Histopathology of postpercutaneous transluminal coronary angioplasty remodeling in human coronary arteries

Advances in mammalian target of rapamycin kinase inhibitors: application to devices used in the treatment of coronary artery disease

Mammalian target of rapamycin (mTOR) inhibitors have been applied to vascular coronary devices to avoid neointimal growth and have become the predominant pharmacological agents used to prevent restenosis. mTOR inhibitors can affect not only proliferating vascular smooth muscle cells but also endothelial cells and therefore can result in delayed healing of the vessel including endothelialization. Emerging evidence suggests accelerated atherosclerosis due to the downstream negative effects on endothelial barrier functional recovery. The development of neoatherosclerosis within the neointima of drug-eluting stents can result in late thrombotic events. This type of problematic healing response may open the way for specific mTOR kinase inhibitors, such as ATP-competitive mTOR inhibitors. These inhibitors demonstrate a better healing profile than traditional limus-based drug-eluting stent and their clinical efficacy remains unknown.

Biomechanical Stress Profiling of Coronary Atherosclerosis: Identifying a Multifactorial Metric to Evaluate Plaque Rupture Risk

OBJECTIVES

The purpose of this study was to derive a biomechanical stress metric that was based on the multifactorial assessment of coronary plaque morphology, likely related to the propensity of plaque rupture in patients.

BACKGROUND

Plaque rupture, the most frequent cause of coronary thrombosis, occurs at locations of elevated tensile stress in necrotic core fibroatheromas (NCFAs). Finite element modeling (FEM), typically used to calculate tensile stress, is computationally intensive and impractical as a clinical tool for locating rupture-prone plaques. This study derived a multifactorial stress equation (MSE) that accurately computes peak stress in NCFAs by combining the influence of several morphological parameters.

METHODS

Intravascular ultrasound and optical frequency domain imaging were conducted in 30 patients, and plaque morphological parameters were defined in 61 NCFAs. Multivariate regression analysis was applied to derive the MSE and compute a peak stress metric (PSM) that was based on the analysis of plaque morphological parameters. The accuracy of the MSE was determined by comparing PSM with FEM-derived peak stress values. The ability of the PSM in locating plaque rupture sites was tested in 3 additional patients.

RESULTS

The following parameters were found to be independently associated with peak stress: fibrous cap thickness (p < 0.0001), necrotic core angle (p = 0.024), necrotic core thickness (p < 0.0001), lumen area (p < 0.0001), necrotic core including calcium areas (p = 0.017), and plaque area (p = 0.003). The PSM showed excellent correlation (R = 0.85; p < 0.0001) with FEM-derived peak stress, thus confirming the accuracy of the MSE. In only 56% (n = 34) of plaques, the thinnest fibrous cap thickness was a determining parameter in identifying the cross section with highest PSM. In coronary segments with plaque ruptures, the MSE precisely located the rupture site.

CONCLUSIONS

The MSE shows potential to calculate the PSM in coronary lesions rapidly. However, further studies are warranted to investigate the use of biomechanical stress profiling for the prognostic evaluation of patients with atherosclerosis.

Preclinical randomised safety, efficacy and physiologic study of the silicon dioxide inert-coated Axetis and bare metal stent: short-, mid- and long-term outcome

AIMS

To evaluate the short-, mid- and long-term safety, efficacy and vascular physiology of Axetis silicon dioxide (SiO2, abrading the micropores) inert-coated stent implantation in a randomised preclinical setting.

METHODS AND RESULTS

Coronary arteries of domestic pigs were randomised to receive either Axetis or BMS (same design) stents with one-, three- and six-month follow-up (FUP), controlled by coronary angiography, optical coherence tomography (OCT), intravascular ultrasound (IVUS) and histology (n=32). The time-dependent vasomotor reaction of coronary arteries to stenting was measured using modified myography (n=12). Complete endothelialisation of the Axetis stent was confirmed by OCT, IVUS and histology at one-month FUP. Histopathology revealed continuous healing of the vessel wall with a gradual reduction of inflammation and fibrin score during the six-month FUP in both stent types. Significantly smaller neointimal area and %area stenosis were measured in Axetis stents compared with BMS at each FUP time point. Vascular reactivity measurements showed significantly better endothelium-dependent vasodilation of stented arteries with Axetis implantation.

