Influence of centre expertise on the diagnosis and management of hypertrophic cardiomyopathy: A study from the French register of hypertrophic cardiomyopathy (REMY).

BACKGROUND: Our knowledge of hypertrophic cardiomyopathy (HCM) mainly originates from quarternary centres. The objective is to assess the current management of HCM patients in a large multicentre French register according to the level of expertise. METHODS AND RESULTS: A total of 1431 HCM patients were recruited across 26 (11 expert and 15 non-expert) centres in REMY, a prospective hospital-based register of adult HCM patients. A sarcomeric origin was suspected in 1284 (89.7%) patients [261 (20.3%) with a reported gene mutation, 242 (18.8%) genotype-negative], while 107 (7.5%) had a diagnosis of non-sarcomeric HCM. Patients managed in non-expert centres were older (P < 0.01) and presented more often with NYHA III/IV class dyspnoea (P < 0.01), congestive heart failure (P < 0.01), low LEVF (P < 0.01), less often with a syncope history (P < 0.01) and lower LV obstruction (P < 0.01) than patients in expert centres. Genotype positive sarcomeric aetiologies were less frequent in non-expert centres (P < 0.01). The use of diagnostic and prognostic tests as cardiac MRI (P < 0.001), genetic (P < 0.001) and alpha-galactosidase A enzyme level testing (P < 0.001), Holter ECG (P < 0.001), and exercise test (P < 0.001), was lower in non-expert centres. Septal ablation procedures using alcohol (P < 0.001) or myectomy (P < 0.001) were more frequent in expert centres. CONCLUSION: In real life practice, only a minority of HCM patients are identified as sarcomere positive as per genetic testing. The management of HCM patients varies according to the centre's level of expertise, with less access to diagnostic and prognostic tests in non-expert centres. Non-sarcomeric HCM may therefore be overlooked despite specific treatment in some aetiologies.

Long-Term Engraftment (16 Years) of Myoblasts in a Human Infarcted Heart.

We report the case of a patient who had undergone injections of myoblasts in an infarct area 16 years before being referred for heart transplantation. The pathological examination of the explanted heart found persisting myotubes embedded in fibrosis. This finding supports the ability of myoblasts to survive in harsh environments, which can make them appealing candidates for transplantation in diseases requiring supply of new myogenic cells. Stem Cells Translational Medicine 2018;7:705-708.

Transplantation of Human Embryonic Stem Cell-Derived Cardiovascular Progenitors for Severe Ischemic Left Ventricular Dysfunction.

BACKGROUND: In addition to scalability, human embryonic stem cells (hESCs) have the unique advantage of allowing their directed differentiation toward lineage-specific cells. OBJECTIVES: This study tested the feasibility of leveraging the properties of hESCs to generate clinical-grade cardiovascular progenitor cells and assessed their safety in patients with severe ischemic left ventricular dysfunction. METHODS: Six patients (median age 66.5 years [interquartile range (IQR): 60.5 to 74.7 years]; median left ventricular ejection fraction 26% [IQR: 22% to 32%]) received a median dose of 8.2 million (IQR: 5 to 10 million) hESC-derived cardiovascular progenitors embedded in a fibrin patch that was epicardially delivered during a coronary artery bypass procedure. The primary endpoint was safety at 1 year and focused on: 1) cardiac or off-target tumor, assessed by imaging (computed tomography and fluorine-18 fluorodeoxyglucose positron emission tomography scans); 2) arrhythmias, detected by serial interrogations of the cardioverter-defibrillators implanted in all patients; and 3) alloimmunization, assessed by the presence of donor-specific antibodies. Patients were followed up for a median of 18 months. RESULTS: The protocol generated a highly purified (median 97.5% [IQR: 95.5% to 98.7%]) population of cardiovascular progenitors. One patient died early post-operatively from treatment-unrelated comorbidities. All others had uneventful recoveries. No tumor was detected during follow-up, and none of the patients presented with arrhythmias. Three patients developed clinically silent alloimmunization. All patients were symptomatically improved with an increased systolic motion of the cell-treated segments. One patient died of heart failure after 22 months. CONCLUSIONS: This trial demonstrates the technical feasibility of producing clinical-grade hESC-derived cardiovascular progenitors and supports their short- and medium-term safety, thereby setting the grounds for adequately powered efficacy studies. (Transplantation of Human Embryonic Stem Cell-derived Progenitors in Severe Heart Failure [ESCORT]; NCT02057900).

