Donato Cappetta

Doxorubicin induces senescence and impairs function of human cardiac progenitor cells

The increasing population of cancer survivors faces considerable morbidity and mortality due to late effects of the antineoplastic therapy. Cardiotoxicity is a major limiting factor of therapy with doxorubicin (DOXO), the most effective anthracycline, and is characterized by a dilated cardiomyopathy that can develop even years after treatment. Studies in animals have proposed the cardiac progenitor cells (CPCs) as the cellular target responsible for DOXO-induced cardiomyopathy but the relevance of these observations to clinical settings is unknown. In this study, the analysis of the DOXO-induced cardiomyopathic human hearts showed that the majority of human CPCs (hCPCs) was senescent. In isolated hCPCs, DOXO triggered DNA damage response leading to apoptosis early after exposure, and telomere shortening and senescence at later time interval. Functional properties of hCPCs, such as migration and differentiation, were also negatively affected. Importantly, the differentiated progeny of DOXO-treated hCPCs prematurely expressed the senescence marker p16INK4a. In conclusion, DOXO exposure severely affects the population of hCPCs and permanently impairs their function. Premature senescence of hCPCs and their progeny can be responsible for the decline in the regenerative capacity of the heart and may represent the cellular basis of DOXO-induced cardiomyopathy in humans.

SIRT1 activation attenuates diastolic dysfunction by reducing cardiac fibrosis in a model of anthracycline cardiomyopathy

BACKGROUNDnDoxorubicin (DOXO) is an effective anti-neoplastic drug but its clinical benefits are hampered by cardiotoxicity. Oxidative stress, apoptosis and myocardial fibrosis mediate the anthracycline cardiomyopathy. ROS trigger TGF-β pathway that activates cardiac fibroblasts promoting fibrosis. Myocardial stiffness contributes to diastolic dysfunction, less studied aspect of anthracycline cardiomyopathy. Considering the role of SIRT1 in the inhibition of the TGF-β/SMAD3 pathway, resveratrol (RES), a SIRT1 activator, might improve cardiac function by interfering with the development of cardiac fibrosis in a model of DOXO-induced cardiomyopathy.nnnMETHODSnF344 rats received a cumulative dose of 15 mg/kg of DOXO in 2 weeks or DOXO+RES (DOXO and RES, 2.5mg/kg/day, concomitantly for 2 weeks and then RES alone for 1 more week). The effects of RES on cardiac fibroblasts were also tested in vitro.nnnRESULTSnAlong with systolic dysfunction, DOXO was also responsible of diastolic abnormalities. Myocardial stiffness correlated with fibroblast activation and collagen deposition. DOXO+RES co-treatment significantly improved ± dP/dt and, more interestingly, ameliorated end-diastolic pressure/volume relationship. Treatment with RES resulted in reduced fibrosis and fibroblast activation and, most importantly, the mortality rate was significantly reduced in DOXO+RES group. Fibroblasts isolated from DOXO+RES-treated rats, in which SIRT1 was upregulated, showed decreased levels of TGF-β and pSMAD3/SMAD3 when compared to cells isolated from DOXO-exposed hearts.nnnCONCLUSIONSnOur findings reveal a key role of SIRT1 in supporting animal survival and functional parameters of the heart. SIRT1 activation by interfering with fibrogenesis can improve relaxation properties of myocardium and attenuate myocardial remodeling related to chemotherapy.

SIRT1 activation rescues doxorubicin-induced loss of functional competence of human cardiac progenitor cells

