modify a number of processes involved in angiogenesis. Although the anticoagulant nature of S-β-CDs was established, the antiangiogenic properties of S-β-CDs within FD(S) were unknown. The effect of S-β-CD and FD(S) on the proliferation and migration of endothelial cells in live-cell kinetic assays, and the reorganization of human umbilical vein endothelial cells into tubule structures in vitro was assessed. The effects of S-β-CD on angiogenesis in vitro were validated ex vivo using the rat aorta ring assay and the chick embryo chorioallantoic membrane assay. S-β-CD does not alter proliferative endothelial cell sensitivity to 5-FU cytotoxicity. S-β-CD alone and within FD(S) significantly inhibited angiogenesis by impeding endothelial cell migration, resulting in the inhibition of tubule formation and hence new vasculature. In addition to the cytotoxic action of the drug 5-FU, therapeutic inhibition of angiogenesis by S-β-CDs within FD(S) could potentially limit local invasion and metastases. This has important implications for the exploitation of S-β-CDs for drug formulation improvements or for drug delivery of anticancer biologics.

In vivo quantitative assessment of catheter patency in rats

Formation of fibrin sleeves around catheter tips is a central factor in catheter failure during chronic implantation, and such tissue growth can occur despite administration of anticoagulants. We developed a novel method for monitoring catheter patency. This method recognizes the progressive nature of catheter occlusion, and tracks this process over time through measurement of changes in catheter resistance to a standardized 1 mL bolus infusion from a pressurized reservoir. Two indirect measures of catheter patency were used: (a) reservoir residual pressure and (b) reservoir discharge time. This method was applied to the study of catheter patency in rats comparing the effect of catheter material (silastic, polyurethane, Microrenathanetrade mark), lock solution (heparin, heparin/dexamethasone) and two different cannulation sites (superior vena cava via the external jugular vein, inferior vena cava via the femoral vein). Our findings reveal that application of flexible smaller-size silastic catheters and a dexamethasone lock solution resulted in prolonged catheter patency. Patency could be maintained over nine weeks with the femoral vein catheters, compared with five weeks with the external jugular vein catheters. The current method for measuring catheter patency provides a useful index for the assessment of tissue growth around the catheter tip. The method also provides an objective and quantitative way of comparing changes in catheter patency for different surgical methods and catheter types. Our method improves on the conventional method of assessing catheter occlusion by judging the ability to aspirate from the catheter.

Separate and combined effects of local and continuous intravenous administration of beta-cyclodextrin tetradecasulfate on intimal hyperplasia after angioplasty in porcine coronary arteries

BACKGROUND

Beta-Cyclodextrin tetradecasulfate binds fibroblast growth factors and possesses anticoagulant properties. This study was designed to assess the separate and combined effects of local intramural delivery and intravenous administration of beta-cyclodextrin tetrade-casulfate on neointimal formation and arterial damage following angioplasty.

METHODS AND RESULTS

Fifty-two pigs randomized into four groups underwent coronary artery angioplasty: 1) control, 2) continuous intravenous infusion of 100 mg/kg/d of beta-cyclodextrin tetradecasulfate, 3) intramural delivery of 1250 mg beta-cyclodextrin tetradecasulfate, 4) intramural delivery of 1250 mg beta-cyclodextrin tetradecasulfate followed by continuous intravenous infusion of 100 mg/kg/d. Fourteen days after injury, morphometric analysis revealed that arteries randomized to the intravenous beta-cyclodextrin tetradecasulfate groups had a decreased normalized neointima area: control, 3.03 +/- 0.75 mm(2); intravenous, 1.67 +/- 0.73 mm(2) (40% decrease; P < 10(-7)); intravenous plus local, 1.95 +/- 0.76 mm(2) (30% decrease; P < 10(-5)). There was no difference in neointimal response following local beta-cyclodextrin tetradecasulfate delivery only (2.82 +/- 1.14 mm(2)). Coronary arterial damage, defined as aneurysm, dissection, adventitial rupture, and retromedial hematoma was similar in all groups (12% in control and local groups, 10% in the intravenous group, 14% in the intravenous plus local; NS). Bleeding complications were more frequent in the intravenous and intravenous plus local groups compared to the local and control groups (23%vs 7.6% and 0%, respectively; P < 0.05).

