Role for substance p-based nociceptive signaling in progenitor cell activation and angiogenesis during ischemia in mice and in human subjects.

BACKGROUND: Pain triggers a homeostatic alarm reaction to injury. It remains unknown, however, whether nociceptive signaling activated by ischemia is relevant for progenitor cells (PC) release from bone marrow. To this end, we investigated the role of the neuropeptide substance P (SP) and cognate neurokinin 1 (NK1) nociceptor in PC activation and angiogenesis during ischemia in mice and in human subjects. METHODS AND RESULTS: The mouse bone marrow contains sensory fibers and PC that express SP. Moreover, SP-induced migration provides enrichment for PC that express NK1 and promote reparative angiogenesis after transplantation in a mouse model of limb ischemia. Acute myocardial infarction and limb ischemia increase SP levels in peripheral blood, decrease SP levels in bone marrow, and stimulate the mobilization of NK1-expressing PC, with these effects being abrogated by systemic administration of the opioid receptor agonist morphine. Moreover, bone marrow reconstitution with NK1-knockout cells results in depressed PC mobilization, delayed blood flow recovery, and reduced neovascularization after ischemia. We next asked whether SP is instrumental to PC mobilization and homing in patients with ischemia. Human PC express NK1, and SP-induced migration provides enrichment for proangiogenic PC. Patients with acute myocardial infarction show high circulating levels of SP and NK1-positive cells that coexpress PC antigens, such as CD34, KDR, and CXCR4. Moreover, NK1-expressing PC are abundant in infarcted hearts but not in hearts that developed an infarct after transplantation. CONCLUSIONS: Our data highlight the role of SP in reparative neovascularization. Nociceptive signaling may represent a novel target of regenerative medicine.

Short- versus long-term duration of dual-antiplatelet therapy after coronary stenting: a randomized multicenter trial.

BACKGROUND: The optimal duration of dual-antiplatelet therapy and the risk-benefit ratio for long-term dual-antiplatelet therapy after coronary stenting remain poorly defined. We evaluated the impact of up to 6 versus 24 months of dual-antiplatelet therapy in a broad all-comers patient population receiving a balanced proportion of Food and Drug Administration-approved drug-eluting or bare-metal stents. METHODS AND RESULTS: We randomly assigned 2013 patients to receive bare-metal, zotarolimus-eluting, paclitaxel-eluting, or everolimus-eluting stent implantation. At 30 days, patients in each stent group were randomly allocated to receive up to 6 or 24 months of clopidogrel therapy in addition to aspirin. The primary end point was a composite of death of any cause, myocardial infarction, or cerebrovascular accident. The cumulative risk of the primary outcome at 2 years was 10.1% with 24-month dual-antiplatelet therapy compared with 10.0% with 6-month dual-antiplatelet therapy (hazard ratio, 0.98; 95% confidence interval, 0.74-1.29; P=0.91). The individual risks of death, myocardial infarction, cerebrovascular accident, or stent thrombosis did not differ between the study groups; however, there was a consistently greater risk of hemorrhage in the 24-month clopidogrel group according to all prespecified bleeding definitions, including the recently proposed Bleeding Academic Research Consortium classification. CONCLUSIONS: A regimen of 24 months of clopidogrel therapy in patients who had received a balanced mixture of drug-eluting or bare-metal stents was not significantly more effective than a 6-month clopidogrel regimen in reducing the composite of death due to any cause, myocardial infarction, or cerebrovascular accident. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00611286.

Different clinical models of CD34 + cells mobilization in patients with cardiovascular disease.