Awareness of Individual Cardiovascular Risk Factors and Self-Perception of Cardiovascular Risk in Women.

BACKGROUND: Cardiovascular risk factors (CVRFs) self-perception by women may be inaccurate. MATERIALS AND METHODS: A questionnaire was completed anonymously Online by women who self-reported their personal CVRF levels including age, weight, contraceptive use, menopausal status, smoking, diet and physical activities. Self-perceived risk was matched to actual cardiovascular risk according to the Framingham score. RESULTS: Among 5,240 young and middle-aged women with a high educational level, knowledge of personal CVRFs increased with age, from 51-90% for blood pressure (BP), 22-45% for blood glucose and 15-47% for blood cholesterol levels, between 30 and 65 years, respectively. This knowledge was lower for smoking compared with nonsmoking women: 62.5% vs. 74.5% for BP (P < 0.001), 22.7% vs. 33.8% for blood glucose (P < 0.001), 21.9% vs. 32.0% for cholesterol levels (P < 0.001). Knowledge of BP level was reduced among women using an estrogen-progestogen contraception (56.8% vs. 62.1%, P = 0.0031) and even more reduced among smokers (52.2%, P < 0.001). Conversely, women with leisure-time physical or sportive activity (60.5%), were less overweight or obese (22.4% vs. 34.2%, P < 0.001). They reported better knowledge of BP (72.4% vs. 68.3%, P < 0.001), blood cholesterol (31.1% vs. 26.4%, P < 0.001) and glucose levels (32.7% vs. 27.8%, P < 0.001). Self-perceived cardiovascular risk was rated low by 1,279 (20.4%), moderate by 3,710 (63.3%) and high by 893 (16.3%) women. Among 3,386 women tested using the Framingham score, 40.8% were at low, 25.2% at moderate and 33.8% at high risk. CONCLUSIONS: Knowledge of CVRFs and self-perception of individual risk are inaccurate in women. Educational interventions should be emphasized.

First clinical use of a bioprosthetic total artificial heart: report of two cases.

BACKGROUND: The development of artificial hearts in patients with end-stage heart disease have been confronted with the major issues of thromboembolism or haemorrhage. Since valvular bioprostheses are associated with a low incidence of these complications, we decided to use bioprosthetic materials in the construction of a novel artificial heart (C-TAH). We report here the device characteristics and its first clinical applications in two patients with end-stage dilated cardiomyopathy. The aim of the study was to evaluate safety and feasibility of the CARMAT TAH for patients at imminent risk of death from biventricular heart failure and not eligible for transplant. METHODS: The C-TAH is an implantable electro-hydraulically actuated pulsatile biventricular pump. All components, batteries excepted, are embodied in a single device positioned in the pericardial sac after excision of the native ventricles. We selected patients admitted to hospital who were at imminent risk of death, having irreversible biventricular failure, and not eligible for heart transplantation, from three cardiac surgery centres in France. FINDINGS: The C-TAH was implanted in two male patients. Patient 1, aged 76 years, had the C-TAH implantation on Dec 18, 2013; patient 2, aged 68 years, had the implantation on Aug 5, 2014. The cardiopulmonary bypass times for C-TAH implantation were 170 min for patient 1 and 157 min for patient 2. Both patients were extubated within the first 12 postoperative hours and had a rapid recovery of their respiratory and circulatory functions as well as a normal mental status. Patient 1 presented with a tamponade on day 23 requiring re-intervention. Postoperative bleeding disorders prompted anticoagulant discontinuation. The C-TAH functioned well with a cardiac output of 4·8-5·8 L/min. On day 74, the patient died due to a device failure. Autopsy did not detect any relevant thrombus formation within the bioprosthesis nor the different organs, despite a 50-day anticoagulant-free period. Patient 2 experienced a transient period of renal failure and a pericardial effusion requiring drainage, but otherwise uneventful postoperative course. He was discharged from the hospital on day 150 after surgery with a wearable system without technical assistance. After 4 months at home, the patient suffered low cardiac output. A change of C-TAH was attempted but the patient died of multiorgan failure. INTERPRETATION: This preliminary experience could represent an important contribution to the development of total artificial hearts using bioprosthetic materials. FUNDING: CARMAT SA.

Human embryonic stem cell-derived cardiac progenitors for severe heart failure treatment: first clinical case report.