CONCLUSIONS

Implantation of the Axetis SiO2-coated stent resulted in a significantly better safety, efficacy and vessel physiology profile compared with BMS of the same design with a continuous decrease in vessel inflammation during the six-month FUP.

Quantification of popliteal artery deformation during leg flexion in subjects with peripheral artery disease: a pilot study

PURPOSE

To quantify the in vivo deformations of the popliteal artery during leg flexion in subjects with clinically relevant peripheral artery disease (PAD).

METHODS

Five patients (4 men; mean age 69 years, range 56-79) with varying calcification levels of the popliteal artery undergoing endovascular revascularization underwent 3-dimensional (3D) rotational angiography. Image acquisition was performed with the leg straight and with a flexion of 70°/20° in the knee/hip joints. The arterial centerline and the corresponding branches in both positions were segmented to create 3D reconstructions of the arterial trees. Axial deformation, twisting, and curvatures were quantified. Furthermore, the relationships between the calcification levels and the deformations were investigated.

RESULTS

An average shortening of 5.9%±2.5% and twist rate of 3.8±2.2°/cm in the popliteal artery were observed. Maximal curvatures in the straight and flexed positions were 0.12±0.04 cm(-1) and 0.24±0.09 cm(-1), respectively. As the severity of calcification increased, the maximal curvature in the straight position increased from 0.08 to 0.17 cm(-1), while an increase from 0.17 to 0.39 cm(-1) was observed for the flexed position. Axial elongations and arterial twisting were not affected by the calcification levels.

CONCLUSION

The popliteal artery of patients with symptomatic PAD is exposed to significant deformations during flexion of the knee joint. The severity of calcification directly affects curvature, but not arterial length or twisting angles. This pilot study also showed the ability of rotational angiography to quantify the 3D deformations of the popliteal artery in patients with various levels of calcification.

Mechanisms of post-intervention arterial remodelling

It has been appreciated over the past two decades that arterial remodelling, in addition to intimal hyperplasia, contributes significantly to the degree of restenosis that develops following revascularization procedures. Remodelling appears to be an adventitia-based process that is contributed to by multiple factors including cytokines and growth factors that regulate extracellular matrix or phenotypic transformation of vascular cells including myofibroblasts. In this review, we summarize the currently available information from animal models as well as clinical investigations regarding arterial remodelling. The factors that contribute to this process are presented with an emphasis on potential therapeutic methods to enhance favourable remodelling and prevent restenosis.

A case of in-stent neointimal plaque rupture 10 years after bare metal stent implantation: intravascular ultrasound and optical coherence tomographic findings

Neointimal hyperplasia mainly develops within several months of coronary stent deployment, after which it stabilizes. Although it was widely accepted, particularly during the bare-metal stent (BMS) era, that in-stent restenosis (ISR) generally does not present as an acute coronary syndrome (ACS), but rather as a gradual recurrence of angina symptoms, recent data have shown that a substantial number of patients with ISR present as ACS. There has also been consistent postmortem evidence of plaque rupture secondary to atherosclerotic change within the neointima of a BMS. We report here a case of ACS in which intravascular ultrasound and optical coherent tomographic assessments revealed neointimal atherosclerotic change and ruptured plaque 10 years after BMS deployment.

Preventing restenosis in early drug-eluting stent era: recent developments and future perspectives

Restenosis is the major limitation of the successful therapy of percutaneous coronary intervention (PCI) for patients with coronary artery disease. The problem was appreciated in the late 1970s to early 1980s. Only in recent years, anti-restenotic therapy has achieved a breakthrough with the development of drug-eluting stents. Here, we provide an overview about pathological mechanisms of restenosis after PCI. Present therapeutic approaches to overcome restenosis and recent clinical results are revisited, and some major concerns in the post-drug-eluting stent era are discussed.