BACKGROUNDnThe search for compounds able to counteract chemotherapy-induced heart failure is extremely important at the age of global cancer epidemic. The role of SIRT1 in the maintenance of progenitor cell homeostasis may contribute to its cardioprotective effects. SIRT1 activators, by preserving progenitor cells, could have a clinical relevance for the prevention of doxorubicin (DOXO)-cardiotoxicity.nnnMETHODSnTo determine whether SIRT1 activator, resveratrol (RES), interferes with adverse effects of DOXO on cardiac progenitor cells (CPCs): 1) human CPCs (hCPCs) were exposed in vitro to DOXO or DOXO+RES and their regenerative potential was tested in vivo in an animal model of DOXO-induced heart failure; 2) the in vivo effects of DOXO+RES co-treatment on CPCs were studied in a rat model.nnnRESULTSnIn contrast to healthy cells, DOXO-exposed hCPCs were ineffective in a model of anthracycline cardiomyopathy. The in vitro activation of SIRT1 decreased p53 acetylation, overcame suppression of the IGF-1/Akt pro-survival and anti-apoptotic signaling, enhanced oxidative stress defense and prevented senescence and growth arrest of hCPCs. Priming with RES counterbalanced the onset of dysfunctional phenotype in DOXO-exposed hCPCs, partly restoring their ability to repair the damage with improvement in cardiac function and animal survival. The in vivo co-treatment DOXO+RES prevented the anthracycline-induced alterations in CPCs, partly preserving cardiac function.nnnCONCLUSIONnSIRT1 activation protects DOXO-exposed CPCs and re-establishes their proper function. Pharmacological intervention at the level of tissue-specific progenitor cells may provide cardiac benefits for the growing population of long-term cancer survivors that are at risk of chemotherapy-induced cardiovascular toxicity.

Doxorubicin cardiotoxicity and target cells: a broader perspective

The cardiotoxicity of doxorubicin is becoming an interdisciplinary point of interest given a growing population of cancer survivors. The complex and not completely understood pathogenesis of this complication makes difficult to design successful preventive or curative measures. Although cardiomyocyte has been considered a classical cellular target, other cells including various types of undifferentiated cells are involved in myocardial homeostasis. Such perspective may shed light on previously unrecognized aspects of cardiotoxicity and promote new experimental and clinical cardioprotective strategies. In this review, different cellular targets of doxorubicin are discussed with the focus on cardiac progenitor cells, oxidative stress, DNA damage, senescence and apoptosis all of which contribute to their compromised functional properties.

Long-term administration of ranolazine attenuates diastolic dysfunction and adverse myocardial remodeling in a model of heart failure with preserved ejection fraction

BACKGROUNDnTo investigate the effects of chronic administration of ranolazine (RAN) on experimental model of heart failure with preserved ejection fraction.nnnMETHODSnSeven-weeks old Dahl salt-sensitive rats were fed a high salt diet for 5weeks to induce hypertension. Afterwards, rats continued with a high salt diet and were administered either with vehicle or RAN (20mg/kg/die, ip) for the following 8weeks. Control rats were maintained on a low salt diet.nnnRESULTSnWhile systolic parameters were not altered, diastolic parameters were changed in high salt animals. Hemodynamic analysis showed a decreased dP/dt min, increased LVEDP, longer time constant and steeper slope of the end-diastolic pressure-volume relationship. Treatment with RAN attenuated these alterations and determined a reduction in mortality. Additionally, the magnitude of myocardial hypertrophy and activation of PI3K/Akt pathway were reduced. Alteration in diastolic compliance as a consequence of elevated myocardial stiffness was confirmed by an increase of collagen deposition and activation of pro-fibrotic TGF-β/SMAD3/CTGF signaling. These effects were counteracted by RAN. High salt rats had a decrease in SERCA2 and an increase in Na(+)/Ca(2+) exchanger (NCX). Treatment with RAN reduced NCX expression and determined an increment of SERCA2. Moreover, the levels of nitrotyrosine and oxidized dyhydroethidium were higher in high salt rats. RAN induced a decrement of oxidative stress, supporting the concept that reduction in ROS may mediate beneficial effects.nnnCONCLUSIONSnOur findings support the possibility that diastolic dysfunction can be attenuated by RAN, indicating its ability to affect active relaxation and passive diastolic compliance.

C-reactive protein and carotid intima-media thickness in children with sleep disordered breathing.