AIMS: Comparative studies suggest that stem cells committed to a cardiac lineage are more effective for improving heart function than those featuring an extra-cardiac phenotype. We have therefore developed a population of human embryonic stem cell (ESC)-derived cardiac progenitor cells. METHODS AND RESULTS: Undifferentiated human ESCs (I6 line) were amplified and cardiac-committed by exposure to bone morphogenetic protein-2 and a fibroblast growth factor receptor inhibitor. Cells responding to these cardio-instructive cues express the cardiac transcription factor Isl-1 and the stage-specific embryonic antigen SSEA-1 which was then used to purify them by immunomagnetic sorting. The Isl-1(+) SSEA-1(+) cells were then embedded into a fibrin scaffold which was surgically delivered onto the infarct area in a 68-year-old patient suffering from severe heart failure [New York Heart Association [NYHA] functional Class III; left ventricular ejection fraction (LVEF): 26%]. A coronary artery bypass was performed concomitantly in a non-infarcted area. The implanted cells featured a high degree of purity (99% were SSEA-1(+)), had lost the expression of Sox-2 and Nanog, taken as markers for pluripotency, and strongly expressed Isl-1. The intraoperative delivery of the patch was expeditious. The post-operative course was uncomplicated either. After 3 months, the patient is symptomatically improved (NYHA functional Class I; LVEF: 36%) and a new-onset contractility is echocardiographically evident in the previously akinetic cell/patch-treated, non-revascularized area. There have been no complications such as arrhythmias, tumour formation, or immunosuppression-related adverse events. CONCLUSION: This observation demonstrates the feasibility of generating a clinical-grade population of human ESC-derived cardiac progenitors and combining it within a tissue-engineered construct. While any conclusion pertaining to efficacy would be meaningless, the patient's functional outcome yet provides an encouraging hint. Beyond this case, the platform that has been set could be useful for generating different ESC-derived lineage-specific progenies.

Rupture of mitral valve chordae in hypertrophic cardiomyopathy.

BACKGROUND: While occasional reports of mitral valve chordal rupture have been described in hypertrophic cardiomyopathy, the exact prevalence and characteristics of this event in a large medical cohort have not been reported. AIM: To assess the prevalence of mitral valve chordal rupture in hypertrophic cardiomyopathy and the clinical, echocardiographic, surgical and histological profiles of those patients. METHODS: We searched for patients with mitral valve chordal rupture diagnosed by echocardiography among all electronic files of patients admitted to our centre for hypertrophic cardiomyopathy between 2000 and 2010. RESULTS: Among 580 patients admitted for hypertrophic cardiomyopathy, six patients (1%, 5 men, age 68-71 years) presented with mitral valve chordal rupture, symptomatic in five cases, always involving the posterior mitral leaflet. In all cases, echocardiography before rupture showed mitral valve systolic anterior motion, with anterior (and not posterior) leaflet elongation compared with a random sample of patients with non-obstructive hypertrophic cardiomyopathy (P=0.006) (and similar to that observed in obstructive hypertrophic cardiomyopathy). Significant resting left ventricular outflow tract obstruction was always present before rupture and disappeared after rupture in the five cases requiring mitral valve surgery for severe mitral regurgitation. Histological findings were consistent with extensive myxomatous degeneration in all cases. CONCLUSION: Mitral valve chordal rupture is: infrequent in hypertrophic cardiomyopathy; occurs in aged patients with obstructive disease; involves, essentially, the posterior mitral leaflet; and causes, in general, severe mitral regurgitation requiring surgery. Myxomatous degeneration may be the substrate for rupture in these patients.

Towards a clinical use of human embryonic stem cell-derived cardiac progenitors: a translational experience.

AIM: There is now compelling evidence that cells committed to a cardiac lineage are most effective for improving the function of infarcted hearts. This has been confirmed by our pre-clinical studies entailing transplantation of human embryonic stem cell (hESC)-derived cardiac progenitors in rat and non-human primate models of myocardial infarction. These data have paved the way for a translational programme aimed at a phase I clinical trial. METHODS AND RESULTS: The main steps of this programme have included (i) the expansion of a clone of pluripotent hESC to generate a master cell bank under good manufacturing practice conditions (GMP); (ii) a growth factor-induced cardiac specification; (iii) the purification of committed cells by immunomagnetic sorting to yield a stage-specific embryonic antigen (SSEA)-1-positive cell population strongly expressing the early cardiac transcription factor Isl-1; (iv) the incorporation of these cells into a fibrin scaffold; (v) a safety assessment focused on the loss of teratoma-forming cells by in vitro (transcriptomics) and in vivo (cell injections in immunodeficient mice) measurements; (vi) an extensive cytogenetic and viral testing; and (vii) the characterization of the final cell product and its release criteria. The data collected throughout this process have led to approval by the French regulatory authorities for a first-in-man clinical trial of transplantation of these SSEA-1(+) progenitors in patients with severely impaired cardiac function. CONCLUSION: Although several facets of this manufacturing process still need to be improved, these data may yet provide a useful platform for the production of hESC-derived cardiac progenitor cells under safe and cost-effective GMP conditions.