Histopathology of clinical coronary restenosis in drug-eluting versus bare metal stents

To characterize in-stent restenosis after the implantation of sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), tacrolimus-eluting stents (TES), and zotarolimus-eluting stents (ZES), 25 patients treated with drug-eluting stents (DES; 9 PES, 10 SES, 4 TES, and 2 ZES) and 19 with bare-metal stents (BMS) underwent directional coronary atherectomy for in-stent restenosis 4 to 36 months after implantation. Restenosis after DES implantation was more frequently focal and associated with smaller specimens compared to that after BMS implantation. Light and confocal microscopy were used. Histologic features were similar in DES and BMS. In-stent restenotic lesions were composed mainly of neointima containing proteoglycan-rich smooth muscle cells and fibrolipidic regions. Small inflammatory infiltrates were observed, mostly in patients with unstable angina; CD18- and/or CD3(+) cells were detected in patients with BMS and DES. Different smooth muscle cell phenotypes were observed: synthetic was more frequent with BMS and PES, intermediate with ZES, contractile or intermediate with SES, and contractile with TES. The mean proliferation index was low and comparable among stent types; cyclins B1 and D1 were expressed in all DES. In conclusion, intra-DES and intra-BMS restenotic tissue was composed mainly of smooth muscle cells with different phenotypes, proliferating at a low rate. The different smooth muscle cell phenotypes within the stent types might suggest different mechanisms of restenosis.

Regulation of arterial remodeling and angiogenesis by urokinase-type plasminogen activatorThis article is one of a selection of papers from the NATO Advanced Research Workshop on Translational Knowledge for Heart Health (published in part 2 of a 2-part Special Issue)

A wide variety of disorders are associated with an imbalance in the plasminogen activator system, including inflammatory diseases, atherosclerosis, intimal hyperplasia, the response mechanism to vascular injury, and restenosis. Urokinase-type plasminogen activator (uPA) is a multifunctional protein that in addition to its fibrinolytic and matrix degradation capabilities also affects growth factor bioavailability, cytokine modulation, receptor shedding, cell migration and proliferation, phenotypic modulation, protein expression, and cascade activation of proteases, inhibitors, receptors, and modulators. uPA is the crucial protein for neointimal growth and vascular remodeling. Moreover, it was recently shown to be implicated in the stimulation of angiogenesis, which makes it a promising multipurpose therapeutic target. This review is focused on the mechanisms by which uPA can regulate arterial remodeling, angiogenesis, and cell migration and proliferation after arterial injury and the means by which it modulates gene expression in vascular cells. The role of domain specificity of urokinase in these processes is also discussed.

Effectiveness of narrow-band ultraviolet-B phototherapy for prevention of intimal hyperplasia in a rat carotid balloon injury model

BACKGROUND AND OBJECTIVE

Narrow-band ultraviolet-B light (NBUVB) (313 nm) is known to have anti-proliferative effects, implying a potential treatment for intimal hyperplasia, but it remains to be ascertained. We assessed the effects of NBUVB irradiation for prevention of intimal hyperplasia.

STUDY DESIGN/MATERIALS AND METHODS

The rat carotid arteries were irradiated with NBUVB after balloon injury (BI), and the degree of intimal hyperplasia was histopathologically assessed. The anti-proliferative effects using cultured human smooth muscle cells were evaluated by flow cytometry and immunoblot analysis.

RESULTS

NBUVB (0.3-4.5 J/cm(2)) irradiation immediately after BI reduced the degree of intimal hyperplasia at 14 and 28 days after BI (P<0.001) without any obvious complications. Neither an increase in the number of medial cells nor upregulation of proliferating cell nuclear antigen was observed in the irradiated arteries. NBUVB irradiation at 2 or 14 days after BI significantly suppressed further intimal hyperplasia (P<0.01). NBUVB-irradiated cultured cells showed inhibited proliferation involved with G(1) and G(2)/M arrests. Increased expression of p53 and inhibition of retinoblastoma protein (pRB) phosphorylation were also seen in the NBUVB-irradiated cells.

CONCLUSIONS

These data suggest that NBUVB irradiation is an effective method for preventing intimal hyperplasia. The anti-proliferative effect is partly due to the cell cycle arrest caused by p53 expression and inhibited pRB phosphorylation.

