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Abstract

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

Left ventricular (LV) remodeling and heart failure (HF) complicate acute myocardial infarction (AMI) even weeks to months after the initial insult. Apoptosis may represent an important pathophysiologic mechanism causing progressive myocardiocyte loss and LV dilatation even late after AMI. This review will discuss the role of apoptosis according to findings in animal experimental data and observational studies in humans in order to assess clinical relevance, determinants, and mechanisms of myocardial apoptosis and potential therapeutic implications. More complete definition of the impact of myocardiocyte loss on prognosis and of the mechanisms involved may lead to improved understanding of cardiac remodeling and possibly improved patients' care. Mitochondrial damage and bcl-2 to bax balance play a central role in ischemia-dependent apoptosis while angiotensin II and β1-adrenergic-stimulation may be major causes of receptor-mediated apoptosis. Benefits due to treatment with ACE-inhibitors and β-blockers appear to be in part due to reduced myocardial apoptosis. Moreover, infarct-related artery patency late after AMI may be a major determinant of myocardial apoptosis and clinical benefits deriving from an open artery late post AMI (the “open artery hypothesis”) may be, at least in part, due to reduced myocardiocyte loss. © 2002 Wiley-Liss, Inc.

Left ventricular (LV) dysfunction and symptomatic heart failure (HF) often complicate the acute and subacute clinical course of acute myocardial infarction (AMI) (Greenberg et al., 1984). In this review, we will discuss major findings regarding the pathophysiologic role of apoptosis (or programmed cell death) in post-infarction LV remodeling according to experimental data in animals and observational studies in humans.

ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

Acute events

As a result of acute ischemia, excitation-contraction uncoupling occurs determining cardiac systolic and diastolic dysfunction, which may be transient and reversible, if prompt reperfusion occurs (“myocardial stunning”) (Braunwald and Kloner, 1982). Persistence of ischemia leads to irreversible cell death. Ischemic necrosis is pathognonomic of AMI, as elevation in biochemical markers of cell lysis, in a compatible clinical scenario, is diagnostic (Antman et al., 2000). A different type of cell death, however, is also implicated in determining myocardiocyte loss in AMI. Myocardial apoptosis peaks at 4–12 h in AMI and is persistently demonstrable up to 10 days (Cheng et al., 1996; Kajstura et al., 1996; Olivetti et al., 1996; Veinot et al., 1997). In this context, apoptosis represents the major form of death, being several times more common than necrosis (peak value of 43% of apoptotic myocardiocytes at 4.5 h vs. peak value of 8% of necrotic cells at 24 h) (Kajstura et al., 1996). Several other studies, both experimental and observational, have confirmed such results (Olivetti et al., 1996; Bardales et al., 1996; Veinot et al., 1997; Saraste et al., 1997; Kajstura et al., 1998; Toyoda et al., 1998; Piro et al., 2000; Kurrelmeyer et al., 2000; Edston et al., 2002).

Apoptosis, known as programmed cell death, is a fundamental physiologic and pathologic mechanism that allows elimination of normal but no-longer-useful cells during embryogenesis or of aged or damaged cells during life (Kerr et al., 1972; Searle et al., 1982; Rich et al., 1999) (Fig. 1). A delicate balance between survival and death exists in cells undergoing physiologic and pathologic stress (such as hypoxia) and initiation of programmed cell death (apoptosis) during initial phases may not always be followed by its completion (Majno and Joris, 1995; Buja and Entman, 1998) (Fig. 1). Abrupt cell rupture may indeed affect initially viable cells (primary necrosis or oncosis) or cells already committed to apoptotic cell death (secondary necrosis) (Majno and Joris, 1995; Ohno et al., 1998). Balance between apoptosis and primary necrosis depends on available energetic levels, as completion of apoptosis needs adequate ATP cellular concentrations (Leist et al., 1997; Formigli et al., 2000). Necrosis of myocardiocytes is usually completed within 24–48 h following abrupt coronary occlusion and phagocytosis and removal of cellular debris by inflammatory cells starts at 24 h (Lodge-Patch, 1951; Fishbein et al., 1978). Features of acute inflammation (interstitial edema and neutrophil polymorphonuclear infiltration) characterize the first 24–72 h and are associated with further reduced cardiac performance, while macrophages infiltrate the infarcted myocardium days later.

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Figure 1. Hibernation, apoptosis, and necrosis represent three possible modalities of cellular response to stress (such as hypoxia) leading to different solutions. Hibernation is associated with cell survival and reversible metabolic changes. Apoptosis and necrosis both lead to myocardiocyte loss; however, while apoptosis causes silent but persistent loss, necrosis is associated with abrupt onset and clinical manifestation associated with secondary inflammatory phenomena.

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Early remodeling

Cardiac dysfunction, however, may occur even days after the initial insult. Infarct expansion has been described as a sudden, necrosis-independent, LV dilatation occurring early after AMI and leading to unfavorable hemodynamics and increased risk of mechanical AMI complications (Hutchins and Bulkley, 1978). The cellular response, involving inflammatory cell infiltration within the myocardium, fibroblast proliferation, and neoangiogenesis, peaks at 4–7 days (Lodge-Patch, 1951; Fishbein et al., 1978; Cowman et al., 1991). Olivetti et al. (1990) have described side-to-side slippage of myocardiocytes as a possible additional pathophysiological mechanism of infarct expansion, leading to elongation of fibers and absolute reduction of number of myocytes in transmural sections (Fig. 2A).

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Figure 2. Hibernation, apoptosis, necrosis, inflammation, and other cellular mechanisms contribute in determining cardiac failure at different periods (A). Apoptosis indeed may be a persistent feature following myocardial damage. Beneficial effects over the long-term associated with the patency of the infarct-related artery (“open artery hypothesis”) may be due to reduced apoptosis at the site of infarction (B). 1Kajstura J, Lab Invest 1996; 2Olivetti G, J Mol Cell Cardiol 1996; 3Veinot, Am J Pathol 1997; 4Palojoki E, Am J Physiol 2001; 5Sharov VG, Am J Pathol 1996; 6Baldi A, J Mol Cell Cardiol 2002; 7Narula J, N Engl J Med 1996; 8Olivetti G, N Engl J Med 1997; 9Saraste A, Eur J Clin Invest 1999; 10Kim CB, Circulation 1993; 11Abbate A, Circulation 2002; 12Saraste A, Circulation 1997.

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Late remodeling and end-stage heart failure

Congestive HF after AMI, however, may also occur even later in the clinical course, and indeed ischemic heart disease constitutes the most common cause of end-stage HF (Pfeffer and Braunwald, 1990; Cohn et al., 2000). Post-infarction LV remodeling consists of progressive chamber dilatation, wall thinning, and systolic/diastolic dysfunction (Pfeffer and Braunwald, 1990). This process involves cellular and molecular mechanisms beginning days after AMI and persisting for weeks and months after the initial insult both at the site of infarction (even after complete infarct healing) as well as in the surviving unaffected areas (Anversa et al., 1991; Beltrami et al., 1994). LV remodeling is associated with unfavorable hemodynamic performance and adverse clinical outcomes during long-term follow-up, such as increasing rate of symptomatic HF, death due to pump failure, and sudden cardiac death (Pfeffer and Braunwald, 1990; Cohn et al., 2000). Several studies have described the presence of apoptosis in end-stage HF (Narula et al., 1996; Olivetti et al., 1997; Sharov et al., 1997; Saraste et al., 1999) and, some in particular, in post-infarction LV remodeling (Prabhu and Chandrasekar, 2000; Sam et al., 2000; Palojoki et al., 2001; Baldi et al., 2002) (Fig. 2A).