[Stem cell therapy and heart failure: hopes and disappointments]. / Thérapie cellulaire et insuffisance cardiaque: ombres et lumières.

Despite therapeutic advances, heart failure remains a common and serious event characterized by initial and progressive loss of cardiac myocytes, a loss that is currently untreatable. Cell therapy has emerged as a promising new approach to the treatment of heart failure, with very encouraging experimental results. Since 2000, when human stem cell therapy was first attempted in France, clinical trials with adult stem cells (myoblasts, bone-marrow derived cells, mesenchymal stem cells) have given variable results. The inconsistent and modest therapeutic benefit observed in these studies is due more to paracrine effects than to the hoped-for cell replacement, as adult stem cells do not turn into cardiomyocytes and their survival rate after transplantation is very low. In order to be effective, cell therapy should use heart muscle cells derived from pluri- or multipotent cells (human embryonic stem cells, induced pluripotent stem cells, resident cardiac cells), which are likely to have a higher survival rate in a hostile biological environment and deteriorated tissue scaffold. Cardiac tissue engineering assisted by nanotechnologies may eventually help to meet this challenge.

Comprehensive annular and subvalvular repair of chronic ischemic mitral regurgitation improves long-term results with the least ventricular remodeling.

BACKGROUND: Undersized ring annuloplasty for ischemic mitral regurgitation (MR) is associated with variable results and >30% MR recurrence. We tested whether subvalvular repair by severing second-order mitral chordae can improve annuloplasty by reducing papillary muscle tethering. METHODS AND RESULTS: Posterolateral myocardial infarction known to produce chronic remodeling and MR was created in 28 sheep. At 3 months, sheep were randomized to sham surgery versus isolated undersized annuloplasty versus isolated bileaflet chordal cutting versus the combined therapy (n=7 each). At baseline, chronic myocardial infarction (3 months), and euthanasia (6.6 months), we measured left ventricular (LV) volumes and ejection fraction, wall motion score index, MR regurgitation fraction and vena contracta, mitral annulus area, and posterior leaflet restriction angle (posterior leaflet to mitral annulus area) by 2-dimensional and 3-dimensional echocardiography. All groups were comparable at baseline and chronic myocardial infarction, with mild to moderate MR (MR vena contracta, 4.6±0.1 mm; MR regurgitation fraction, 24.2±2.9%) and mitral annulus dilatation (P<0.01). At euthanasia, MR progressed to moderate to severe in controls but decreased to trace with ring plus chordal cutting versus trace to mild with chordal cutting alone versus mild to moderate with ring alone (MR vena contracta, 5.9±1.1 mm in controls, 0.5±0.08 with both, 1.0±0.3 with chordal cutting alone, 2.0±0.4 with ring alone; P<0.01). In addition, LV end-systolic volume increased by 108% in controls versus 28% with ring plus chordal cutting, less than with each intervention alone (P<0.01). In multivariate analysis, LV end-systolic volume and mitral annulus area most strongly predicted MR (r(2)=0.82, P<0.01). CONCLUSIONS: Comprehensive annular and subvalvular repair improves long-term reduction of both chronic ischemic MR and LV remodeling without decreasing global or segmental LV function at follow-up.

Immune response to human embryonic stem cell-derived cardiac progenitors and adipose-derived stromal cells.