Association of Circulating Transforming Growth Factor beta, Tumor Necrosis Factor alpha and Basic Fibroblast Growth Factor with Restenosis after Transluminal Angioplasty

OBJECTIVES

To assess prospectively the early time course of Transforming Growth Factor beta-1 (TGFbeta-1), basic Fibroblast Growth Factor (bFGF) and Tumor Necrosis Factor alpha (TNFalpha) as possible contributors to restenosis development after angioplasty.

DESIGN

Prospective Study.

METHODS

The levels of the soluble forms of these factors in the early response to Percutaneous Transluminal Angioplasty (PTA) in the arteries of the lower limb were prospectively assessed. 32 patients with peripheral arterial occlusive disease (PAOD), presenting with intermittent claudication (Fontaine stage IIb) were scheduled for angioplasty treatment. Serum levels of TGFbeta-1, TNFalpha and bFGF were assessed before intervention, 15 and 60 minutes after, 24 hours after as well as 2 and 4 weeks after intervention. We compared the distribution patterns between patients treated with balloon angioplasty and patients who required secondary stent implantation. Endpoint was the development of restenosis within 6 months after interventional treatment, defined as a lumen diameter reduction of more than 50% by ultrasound measurement compared to the result after PTA.

RESULTS

The patients who later developed restenosis had significantly higher levels of TGFbeta-1 at 15 minutes, 24 hours and 2 weeks after PTA (p<0.05). TNFalpha and bFGF were only detected in a few patients and no significant change of serum levels was observed.

CONCLUSION

The results demonstrate a possible role of TGFbeta-1 in the formation of restenosis after PTA.

Topological determinants and consequences of adventitial responses to arterial wall injury

Arteries are composed of 3 concentric tissue layers which exhibit different structures and properties. Because arterial injury is generally initiated at the interface with circulating blood, most studies performed to unravel the mechanisms involved in injury-induced arterial responses have focused on the innermost layer (intima) rather than on the outermost adventitial layer. In the present review, we focus on the involvement of the adventitia in response to various types of arterial injury leading to vascular remodeling. Physiologically, soluble vascular mediators are centrifugally conveyed by mass transport toward the adventitia. Moreover, in pathological conditions, neomediators and antigens can be generated within the arterial wall, whose outward conveyance triggers different patterns of local adventitial response. Adventitial angiogenesis, immunoinflammation, and fibrosis sequentially interact and their net balance defines the participation of the adventitial response in arterial pathology. In the present review we discuss 4 pathological entities in which the adventitial response to arterial wall injury participates in arterial wall remodeling. Hence, the adventitial adaptive immune response predominates in chronic rejection. Inflammatory phagocytic cell recruitment and initiation of a shift from innate to adaptive immunity characterize the adventitial response to products of proteolysis in abdominal aortic aneurysm. Adventitial sprouting of neovessels, leading to intraplaque hemorrhages, predominates in atherothrombosis. Adventitial fibrosis characterizes the response to mechanical stress and is responsible for the constrictive remodeling of arterial segments and initiating interstitial fibrosis in perivascular tissues. These adventitial events, therefore, have an impact not only on the vessel wall biology but also on the surrounding tissue.

Inhibition of vascular remodelling in a porcine coronary injury model by herbal extract XS0601

Background

Arterial remodelling is a major pathologic change of restenosis after percutaneous coronary intervention (PCI). Our previous studies showed that XS0601 (consisting of Chuangxingol and paeoniflorin) had some effects on the prevention of restenosis after PCI. Therefore, the purpose of this study was to examine whether and how its mechanism was related to the regulation of the arterial remodelling after endothelial injury by balloon dilation.

Methods

Twenty Chinese mini-pigs were randomized into four groups: control, probucol, low-dose XS0601 and high-dose XS0601 group before oversized balloon injury of the left anterior descending coronary arteries. Starting from two days before balloon injury, the mini-pigs in the treated group were administered with probucol (2 g/day) and XS0601 (0.02 g/kg/day for low dose; 0.04 g/kg/day for high dose) for four weeks after balloon injury. The animals receiving balloon injury alone were used as control. Morphometric and angiographic analysis of the injured arteries were performed.

Results

The contribution of intimal hyperplasia and arterial remodelling to angiographic late lumen loss was 41% and 59% respectively. XS0601 markedly inhibited proliferation of smooth muscle cells (SMCs) and transformation of SMCs from contractile to synthetic phenotype in neointima, inhibited hyperplasia-related indices of morphometric analysis and reduce late angiographic lumen loss. The reduction of the late angiographic lumen loss resulting from vascular remodelling was greater after XS0601 treatment.

