Eugenio Quaini

Apoptosis in the Failing Human Heart

BACKGROUND Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.

Intense myocyte formation from cardiac stem cells in human cardiac hypertrophy.

It is generally believed that increase in adult contractile cardiac mass can be accomplished only by hypertrophy of existing myocytes. Documentation of myocardial regeneration in acute stress has challenged this dogma and led to the proposition that myocyte renewal is fundamental to cardiac homeostasis. Here we report that in human aortic stenosis, increased cardiac mass results from a combination of myocyte hypertrophy and hyperplasia. Intense new myocyte formation results from the differentiation of stem-like cells committed to the myocyte lineage. These cells express stem cell markers and telomerase. Their number increased >13-fold in aortic stenosis. The finding of cell clusters with stem cells making the transition to cardiogenic and myocyte precursors, as well as very primitive myocytes that turn into terminally differentiated myocytes, provides a link between cardiac stem cells and myocyte differentiation. Growth and differentiation of these primitive cells was markedly enhanced in hypertrophy, consistent with activation of a restricted number of stem cells that, through symmetrical cell division, generate asynchronously differentiating progeny. These clusters strongly support the existence of cardiac stem cells that amplify and commit to the myocyte lineage in response to increased workload. Their presence is consistent with the notion that myocyte hyperplasia significantly contributes to cardiac hypertrophy and accounts for the subpopulation of cycling myocytes.

End-stage cardiac failure in humans is coupled with the induction of proliferating cell nuclear antigen and nuclear mitotic division in ventricular myocytes.

Proliferating cell nuclear antigen (PCNA) is a late growth-regulated gene that is expressed at the G1-S boundary of the cell cycle and is required for DNA synthesis and cell proliferation. Since quantitative results suggest that myocyte hyperplasia occurs in the decompensated human heart, we postulated that induction of the PCNA gene may be present in the failing heart in humans. PCNA protein was detected in myocardial samples obtained from the left and right ventricles of patients with congestive heart failure. Endomyocardial biopsies collected from donor subjects were used as control tissue. The percentage of positively stained myocyte nuclei in the ventricles was established by using PCNA monoclonal antibody and the immunoperoxidase technique. The localization of PCNA in myocytes was confirmed by alpha-sarcomeric actin antibody staining. PCNA labeling was present in left ventricular myocytes of 29 of the 32 hearts examined. In the right ventricle, 24 of the 29 samples showed positive staining. In a subset of 25 patients, the percentage of PCNA-labeled myocyte nuclei was measured and found to constitute 49 +/- 22% of left ventricular myocytes. A similar analysis for the right ventricle, conducted in 21 patients, showed that 49 +/- 19% of the myocyte nuclei exhibited PCNA protein. In addition, mitotic figures in myocytes were documented. A quantitative analysis of this cellular process revealed that 11 myocyte nuclei per 1 million cells exhibited mitotic images in chronic heart failure. Immediately after myocardial infarction, two cells per million showed mitotic division, and this phenomenon was restricted to the region adjacent to the necrotic tissue. No PCNA labeling or nuclear mitotic images were detected in the ventricular myocardium of control subjects. Thus, the observation that diffuse PCNA labeling and myocyte mitotic division are present in hearts with end-stage failure strongly suggests that adult ventricular myocytes are not terminally differentiated cells and that myocyte cellular hyperplasia may constitute a growth reserve mechanism of the diseased heart.

Human cardiac and bone marrow stromal cells exhibit distinctive properties related to their origin

AIMS Bone marrow mesenchymal stromal cell (BMStC) transplantation into the infarcted heart improves left ventricular function and cardiac remodelling. However, it has been suggested that tissue-specific cells may be better for cardiac repair than cells from other sources. The objective of the present work has been the comparison of in vitro and in vivo properties of adult human cardiac stromal cells (CStC) to those of syngeneic BMStC. METHODS AND RESULTS Although CStC and BMStC exhibited a similar immunophenotype, their gene, microRNA, and protein expression profiles were remarkably different. Biologically, CStC, compared with BMStC, were less competent in acquiring the adipogenic and osteogenic phenotype but more efficiently expressed cardiovascular markers. When injected into the heart, in rat a model of chronic myocardial infarction, CStC persisted longer within the tissue, migrated into the scar, and differentiated into adult cardiomyocytes better than BMStC. CONCLUSION Our findings demonstrate that although CStC and BMStC share a common stromal phenotype, CStC present cardiovascular-associated features and may represent an important cell source for more efficient cardiac repair.