Transplantation of allogeneic human embryonic stem cell-derived cardiac progenitors triggers an immune response. We assessed whether this response could be modulated by the concomitant use of adipose-derived stromal cells (ADSC). Peripheral blood mononuclear cells were collected from 40 patients with coronary artery disease (CAD) and nine healthy controls. Cardiac progenitors (CD15(+) Mesp1(+)) were generated as already reported from the I6 cell line treated with bone morphogenetic protein (BMP)-2. Adipose-derived stromal cells were obtained from abdominal dermolipectomies. We assessed the proliferative response of peripheral lymphocytes from patients and controls to cardiac progenitors cultured on a monolayer of ADSC, to allogeneic lymphocytes in mixed lymphocyte culture and to the T cell mitogen phytohemaglutin A in presence or absence of ADSC. Cardiac progenitors cultured on a monolayer of ADSC triggered a proliferation of lymphocytes from both patients and controls albeit lower than that induced by allogeneic lymphocytes. When cultured alone, ADSC did not induce any proliferation of allogeneic lymphocytes. When added to cultures of lymphocytes, ADSC significantly inhibited the alloantigen or mitogen-induced proliferative response. Compared to healthy controls, lymphocytes from patients presenting CAD expressed a decreased proliferative capacity, in particular to mitogen-induced stimulation. Adipose-derived stromal cells express an immunomodulatory effect that limits both alloantigen and mitogen-induced lymphocyte responses. Furthermore, lymphocytes from patients with CAD are low responders to conventional stimuli, possibly because of their age and disease-associated treatment regimens. We propose that, in combination, these factors may limit the in vivo immunogenicity of cardiac progenitors co-implanted with ADSC in patients with CAD.

Heart rate and risk of cancer death in healthy men.

BACKGROUND: Data from several previous studies examining heart-rate and cardiovascular risk have hinted at a possible relationship between heart-rate and non-cardiac mortality. We thus systematically examined the predictive value of heart-rate variables on the subsequent risk of death from cancer. METHODS: In the Paris Prospective Study I, 6101 asymptomatic French working men aged 42 to 53 years, free of clinically detectable cardiovascular disease and cancer, underwent a standardized graded exercise test between 1967 and 1972. Resting heart-rate, heart-rate increase during exercise, and decrease during recovery were measured. Change in resting heart-rate over 5 years was also available in 5139 men. Mortality including 758 cancer deaths was assessed over the 25 years of follow-up. FINDINGS: There were strong, graded and significant relationships between all heart-rate parameters and subsequent cancer deaths. After adjustment for age and tobacco consumption and, compared with the lowest quartile, those with the highest quartile for resting heart-rate had a relative risk of 2.4 for cancer deaths (95% confidence interval: 1.9-2.9, p<0.0001) This was similar after adjustment for traditional cardiovascular risk factors and was observed for the commonest malignancies (respiratory and gastrointestinal). Similarly, significant relationships with cancer death were observed between poor heart rate increase during exercise, poor decrease during recovery and greater heart-rate increase over time (p<0.0001 for all). INTERPRETATION: Resting and exercise heart rate had consistent, graded and highly significant associations with subsequent cancer mortality in men.

Composite cell sheets: a further step toward safe and effective myocardial regeneration by cardiac progenitors derived from embryonic stem cells.

BACKGROUND: The safety and efficacy of myocardial regeneration using embryonic stem cells are limited by the risk of teratoma and the high rate of cell death. METHODS AND RESULTS: To address these issues, we developed a composite construct made of a sheet of adipose tissue-derived stroma cells and embryonic stem cell-derived cardiac progenitors. Ten Rhesus monkeys underwent a transient coronary artery occlusion followed, 2 weeks later, by the open-chest delivery of the composite cell sheet over the infarcted area or a sham operation. The sheet was made of adipose tissue-derived stroma cells grown from a biopsy of autologous adipose tissue and cultured onto temperature-responsive dishes. Allogeneic Rhesus embryonic stem cells were committed to a cardiac lineage and immunomagnetically sorted to yield SSEA-1(+) cardiac progenitors, which were then deposited onto the cell sheet. Cyclosporine was given for 2 months until the animals were euthanized. Preimplantation studies showed that the SSEA-1(+) progenitors expressed cardiac markers and had lost pluripotency. After 2 months, there was no teratoma in any of the 5 cell-treated monkeys. Analysis of >1500 histological sections showed that the SSEA-1(+) cardiac progenitors had differentiated into cardiomyocytes, as evidenced by immunofluorescence and real-time polymerase chain reaction. There were also a robust engraftment of autologous adipose tissue-derived stroma cells and increased angiogenesis compared with the sham animals. CONCLUSIONS: These data collected in a clinically relevant nonhuman primate model show that developmentally restricted SSEA-1(+) cardiac progenitors appear to be safe and highlight the benefit of the epicardial delivery of a construct harboring cells with a cardiomyogenic differentiation potential and cells providing them the necessary trophic support.

