Ciro Maiello

CD117‐Positive Cells in Adult Human Heart Are Localized in the Subepicardium, and Their Activation Is Associated with Laminin‐1 and α6 Integrin Expression

CD117‐positive cells contributing to cardiac cell turnover in normal and pathological conditions have recently been described in adult human heart. Since the precise spatial and temporal expression of extracellular matrix proteins and their receptors is critical for organ formation, we compared the distribution of cardiac primitive CD117‐positive cells in the human adult normal and pathological hearts with ischemic cardiomyopathy, with respect to localization and expression of laminin and integrin isoforms. In the pathological hearts, CD117‐positive cells were significantly more numerous than in the normal hearts. They were localized mainly in the atria and were up to 38‐fold more numerous in the subepicardium than in the myocardium. Compared with normal hearts, most CD117‐positive cells in the subepicardium of pathological hearts were α6 integrin‐positive. Laminin‐1, typical of developing heart, was found predominantly in the subepicardium of adult heart. Immunoblotting revealed its highest expression in the normal atrium and pathological left ventricle. Both laminin isoforms reduced apoptosis and increased proliferation and migration of CD117‐positive cells in vitro with respect to control, but the effects of laminin‐1 significantly outweighed those of laminin‐2. Signaling mediated by α6 integrin was implicated in the migration and protection from apoptosis, as documented by transfection with specific small interfering RNA. These data reveal that the increase in the number of cardiac CD117‐positive cells and the expression of laminin‐1 are observed in ischemic cardiomyopathy. Subepicardial localization of CD117‐positive cells and expression of laminin‐1 and α6 integrin subunits may all correspond to the activation of regeneration involving an epithelial‐mesenchymal transition recently described in adult heart.

Role of Sildenafil in Acute Posttransplant Right Ventricular Dysfunction: Successful Experience in 13 Consecutive Patients

BACKGROUND Superimposed acute right ventricular dysfunction in the setting of preexisting pulmonary hypertension is a nearly fatal complication after heart transplantation. The optimal treatment modality remains a matter of debate. Recently, sildenafil citrate, a nonselective pulmonary vasodilator, has gained popularity in the treatment of pulmonary hypertension in transplant candidates. METHODS Herein we have presented a series of 13 patients in whom sildenafil was used to treat right ventricular dysfunction and pulmonary hypertension as detected by transesophageal echocardiography and Swan-Ganz right heart catheterization after heart transplant. Their characteristics were mean age 49+/-11.4 years; 38.4% with previous cardiac procedures, 30.8% status I, basal pulmonary vascular resistance index 10.4+/-4.6 WoodU, mean transpulmonary gradient 18.7+/-5.4 mmHg. In addition to conventional inodilator support, we administered 1 to 3 mg per kilogram of sildenafil. Complete hemodynamic measurements were obtained before and after the institution of the therapy and at 1-month follow-up. RESULTS Within the first 72 hours, acute right ventricular dysfunction resolved in all cases without untoward side effects or significant systemic impact. Sildenafil significantly decreased the transpulmonary gradient and pulmonary vascular resistance index relative to baseline values; 5.6+/-1.82 versus 10.4+/-4.6 WU, (P< .05), 13.5+/-3.4 mm Hg versus 18.7+/-5.4 mm Hg (P< .05), respectively. Improved indices of right ventricular function were observed on echocardiographic monitoring. After 1 month, sildenafil treatment was discontinued. CONCLUSION Management of acute right ventricular dysfunction in heart transplant recipients with pulmonary hypertension using sildenafil proved safe and effective.

Implications of acute kidney injury after heart transplantation: what a surgeon should know