However, myocardiocytes surviving through the acute phases undergo major metabolic rearrangements in order to favor survival in the delicate balance between hibernation and apoptosis (Canty and Suzuki, 2002; Sawyer and Loscalzo, 2002) (Fig. 1). The term “hibernation” refers to a chronic condition of severe energy deprivation of the myocardium due to chronic or repetitive underperfusion associated to reversible contractile dysfunction (Braunwald and Kloner, 1982; Braunwald and Rutherford, 1986). Underperfused myocardium retains its viability by down-regulating its function, thereby regaining the balance between the request for and the availability of oxygen supply. Structural and functional alterations occurring in hibernating myocardium include expression of fetal proteins, suggesting the use of the term of “dedifferentiated” myocardiocytes (Dispersyn et al., 2000; Elsässer et al., 2002). Under the same experimental conditions of chronic underperfusion, cells with metabolic down-regulation and apoptotic cells coexist (Chen et al., 1997; Elsässer et al., 1997; Lim et al., 1999; Dispersyn et al., 2002). Apoptosis, therefore, determines myocardiocyte loss also in chronic ischemia, however, whether hibernation represents a prelude to apoptosis is unknown (Canty and Suzuki, 2002; Dispersyn et al., 2002) (Fig. 1). Regarding this issue, Elsässer et al. (1999) have suggested that myocardial apoptosis may be responsible for incomplete recovery of cardiac contractility after coronary revascularization (Fig. 2A).

APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

Experimental data

Left coronary artery ligation in mice and rats is associated with development of progressive HF after AMI in those animals surviving for at least 12–18 weeks after surgery (Prabhu and Chandrasekar, 2000; Sam et al., 2000; Palojoki et al., 2001; Bayat et al., 2002). Palojoki et al. (2001) have shown that AMI in rats is associated with persistently elevated apoptotic rate (AR) at border zone up to 12 weeks later and that apoptosis is correlated with end-diastolic LV diameters at echocardiography. Similar results were later presented by Sam et al. (2000) in mice, showing increasing AR up to 6 months after surgery also in remote unaffected LV regions (0.75–1.10% of cells), and by Prabhu et al. (2000), with a 30-fold increase of AR in post AMI (0.6% vs. 0.02% in sham operated rats). A gradual decrease of AR over time has been shown, however, in every published study apoptosis was still demonstrable in a low but relevant rate up to 3–6 months after AMI (Ravalli et al., 1996; Palojoki et al., 2001). Other studies have looked at this issue showing similar results (Oskarsson et al., 2000; Palmen et al., 2001).

Likewise, transcatheter coronary embolization with polystyrene latex microspheres causing multiple AMI in dogs is associated with occurrence of LV dilatation weeks to months after the procedure (Sabbah et al., 1991). In this experimental model of ischemic heart failure, Sharov et al. (1996) have shown that 3–4 months after the last embolization a significantly higher number of apoptotic myocardiocytes were found in dogs with post-infarction LV remodeling compared to sham-operated animals. Interestingly, also in this model (up to 4 months after the AMI) a statistically significant difference in localization of apoptotic cells was found, with a nearly 20-fold increased AR at border of infarction scars. This model was subsequently confirmed in two other protocols performed by the same authors (Goussev et al., 1998; Sabbah et al., 2000) and elevated AR with a preferential localization at the site of infarction scars was confirmed by the same authors in failing human hearts (Sharov et al., 1997). Multiple coronary embolization was associated with development of HF, caspase-3 activation and increased AR also in sheep (Jiang et al., 1999; Dispersyn et al., 2002).

Observational studies in humans

Olivetti et al. (1996) showed that myocardial apoptosis is present at post-mortem examination in hearts of patients who died within 10 days after AMI. An AR of 11.6% (range 1–26%) was found in the zone bordering the infarction and 0.74% in the remote region, leading to significant myocardiocyte loss. Others have shown that post-infarction cardiac remodeling (with a variable time after AMI) was associated at autopsy with an AR of 8.5% (range 1.5–11.9%) (Matturi et al., 2002) and similar qualitative data have been presented by Veinot et al. (1997).

Several other studies have assessed apoptosis in hearts explanted ex vivo from patients undergoing cardiac transplantation due to intractable HF. Narula et al. (1996) have shown significantly increased apoptosis in four hearts of patients with end-stage HF due to idiopathic dilated cardiomyopathy and in one out of three cases of HF due to severe coronary artery disease (AR of 17.3%) (Narula et al., 1996). Olivetti et al. (1997) showed, a few months later, a more than 200-fold increase in myocardial apoptosis in eight cases of end-stage ischemic cardiomyopathy versus controls (0.24% vs. 0.001%, respectively) (Olivetti et al., 1997). In the data later presented by Saraste et al. (1999), not only did apoptosis increase in cases versus controls, but AR also correlated with clinical severity of HF with a preferential localization at the site of infarction scars. Anecdotic data in their series showed the highest AR in the only case of patients with previous AMI within 12 months before transplantation (14%). Other studies have shown similar results, although with a wide variability in estimated AR, ranging from 0.05% (Latif et al., 2000; Saraste et al., 2002) to 8.9% in biopsies taken from patients with ischemic cardiomyopathy (Angelini et al., 1998) and up to 20% in hearts with dilated cardiomyopathy at time of transplantation (Song et al., 1999).

The first study designed to assess occurrence of apoptotic myocardiocytes late post AMI in humans was published recently. Baldi et al. (2002) have shown data supporting a regional occurrence of myocardial apoptosis at the site of recent infarction versus remote unaffected areas at time of autopsy up to 60 days after AMI (25.4% vs. 0.7%). Although major limitations are present in the interpretation of these findings (as the exact duration of the apoptotic cascade in vivo is unknown), these data show that persistent myocardiocyte loss still occurs during the subacute phases of AMI. Moreover, a strong correlation between AR and macroscopic signs of LV remodeling was present in their series (Baldi et al., 2002).

Determinants of apoptotic rate

The different studies presented show a wide variability of estimated AR among different series and also among different individuals within each study. Although conclusions should be drawn with caution, these data suggest the existence of a probable modulation of apoptosis in post-infarction LV remodeling. The comparison between the studies is fraught by severe inherent limitations and probably of limited usefulness since they differed in the definitions of the cases, selection of the histological samples, and methods used to assess apoptosis (see Unresolved Issues). Indeed, one major limitation when comparing animal studies to findings in humans is the selection criteria. Most of the studies in animals have included in the analysis only those individuals who survive late after AMI and being electively sacrificed, without therefore considering an approximate 30% dying spontaneously (Sabbah et al., 1991; Cheng et al., 1996; Kajstura et al., 1996; Sam et al., 2000). This may have led to an underestimation of effective AR, as previously discussed by Sam et al. (2000). On the other hand, part of the studies in humans have selected patients dying, rather than surviving, late after AMI (Olivetti et al., 1996; Baldi et al., 2002) and other studies have evaluated living patients at the time of cardiac transplantation or by ex vivo biopsies (Narula et al., 1996; Olivetti et al., 1997; Sharov et al., 1997; Angelini et al., 1998; Saraste et al., 1999). These selection bias may in part explain the differences in estimated AR in the different studies: AR ranged from 0.02 to 1.10% in experimental post-AMI animal models, from 8.5 to 25.4% in post-mortem human samples, and from 0.04 to 20.0% in explanted human hearts at time of transplantation or from ex vivo biopsies. Indeed, the evaluation of subjects dying early after AMI may have led to the selection of a group of patients with more adverse prognosis and extremely elevated AR, in comparison to the great majority of cases surviving several weeks and months after AMI. Similarly, the analysis of the hearts explanted from patients undergoing cardiac transplantation may have not been able to assess the effective occurrence of apoptosis in those patients with more severe HF who did not survive long enough to receive transplantation or may have only examined a “burnout state, characterized by minimal ongoing apoptosis, much like a battlefield days after the fighting has ended” (Kang and Izumo, 2000). Interestingly, when in an experimental study conducted on mice (Hirota et al., 1999), all animals were followed from time of intervention (surgical constriction of the aorta) until death, these mice (apoptosis-prone due to genetic manipulation) had an AR greater than 30% and almost all died of dilated cardiopathy within 2 weeks.

