Fabio Miraldi

Cardiac stem cells: isolation, expansion and experimental use for myocardial regeneration

Cellular cardiomyoplasty (myogenic cell grafting) is actively being explored as a novel method to regenerate damaged myocardium. The adult human heart contains small populations of indigenous committed cardiac stem cells or multipotent cardiac progenitor cells, identified by their cell-surface expression of c-kit (the receptor for stem cell factor), P-glycoprotein (a member of the multidrug resistance protein family), and Sca-1 (stem cell antigen 1, a mouse hematopoietic stem cell marker) or a Sca-1-like protein. Cardiac stem cells represent a logical source to exploit in cardiac regeneration therapy because, unlike other adult stem cells, they are likely to be intrinsically programmed to generate cardiac tissue in vitro and to increase cardiac tissue viability in vitro. Cardiac stem cell therapy could, therefore, change the fundamental approach to the treatment of heart disease.

Differentiation of human adult cardiac stem cells exposed to extremely low-frequency electromagnetic fields

AIMS Modulation of cardiac stem cell (CSC) differentiation with minimal manipulation is one of the main goals of clinical applicability of cell therapy for heart failure. CSCs, obtained from human myocardial bioptic specimens and grown as cardiospheres (CSps) and cardiosphere-derived cells (CDCs), can engraft and partially regenerate the infarcted myocardium, as previously described. In this paper we assessed the hypothesis that exposure of CSps and CDCs to extremely low-frequency electromagnetic fields (ELF-EMFs), tuned at Ca2+ ion cyclotron energy resonance (Ca2+-ICR), may drive their differentiation towards a cardiac-specific phenotype. METHODS AND RESULTS A significant increase in the expression of cardiac markers was observed after 5 days of exposure to Ca2+-ICR in both human CSps and CDCs, as evidenced at transcriptional, translational, and phenotypical levels. Ca2+ mobilization among intracellular storages was observed and confirmed by compartmentalized analysis of Ca2+ fluorescent probes. CONCLUSIONS These results suggest that ELF-EMFs tuned at Ca2+-ICR could be used to drive cardiac-specific differentiation in adult cardiac progenitor cells without any pharmacological or genetic manipulation of the cells that will be used for therapeutic purposes.

Emergency surgery for retrograde extension of type B dissection after endovascular stent graft repair.

Endovascular stent graft repair of type B dissection is a new and alternative treatment to the surgical or medical therapy. This technique is not free from minor or major complications and we herein report the case of a patient who developed a retrograde dissection after endovascular stent graft placement. The emergent surgical treatment undertaken consisted of ascending aorta replacement without treating the arch in account of the presence of the endoluminal prosthesis.

Systematic Preoperative Coronary Angiography and Stenting Improves Postoperative Results of Carotid Endarterectomy in Patients with Asymptomatic Coronary Artery Disease: A Randomised Controlled Trial

OBJECTIVE To evaluate the usefulness of systematic coronary angiography followed, if needed, by coronary artery angioplasty (percutaneous coronary intervention (PCI)) on the incidence of cardiac ischaemic events after carotid endarterectomy (CEA) in patients without evidence of coronary artery disease (CAD). MATERIALS AND METHODS From January 2005 to December 2008, 426 patients, candidates for CEA, with no history of CAD and with normal cardiac ultrasound and electrocardiography (ECG), were randomised into two groups. In group A (n=216) all the patients had coronary angiography performed before CEA. In group B, all the patients had CEA without previous coronary angiography. In group A, 66 patients presenting significant coronary artery lesions at angiography received PCI before CEA. They subsequently underwent surgery under aspirin (100 mg day(-1)) and clopidogrel (75 mg day(-1)). CEA was performed within a median delay of 4 days after PCI (range: 1-8 days). Risk factors, indications for CEA and surgical techniques were comparable in both groups (p>0.05). The primary combined endpoint of the study was the incidence of postoperative myocardial ischaemic events combined with the incidence of complications of coronary angiography. Secondary endpoints were death and stroke rates after CEA and incidence of cervical haematoma. RESULTS Postoperative mortality was 0% in group A and 0.9% in group B (p=0.24). One postoperative stroke (0.5%) occurred in group A, and two (0.9%) in group B (p=0.62). No postoperative myocardial event was observed in group A, whereas nine ischaemic events were observed in group B, including one fatal myocardial infarction (p=0.01). Binary logistic regression analysis demonstrated that preoperative coronary angiography was the only independent variable that predicted the occurrence of postoperative coronary ischaemia after CEA. The odds ratio for coronary angiography (group A) indicated that when holding all other variables constant, a patient having preoperative coronary angiography before carotid surgery was 4 times less likely to have a cardiac ischaemic event after carotid surgery. No complications related to coronary angiography were observed and no cervical haematomas occurred in patients undergoing surgery under aspirin and clopidogrel in this study. CONCLUSIONS Systematic preoperative coronary angiography, possibly followed by PCI, significantly reduces the incidence of postoperative myocardial events after CEA in patients without clinical evidence of CAD.