CONCLUSIONS

Continuous intravenous administration of beta-cyclodextrin tetradecasulfate substantially reduced intimal hyperplasia, while intramural delivery had no effect, indicating that a single bolus of beta-cyclodextrin tetradecasulfate did not reduce intimal hyperplasia. There was no additive effect of local intramural delivery of beta-cyclodextrin tetradecasulfate. However, local delivery of beta-cyclodextrin tetradecasulfate induced less bleeding complications and did not lead to additional arterial injury, indicating that local delivery of an anticoagulant does not cause additional arterial injury.

Beta-cyclodextrin tetradecasulfate, a novel cyclic oligosaccharide, inhibits thrombus and neointimal formation after coronary vascular injury

BACKGROUND

Neointimal formation is a major cause of restenosis after interventional vascular procedures. Beta-cyclodextrin tetradecasulfate (beta-CDT) has been shown to inhibit fibroblast growth factor activity and we hypothesized that beta-CDT would reduce intimal formation.

DESIGN

Three studies were performed: (1) pharmacokinetics of oral and intravenous beta-CDT and determination of optimal dose, (2) determination of efficacy of oral and intravenous beta-CDT in reducing neointimal formation after balloon-overstretch injury and (3) determination of the effect of beta-CDT on cellular proliferation, factor Xa activity, activated clotting time, activated partial thromboplastin time and thrombus formation.

METHODS

Pharmacokinetics were determined in eight domestic swine following administration of oral beta-CDT and intravenous beta-CDT at three doses each. In the efficacy study, balloon-overstretch injury of 37 pigs (69 arteries) was performed and randomized into three groups (n = 23 arteries/group): control, oral administration of 300 mg beta-CDT/kg per day or intravenous infusion of 100 mg beta-CDT/kg per day. Animals were sacrificed 14 days later. Cellular proliferation and mural thrombus were determined in six arteries/group at 5 days and endothelial coverage was evaluated at 5 and 14 days.

RESULTS

Oral and intravenous beta-CDT reduced the intimal hyperplasia area normalized to injury index by 24 and 48%, respectively: control, 3.03 +/- 0.75 mm2, oral, 2.31 +/- 0.83 mm2 (P = 0.004) and intravenous, 1.67 +/- 0.73 mm2 (P = 0.0000002). beta-CDT reduced cellular proliferation (control, 55 +/- 18%, oral, 35 +/- 7%, P = 0.03 and intravenous, 30 +/- 12%, P = 0.01) and mural thrombus formation (control, 0.84 +/- 0.4 mm2, oral, 0.44 +/- 0.14 mm2, P = 0.04, intravenous, 0.42 +/- 0.09 mm2, P = 0.03). Endothelial coverage was increased in the experimental groups (P = 0.008, oral versus control, P < 0.0001, intravenous versus control). Factor Xa activity was inhibited 9-10 fold following intravenous administration while oral administration demonstrated no effect.

CONCLUSIONS

Both oral and intravenous formation of beta-CDT reduced intimal hyperplasia with the greatest reduction in the intravenous group. We postulate that beta-CDT was effective by the combination of increasing endothelial coverage, reducing mural thrombus formation, inhibiting factor Xa activity and reducing cellular proliferation.

Adenoviral mediated uteroglobin gene transfer to the adventitia reduces arterial intimal hyperplasia

PURPOSE

The aim of this study was to investigate the feasibility of gene transfer of uteroglobin, a potent anti-inflammatory and immunomodulatory agent, via adenoviral mediated gene transfer to the adventitia in the mouse carotid ligation injury model and also to investigate the efficacy of uteroglobin in reducing neointimal hyperplasia.