Conclusion

Both intimal hyperplasia and vascular remodelling are attributed to late lumen loss in this porcine coronary injury model. XS0601 markedly reduced angiographic late lumen loss resulting from intimal hyperplasia, vascular remodelling and XS0601 may be a potential agent to prevent restenosis after PCI.

Preinterventional peak monocyte count and in-stent intimal hyperplasia after coronary stent implantation in human coronary arteries

BACKGROUND

The mechanism of restenosis after stent implantation principally is neointimal hyperplasia. There is evidence that monocytes play a important role in in-stent restenosis (ISR) after stent implantation.

HYPOTHESIS

This study assessed the relationship between preinterventional peak monocyte count and neointimal growth after successful stent implantation.

METHODS

We performed coronary stent implantation in 85 patients (85 de novo lesions). Peripheral blood sample was obtained in all patients every 12 h before coronary angiography for measurement of peripheral monocytes. All patients received angiographic and intravascular ultrasound (IVUS) follow-up at 6 months after stenting.

RESULTS

The preinterventional circulating monocyte count was significantly higher in the ISR group than that in the group without ISR (654 +/- 62/vs. 461 +/- 222/mm3, p < 0.001) and was significantly higher in the reintervention group than that in the no-reintervention group (660 +/- 72/ vs. 470 +/- 216/mm3, p< 0.001). The incidence of ISR and repeat intervention associated with preinterventional monocyte count was highest among the patients in the highest tertile, who were at a 2.64-fold increased risk of ISR and 3.22-fold increased risk of repeat intervention compared with the patients in the lowest tertile. A significant positive correlation was found between preinterventional peak monocyte count and preinterventional plaque and media cross-sectional area and follow-up neointima area (r = 0.311, p = 0.007, r = 0.465, p < 0.001, respectively). The neointima area associated with preinterventional monocyte count was largest among the patients in the highest tertile, that is, 2-fold larger than that of the patients in the lowest tertile (p < 0.001) and 1.44-fold larger than that of the patients in the middle tertile (p = 0.001).

CONCLUSION

Our results suggest that circulating preinterventional monocytes play a principal role in the process of in-stent neointimal growth after successful stent implantation.

Renin-Angiotensin System Intervention to Prevent In-Stent Restenosis

The occurrence of in-stent restenosis is a major drawback of percutaneous transluminal coronary angioplasty with stent placement. Target vessel revascularization is necessary in 15% of patients who receive a stent. Recent advances in the development of drug-eluting stents have reduced these numbers tremendously. However refinement of antirestenotic therapies remains obligatory. The emerging interest in more physiological antirestenotic therapies might unchain an interest in the well-known inhibitors of the rennin-angiotensin system (RAS), the angiotensin-converting enzyme inhibitors, and the angiotensin II type I receptor blockers. Contradictory results overshadow the discussion of whether intervention in the RAS could prevent in-stent restenosis. This review discusses the pathophysiology of in-stent restenosis, the role of the RAS in in-stent restenosis, and the possible role of RAS intervention in the prevention of in-stent restenosis.

Role of Bone Marrow–Derived Progenitor Cells in Cuff-Induced Vascular Injury in Mice

OBJECTIVE

Arterial injury results in vascular remodeling associated with proliferation and migration of smooth muscle cells (SMCs) and the development of intimal hyperplasia, which is a critical component of restenosis after angioplasty of human coronary arteries and an important feature of atherosclerotic lesions. However, the origin of SMCs and other cells in the development of vascular remodeling is not yet fully understood.

METHODS AND RESULTS

We utilized a cuff-induced vascular injury model after transplantation of the bone marrow (BM) from green fluorescent protein (GFP)-transgenic mice. We found that macrophages were major cells recruited to the adventitia of the vascular injury lesion along with SMCs and endothelial cells (ECs). While investigating whether those cells are derived from the donor, we found that most of the macrophages were GFP-positive, and some of the SMCs and ECs were also GFP-positive. Administration of the anti-c-fms antibody resulted in a marked decrease in macrophages and a relative increase of SMCs, while administration of antibodies against the platelet-derived growth factor receptor-beta caused a prominent decrease in SMCs and a relative increase in macrophages.