In other cases, apoptosis may be overestimated. In particular, biopsies taken at time of coronary artery surgery with aortic cross-clamping and extracorporeal circulation in patients with ischemic HF (Filippatos et al., 1999) may be associated with an overestimated AR, perhaps due to transient increase related to the procedure (range of apoptotic cells 60–70%).

Considering in details the factors associated with increased apoptosis, however, some studies need to be mentioned. The senescent heart is more susceptible to apoptosis due to ischemia-reperfusion damage (Liu et al., 1998), however, no study has found a clear correlation between AR and age in LV remodeling. Guerra et al. (1999) have shown that the female sex is relatively protected from apoptosis in end-stage heart failure. In post-infarction LV remodeling, a fourfold higher AR in males versus females was present (Baldi et al., personal communication), suggesting a role of apoptosis in determining the different pathologic and clinical evolution of cardiac remodeling in women (Luchner et al., 2002). Sex-related hormonal differences could in part explain such gender-dependent modulation of myocardial apoptosis (Zaugg et al., 2001). Moreover, AR tended to be higher in those patients with more severe LV remodeling as suggested by clinical and pathological data (Saraste et al., 1999).

One of the major clinical determinants in LV remodeling after an AMI, however, is the presence of an open or an occluded infarct-related artery (IRA) (Marroquin and Lamas, 2000). Abbate et al. (2002) have shown that potential benefits of IRA patency after AMI (the “open-artery hypothesis”) (Kim and Braunwald, 1993) may be in part due to reduced apoptosis at the site of infarction in those cases with patent artery at time of death. In their series, occluded IRA was associated with significantly higher AR at the site of infarction versus cases with patent artery (25.8% vs. 2.3%, P < 0.001) and this association remained statistically significant even after correction for clinical characteristics, such as sex, age, history of previous remote AMI and/or heart failure, transmural AMI, anterior AMI, fibrinolytic treatment, time from AMI to death, trauma as cause of death, and multivessel coronary disease (P = 0.003) (Abbate et al., 2002). Although, comparisons between different studies may be methodologically biased, we may reach the same conclusions even if we compare AR at border of infarction in AMI in humans with occluded infarct-related artery (11.6%), as presented by Olivetti et al. (1996), with AR assessed by Saraste et al. (1997) in humans who died after AMI with a patent artery at time of death (0.8%) (Fig. 2B).

MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

The apoptotic cascade is associated with sequential activation of several enzymatic reactions (Hengartner, 2000). Understanding of modulators and effectors in these complicated cascades may lead to the definition of potential targets for therapeutical interventions.

A pivotal role in apoptosis is occupied by the family of cysteine proteases known as caspases (Wang and Lenardo, 2000). Activated caspase-3 is a central mediator of apoptosis also in myocardiocytes (Black et al., 1998). In particular, caspase-3 induces caspase-activated DNAse activation, which leads to DNA fragmentation and also cleaves cytoskeletal and myofibrillar proteins, leading to significant alteration of the cytoskeleton and cell death, even in the absence of DNA fragmentation (Sakahira et al., 1998; Communal et al., 2001). Heart-targeted overexpression of caspase-3 in mice increases infarct size and depresses cardiac function (Condorelli et al., 2001), while apoptosis was significantly reduced in vitro by caspase-3 inhibitors (Nicholson et al., 1995) and was practically abolished in caspase-3 knock-out mice (Kuida et al., 1996). Activation of caspase-3 requires mytochondrial damage and release of specific mytochondrial proteins in the cytosol (Wang and Lenardo, 2000). Narula et al. (1999) have shown that myocardial apoptosis is associated with significant accumulation of cytochrome c in the cytosol and subsequent caspase-3 activation in failing human hearts. During apoptosis, permeability transition pores are formed in the mitochondrial membrane leading to a collapse of the inner membrane potential which is fundamental to activate the apoptotic cascade (Marchetti et al., 1996; Crompton, 2000). Indeed, when a permeability pores blocker (bongkrekik acid) was used in an in vitro model of apoptosis, classical pro-apoptotic stimuli failed to activate the cascade (Marchetti et al., 1996).

Permeability of mitochondrial membrane is strictly regulated by a family of proteins know as Bcl-2 family (Crompton, 2000). The two principal proteins of this family are Bcl-2 and Bax. They are part of the outer mitochondrial membrane and interact forming either homo- or heterodimers. Bax-homodimers cause increased permeability and loss of cytochrome c and apoptosis-inducing factor (AIF) from mytochondria, which ultimately cause activation of caspase-9 and thereafter caspase-3 (Crompton, 2000). Bcl-2 anti-apoptotic activity depends, on the other hand, on the ability to form heterodimers with Bax and prevent release of those pro-apoptotic mytochondrial factors (Susin et al., 1996; Crompton, 2000). Overexpression of both Bax and Bcl-2 has been demonstrated in several heart diseases (Misao et al., 1996; Olivetti et al., 1997; Saraste et al., 1999; Baldi et al., 2002), however, survival depends mostly on Bcl-2-to-Bax ratio. This ratio varies under physiologic and pathologic stresses and increased Bcl-2 levels may be found in salvaged myocardium in ischemic cardiomyopathy. Condorelli et al. (1999) have shown progressive decrease in Bcl-2-to-Bax ratio in hypertensive rats developing progressive cardiac hypertrophy and dilatation.

Mitochondrial damage, however, is only one of the mechanisms leading to caspase-3 activation and completion of apoptosis. Indeed, Scarabelli et al. (2001a) have shown that, in experimental model of ischemia-reperfusion in rats, endothelial apoptosis precedes myocardial apoptosis (Scarabelli et al., 2001a) and myocardial apoptosis is mostly dependent on activation of caspase-8, rather than caspase-9 (Scarabelli et al., 2001b). Whether this is true also in ischemic cardiomyopathy is unknown. Caspase-8 activation is strictly linked to death receptor-dependent apoptosis (Crompton, 2000) (Fig. 3). It is possible (although it remains speculative) that ischemic damage to endothelial cells causes endothelial apoptosis and stimulates myocardial apoptosis through the release of a soluble pro-apoptotic factor (Scarabelli et al., 2001a,b). Myocardiocyte apoptosis, however, may occur also in a caspase-independent fashion (Knaapen et al., 2001).