To test the role of necrosis, ischemia or both in bone marrow cells (BMC) mobilization in patients with cardiovascular disease. We studied three groups of patients: group 1, Iatrogenic Necrosis, with pure necrosis (28 patients undergoing transcatheter radiofrequency ablation); group 2, Ischemic Necrosis (30 patients with myocardial infarction); group 3, Pure Ischemia (24 patients with unstable angina). As control groups, we studied 27 patients with stable coronary artery disease (CAD), and 20 patients without CAD undergoing angiography for valvular diseases or cardiomiopathy. CD34 + cells and cytokines were evaluated at: T(0) (baseline), 48 h and 5, 7, 10, 14 days thereafter. We observed a significant increase of CD34 + cells at T(3) and T(4) only in Iatrogenic Necrosis and Ischemic Necrosis group. The peak of mobilization was observed ten days after the necrotic event (2.8 ± 1.4 vs. 5.9 ± 1.9 in the group 1, P = 0.03; and 3 ± 1.5 vs. 5.6 ± 2 in the group 2, P = 0.04; respectively). We found a good correlation between CD34 + and vascular endothelial growth factor (VEGF) and stromal derived factor (SDF-1α) peak values (r = 0.77 and r = 0.63, respectively). At multivariable analysis, myocardial necrosis (OR 3.5, 95%CI 2.2-4.2, P < 0.01), VEGF (OR 2, 95%CI 1.1-3, P = 0.01 as above versus below median value), and SDF-1α (OR 1.6, 95%CI 1.1-2.5, P = 0.02 as above versus below median value) emerged as independent predictors of C34 + cells increase. Myocardial necrosis with simultaneous elevation of VEGF and SDF-1α causes a significant CD34 + cells mobilization in patients with cardiovascular disease.

Randomized comparison of 6- versus 24-month clopidogrel therapy after balancing anti-intimal hyperplasia stent potency in all-comer patients undergoing percutaneous coronary intervention Design and rationale for the PROlonging Dual-antiplatelet treatment after Grading stent-induced Intimal hyperplasia study (PRODIGY).

BACKGROUND: The optimal duration of clopidogrel therapy after coronary stenting is debated because of the scarcity of randomized controlled trials and inconsistencies arising from registry data. Although prolonged clopidogrel therapy after bare metal stenting is regarded as an effective secondary prevention measure, the safety profile of drug-eluting stents itself has been questioned in patients not receiving ≥ 12 months of dual-antiplatelet therapy. HYPOTHESIS: Twenty-four months of clopidogrel therapy after coronary stenting reduces the composite of death, myocardial infarction, or stroke compared with 6 months of treatment. STUDY DESIGN: PRODIGY is an unblinded, multicenter, 4-by-2 randomized trial. All-comer patients with indication to coronary stenting are randomly treated-balancing randomization-with bare metal stent (no active late loss inhibition), Endeavor Sprint zotarolimus-eluting stent (Medtronic, Santa Rosa, CA) (mild late loss inhibition), Taxus paclitaxel-eluting stent (Boston Scientific, Natick, MA) (moderate late loss inhibition), or Xience V everolimus-eluting stent (Abbott Vascular, Santa Clara, CA) (high late loss inhibition). At 30 days, patients in each stent group are randomly allocated to receive 24 or up to 6 months of clopidogrel therapy-primary end point randomization. With 1,700 individuals, this study will have >80% power to detect a 40% difference in the primary end point after sample size augmentation of 5% and a background event rate of 8%. SUMMARY: The PRODIGY trial aims to assess whether 24 months of clopidogrel therapy improves cardiovascular outcomes after coronary intervention in a broad all-comer patient population receiving a balanced mixture of stents with various anti-intimal hyperplasia potency.

Poor response to clopidogrel: current and future options for its management.