CONCLUSIONS

The current study indicates that BM-derived cells play an important role in vascular injury, and that differentiation of macrophages and SMCs might be dependent on each other.

Histological findings after angioplasty using conventional balloon, radiofrequency thermal balloon, and stent for experimental aortic coarctation

BACKGROUND

Use of balloon angioplasty or stent implantation has been reported to be effective in relieving coarctation of the aorta. However, restenosis frequently occurs after balloon angioplasty for native aortic coarctation in small infants, and sometimes develops after stent implantation because of vessel growth. The causes of restenosis remain uncertain. The purpose of this study was to assess the histologic differences in vascular responses to angioplasty using conventional balloon, radiofrequency thermal balloon (RFTB), or stent for experimental aortic coarctation.

METHODS

The authors surgically created an aortic coarctation model using 14 puppies. Angioplasty using conventional balloon, RFTB, or stent was performed 1 month after the initial operation. At the acute or chronic phase after angioplasty, the animals were killed and histologic studies were performed.

RESULTS

More vascular injuries were noted in the specimens from animals undergoing conventional angioplasty than in those with RFTB or stent. However, neointimal hyperplasia was seen more often after RFTB or stent because of the proliferation of smooth muscle cells from the tunica media, caused by secretion of growth factors. Apoptosis reached a peak 1-2 weeks after angioplasty, regardless of the type of intervention.

CONCLUSIONS

The authors conclude that angioplasty with RFTB or stent can provide relatively small injuries in the vessel wall for aortic coarctation, but care must be taken to prevent restenosis caused by intimal hyperplasia, because neointima hyperplasia is more frequent after RFTB or stent.

Perivascular inflammation after balloon angioplasty of porcine coronary arteries

BACKGROUND

Inflammation has been suggested to play a role in vascular lesion formation after angioplasty. Whereas previous studies have focused on inflammatory reactions in the intima and media, less attention has been paid to adventitial and perivascular responses and their potential role in vascular remodeling.

METHODS AND RESULTS

Balloon overstretch injury of porcine coronary arteries was performed with standard clinical angioplasty catheters. Vessels were examined from 0.5 hour to 14 days after injury by immunohistochemistry and in situ hybridization (ISH) for neutrophil and macrophage markers, cell adhesion molecules (P-selectin, E-selectin, and vascular cell adhesion molecule-1), and neutrophil-specific CXC chemokines (alveolar macrophage-derived neutrophil chemotactic factor [AMCF]-I/interleukin-8 and AMCF-II). Neutrophils accumulated in the adventitia surrounding the injury site from 2 hours to 3 days, followed by macrophages from 1 to 7 days after angioplasty. Inflammation was associated temporally with the expression of mRNAs encoding cell adhesion molecules and chemokines. The main inflammatory and proliferative foci were not limited to the adventitia but rather extended many millimeters away from the injured vessel throughout the surrounding adipose and myocardial tissues.

CONCLUSIONS

Inflammatory responses after angioplasty of porcine coronary arteries occurred throughout the entire perivascular tissue. We hypothesize that perivascular inflammatory cells play a role in the recruitment and/or proliferation of adventitial myofibroblasts, possibly through the release of reactive oxygen species and/or cytokines, and thus contribute to vascular remodeling associated with postangioplasty restenosis.

Mechanisms of angioplasty and stent restenosis: implications for design of rational therapy

Restenosis after angioplasty or stenting remains the major limitation of both procedures. A vast array of drug therapies has been used to prevent restenosis, but they have proven to be predominantly unsuccessful. Recent trends in drug therapy have attempted to refine the molecular and biological targets of therapy, based on the assumption that a single biological process or molecule is critical to restenosis. In contrast, both stenting and brachytherapy, which are highly nonspecific, can successfully reduce restenosis after angioplasty or stenting, respectively. This review examines the biology of both angioplasty and stent stenosis, focussing on human studies. We also review the landmark human trials that have definitively proven successful therapies, such as stenting and brachytherapy. We suggest that the successful trials of stenting and brachytherapy and the failure of other treatments have highlighted the shortcomings of conventional animal models of arterial intervention, and gaps in our knowledge of human disease. In contrast to arguments advocating gene therapy, these studies suggest that the most likely successful drug therapy will have a wide therapeutic range, targeting as many of the components or biological processes contributing to restenosis as possible.