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Figure 3. Schematic representation of ischemia-dependent apoptotic and receptor-mediated apoptotic cascade in myocardiocytes.

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Safe phagocytosis of intact apoptotic cells represents the final phase of this highly regulated energy-dependent process (Savill and Fadok, 2000). Dying cells display a number of membrane proteins in order to favor phagocytosis. Interestingly, clearance of apoptotic bodies may be performed also by neighboring cells, acting as “semi-professional” phagocytes. Apoptotic bodies may therefore be found in the interstitium, in macrophages and also in myocardiocytes (Savill and Fadok, 2000; Knaapen et al., 2001). While phagocytosis of foreign bodies is usually associated with a local inflammatory reaction, apoptosis is not. This suggests that the mechanisms allowing macrophages to recognize apoptotic “self” cells are uncoupled from inflammatory response. Corpse clearance is particularly important because failure in removing cell remnants may cause secondary necrosis and subsequent inflammatory reaction within the myocardium. The molecules involved in phagocyte-apoptotic cell interaction have been only partially defined. A major role of phosphatidylserine, normally restricted to the inner-membrane leaflet of the cell, has been suggested. Externalization of phosphatidylserine is considered specific of apoptosis and in particular of its final phases (Fadok et al., 1998) and this may have clinical implications. In fact, labeled annexin-V, which has a high affinity for this molecule, is a reliable tool for the detection of apoptosis under various experimental conditions (Van Heerde et al., 2000) and technetium-99 m-labeled human recombinant annexin-V (evaluated by single-photon-emission computed tomography) was shown to be able to define the infarcted area in human patients with evolving AMI (Hofstra et al., 2000). Bridging molecules may be also implicated in corpse clearance. In particular, the component C1q of the complement acts as a bridge between the macrophage and the dying cell favoring phagocytosis (Taylor et al., 2000).

Precise definition of molecular mechanisms leading apoptotic cell death and “silent” apoptotic bodies removal may lead to effective innovative therapeutic interventions.

UNRESOLVED ISSUES

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

There are many unresolved issues regarding the role of apoptosis in the pathophysiology of ischemic injury and heart failure (Elsässer et al., 2000). In particular, the sensitivity and specificity of the methods used to assess myocardial apoptosis have been questioned. The different methods used may in part explain the wide variability in estimate of apoptosis in different studies. While in situ end-labeling of DNA fragmentation (TUNEL) is currently the most widely used technique allowing easy qualitative and quantitative evaluation of apoptosis, many studies suggest that it should not be the sole method used in experimental models. Indeed, Baldi et al. (2002) have shown that in post-infarction LV remodeling in humans up to 15% of TUNEL-positive myocardiocytes should not have been considered apoptotic because of failure to demonstrate selective caspase-3 expression or because of expression of PCNA positivity (expression of active DNA synthesis) and/or of SC-35 positivity (expression of RNA splicing), the latter two associated with false positive results at TUNEL (Kockx et al., 1998; Kanoh et al., 1999; Knaapen et al., 2001) (Fig. 4).

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Figure 4. Specificity of the TUNEL technique. Modified from Baldi et al. (2002).

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Co-localization of TUNEL and activated caspase-3 (after performing adequate positive and negative controls and correction for PCNA and SC-35 positive cells) may represent a reliable method to assess myocardial apoptosis. TUNEL determination using electron microscope, however, should be considered the gold standard for qualitative (although not quantitative) determination of apoptosis (Schaper et al., 1999). On the other hand, use of Taq-polymerase reaction, instead of TUNEL, adds no clear advantages (Guerra et al., 1999; Schaper et al., 1999).

Moreover, the significance of a number of myocardiocytes expressing activated caspase-3 but TUNEL-negative (Baldi et al., 2002) remains to be ascertained, especially in view of possible reversibility of the apoptotic cascade in its initial phases. It has been suggested that activation of caspase-3 in absence of DNA fragmentation may represent an initial and reversible stage of ischemia-driven apoptotic cascade (Scarabelli et al., 2001c).

Other unresolved issues are the uncertainties regarding the time needed for completion of apoptosis from stimulus to DNA fragmentation, reversibility of apoptosis, causal role of apoptosis in HF and reliable quantification of AR in order to assess the true impact of apoptosis on myocardiocyte loss.

THERAPEUTIC PERSPECTIVES

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

Significant improvements have been made in the last decades in managing patients with heart failure and more specifically those with previous AMI. Several studies have shown major benefits of treatment with ACE-inhibitors in limiting LV remodeling and reducing morbidity and mortality (Flather et al., 2000). Similar results have been shown for β-blocker therapy (Bristow, 2000). A working hypothesis to explain the benefits achieved with these treatments is a selective reduction of myocardiocyte loss due to apoptosis in ischemic HF.

To this aim, Goussev et al. (1998) and Sabbah et al. (2000) have compared the occurrence of myocardial apoptosis in a dog model of ischemic HF (Sabbah et al., 1991) in placebo-treated animals versus animals treated with enalapril or metoprolol, respectively. In both cases, they have shown a significant reduction of apoptotic myocardiocytes, both at the site of AMI and in remote areas, with the treatment compared to placebo. A 70% reduction in apoptosis was obtained with 10 mg daily of enalapril (Goussev et al., 1998) and treatment with 25 mg metoprolol twice daily was associated with a greater than 90% reduction in AR (Sabbah et al., 2000). Beneficial effects of metoprolol in reducing post AMI apoptosis by about 50% were shown also in rats (Prabhu et al., 2000), and carvedilol was found equally effective in rabbits (Yue et al., 1996). Whether ACE-inhibitors and β-blockers reduce apoptosis through a direct or indirect mechanism is unknown. Certainly they favorably affect hemodynamics and cardiac pre- and after-load, however, there is evidence that angiotensin II (via both AT-I and AT-II receptors) and β1-adrenergic stimulation activate the apoptotic cascade in vitro (Cigola et al., 1997; Communal et al., 1999; Cleutjens et al., 1999; Leri et al., 2000; Singh et al., 2001). Angiotensin II and catecolamines may therefore be valid candidates for soluble proapoptotic factors in the context of neurohormonal rearrangements in HF (Hasegawa et al., 2001). This may be true also in other noncardiac clinical conditions (Wang et al., 2000).

Other experimental studies have looked at novel therapies to suppress apoptosis. Initial experience in vitro by Leri et al. (1999) suggested beneficial effects of IGF-1 treatment on apoptosis, however, the same group failed to show benefits from constitutive IGF-1 expression in transgenic mice who underwent surgical coronary constriction (Li et al., 1999).

Caspase inhibition by treatment with Z-VAD.fmk (a selective AIF blocker) in mice was associated with a promising 70% reduction in TUNEL positive cells (Yaiota et al., 1998). Potential benefits of stem-cell or myoblast transplantation need to be further assessed (Menaschè and Desnos, 2002). The occurrence of myocardiocyte regeneration in AMI (Beltrami et al., 2001) supports the concept of plasticity of human heart after ischemic insults, oscillating in a balance between death, survival, and regeneration. Beltrami et al. (2001) showed up to 0.7% of regenerating myocardiocytes early during AMI and likewise Baldi et al. (2002) have shown a similar rate of myocardiocytes expressing PCNA, even up to 2 months after AMI.