Antiplatelet therapy is the cornerstone of treatment for patients with acute coronary syndromes and/or undergoing percutaneous coronary interventions (PCI). Clopidogrel, a thienopyridine antiplatelet agent, has been used to prevent vascular complication in atherothrombotic patients, to prevent stent thrombosis in patients undergoing PCI, and in long term prevention of cardiovascular and cerebrovascular events. More than 40 million patients in the world receive clopidogrel but unfortunately about 20% of these are either non or poor responders. Several methods have been used to assess clopidogrel-induced antiplatelet effects. However, none of these tests have been fully standardized or fully agreed upon to measure clopidogrel responsiveness. Nevertheless, many studies using different techniques, platelet agonists and definitions, showed that patients with a poor response to clopidogrel have an increased risk of death, reinfarction and stent thrombosis. The mechanisms leading to poor responsiveness are not fully clarified and are likely multifactorial: genetic factors, accelerated platelet turnover, up-regulation of the P2Y(12) pathways, high baseline platelet reactivity, poor compliance, under-dosing and drug-drug interactions. The management of these patients is very difficult, but some evidence showed that a strategy of higher maintenance dose or switch to different thienopyridine (e.g. ticlopidine or prasugrel) or use of glycoprotein IIb/IIIa inhibitors during PCI may be helpful to overcome poor responsiveness and improve the long-term clinical outcome. This paper reviews the impact of clopidogrel poor responsiveness on clinical outcomes, the mechanisms leading to poor effect and the different assays to assess it. Finally, current and future options for its management is discussed.

Mechanisms of remodelling: a question of life (stem cell production) and death (myocyte apoptosis).

Remodeling myocytes show a typical switch between the embryonic and classical features of apoptosis and/or hypertrophy representing a signal of death (ie, apoptosis) and a signal of life (ie, hypertrophy). The adult myocyte, however, is a terminal cell; usually it is unable to reproduce and death is not genetically programmed (apoptosis), but occurs by necrosis. The reinstatement of apoptosis and development of hypertrophy during remodeling could be part of the switch forward to the embryonic phenotype with reinstatement of the early embryonic genetic program. Hypertrophy and apoptosis are "sons" of the same "mother": the local, tissue neuroendocrine-neurohumoral response to a mechanical stretch of the myocytes consequent to the geometric changes imposed on the viable myocytes by the necrotic ones. As expected, the life and death cycle is very closely regulated by several autocrine systems, one of which is linked to the interleukin-6 family via a regulatory protein named GP-130. Activation of the GP-130 slows down the death signals, thus favoring hypertrophy and reducing fibrosis.

Two-year outcomes after first- or second-generation drug-eluting or bare-metal stent implantation in all-comer patients undergoing percutaneous coronary intervention: a pre-specified analysis from the PRODIGY study (PROlonging Dual Antiplatelet Treatment After Grading stent-induced Intimal hyperplasia studY).

OBJECTIVES: This study sought to assess device-specific outcomes after implantation of bare-metal stents (BMS), zotarolimus-eluting Endeavor Sprint stents (ZES-S), paclitaxel-eluting stents (PES), or everolimus-eluting stents (EES) (Medtronic Cardiovascular, Santa Rosa, California) in all-comer patients undergoing percutaneous coronary intervention. BACKGROUND: Few studies have directly compared second-generation drug-eluting stents with each other or with BMS. METHODS: We randomized 2,013 patients to BMS, ZES-S, PES, or EES implantation. At 30 days, each stent group received up to 6 or 24 months of clopidogrel therapy. The key efficacy endpoint was the 2-year major adverse cardiac event (MACE) including any death, myocardial infarction, or target vessel revascularization, whereas the cumulative rate of definite or probable stent thrombosis (ST) was the key safety endpoint. RESULTS: Clinical follow-up at 2 years was complete for 99.7% of patients. The MACE rate was lowest in EES (19.2%; 95% confidence interval [CI]: 16.0 to 22.8), highest in BMS (32.1%; 95% CI: 28.1 to 36.3), and intermediate in PES (26.2%; 95% CI: 22.5 to 30.2) and ZES-S (27.8%; 95% CI: 24.1 to 31.9) groups (chi-square test = 18.9, p = 0.00029). The 2-year incidence of ST in the EES group (1%; 95% CI: 0.4 to 2.2) was similar to that in the ZES-S group (1.4%; 95% CI: 0.7 to 2.8), whereas it was lower compared with the PES (4.6%, 95% CI: 3.1 to 6.8) and BMS (3.6%; 95% CI: 2.4 to 5.6) groups (chi-square = 16.9; p = 0.0001). CONCLUSIONS: Our study shows that cumulative MACE rate, encompassing both safety and efficacy endpoints, was lowest for EES, highest for BMS, and intermediate for PES and ZES-S groups. EES outperformed BMS also with respect to the safety endpoints with regard to definite or probable and definite, probable, or possible ST. (PROlonging Dual antiplatelet treatment after Grading stent-induced Intimal hyperplasia studY [PRODIGY]; NCT00611286).