Recombinant soluble p-selectin glycoprotein ligand-1-Ig reduces restenosis through inhibition of platelet-neutrophil adhesion after double angioplasty in swine

BACKGROUND

P-selectin mediates leukocyte recruitment to activated platelets and endothelium through its high-affinity receptor P-selectin glycoprotein ligand-1 (PSGL-1). Platelet and leukocyte activation and binding have been reported after coronary angioplasty and were correlated with restenosis. We investigated the effect of a recombinant soluble PSGL-1 (rPSGL-Ig) on the adhesion of platelets and neutrophils and the development of restenosis after double arterial injury.

METHODS AND RESULTS

Four weeks after angioplasty of both carotid arteries in pigs, a second angioplasty was performed at the same sites, 15 minutes after a single administration of vehicle or rPSGL-1 (1 mg/kg IV). Animals were euthanized 1 hour, 4 hours, 1 week, or 4 weeks later. Adhesion of autologous (51)Cr-platelets and (111)In-neutrophils was quantified and histological/morphometric analyses were performed. Although rPSGL-Ig did not affect adherence of these cells 1 hour after injury, it significantly reduced the adhesion of platelets (50% at 4 hours and 85% at 1 week) and neutrophils (50% at 4 hours and 78% at 1 week) to deeply injured arteries. At 4 weeks, the residual lumen was 63% larger in rPSGL-Ig-treated arteries as compared with control arteries (6.1+/-0.6 versus 3.8+/-0.1 mm(2); P:<0.002). The neointimal area was slightly reduced (0.5 in rPSGL-Ig versus 0.7 mm(2) in control). The ratio of the external elastic lamina of injured to uninjured reference segments was >1 in treated arteries and <1 in control arteries.

CONCLUSIONS

P-selectin antagonism with rPSGL-Ig inhibits early platelet/leukocyte adhesion on injured arteries and reduces restenosis through a positive impact on vascular remodeling. Hence, rPSGL-Ig may have potential in the prevention of restenosis.

Three dimensional intravascular ultrasonic assessment of the local mechanism of restenosis after balloon angioplasty

OBJECTIVE

To assess the mechanism of restenosis after balloon angioplasty.

DESIGN

Prospective study.

PATIENTS

13 patients treated with balloon angioplasty.

INTERVENTIONS

111 coronary subsegments (2 mm each) were analysed after balloon angioplasty and at a six month follow up using three dimensional intravascular ultrasound (IVUS).

MAIN OUTCOME MEASURES

Qualitative and quantitative IVUS analysis. Total vessel (external elastic membrane), plaque, and lumen volume were measured in each 2 mm subsegment. Delta values were calculated (follow up - postprocedure). Remodelling was defined as any (positive or negative) change in total vessel volume.

RESULTS

Positive remodelling was observed in 52 subsegments while negative remodelling occurred in 44. Remodelling, plaque type, and dissection were heterogeneously distributed along the coronary segments. Plaque composition was not associated with changes in IVUS indices, whereas dissected subsegments had a greater increase in total vessel volume than those without dissection (1.7 mm(3) v -0.33 mm(3), p = 0.04). Change in total vessel volume was correlated with changes in lumen (p < 0.05, r = 0.56) and plaque volumes (p < 0.05, r = 0.64). The site with maximum lumen loss was not the same site as the minimum lumen area at follow up in the majority (n = 10) of the vessels. In the multivariate model, residual plaque burden had an influence on negative remodelling (p = 0.001, 95% confidence interval (CI) -0.391 to -0.108), whereas dissection had an effect on total vessel increase (p = 0.002, 95% CI 1.168 to 4.969).

CONCLUSIONS

The mechanism of lumen renarrowing after balloon angioplasty appears to be determined by unfavourable remodelling. However, different patterns of remodelling may occur in individual injured coronary segments, which highlights the complexity and influence of local factors in the restenotic process.