However, to date the only treatments resulting in definite clinical benefits in humans presumably in part due to reduced apoptosis are medical therapy with ACE-inhibitors and beta-blockers and prompt reperfusion of the ischemic myocardium. Clinical trials with caspase-inhibitors are on their way (Nicholson, 2000).

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED

LV remodeling and HF complicate AMI even weeks to months after the initial insult. Experimental animal models and pathologic studies in humans show that apoptosis may represent an important pathophysiologic mechanism causing progressive myocardiocyte loss and LV dilatation even late after AMI. More complete definition of the impact of ongoing myocardiocyte loss on prognosis and of the mechanisms involved may lead to improved comprehension of cardiac remodeling and possibly improved patients' care.

LITERATURE CITED

  1. Top of page
  2. Abstract
  3. ACUTE MYOCARDIAL INFARCTION, CARDIAC FAILURE, AND APOPTOSIS
  4. APOPTOSIS IN POST-INFARCTION LEFT VENTRICULAR REMODELING
  5. MOLECULAR MECHANISMS IN ISCHEMIC CARDIOMYOPATHY
  6. UNRESOLVED ISSUES
  7. THERAPEUTIC PERSPECTIVES
  8. CONCLUSIONS
  9. LITERATURE CITED
  • Abbate A, Bussani R, Biondi-Zoccai GL, Rossiello R, Silvestri F, Baldi F, Biasucci LM, Baldi A. 2002. Persistent infarct-related artery occlusion is associated with an increased myocardial apoptosis at post-mortem examination in humans late after an acute myocardial infarction. Circulation 26: 10511054.
  • Angelini A, Calabrese F, Pettenazzo E, Valente M, Ceconi C, La Canna G, Corrado A, Alfieri O, Ferrari R, Thiene G. 1998. Apoptosis in chronic ischemic myocardium in human. Circulation (Abstract) 98: 1769.
  • Antman E, Bassand JP, Klein W, Ohman M, Lopez Sendon JL, Rydeń L, Simoons M, Tenderaet M. 2000. Myocardial infarction redefined—A consensus document of the Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction. J Am Coll Cardiol 36: 959969.
  • Anversa P, Olivetti G, Capasso JM. 1991. Cellular basis of ventricular remodeling after myocardial infarction. Am J Cardiol 68: 7D16D.
  • Baldi A, Abbate A, Bussani R, Patti G, Melfi R, Angelini A, Dobrina A, Rossiello R, Silvestri F, Baldi F, Di Sciascio G. 2002. Apoptosis and post-infarction left ventricular remodeling. J Mol Cell Cardiol 34: 165174.
  • Bardales RH, Hailey LS, Xie SS, Schaefer RF, Hsu SM. 1996. In situ apoptosis assay for the detection of early acute myocardial infarction. Am J Pathol 149: 821829.
  • Bayat H, Swaney JS, Ander AN, Dalton N, Kennedy BP, Hammond HK, Roth DM. 2002. Progressive heart failure after myocardial infarction in mice. Basic Res Cardiol 97: 206213.
  • Beltrami CA, Finato N, Rocco M, Feruglio GA, Pulicelli C, Cigola E, Quaini F, Sonnenblick EH, Olivetti G, Anversa P. 1994. Structural basis of end-stage failure in ischemic cardiomyopathy in humans. Circulation 89: 151163.
  • Beltrami AP, Urbanek K, Kajstura J, Yan SM, Finato N, Bussani R, Nadal-Ginard B, Silvestri F, Leri A, Beltrami CA, Anversa P. 2001. Evidence that human cardiac myocytes divide after myocardial infarction. N Engl J Med 344: 17501757.
  • Black SC, Huang JQ, Rezaiefar P, Radinovich S, Eberhart A, Nickolson DV, Rodger IW. 1998. Co-localization of the cysteine protease caspase-3 with apoptotic myocytes after in vivo myocardial ischemia and reperfusion in the rat. J Mol Cell Cardiol 30: 733742.
  • Braunwald E, Kloner RA. 1982. The stunned myocardium: Prolonged, postischemic ventricular dysfunction. Circulation 66: 11461149.
  • Braunwald E, Rutherford JD. 1986. Reversible ischemic left ventricular dysfunction: Evidence for the “hibernating” myocardium. J Am Coll Cardiol 8: 14671470.
  • Bristow MR. 2000. β-Adrenergic receptor blockade in chronic heart failure. Circulation 101: 558569.
  • Buja LM, Entman M. 1998. Modes of myocardial cell injury and cell death in ischemic heart disease. Circulation 98: 13551357.
  • Canty JM, Suzuki G. 2002. Heterogeneity of apoptosis and myolysis in coronary microembolization: A competition between programmed cell death and programmed cell survival. Eur Heart J 23: 838840.
  • Chen C, Ma L, Linfert DR, Lai T, Fallon JT, Gillam LD, Waters DD, Tsongalis GJ. 1997. Myocardial cell death and apoptosis in hibernating myocardium. J Am Coll Cardiol 30: 14071412.
  • Cheng W, Kajstura J, Nitahara JA, Li B, Reiss K, Liu Yu, Clark WA, Krajeswski S, Reed JC, Olivetti G, Anversa P. 1996. Programmed myocyte cell death affects the viable myocardium after infarction in rats. Exp Cell Res 226: 316327.
  • Cigola E, Kajstura J, Li B, Meggs LG, Anversa P. 1997. Angiotensin II activates programmed myocyte cell death in vitro. Exp Cell Res 231: 363371.
  • Cleutjens JFM, Passier RC, Smits JFM, Daemen MJAP. 1998. The effect of angiotensin type I and II receptor antagonists on apoptosis in infarcted rat heart. Circulation (Abstract) 98: 1116.
  • Cohn JN, Ferrari R, Sharpe N, on behalf of an Internation Forum on Cardiac Remodeling. 2000. Cardiac remodeling—Concepts and clinical implications: A consensus paper from international forum on cardiac remodeling. J Am Coll Cardiol 35: 569582.
  • Communal C, Singh K, Sawyer DB, Colucci WS. 1999. Opposing effects of β1-and β2-adrenergic receptors on cardiac myocyte apoptosis: Role of a pertussis-toxin sensitive G protein. Circulation 100: 22102212.
  • Communal C, Sumandea M, Solaro JR, Narula J, Hajjar RJ. 2001. Functional consequences of apoptosis in cardiac myocytes: Myofibrillar proteins are targets for caspase-3. Circulation (Abstract) 104: 2162.
  • Condorelli G, Morisco C, Stassi G, Notte A, Farina F, Sgaramella G, de Rienzo A, Roncarati R, Trimarco B, Lembo G. 1999. Increased cardiomyocyte apoptosis and changes in proapoptotic and antiapoptotic genes bax and bcl-2 during left ventricular adaptations to chronic pressure overload in the rat. Circulation 99: 30713078.
  • Condorelli G, Roncarati R, Ross J, Pisani A, Stassi G, Todaro M, Trocha S, Drusco A, Gu Y, Russo MA, Frati G, Jones SP, Lefer DJ, Napoli C, Croce CM. 2001. Heart-targeted overexpression of caspase3 in mice increases infarct size and depresses cardiac function. Proc Natl Acad Sci USA 98: 99779982.