STUDY OBJECTIVESnObesity is a risk factor for sleep disordered breathing (SDB) in children. Plasma levels of high-sensitivity C-reactive protein (Hs-CRP) are predictive of cardiovascular morbidity in adults, and CRP levels are associated with over-weight. Increased carotid intima-media thickness (IMT) is associated with several cardiovascular risk factors. We evaluated the effect of SDB on CRP levels and IMT in lean and obese children not selected for snoring.nnnMETHODSn101 children (age 5-15 years) attending a weight clinic or scheduled for routine visit. IMT was measured with quantitative B-mode ultrasound scans. The apnea-hypopnea index (AHI) was measured overnight: AHI < 1 defined controls, AHI ≥ 1 to < 5 = mild SDB, and AHI ≥ 5 = obstructive sleep apnea (OSA).nnnRESULTSnAHI was significantly associated with Hs-CRP concentration (r = 0.32, p = 0.002) in all 101 children irrespective of age and sex. Body mass index (BMI) was higher in OSA children than controls (25.5 ± 7.0 vs 22.1 ± 6.9, p = 0.05). Obese children had 3.3 times more probability of having OSA (HR 3.3, 95% CI 1.2-9.3, p = 0.02) than lean children. Hs-CRP values were significantly higher in children with OSA than in children without (p = 0.011), but not when BMI z-score was added as covariate. IMT was not associated with AHI or SDB.nnnCONCLUSIONSnThe results of this study suggest an association between OSA and Hs-CRP concentrations (mainly mediated by overweight and obesity), but not between OSA and subclinical atherosclerosis. There is scope for prevention in childhood before OSA syndrome causes the irreversible damage to arteries observed in adult patients.

Mechanical Stress Regulates Endothelial Progenitor Cell Angiogenesis Through VEGF Receptor Endocytosis

The clinical goal of cell-based treatment for chronic heart failure is to coordinately reconstitute the cardiomyocytes and associated circulation environment including coronary resistance arteries, arterioles, and capillary profiles.(1)) This goal can be possibly achieved by implementing multipotent adult stem cells. However, it remains a challenge to modify the capillary network in the decompensated heart. A mechanical stress model was used in this study to mimic the hemodynamic and hormonal states of the decompensated heart in vitro. The angiogenesis role of endothelial progenitor cells (EPCs) under stress has been well-recognized in vascular repair. We investigated the molecular mechanisms of EPCs in this model. We found that expression of vascular endothelial growth factor (VEGF) in EPCs was significantly decreased by mechanical stress, and this effect was accompanied by a decrease in angiogenesis in vitro. Interestingly, the defective angiogenesis can be reversed by upregulating the membrane VEGF receptor (VEGFR) endocytosis. An atypical protein kinase C (aPKC) inhibitor can promote the VEGFR internalization in EPCs and enhance the formation of vascular networks. Thus, the upregulation of VEGFR endocytosis in EPCs could be a potential therapy for the cell-based treatment of chronic heart failure by enhancing the cardiomyocytes.

Recumbent deoxygenation in mild/moderate liver cirrhosis: the “Clinodeoxia”. The ortho-clino paradigm

BACKGROUNDnWhile the effects of postural change on arterial oxygenation have been well documented in normal subjects, and attributed to the relationship of closing volume (CV) to the tidal volume, in liver cirrhosis such postural changes have been evaluated mainly in a rare, peculiar clinical end-stage condition which is characterized by increased dyspnea shifting from supine to upright position (platypnea). The latter is associated with worsening of PaO2 (orthodeoxia). We evaluated the effects of postural changes on arterial oxygenation in patients affected by mild/moderate liver cirrhosis.nnnMETHODSnWe performed pulmonary function tests and arterial blood gas evaluation in sitting and supine positions in 22 patients with mild/moderate liver cirrhosis, biopsy-proved, and 22 matched non-smokers control subjects.nnnRESULTSnRecumbency elicited a decrease of PaO2 (Δ(sup-sit)PaO2) in 19 out of 22 controls and in all but one cirrhotics. The magnitude of this postural change was significantly (pxa0=xa00.04) greater in cirrhotics (9.6xa0±xa05.3%) compared to controls (6.7xa0±xa03.7%). In the subset of cirrhotics younger than 60xa0yrs and with PaO2 greater than 80xa0mmHg in sitting position, the Δ(sup-sit)PaO2 in recumbency further increased to 12xa0±xa05.8%, significantly (pxa0=xa00.014) greater than in same subgroup of controls (7.1xa0±xa03.8%).nnnCONCLUSIONSnIn mild/moderate liver cirrhosis the postural variations in PaO2 follow the normal trends, but are of greater magnitude probably as a consequence of hypoventilated units of lung for postural and disease-linked tidal airway closure, resulting in more pronounced recumbent hypoxemia (clinodeoxia).