Recombinant activated factor VII for refractory bleeding after acute aortic dissection surgery: a propensity score analysis.

Objective:The aim of this study was to assess safety and effectiveness of recombinant activated factor VII (rFVIIa) in patients with refractory bleeding undergoing acute aortic dissection surgery with deep hypothermic circulatory arrest. Design:Propensity score-matched analysis. Setting:University hospital. Patients:Twenty-three cardiac surgery patients receiving rFVIIa compared with 23 matched controls. Interventions:An intravenous bolus of rFVIIa (70 &mgr;g/kg) was administered at the end of a complete transfusion protocol. Five patients received rFVIIa in the operating room, and 18 patients received rFVIIa in the intensive care unit. Four of the intensive care unit patients required a second dose. Measurements and Main Results:Blood loss and transfusion requirements were significantly reduced in the period after rFVIIa administration. A highly significant reduction in hourly blood loss was found at −1 hr vs. 0 hrs and 0 hrs vs. 1 hr (−194 and −77.5 mL, respectively; both adjusted p < .001). In addition, significant improvements of international normalized ratio (p < .001), partial thromboplastin time (p < .001), platelet count (p < .001), fibrinogen (p < .001), and antithrombin (p < .001) were detected after rFVIIa administration. The two groups did not differ regarding adverse events. Conclusions:rFVIIa was successfully used as an additional therapy both during and after acute aortic dissection surgery with deep hypothermic circulatory arrest, when bleeding was refractory to conventional methods. Randomized studies are necessary to confirm the safety and efficacy of rFVIIa in this setting.

Cardinal vein isomerism An embryological hypothesis to explain a persistent left superior vena cava draining into the roof of the left atrium in the absence of coronary sinus and atrial septal defect

BACKGROUND A persistent left superior vena cava (PLSVC) is a relatively frequent systemic venous anomaly associated with congenital heart defects. This anomaly has been explained with the persistence of the left superior cardinal vein. PLSVC usually drains into the right atrium, via coronary sinus, but it joins the left atrium in approximately 8% of the cases either directly in the setting of atrial isomerism, or via an unroofed coronary sinus, or through a coronary sinus type atrial septal defect. CASE REPORT We describe a case of an adult patient with atria in the situs solitus, PLSVC draining into the left atrium, atresia of coronary sinus without atrial septal defect, and with additional cardiac anomalies (ventricular septal defect and discrete subaortic stenosis). CONCLUSION A possible embryological explanation to this case rises from a right partial isomerism of the superior cardinal veins, which gives reason for both the coexistence of the PLSVC draining into the left atrium and the absence of coronary sinus, atrial septal defect, or coronary sinus ostium.

Short-term results of a randomized trial examining timing of carotid endarterectomy in patients with severe asymptomatic unilateral carotid stenosis undergoing coronary artery bypass grafting