Relief of mitral leaflet tethering following chronic myocardial infarction by chordal cutting diminishes left ventricular remodeling.

BACKGROUND: one of the key targets in treating mitral regurgitation (MR) is reducing the otherwise progressive left ventricular (LV) remodeling that exacerbates MR and conveys adverse prognosis. We have previously demonstrated that severing 2 second-order chordae to the anterior mitral leaflet relieves tethering and ischemic MR acutely. The purpose of this study was to test whether this technique reduces the progression of LV remodeling in the chronic ischemic MR setting. METHODS AND RESULTS: a posterolateral MI was created in 18 sheep by obtuse marginal branch ligation. After chronic remodeling and MR development at 3 months, 6 sheep were randomized to sham surgery (control group) and 12 to second-order chordal cutting (6 each to anterior leaflet [AntL] and bileaflet [BiL] chordal cutting, techniques that are in clinical application). At baseline, chronic infarction (3 months), and follow-up at a mean of 6.6 months post-myocardial infarction (MI) (euthanasia), we measured LV end-diastolic (EDV) and end-systolic volume (ESV), ejection fraction, wall motion score index, and posterior leaflet (PL) restriction angle relative to the annulus by 2D and 3D echocardiography. All measurements were comparable among groups at baseline and chronic MI. At euthanasia, AntL and BiL chordal cutting limited the progressive remodeling seen in controls. LVESV increased relative to chronic MI by 109±8.7% in controls versus 30.5±6.1% with chordal cutting (P<0.01) (LVESV in controls, 82.5±2.6 mL; in AntL, 60.6±5.1 mL; in BiL, 61.8±4.1 mL). LVEDV increased by 63±2.0% in controls versus 26±5.5% and 22±3.4% with chordal cutting (P<0.01). LV ejection fraction and wall motion score index were not significantly different at follow-up among the chordal cutting and control groups. MR progressively increased to moderate in controls but decreased to trace-mild with AntL and BiL chordal cutting (MR vena contracta in controls, 5.9±1.1 mm; in AntL, 2.6±0.1 mm; in BiL, 1.7±0.1 mm; P<0.01). BiL chordal cutting provided greater PL mobility (decreased PL restriction angle to 54.2±5.0° versus 83±3.2° with AntL chordal cutting; P<0.01). CONCLUSIONS: reduced leaflet tethering by chordal cutting in the chronic post-MI setting substantially decreases the progression of LV remodeling with sustained reduction of MR over a chronic follow-up. These benefits have the potential to improve clinical outcomes.

A purified population of multipotent cardiovascular progenitors derived from primate pluripotent stem cells engrafts in postmyocardial infarcted nonhuman primates.

Cell therapy holds promise for tissue regeneration, including in individuals with advanced heart failure. However, treatment of heart disease with bone marrow cells and skeletal muscle progenitors has had only marginal positive benefits in clinical trials, perhaps because adult stem cells have limited plasticity. The identification, among human pluripotent stem cells, of early cardiovascular cell progenitors required for the development of the first cardiac lineage would shed light on human cardiogenesis and might pave the way for cell therapy for cardiac degenerative diseases. Here, we report the isolation of an early population of cardiovascular progenitors, characterized by expression of OCT4, stage-specific embryonic antigen 1 (SSEA-1), and mesoderm posterior 1 (MESP1), derived from human pluripotent stem cells treated with the cardiogenic morphogen BMP2. This progenitor population was multipotential and able to generate cardiomyocytes as well as smooth muscle and endothelial cells. When transplanted into the infarcted myocardium of immunosuppressed nonhuman primates, an SSEA-1+ progenitor population derived from Rhesus embryonic stem cells differentiated into ventricular myocytes and reconstituted 20% of the scar tissue. Notably, primates transplanted with an unpurified population of cardiac-committed cells, which included SSEA-1- cells, developed teratomas in the scar tissue, whereas those transplanted with purified SSEA-1+ cells did not. We therefore believe that the SSEA-1+ progenitors that we have described here have the potential to be used in cardiac regenerative medicine.

New trends in treatment of hypertrophic cardiomyopathy.