The Concerted Action 'Heart' European registry on clinical application of mechanical circulatory support systems : Bridge to transplant

OBJECTIVE The goal of this paper is to identify in the field of mechanical support as bridge to transplant, by statistical analysis, variables influencing survival during support (transplanted patients) and the overall survival (discharged after transplant). METHODS Clinical factors are analysed in 258 patients in the period 1986-1993. All variables were analyzed by a univariate and multivariate analysis. RESULTS The indications for mechanically circulatory support were hemodynamic deterioration before transplantation in 177 (69%), post acute myocardial infarction in 40 (15%), postcardiotomy cardiogenic shock in 20 (8%), graft failure in 12 (5%) and cardiac rejection 9 (3%). The devices implanted have been: pneumatic VAD in 145 cases (56%), electromechanical LVAS in 15 cases (6%), TAH in 78 cases (30%) and centrifugal pumps in 20 cases (8%). The patients were supported for period ranging from 2 h to 623 days (mean 18.3 days +/- 43.2). The type of support was: LVAD 50 cases (20%), RVAD 3 cases (1%), BVAD 127 cases (49%), and TAH 78 cases (30%). Bleeding occurred in 84 patients (32.5%), infections in 83 patients (32.1%); 21 embolic complications were reported in 16 patients (6%). Renal failure occurred in 64 cases (25%) requiring dialysis in 33 (13%); respiratory failure in 47 cases (18%); neurological impairment was noted in 22 patients (9%). One hundred-sixty patients were transplanted (62%) and 104 ultimately discharged (40% out of total 258 patients and 65% out of 160 transplanted patients). Among postoperative parameters, renal failure, TAH, neurological impairment and infection shown statistical power. Some pre- and post-operative variables were identified as independent risk factors for overall mortality: age, indication for graft failure, all indications different from cardiomyopathy, neurological impairment, renal insufficiency, infection, bleeding and any type of support different from LVAD. The improvement in the success rate in the last 2 years is statistically significant (P = 0.0282) considering both the percentage of transplanted patients and of discharged patients. CONCLUSIONS The results are encouraging if mechanical support is performed in patients with deterioration while awaiting transplant, when LVAD is feasible and effective, when an ideal timing of transplant during support period is identified.

Mass regression in aortic stenosis after valve replacement with small size pericardial bioprosthesis

BACKGROUND The aim of the study was to determine whether left ventricular mass regression is influenced by valve size after the implantation of a Carpentier-Edwards Perimount (CEP) pericardial bioprosthesis for pure aortic stenosis. METHODS Patients receiving 19-mm, 21-mm, and 23-mm CEP aortic valves underwent echocardiography preoperatively and at least 1 year after surgery (mean, 2.3 +/- 1 years) and the echocardiograms were compared within and between groups. RESULTS The study involved a total of 88 patients: 34 receiving 19-mm CEPs, 29 receiving 21-mm CEPs, and 25 receiving 23-mm CEPs. The mean postoperative prosthetic gradients were respectively 20.6 +/- 6.6 mm Hg, 17.9 +/- 5.8 mm Hg, and 13.2 +/- 4.1 mm Hg (p = 0.0001); the mean postoperative valve areas were respectively 1.24 +/- 0.16 cm(2), 1.45 +/- 0.2 cm(2), and 1.63 +/- 0.21 cm(2) (p = 0.0001). In comparison with the preoperative echocardiographic measurements absolute left ventricular mass significantly decreased by -54.1 +/- 48.8 g, -54.1 +/- 55.1 g, and -74.4 +/- 57.4 g respectively with no statistically significant between-group difference (analysis of variance) but ventricular septum and posterior wall thickness significantly decreased in each group (p < 0.05). CONCLUSIONS The implantation of 19-mm, 21-mm, and 23-mm CEP aortic prostheses significantly reduces left ventricular mass without any size-related differences.

Minimally invasive aortic valve replacement with a sutureless valve through a right anterior mini-thoracotomy versus transcatheter aortic valve implantation in high-risk patients