OBJECTIVE Data regarding risks and consequences of acute kidney injury (AKI) after cardiac transplantation are dismissingly few and unclear. This study defined the incidence, risk factors and prognostic implication of AKI in a single-center cohort operated on between January 1999 and December 2008. METHODS Data from 307 consecutive recipients (mean age: 47.42 ± 13.58, 20.5% female, 18.9% diabetics, 19.5% with previous cardiac operations, 26.4% hospitalized, 78.4 ± 33.7 ml min(-1) preoperative glomerular filtration rate (eGFR)) were analyzed using multivariable logistic regression modeling. AKI was defined according to RIFLE (Risk, Injury, and Failure; and Loss, and End-stage kidney disease) criteria. RESULTS RIFLE scores of I or F were detected in 14%, and continuous venovenous hemofiltration was needed in 6.1%. Risk factors for AKI were: previous cardiac operation (odds ratio (OR) 2.35; 95% confidence interval (CI), 1.11-4.9), blood transfusion (OR 1.08; 95% CI, 1.011-1.16), troponin I release >10 (OR 1.031; 95% CI, 1.001-1.064), length of ischemic time (OR 1.008; 95% CI, 1.011-1.16). Overall hospital mortality averaged 7.8% and overall 1-year mortality was 10.4%; both mortality rates increased with each RIFLE stratification (Normal 3.4%, RIFLE R = 7.1%; RIFLE I = 25.7%; and RIFLE F = 37.5% and Normal 5.6%, RIFLE R = 11.8%, RIFLE I = 25.7%, and RIFLE F = 37.5%, respectively). AKI proved independent predictors of both early and 1-year mortality. The burden of AKI significantly affected 1-year kidney function (Δ preoperative GFR-1-year GFR in AKI vs no AKI = -25.872 ± 22.54 vs -7.968 ± 34.18, p = 0.015). CONCLUSIONS AKI is a highly prevalent and prognostically important complication. Some of the risk factors for AKI identified may be modifiable.

Pulmonary artery hypertension in heart transplant recipients: how much is too much?

OBJECTIVES Unresponsive pulmonary hypertension (PH) may contraindicate heart transplant since it implies poor early outcomes. The present study reports the effectiveness of oral perioperative sildenafil in allowing heart transplant candidacy and surgery in a selected group of patients initially deemed ineligible because of PH. METHODS Between May 2005 and December 2009, 31 consecutive patients (5 females, 9 with a history of idiopatic cardiomyopathy and 16 with a history of coronary artery disease, 10 with previous sternotomies, 71.42 ± 27.69 ml/min/m(2) mean preoperative epidermal growth factor receptor) were qualified for oral sildenafil because of unresponsive PH at baseline right heart catheterization (RHC). After a 12-week trial, RHC disclosed PH reversibility (mean pulmonary vascular resistance index: 9.57 ± 4.07 WU, mean transpulmonary gradient 14.47 ± 5.66 mmHg and mean systolic pulmonary artery pressure: 68.96 ± 15.15 mmHg), allowing listing despite a higher risk for early post-transplant RV failure. Transplant protocol included donor/recipient size matching ≥ 0.8 and inhaled nitric oxide in the early postoperative period followed by reinstitution of oral sildenafil. RESULTS All patients underwent heart transplantation. Mean overall graft ischaemic time was 179 ± 47 min; mean donor recipient weight ratio was 1.04 ± 0.17. Right ventricular failure developed in three patients (9.6%) and hospital mortality was 3.2%. Protocol RHC disclosed pulmonary haemodynamic profile normalization within the third postoperative month allowing weaning from sildenafil in the 30 hospital survivors. One-year RHC confirmed PH reversal (n = 29 patients, all who survived up to 1 year). CONCLUSIONS This pilot prospective uncontrolled trial suggests that oral sildenafil is effective in allowing candidacy, safe transplantation and postoperative pulmonary profile normalization in potential recipients initially disqualified because of PH.

Improved outcome of pulmonary aspergillosis in heart transplant recipients with early diagnosis and itraconazole treatment

Pulmonary aspergillosis is a severe complication in heart transplant recipients. The drug of choice for this infection is amphotericin B, but its use is limited because of its side effects. We observed six cases of pulmonary aspergillosis in a group of 200 patients who had received heart transplants from January 1988 to January 1999. Predisposing factors such as previous rejection, neutropenia and/or cytomegalovirus reactivation were present in all patients. The clinical presentation was characterized by fever and a non‐productive cough. X‐rays showed monolateral or diffuse infiltrate with or without nodular lesions. The median interval between symptoms and diagnosis was 5 d (range 4–7). Diagnosis was made by culturing trans‐tracheal aspirate samples. Aspergillus fumigatus was isolated in 3 patients and A. niger in the other 3. All patients were treated with itraconazole at 200–400 mg/day for 20–60 d and all recovered. One patient treated with the lowest dosage for the shortest term had a recurrence after 1 month and needed a second 30‐day course of itraconazole at a higher dosage. No significant side effects were registered. Itraconazole is effective in the therapy of pulmonary aspergillosis, particularly when an early diagnosis is made.