The management of patients with hypertrophic cardiomyopathy (HCM) has evolved markedly over the past 20 years, particularly with the rising number of indications for implantable cardiac defibrillators (ICDs) and alcohol septal ablation (ASA). However, medical therapies targeted to improve quality of life are underused; when resting and/or exercise obstruction is present, an incremental and additive approach should be used based on a high dosage of beta-blockers, verapamil and/or disopyramide. Radiofrequency catheter ablation of atrial fibrillation or A-V node has been proposed in some instances. Treatment of syncope or presyncope due to an abnormal blood pressure response during exercise remains challenging. Only patients with obstruction who remain severely symptomatic despite maximal medical therapy should be considered for invasive procedures, including dual-chamber (DDD) pacing, ASA or surgery. The reported complication rates of ASA (essentially complete A-V block, incidence above 5-10%, with mortality rates ranging from 0-4%) and the benefits at medium-term follow-up appear comparable to those observed after myectomy, which, according to guidelines, should remain the primary treatment for most severely symptomatic drug-refractory young patients with obstruction. While the overall survival of patients with HCM is similar to that of the general population, detection of patients at high risk of sudden cardiac death remains challenging, particularly in the young, and indications for ICDs in high risk patients without prior cardiac arrest should be patient- and family-orientated.

Can mesenchymal stem cells induce tolerance to cotransplanted human embryonic stem cells?

Mesenchymal stem cells (MSCs) are reported to be immune privileged. We assessed whether their transplantation (Tx) could create a suppressive microenvironment mitigating rejection of coinjected human embryonic stem cells (hESCs). Three weeks after ligation-induced myocardial infarction, 40 immunocompetent rats received 150 microl of cardiac-specified hESCs (5 x 10(6)), MSCs (5 x 10(6)), hESC + MSC (5 x 10(6) for each), or control medium. Two months after Tx, left ventricle (LV) function was assessed by echocardiography, and hearts were processed for the detection of human cells by immunostaining and quantitative RT-PCR, patterns of rejection, fibrosis, and angiogenesis. Two months after Tx, LV ejection fraction (LVEF) was significantly higher in the ESC and ESC + MSC groups compared with controls. There were few engrafted cells, which expressed markers of endothelial, smooth muscle, and ventricular cardiac cells, particularly in the MSC group. Hearts of all groups demonstrated a similar infiltration by CD4(+) and CD3(+) cells but MSC-Tx resulted in a greater infiltration of FoxP3 compared with the control and ESC-alone groups. No teratoma was observed. Thus, cotransplantation of ESCs and MSCs provided better functional preservation compared with single-cell treatment alone. However, there was only modest evidence for an immunosuppressive effect of coinjected MSCs and their beneficial effects seemed rather mediated by trophic effects on the host tissue.

Characterization of the paracrine effects of human skeletal myoblasts transplanted in infarcted myocardium.

BACKGROUND: The discrepancy between the functional improvements yielded experimentally by skeletal myoblasts (SM) transplanted in infarcted myocardium and the paucity of their long-term engraftment has raised the hypothesis of cell-mediated paracrine mechanisms. METHODS AND RESULTS: We analyzed gene expression and growth factors released by undifferentiated human SM (CD56(+)), myotubes (SM cultured until confluence) and fibroblasts-like cells (CD56(-)). Gene expression revealed up-regulation of pro-angiogenic (PGF), anti-apoptotics (BAG-1, BCL-2), heart development (TNNT2, TNNC1) and extracellular matrix remodelling (MMP-2, MMP-7) genes in SM. In line with the gene expression profile, the analysis of culture supernatants of SM by ELISA identified the release of growth factors involved in angiogenesis (VEGF, PIGF, angiogenin, angiopoietin, HGF and PDGF-BB) as well as proteases involved in matrix remodelling (MMP2, MMP9 and MMP10) and their inhibitors (TIMPs). Culture of smooth muscle cells (SMC), cardiomyocytes (HL-1) and human umbilical vein endothelial cells (HUVECs) with SM-released conditioned media demonstrated an increased proliferation of HUVEC, SMC and cardiomyocytes (p<0.05) and a decrease in apoptosis of cardiomyocytes (p<0.05). Analysis of nude rats transplanted with human SM demonstrated expression of human-specific MMP-2, TNNI3, CNN3, PGF, TNNT2, PAX7, TGF-beta, and IGF-1 1 month after transplant. CONCLUSIONS: Our data support the paracrine hypothesis whereby myoblast-secreted factors may contribute to the beneficial effects of myogenic cell transplantation in infarcted myocardium.