OBJECTIVE This study evaluated the timing of carotid endarterectomy (CEA) in the prevention of stroke in patients with asymptomatic carotid stenosis >70% receiving a coronary artery bypass graft (CABG). METHODS From January 2004 to December 2009, 185 patients with unilateral asymptomatic carotid artery stenosis >70%, candidates for CABG, were randomized into two groups. In group A, 94 patients received a CABG with previous or simultaneous CEA. In group B, 91 patients underwent CABG, followed by CEA. All patients underwent preoperative helical computed tomography scans, excluding significant atheroma of the ascending aorta or aortic arch. Baseline characteristics of the patients, type of coronary artery lesion, and preoperative myocardial function were comparable in the two groups. In group A, all patients underwent CEA under general anesthesia with the systematic use of a carotid shunt, and 79 patients had a combined procedure and 15 underwent CEA a few days before CABG. In group B, all patients underwent CEA, 1 to 3 months after CABG, also under general anesthesia and with systematic carotid shunting. RESULTS Two patients (one in each group) died of cardiac failure in the postoperative period. Operative mortality was 1.0% in group A and 1.1% in group B (P = .98). No strokes occurred in group A vs seven ipsilateral ischemic strokes in group B, including three immediate postoperative strokes and four late strokes, at 39, 50, 58, and 66 days, after CABG. These late strokes occurred in patients for whom CEA was further delayed due to an incomplete sternal wound healing or because of completion of a cardiac rehabilitation program. The 90-day stroke and death rate was 1.0% (one of 94) in group A and 8.8% (eight of 91) in group B (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.01-0.91; P = .02). Logistic regression analysis showed that only delayed CEA (OR, 14.2; 95% CI, 1.32-152.0; P = .03) and duration of cardiopulmonary bypass (OR, 1.06; 95% CI, 1.02-1.11; P = .004) reliably predicted stroke or death at 90 days. CONCLUSIONS This study suggests that previous or simultaneous CEA in patients with unilateral severe asymptomatic carotid stenosis undergoing CABG could prevent stroke better than delayed CEA, without increasing the overall surgical risk.

TGFβ-Dependent Epithelial-to-Mesenchymal Transition Is Required to Generate Cardiospheres from Human Adult Heart Biopsies

Autologous cardiac progenitor cells (CPCs) isolated as cardiospheres (CSps) represent a promising candidate for cardiac regenerative therapy. A better understanding of the origin and mechanisms underlying human CSps formation and maturation is undoubtedly required to enhance their cardiomyogenic potential. Epithelial-to-mesenchymal transition (EMT) is a key morphogenetic process that is implicated in the acquisition of stem cell-like properties in different adult tissues, and it is activated in the epicardium after ischemic injury to the heart. We investigated whether EMT is involved in the formation and differentiation of human CSps, revealing that an up-regulation of the expression of EMT-related genes accompanies CSps formation that is relative to primary explant-derived cells and CSp-derived cells grown in a monolayer. EMT and CSps formation is enhanced in the presence of transforming growth factor β1 (TGFβ1) and drastically blocked by the type I TGFβ-receptor inhibitor SB431452, indicating that TGFβ-dependent EMT is essential for the formation of these niche-like 3D-multicellular clusters. Since TGFβ is activated in the myocardium in response to injury, our data suggest that CSps formation mimics an adaptive mechanism that could potentially be enhanced to increase in vivo or ex vivo regenerative potential of adult CPCs.

New Perspectives to Repair a Broken Heart

The aim of cardiac cell therapy is to restore at least in part the functionality of the diseased or injured myocardium by the use of stem/progenitor cells. Recent clinical trials have shown the safety of cardiac cell therapy and encouraging efficacy results. A surprisingly wide range of non-myogenic cell types improves ventricular function, suggesting that benefits may result in part from mechanisms that are distinct from true myocardial regeneration. While clinical trials explore cells derived from skeletal muscle and bone marrow, basic researchers are investigating sources of new cardiomyogenic cells, such as resident myocardial progenitors and embryonic stem cells. In this commentary we briefly review the evolution of cell-based cardiac repair, some progress that has been made toward this goal, and future perspectives in the regeneration of cardiac tissue.

Cardiac Angiosarcoma Arising From Pulmonary Artery: Endovascular Treatment

We report a case of unusual origin of cardiac angiosarcoma rising from the pulmonary trunk. The tumor caused severe obstruction of the right ventricular outflow tract with serious symptoms of right ventricular failure and tricuspid insufficiency. The angiosarcoma was surgically unresectable because of infiltration of the pulmonary artery and cardiac structures. To relieve the patients symptoms we chose an endovascular stent treatment to dilate the right ventricular outflow tract obstruction. Consequently this palliative treatment changed the short-term prognosis of the patient, improving his quality of life, and at 6 months follow-up he remains asymptomatic.