Cardiac primitive cells become committed to a cardiac fate in adult human heart with chronic ischemic disease but fail to acquire mature phenotype: genetic and phenotypic study

Adult human heart hosts a population of cardiac primitive CD117-positive cells (CPCs), which are responsible for physiological tissue homeostasis and regeneration. While the bona fide stem cells express telomerase, their progenies are no longer able to preserve telomeric DNA; hence the balance between their proliferation and differentiation has to be tightly controlled in order to prevent cellular senescence and apoptosis of CPCs before their maturation can be accomplished. We have examined at cellular and molecular level the proliferation, apoptosis and commitment of CPCs isolated from normal (CPC-N) and age-matched pathological adult human hearts (CPC-P) with ischemic heart disease. In the CPC-P, genes related to early stages of developmental processes, nervous system development and neurogenesis, skeletal development, bone and cartilage development were downregulated, while those involved in mesenchymal cell differentiation and heart development were upregulated, together with the transcriptional activation of TGFβ/BMP signaling pathway. In the pathological heart, asymmetric division was the prevalent type of cardiac stem cell division. The population of CPC-P consisted mainly of progenitors of cardiac cell lineages and less precursors; these cells proliferated more, but were also more susceptible to apoptosis with respect to CPC-N. These results indicate that CPCs fail to reach terminal differentiation and functional competence in pathological conditions. Adverse effects of underlying pathology, which disrupts cardiac tissue structure and composition, and cellular senescence, resulting from cardiac stem cell activation in telomere dysfunctional environment, can be responsible for such outcome.

Early graft failure after heart transplant: risk factors and implications for improved donor-recipient matching.

Early graft failure (EGF) is a dreaded complication after heart transplantation (HT). Despite several improvements, no effective therapy has been developed and the prognosis is poor. We evaluated the risk factors and clinical impact of EGF. In a consecutive series of 317 HTs performed at a single institution between January 1999 and December 2008, variables associated significantly with EGF were sought in bivariate and multivariable discriminant analyses. The deriving propensity score was used to stratify the study sample in to three groups (low, intermediate and high risk for EGF). Comparisons were performed between the higher-risk group and the remaining population in terms of preoperative features and outcomes. EGF occurred in 10.1% of the overall population (2.9, 3.8 and 23.6%, respectively, in the three groups). Overall, EGF-related mortality was 56.3% (100, 75 and 48%, respectively, in the three groups). Determinants of EGF in the highest-risk group were: redo procedure, valvular cardiomyopathy, status one at transplant, recipient male sex, donor-recipient (D/R) weight mismatch, high inotropic donor support, ischaemic time and first day troponin I release. In conclusion, several donor and recipient features predicted EGF. Since such characteristics are not readily modifiable but synergistically determine the occurrence of EGF, optimization of D/R matching is crucial to prevent it.

High-risk heart grafts: effective preservation with Celsior solution.

Celsior solution has already proved effective in heart graft preservation because it reduces myocardial edema, prevents free radical damage, and limits calcium overload. The aim of this study was to evaluate the effectiveness of Celsior solution as myocardial protection in high-risk transplantation. Hospital charts and follow-up data of 200 consecutive heart recipients (162 males, 38 females, mean age 47.4 ± 12.6 years) were reviewed. Patients were divided into two groups: group A (73 patients) included recipients of high-risk grafts (at least two of the following: age >45; female sex; high preretrieval inotropic support, viz. dobutamine or dopamine >10 µg/kg per minute and/or infusion of norepinephrine regardless of its dosage; size mismatch >20%; ischemia time >180 min) and group B (127 patients) included recipients of standard grafts. Quality of preservation was assessed through enzyme release, echocardiographic evaluation, the need for inotropic support or pacemaker, and histology of biopsy samples. Hospital and 1-year mortality were also evaluated. Comparisons between the two groups were made through univariate analysis. Study groups proved homogeneous as to recipient age, pretransplant cardiomyopathy, status at transplantation, mean panel reactive antibodies, and redo cardiac surgery. Hospital mortality was 8% (11% vs 6.3%, P = 0.18) while 1-year mortality reached 12% (15.1% vs 10.2%, P = 0.6) without significant difference between groups. Graft performance as described by the need for inotropic support and/or pacemaker as well as echocardiography (left and right ventricular ejection fraction) proved comparable. There were no significant differences as to histology findings and patterns of enzyme release. Celsior provides optimal myocardial preservation in both standard and high-risk procedures. Such advances help to enhance donor pool expansion.