METHODS

Forty-five C57bl/6NHSD mice were anesthetized and left common carotid artery ligation was performed. Adenoviral vector encoding the uteroglobin gene (Ad.UG; 15 microl of 1.35 x 10(11) pfu/mL) was applied to the adventitia of the injured artery in 16 mice. In our control groups, 16 mice received adenoviral vector encoding the beta-galactosidase reporter gene (Ad.lacZ; 15 microl of 1.0 x 10(11) pfu/mL) and 13 mice received PBS only. Six mice from each group were sacrificed at 4 days for carotid artery protein extraction and Western blot analysis. The remainder were harvested at 30 days for histologic and morphometric analysis. The intima/media area ratios were calculated for each artery. The results were analyzed and compared using ANOVA and Bonferroni/Dunn post hoc testing.

RESULTS

Two mice from the LacZ group and one from the PBS group died before the 30-day endpoint. Uteroglobin expression was demonstrated in the Ad.UG treated arteries by Western blot analysis. Morphometric analysis demonstrated a statistically significant reduction in the intima/media area ratio of Ad.UG treated carotids compared to controls. There was a reduction of intima/media ratio with Ad. UG treatment of 68% compared to Ad.lacZ treatment (P < 0.0001) and 62% compared to PBS treatment (P = 0.0006). There was no statistical difference between the control groups.

CONCLUSION

Adenoviral mediated gene transfer via the adventitia is an effective mode of gene delivery. Adventitial uteroglobin gene transfer using an adenoviral vector induces uteroglobin protein production and significantly reduces neointimal hyperplasia in the mouse carotid ligation injury model.

Targeting endogenous platelet-derived growth factor B-chain by adenovirus-mediated gene transfer potently inhibits in vivo smooth muscle proliferation after arterial injury

Platelet-derived growth factor (PDGF), especially its B chain, has been implicated in the pathogenesis of vascular proliferative disorders such as atherosclerosis and restenosis after angioplasty. We constructed a replication-deficient recombinant adenovirus containing the gene encoding the extracellular region of PDGF beta-receptor (PDGFXR) that binds PDGF-B chain and acts as its antagonist. The administration into balloon-injured rat carotid arteries of an adenovirus containing the Escherichia coli lacZ gene as a marker gene at 5 days after injury markedly facilitated efficacy of gene transfer, as compared with its administration immediately after injury. Adenovirus-mediated gene transfer of PDGFXR into injured arteries performed at 5 days resulted in a more than 50% reduction in the neointimal area of injured arteries at 14 days. In contrast, the administration of control adenoviruses containing lacZ gene or containing no foreign gene was without suppressive effects on neointima formation. The inhibition of neointima formation by the expression of PDGFXR was accompanied by a reduction in bromodeoxyuridine-labeled cells and nearly complete inhibition of tyrosine phosphorylation of both alpha- and beta-receptors for PDGF, but not of epidermal growth factor receptor, in injured arteries. This is the first report to indicate the usefulness of targeting a growth factor by expressing an extracellular binding region of a receptor using an adenovirus for the treatment of vascular proliferative disorders, and provide direct evidence that PDGF-B chain plays an essential role in neointimal formation.

A basic compositional requirement of agents having heparin-like cell-modulating activities

Heparin has been recognized as possessing a large variety of cell-modulating activities. Using compositionally simple, structurally rigid, and low molecular weight saccharide molecules (cyclodextrins), we demonstrated that these activities depend primarily on a single, gross compositional parameter: a minimum intramolecular density of neighboring anionic (sulfate) groups. This same critical parameter is shown to be involved in achieving cell-modulating behavior as diverse as angiogenesis, endothelial proliferation, inhibition of smooth muscle cell growth, and cell protection against virus invasion. Physical chemical evidence is presented that associates this property with multi-ionic complex formation between the clusters of anionic and cationic sites on the complexing partners. These observations revive early suggestions of the decisive role of electrostatic complexation capabilities of glycosaminoglycans like heparin; taken together with numerous observations on heparinoids and other agents reported in diverse specialized fields of cell biology and medicine, they provide evidence that molecular agents of critical anionic (sulfate) density (MACADs) represent a broad class of molecules that, in contrast to proteins, do not rely on structural detail for their cell biological activities, but function by ionic complexation with proteinic agents (e.g. growth factors), thereby modifying their structure-specific activities.