  • Cowman MJ, Reichenbach D, Turner P, Thostenson C. 1991. Cellular response of the evolving myocardial infarction after therapeutic coronary artery reperfusion. Hum Pathol 22: 154163.
  • Crompton M. 2000. Mitochondrial intermembrane junctional complexes and their role in cell death. J Physiol 529: 1121.
  • Dispersyn GD, Borgers M, Flameng W. 2000. Apoptosis in chronic hibernating myocardium: Sleeping to death? Cardiovasc Res 45: 696703.
  • Dispersyn GD, Mesotten L, Meuris B, Maes A, Mortelmans L, Flameng W, Ramaekers F, Borgers M. 2002. Dissociation of cardiomyocyte apoptosis and dedifferentiation in infarct border zones. Eur Heart J 23: 849857.
  • Edston E, Gröntoft L, Johnson J. 2002. TUNEL: A useful screening method in sudden cardiac death. Int J Legal Med 116: 2226.
  • Elsässer A, Schlepper M, Klövekorn WP, Cai WJ, Zimmerman R, Müller KD, Strasser R, Kostin S, Gagel C, Münkel B, Schaper W, Schaper J. 1997. Hibernating myocardium—An incomplete adaptation to ischemia. Circulation 96: 29202931.
  • Elsässer A, Greiber S, Hein S, Clin K, Kostin S, Skwara W, Müller KD, Schaper J. 1999. Hibernating myocardium: Upregulation of the caspase-3 gene and reduction of bcl-2. Circulation (Abstract) 100: 1758.
  • Elsässer A, Suzuki K, Schaper J. 2000. Unresolved issues regarding the role of apoptosis in the pathogenesis of ischemic injury and heart failure. J Mol Cell Cardiol 32: 711724.
  • Elsässer A, Müller KD, Skwara W, Bode C, Kübler W, Vogt AM. 2002. Sever energy deprivation of human hibernating myocardium as possible common pathomechanism of contractile dysfunction, structural degeneration and cell death. J Am Coll Cardiol 39: 11891198.
  • Fadok VA, Bratton DL, Frascg SC, Warner ML, Henson PM. 1998. The role of phosphatidylserine in recognition of apoptotic cells by phagocytes. Cell Death Differ 5: 557563.
  • Filippatos G, Leche C, Sunga R, Tsoukas A, Anthopoulos P, Joshi I, Bifero A, Pick R, Uhal B. 1999. Expression of FAS adjacent to fibrotic foci in the failing human heart is not associated with increased apoptosis. Am J Physiol 277: H445H451.
  • Fishbein MC, Maclean D, Maroko PR. 1978. The histopathologic evolution of myocardial infarction. Chest 73: 843849.
  • Flather MD, Yusuf S, Køber L, Pfefer M, Hal A, Murray G, Torp-Pedersen C, Ball S, Pogue J, Moyè L, Braunwald E, Ford E, for the ACE-inhibitor myocardial infarction collaborative group. 2000. Long-term ACE-inhibitor therapy in patients with heart failure or left ventricular dysfunction: A systematic overview of data from individual patients. Lancet 355: 15751581.
  • Formigli L, Papucci L, Tani A, Schiavone N, Tempestini A, Orlandini GE, Capaccioli S, Orlandini SZ. 2000. Aponecrosis: Morphological and biochemical exploration of a syncretic process of cell death sharing apoptosis and necrosis. J Cell Physiol 182: 4149.
  • Goussev A, Sharov VG, Shimoyama H, Tanimura M, Lesch M, Goldstein S, Sabbah AN. 1998. Effects of ACE inhibition on cardiomyocyte apoptosis in dogs with heart failure. Am J Physiol 275: H626H631.
  • Greenberg H, Mc Master P, Dwyer EM, and the Multicenter Post-Infarction Research Group. 1984. Left ventricular dysfunction after acute myocardial infarction: Results of a prospective multicenter study. J Am Coll Cardiol 5: 867874.
  • Guerra S, Leri A, Wang X, Finato N, Di Loreto C, Beltrami C, Kajstura J, Anversa P. 1999. Myocyte death in the failing human heart is gender dependent. Circ Res 85: 856866.
  • Hasegawa K, Iwai-Kanai E, Sasayama S. 2001. Neurohormonal regulation of myocardial cell apoptosis during the development of heart failure. J Cell Physiol 186: 1118.
  • Hengartner MO. 2000. The biochemistry of apoptosis. Nature 407: 770776.
  • Hirota H, Chen J, Betz UA, Rajewsky K, Gu Y, Ross JJ, Muller W, Chien KR. 1999. Loss of a gp130 cardiac muscle survival pathway is a critical event in the onset of heart failure during biomechanical stress. Cell 97: 189198.
  • Hofstra L, Liem IH, Dumont EA, Boersma HH, van Heerde WL, Doevendans PA, DeMuinck E, Wellens HJJ, Kemerink GJ, Reutelingsperger CPM, Heidendal GA. 2000. Visualisation of cell death in vivo in patients with acute myocardial infarction. Lancet 356: 209212.
  • Hutchins GM, Bulkley BH. 1978. Infarct expansion versus extension: Two different complications of acute myocardial infarction. Am J Cardiol 41: 11271131.
  • Jiang L, Huang Y, Yuasa T, Hunyor S, dos Remedios CG. 1999. Elevated DNase activity and caspase expression in association with apoptosis in failing ischemic sheep left ventricles. Electrophoresis 20: 20462052.
  • Kajstura J, Cheng W, Reiss K, Clark WA, Sonneblick EH, Krajewski S, Reed JC, Olivetti G, Anversa P. 1996. Apoptotic and necrotic myocyte cell deaths are independent contributing variables of infarct size in rats. Lab Invest 74: 86107.
  • Kajstura J, Baldini A, Li B, Olivetti G, Leri A, Anversa P. 1998. Coronary artery constriction in rats: Necrotic and apoptotic myocyte death. Am J Cardiol 82: 30K41K.
  • Kang PM, Izumo S. 2000. Apoptosis and heart failure—A critical review of the literature. Circ Res 86: 11071113.
  • Kanoh M, Takemura G, Misao J, Hayakawa Y, Haoyama T, Nishigaki K, Noda T, Fujiwara T, Fukuda K, Minatoguchi S, Fujiwara H. 1999. Significance of myocytes with positive DNA in situ nick end-labeling (TUNEL) in hearts with dilated cardiomyopathy. No apoptosis but DNA repair. Circulation 99: 27572764.
  • Kerr JFR, Wyllie AH, Curie AR. 1972. Apoptosis: A basic biological phenomenon with wide ranging implications in tissue kinetics. Br J Cancer 26: 239256.
  • Kim CB, Braunwald E. 1993. Potential benefits of late reperfusion of infarcted myocardium: The open artery hypothesis. Circulation 88: 24262436.
  • Knaapen MWM, Davies MJ, De Bie M, Haven AJ, Martinet W, Kockx MM. 2001. Apoptotic versus autophagic cell death in heart failure. Cardiovasc Res 51: 304312.
  • Kockx MM, Muhring J, Knaapen MW, De Meyer G. 1998. RNA synthesis and splicing interferes with DNA in situ end labeling techniques used to detect apoptosis. Am J Pathol 152: 885888.