OBJECTIVES The aim of this study was to compare early outcomes and mid-term survival of high-risk patients undergoing minimally invasive aortic valve replacement through right anterior mini-thoracotomy (RT) with sutureless valves versus patients undergoing transcatheter aortic valve implantation (TAVI) for severe aortic stenosis. METHODS From October 2008 to March 2013, 269 patients with severe aortic stenosis underwent either RT with perceval S sutureless valves (n = 178 patients, 66.2%) or TAVI (n = 91, 33.8%: 44 transapical and 47 trans-femoral). Of these, 37 patients undergoing RT with the perceval S valve were matched to a TAVI group by the propensity score. RESULTS Baseline characteristics were similar in both groups (mean age 79 ± 6 years) and the median logistic EuroSCORE was 14% (range 9-20%). In the matched group, the in-hospital mortality rate was 8.1% (n = 3) in the TAVI group and 0% in the RT group (P = 0.25). The incidence rate of stroke was 5.4% (n = 2) versus 0% in the TAVI and RT groups (P = 0.3). In the TAVI group, 37.8% (n = 14) had mild paravalvular leakage (PVL) and 27% (n = 10) had moderate PVL, whereas 2.7% (n = 1) had mild PVL in the RT group (P < 0.001). One- and 2-year survival rates were 91.6 vs 78.6% and 91.6 vs 66.2% in patients undergoing RT with the perceval S sutureless valve compared with those undergoing TAVI, respectively (P = 0.1). CONCLUSIONS Minimally invasive aortic valve replacement with perceval S sutureless valves through an RT is associated with a trend of better early outcomes and mid-term survival compared with TAVI.

Resident Cardiac Stem Cells

The introduction of stem cells in cardiology provides new tools in understanding the regenerative processes of the normal and pathologic heart and opens new options for the treatment of cardiovascular diseases. The feasibility of adult bone marrow autologous and allogenic cell therapy of ischemic cardiomyopathies has been demonstrated in humans. However, many unresolved questions remain to link experimental with clinical observations. The demonstration that the heart is a self-renewing organ and that its cell turnover is regulated by myocardial progenitor cells offers novel pathogenetic mechanisms underlying cardiac diseases and raises the possibility to regenerate the damaged heart. Indeed, cardiac stem progenitor cells (CSPCs) have recently been isolated from the human heart by several laboratories although differences in methodology and phenotypic profile have been described. The present review points to the potential role of CSPCs in the onset and development of congestive heart failure and its reversal by regenerative approaches aimed at the preservation and expansion of the resident pool of progenitors.

Factors affecting left ventricular remodeling after valve replacement for aortic stenosis. An overview

Although a small percentage of patients with critical aortic stenosis do not develop left ventricle hypertrophy, increased ventricular mass is widely observed in conditions of increased afterload. There is growing epidemiological evidence that hypertrophy is associated with excess cardiac mortality and morbidity not only in patients with arterial hypertension, but also in those undergoing aortic valve replacement. Valve replacement surgery relieves the aortic obstruction and prolongs the life of many patients, but favorable or adverse left ventricular remodeling is affected by a large number of factors whose specific roles are still a subject of debate. Age, gender, hemodynamic factors, prosthetic valve types, myocyte alterations, interstitial structures, blood pressure control and ethnicity can all influence the process of left ventricle mass regression, and myocardial metabolism and coronary artery circulation are also involved in the changes occurring after aortic valve replacement. The aim of this overview is to analyze these factors in the light of our experience, elucidate the important question of prosthesis-patient mismatch by considering the method of effective orifice area, and discuss surgical timings and techniques that can improve the management of patients with aortic valve stenosis and maximize the probability of mass regression.

Cancer treatment-induced cardiotoxicity: a cardiac stem cell disease?

Cardiovascular diseases and cancer represent respectively the first and second cause of death in industrialized countries. These two conditions may become synergistic when cardiovascular complications of anti-cancer therapy are considered. More than 70% of childhood and 50% of adult cancer patients can be cured, however this important success obtained by the biological and medical research is obfuscated by emerging findings of early and late morbidity due to cardiovascular events. Although anthracyclines are effective drugs against cancer a dose-dependent cardiotoxic effects whose mechanism has not been elucidated resulting in failure of therapeutic interventions limit their use. Unexpectedly, tyrosine/kinase inhibitors (TKIs) aimed at molecularly interfering with oncogenic pathways, have been implicated in cardiac side effects. Possible explanations of this phenomenon have been ambiguous, further strengthening the need to deepen our understanding on the mechanism of cardiotoxicity. In addition to a detailed description of anthracyclines and TKIs-related cardiovascular effects, the present review highlights recent observations supporting the hypothesis that the cellular target of anthracyclines and TKIs may include myocardial compartments other than parenchymal cells. The demonstration that the adult mammalian heart possesses a cell turnover regulated by primitive cells suggests that this cell population may be implicated in the onset and development of cardiovascular effects of anti-cancer strategies. The possibility of preventing cardiotoxicity by preservation and/or expansion of the resident stem cell pool responsible for cardiac repair may open new therapeutic options to unravel an unsolved clinical issue.