Pharmaceutical applications of cyclodextrins. III. Toxicological issues and safety evaluation

The objective of this review is to summarize recent findings on the safety profiles of three natural cyclodextrins (alpha-, beta- and gamma-CDs) and several chemically modified CDs. To demonstrate the potential of CDs in pharmaceutical formulations, their stability against non-enzymatic and enzymatic degradations in various body fluids and tissue homogenates and their pharmacokinetics via parenteral, oral, transmucosal, and dermal routes of administration are outlined. Furthermore, the bioadaptabilities of CDs, including in vitro cellular interactions and in vivo safety profiles, via a variety of administration routes are addressed. Finally, the therapeutic potentials of CDs are discussed on the basis of their ability to interact with various endogenous and exogenous lipophiles or, especially for sulfated CDs, their effects on cellular processes mediated by heparin binding growth factors.

Sequence-independent inhibition of in vitro vascular smooth muscle cell proliferation, migration, and in vivo neointimal formation by phosphorothioate oligodeoxynucleotides

Phosphorothioate oligodeoxynucleotides (PS oligos) are antisense (sequence-specific) inhibitors of vascular smooth muscle cell (SMC) proliferation when targeted against different genes. Recently an aptameric G-quartet inhibitory effect of PS oligos has been demonstrated. To determine whether PS oligos manifest non-G-quartet, non-sequence-specific effects on human aortic SMC, we examined the effects of S-dC28, a 28-mer phosphorothioate cytidine homopolymer, on SMC proliferation induced by several SMC mitogens. S-dC28 significantly inhibited SMC proliferation induced by 10% FBS as well as the mitogens PDGF, bFGF, and EGF without cytotoxicity. Moreover, S-dC28 abrogated PDGF-induced in vitro migration in a modified micro-Boyden chamber. Furthermore, S-dC28 manifested in vivo antiproliferative effects in the rat carotid balloon injury model. S-dC28 suppressed neointimal cross-sectional area by 73% and the intima/media area ratio by 59%. Therefore, PS oligos exert potent non-G-quartet, non-sequence-specific effects on in vitro SMC proliferation and migration as well as in vivo neointimal formation.

Inhibition of vein graft intimal and medial thickening by periadventitial application of a sulfated carbohydrate polymer

PURPOSE

The purpose of this study was to determine whether the wall thickening observed in vein grafts after they were placed into the arterial circulation could be inhibited by periadventitial delivery of an insoluble sulfated polymer of beta-cyclodextrin (P-CDS) capable of tightly binding heparin binding growth factors.

METHODS

Thirty-four New Zealand white rabbits underwent implantation of reversed autologous jugular vein interposition grafts in the common carotid artery and were randomized to receive either 20 mg P-CDS (n = 18) topically around the graft or no additional therapy (n = 16). Before being killed at 28 days, animals were given bromodeoxyuridine to assess smooth muscle cell proliferation. Histomorphometric analyses were performed after perfusion fixation.

RESULTS

Compared to controls, treatment with P-CDS was associated with reduced mean intimal thickness (24 +/- 3 vs 38 +/- 4 microns; mean SEM, p < 0.01) and intimal area (0.25 +/- 0.03 vs 0.54 +/- 0.09 mm2; p < 0.01). There was also significantly less medial thickness in the P-CDS group (45 +/- 3 vs 63 +/-3, p < 0.001). There was no significant difference in intimal or medial smooth muscle cell proliferation between P-CDS-treated and control vein grafts at 28 days. The polymer persisted in the adventitia with a mild foreign body reaction.

CONCLUSION

Periadventitial placement of P-CDS, a novel, insoluble, sulfated carbohydrate polymer, inhibits intimal and medial thickening of vein bypass grafts in this model of vein grafting. The persistence of P-CDS in vivo for prolonged periods, and the ease of topical application of P-CDS during vascular bypasses may have important implications for its future use in vascular surgery.