  • Kuida K, Zheng TS, Na S, Kuan C, Yang D, Karasuyama H, Rakic P, Flavell RA. 1996. Decreased apoptosis in the brain and premature lethality in CPP32-deficient mice. Nature 384: 368372.
  • Kurrelmeyer KM, Michael LH, Baumgarten G, Taffet GE, Peschon JJ, Sivasubramanian N, Entman ML, Mann DL. 2000. Endogenous tumor necrosis factor protects the adult cardiac myocyte against ischemic-induced apoptosis in a murine model of acute myocardial infarction. Proc Natl Acad Sci USA 97: 54565461.
  • Latif N, Khan MA, Birks E, O'Farrell A, Westbrook J, Dunn MJ, Yacoub MH. 2000. Upregulation of the bcl-2 family of proteins in end stage heart failure. J Am Coll Cardiol 35: 17691777.
  • Leist M, Single B, Castoldi AF, Kuhnle S, Nicotera P. 1997. Intracellular adenosine triphosfate (ATP) concentration: A switch in the decision between apoptosis and necrosis. J Exp Med 185: 14811486.
  • Leri A, Liu Y, Claudio PP, Kajstura J, Wang X, Wang S, Kang P, Malhotra A, Anversa P. 1999. Insulin-like growth factor-1 induces Mdm-2 and down-regulates p53, attenuating the myocyte renin-angiotensin system and stretch-mediated apoptosis. Am J Pathol 154: 567580.
  • Leri A, Liu Y, Li B, Fiordaliso F, Malhotra A, Latini R, Kajstura J, Anversa P. 2000. Up-regulation of AT1 and AT2 receptors in postinfarcted hypertrophied myocytes and stretch-mediated apoptotic cell death. Am J Pathol 156: 16631672.
  • Li B, Setoguchi M, Wang X, Andreoli AM, Leri A, Malhotra A, Kajstura J, Anversa P. 1999. Insulin-like growth factor-1 attenuates the detrimental impact of nonocclusive coronary constriction on the heart. Circ Res 84: 10071019.
  • Lim H, Fallavollita JA, Hard R, Kerr CW, Canty JM. 1999. Profound apoptosis-mediated regional myocyte loss and compensatory hypertrophy in pigs with hibernating myocardium. Circulation 100: 23802386.
  • Liu L, Azhar G, Gao W, Zhang X, Wei JY. 1998. Bcl-2 and Bax expression in adult rat hearts after coronary occlusion: Age-associated differences. Am J Physiol 275: R315R322.
  • Lodge-Patch I. 1951. The ageing of cardiac infarcts, and its influence on cardiac rupture. Br Heart J 13: 3742.
  • Luchner A, Brockel U, Muscholl M. 2002. Gender-specific differences of cardiac remodeling in subjects with left ventricular dysfunction: A population-based study. Cardiovasc Res 53: 720727.
  • Majno G, Joris L. 1995. Apoptosis, oncosis and necrosis. Am J Pathol 146: 315.
  • Marchetti P, Castedo M, Susin SA, Zampami N, Hirsch T, Macho A, Haeffner A, Hirsch F, Geuskens M, Kroemer G. 1996. Mitochondrial permeability transition is a central coordinating event of apoptosis. J Exp Med 184: 11551160.
  • Marroquin OC, Lamas GA. 2000. Beneficial effects of an open artery on left ventricular remodeling after myocardial infarction. Progr Cardiovasc Dis 42: 471483.
  • Matturi L, Milei J, Grana DR, Lavezzi AM. 2002. Characterization of myocardial hypertrophy by DNA content, PCNA expression and apoptotic index. Int J Cardiol 82: 3339.
  • Menaschè P, Desnos M. 2002. Cardiac reparation: Fixing the heart with cells, new vessels and genes. Eur Heart J 4: D73D81.
  • Misao J, Hayakawa Y, Ohno M, Kato S, Fujiwara T, Fujiwara H. 1996. Expression of bcl-2 protein, an inhibitor of apoptosis, and bax, an accelerator of apoptosis, in ventricular myocytes of human hearts with myocardial infarction. Circulation 94: 15061512.
  • Narula J, Haider N, Virmani R, DiSalvo TG, Kolodgie FD, Hajjar RJ, Schmidt U, Semigran MJ, Dec GW, Khaw BA. 1996. Apoptosis in myocytes in end-stage heart failure. N Engl J Med 335: 11821189.
  • Narula J, Pandley P, Arbustini E, Heider N, Narula N, Kolodgie FD, Dal Bello B, Semigran MJ, Bielsa-Masdeu A, Dec GW, Israels S, Ballester M, Virmani R, Saxena S, Kharbanda S. 1999. Apoptosis in heart failure: Release of cytochrome c from mitochondria and activation of caspase-3 in human cardiomyopathy. Proc Natl Acad Sci USA 96: 81448149.
  • Nicholson DW, Ali A, Thornberry NA, Vaillancourt JP, Ding CK, Gallant M, Gareau Y, Griffin PR, Labelle M, Lazebnik YA. 1995. Identification and inhibition of the ICE/CED-3 protease necessary for mammalian apoptosis. Nature 376: 3743.
  • Nicholson DW. 2000. From bench to clinic with apoptosis-based therapeutic agents. Nature 407: 810816.
  • Ohno M, Takemura G, Ohno A, Misao J, Hayakawa Y, Minatoguchi S, Fujiwara T, Fujiwara H. 1998. “Apoptotic” myocytes in infarct area in rabbit hearts may be oncotic myocytes with DNA fragmentation. Circulation 98: 14221430.
  • Olivetti G, Capasso JM, Sonnenblick EH, Anversa P. 1990. Side-to-side slippage of myocytes participates in ventricular wall remodeling acutely after myocardial infarction in rats. Circ Res 67: 2334.
  • Olivetti G, Quaini F, Sala R, Lagrasta C, Corradi D, Bonacina E, Gambert SR, Cigola E, Anversa P. 1996. Acute myocardial infarction in humans is associated with activation of programmed myocyte cell death in the surviving portion of the heart. J Mol Cell Cardiol 28: 20052016.
  • Olivetti G, Abbi R, Quaini F, Kajstura J, Cheng W, Nitahara JA, Quaini E, Di Loreto C, Beltrami CA, Krajewski S, Reed JC, Anversa P. 1997. Apoptosis in the failing human heart. N Engl J Med 336: 11311141.
  • Oskarsson HJ, Coppey L, Weiss RM, Li WG. 2000. Antioxidants attenuate myocyte apoptosis in the remote non-infarcted myocardium following large myocardial infarction. Cardiovasc Res 45: 679687.
  • Palmen M, Daemen MJAP, Bronsaer R, Dassen WRM, Zandbergen HR, Kockx M, Smits JFM, van der Zee R, Doevendans PA. 2001. Cardiac remodeling after myocardial infarction is impaired in IGF-1 deficient mice. Cardiovasc Res 50: 516524.
  • Palojoki E, Saraste A, Eriksson A, Pulkki K, Kallajoki M, Voipio-Pulkki LM, Tikkanen I. 2001. Cardiomyocyte apoptosis and ventricular remodeling after myocardial infarction in rats. Am J Physiol 280: H2726H2730.
  • Pfeffer MA, Braunwald E. 1990. Ventricular remodeling after myocardial infarction – Experimental observations and clinical implications. Circulation 81: 11611172.
  • Piro FR, di Gioia CRT, Gallo P, Giordano C, d'Amati G. 2000. Is apoptosis a diagnostic marker of acute myocardial infarction? Arch Pathos Lab Med 124: 827831.