Right heart morphology and function in heart transplantation recipients.

Background The right heart is a major determinant of prognosis in cardiac transplant recipient patients. Aim To investigate right ventricular morphology and function and their relationship with exercise capacity in cardiac transplant recipient patients using standard tranthoracic echocardiography and a new three-dimensional echocardiographic software adapted for right ventricular analysis. Methods One hundred fifteen relatively stable cardiac transplant recipient patients (71 men; 58.3 ± 5.8 years; 7.8 ± 4.5 years after transplantation) and 80 healthy age-comparable and sex-comparable controls underwent standard echocardiography, tissue Doppler imaging (TDI), and three-dimensional echocardiography, focused on the right ventricular analysis. Along with left heart parameters, right ventricular measurements included end-diastolic diameters at basal and mid-cavity level; base-to-apex length; tricuspid annulus plane systolic excursion (TAPSE); TDI right ventricular systolic peak velocity (Sm); and three-dimensional ejection fraction. Using the peak systolic tricuspid regurgitation velocity (TRV) and the end-diastolic pulmonary regurgitation velocity, the modified Bernoulli equation was used to calculate the pulmonary artery systolic (PASP) and diastolic pressures. Pulmonary artery vascular conductance (PAVC) was estimated by left ventricular stroke volume/4 × (TRV2 – pulmonary regurgitation velocity2). Results Left ventricular diameters and ejection fraction did not significantly differ between the two groups, whereas mass index was increased in cardiac transplant recipient patients (P < 0.01). Right ventricular diameters were significantly increased (P < 0.001), whereas TAPSE and right ventricular Sm were significantly lower in cardiac transplant recipient patients. Conversely, in cardiac transplant recipient patients, three-dimensional right ventricular ejection fraction (RVEF) was not significantly reduced (P < 0.001), whereas both PASP and PAVC were impaired. By multivariable analysis, age at transplantation (P < 0.01) and pulmonary artery mean pressure (P < 0.001) were the only independent determinants of right ventricular diameters and RVEF in cardiac transplant. Furthermore, RVEF measured by real-time three-dimensional echocardiography was a powerful independent determinant of functional capacity in cardiac transplant recipient patients. Conclusion Despite the reduction of right ventricular performance along the long axis suggested by TAPSE and right ventricular Sm, the increased right ventricular diameters along with absence of a decrease in three-dimensional RVEF support the hypothesis of geometrical rather than functional changes of the right ventricle in cardiac transplant recipient patients.

Differential expression of proteins related to smooth muscle cells and myofibroblasts in human thoracic aortic aneurysm.

OBJECTIVES Increasing knowledge is required for a better comprehension of the etiology of thoracic aortic aneurysm (TAA). The aim of this study was to highlight the modulations in vascular cell phenotypes, including myofibroblasts (MFs), in human TAA specimens compared to healthy aortas. METHODS histology, RT-PCR and immunohistochemical analysis of a panel of molecules, including ED-A Fibronectin (Fn), smoothelin, CD34 and alpha-smooth muscle actin (alpha-SMA), selected on the basis of their informative potential as markers of smooth muscle cells (SMCs) and MF phenotypic modulation, were performed on all samples. RESULTS The media of TAAs was characterized by the absence of smoothelin, the unaltered expression of alpha-SMA accompanied by an alteration of its distribution pattern, and by the activated expression of the ED-A isoform of Fn. We found a concentration of round-shaped cells exclusively in the adventitia and in the perivascular tissue of TAAs, also rich in vasa vasorum, largely expressing alpha-SMA, while a sub-population also expressed ED-A Fn and CD34. CD34 was expressed by several cells in the intima of TAAs, together with cells expressing cytoplasmatic ED-A Fn and alpha-SMA in comparison to healthy aortas. CONCLUSION TAA specimens show an altered expression and localization of SMC and MF differentiation markers in comparison to healthy aortas, with possible implications on remodeling.