Migratory activity of circulating progenitor cells and serum SDF-1α predict adverse events in patients with myocardial infarction.

AIMS: Following acute myocardial infarction (AMI), pro-angiogenic progenitor cells (PCs) are released from the bone marrow into the circulation and home to the ischaemic site attracted by a chemokine gradient. It is unknown if components of this early homeostatic response might help forecast the long-term clinical outcome. This study investigates if the number and migratory activity of circulating PCs predict adverse events in patients with AMI (clinical trial: NCT01271309). METHODS AND RESULTS: Basal counts and in vitro migratory activity of CD34/CD45/CD133/CXCR4 PCs and serum cytokine levels were assessed during the first 5 days after AMI in a consecutive series of 172 patients. Clinical outcomes of the study were death, repeat AMI, and new-onset heart failure at a 1-year follow-up. The association between PC counts and cytokine levels with the incidence of clinical outcomes was assessed by multivariable regression models. AMI patients who underwent an event showed higher serum stromal cell-derived factor 1α (SDF-1α) levels and reduced spontaneous motility of PCs in an in vitro migration assay when compared with event-free subjects. After adjustment for age, gender, the presence or absence of ST elevation, or diabetes, the percentage of PCs non-migrated towards vehicle or SDF-1α were both independent predictors of death or repeat AMI and new-onset heart failure (odds ratio [OR] = 2, P = 0.015 and OR = 1.90, P = 0.018, respectively). Moreover, serum SDF-1α levels predict adverse events (OR = 3.8, P = 0.007). CONCLUSION: Biomarkers reflecting the migratory activity of circulating PCs may aid the assessment of secondary risk in AMI patients.

ACE inhibition modulates endothelial apoptosis and renewal via endothelial progenitor cells in patients with acute coronary syndromes.

BACKGROUND: The equilibrium between endothelial apoptosis and endothelial renewal is altered in acute coronary syndromes and may be related to differences in the beneficial effects of angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists (angiotensin receptor blockers). METHODS: We evaluated the effect of treatment on endothelial function in post-myocardial infarction (MI) patients treated with perindopril (group 2, n = 16) or valsartan (group 3, n = 17) at baseline and after 7, 15, and 30 days and in normal controls (group 1, n = 20). Endothelial apoptosis was determined by cultivating serum samples in vitro with human umbilical vein endothelial cells (HUVECs), while endothelial renewal was assessed by mobilization of CD34+ bone marrow cells. RESULTS: At baseline, post-MI patients had significantly elevated rates of apoptosis (16.6 ± 5.0% and 16.5 ± 8.4% in groups 2 and 3, respectively [both p = 0.01] vs 1.6 ± 0.7% in group 1), which declined in group 2 (10.5 ± 4.4% at 30 days, p = 0.04), but not in group 3. Similar results and trends were found for the Bax/Bcl-2 ratio. CD34+ mobilization was significantly increased in group 2 (3.0 ± 1.0 at baseline to 6.2 ± 1.6 at 15 days, p = 0.03), whereas in group 3 CD34+ mobilization did not change significantly. The findings in group 2 were accompanied by an increase in vascular endothelial growth factor at 15 days, and a reduction in tumor necrosis factor-α and its soluble receptors, versus no change in group 3. Similar findings were observed for angiotensin II and bradykinin. CONCLUSION: Our results indicate that perindopril, but not valsartan, reduces the proapoptotic effect of serum on the endothelium and increases endothelial renewal in patients with acute coronary syndromes.