  • Prabhu SD, Chandrasekar B. 2000. β-Adrenergic blockade in developing heart failure reduces myocardial BCL-xS gene expression and apoptosis. Circulation (Abstract) 102: 2214.
  • Ravalli S, Cai B, Kohmoto T, Szabolcs M, DeRosa CM, Uzun G, Packer M, Burkhoff D. 1996. Apoptosis contributes to myocyte loss late after myocardial infarction in rats. Circulation 94: 132.
  • Rich T, Watson CJ, Wyllie A. 1999. Apoptosis: The germs of death. Nat Cell Biol 1: E69E71.
  • Sabbah HN, Stein PD, Kono T, Gheorghiade M, Levine TB, Jafri S, Hawkins ET, Goldstein S. 1991. A canine model of chronic heart failure produced by multiple sequential coronary microembolization. Am J Physiol 260: H1379H1384.
  • Sabbah HN, Sharov VG, Gupta RC, Todor A, Singh V, Goldstein S. 2000. Chronic therapy with metoprolol attenuates cardiomyocyte apoptosis in dogs with heart failure. J Am Coll Cardiol 36: 16981705.
  • Sakahira H, Enari M, Nagata S. 1998. Cleavage of CAD inhibitor in CAD activation and DNA degradation during apoptosis. Nature 391: 79948004.
  • Sam F, Sawyer DB, Chang DLF, Eberli FR, Ngoy S, Jain M, Amin J, Apstein CS, Colucci WS. 2000. Progressive left ventricular remodeling and apoptosis late after myocardial infarction in mouse heart. Am J Physiol 279: H422H428.
  • Saraste A, Pulkki K, Kallajoki M, Henriksen K, Parvinen M, Voipio-Pulkki LM. 1997. Apoptosis in human acute myocardial infarction. Circulation 95: 320323.
  • Saraste A, Pulkki K, Kallajoki M, Heikkilä P, Laine P, Mattila S, Nieminen NS, Parvinen M, Voipio-Pulkki LM. 1999. Cardiomyocyte apoptosis and progression of heart failure to transplantation. Eur J Clin Invest 29: 380386.
  • Saraste A, Voipio-Pulkki LM, Heikkila P, Laine P, Nieminem MS, Pulkki K. 2002. Soluble tumor necrosis factor receptor levels identify a subgroup of heart failure patients with increased cardiomyocyte apoptosis. Clin Chim Acta 320: 6567.
  • Savill J, Fadok V. 2000. Corpse clearance defines the meaning of cell death. Nature 407: 784788.
  • Sawyer DB, Loscalzo J. 2002. Myocardial hibernation—Restorative or preterminal sleep? Circulation 105: 15171519.
  • Scarabelli T, Stephanou A, Rayment N, Pasini E, Comini L, Curello S, Ferrari R, Knight R, Latchman D. 2001a. Apoptosis of endothelial cells precedes myocyte cell apoptosis in ischemia/reperfusion injury. Circulation 104: 253256.
  • Scarabelli T, Stephanou A, Chen Scarabelli C, Pasini E, Comini L, Curello S, Ferrari R, Knight R, Latchman D. 2001(b. Endothelial and myocardial apoptosis follow different signaling pathways during ischaemia-reperfusion injury. Eur Heart J (Abstract) 22: 371.
  • Scarabelli T, Stephanou A, Chen Scarabelli C, Pasini E, Comini L, Curello S, Ferrari R, Knight R, Latchman D. 2001(c. Caspase activation independent from DNA fragmentation after brief periods of ischaemia: An hypothetical cut off point for simulated angina? Eur Heart J (Abstract) 22: 371.
  • Schaper J, Elsässer A, Kostin S. 1999. The role of cell death in heart failure. Circ Res 85: 867869.
  • Searle J, Kerr JFR, Bishop CH. 1982. Necrosis and apoptosis: Distinct modes of cell death with fundamentally different significance. Pathol Annu 17: 229259.
  • Sharov VG, Sabbah HN, Shimoyama H, Goussev AV, Lesch M, Goldstein S. 1996. Evidence of cardiocyte apoptosis in myocardium of dogs with chronic heart failure. Am J Pathol 148: 141149.
  • Sharov VG, Goussev A, Higgins RSD, Silverman NA, Lesch M, Goldstein S, Sabbah HN. 1997. Higher incidence of cardiocyte apoptosis in failed explanted hearts of patients with ischemic versus idiopathic dilated cardiomyopathy. Circulation (Abstract) 95: 117.
  • Singh K, Xiao L, Remondino A, Sawyer DB, Colucci WS. 2001. Adrenergic regulation of cardiac myocyte apoptosis. J Cell Physiol 189: 257265.
  • Song H, Conte JV, Foster AH, McLaughlin JS, Wei C. 1999. Increased p53 protein expression in human failing myocardium. J Heart Lung Transpl 18: 744749.
  • Spencer FA, Meyer TE, Gore TE, Gore JM, Goldberg RJ. 2002. Heterogeneity in the management and outcomes of patients with acute myocardial infarction complicated by heart failure. Circulation 105: 26052610.
  • Susin SA, Zamzami N, Castedo M, Hirsch T, Marchetti P, Macho A, Daugas E, Geuskens M, Kroemer G. 1996. Bcl-2 inhibits the mitochondrial release of an apoptogenic protease. J Exp Med 184: 13311341.
  • Taylor PR, Carugati A, Fadok VA, Cook HT, Andrews M, Carroll MC, Savill JS, Henson PM, Botto M, Walport MJ. 2000. A hierarchial role for classical pathway complement proteins in the clearance of apoptotic bodies. J Exp Med 192: 359366.
  • Toyoda Y, Shida T, Watika N, Ozaki X, Takahashi R, Okada M. 1998. Evidence of apoptosis induced by myocardial ischemia: A case of ventricular septal rupture following acute myocardial infarction. Cardiology 90: 149151.
  • van Heerde WL, Robert-Offerman S, Dumont E, Hofstra L, Doevendans PA, Smits JF, Daemen MJ, Reutelingsperger CP. 2000. Markers of apoptosis in cardiovascular tissues: Focus on annexin-V. Cardiovasc Res 45: 549559.
  • Veinot JP, Gattinger DA, Fliss H. 1997. Early apoptosis in human myocardial infarcts. Am J Pathol 28: 485492.
  • Wang J, Lenardo MJ. 2000. Roles of caspases in apoptosis, development, and cytokine maturation revealed by homozygous gene deficiencies. J Cell Sci 113: 753757.
  • Wang R, Alam G, Zagariya A, Gidea C, Pinillos H, Lalude O, Choudhary G, Oezatalay D, Uhal BD. 2000. Apoptosis of lung epithelial cells in response to TNF-alpha requires angiotensin II generation de novo. J Cell Physiol 185: 253259.
  • Yaiota H, Ogawa K, Machara K, Maruyama Y. 1998. Attenuation of ischemia/reperfusion injury in rats by a caspase inhibitor. Circulation 97: 276281.
  • Yue TL, Ma XL, Chen XS, Louden C, Ruffolo RR, Feuerstein GZ. 1996. Carvedilol prevents cardiac ischemic damage and apoptosis in rabbit cardiomyocytes. Circulation (Abstract) 94: 1226.
  • Zaugg M, Jamali NZ, Lucchinetti E, Xu W, Alam M, Shafiq SA, Siddiqui MA. 2001. Anabolic-androgenic steroids induce apoptotic cell death in adult rat ventricular myocytes. J Cell Physiol 187: 9095.