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Cardiac cell therapy has been initially designed to regenerate the infarcted myocardium through its repopulation by new cells able to restore function of scar areas. Six years after the first human application of this novel approach, it is timely appropriate to review the results of the first randomised trials in the three major indications, i.e., acute myocardial infarction, heart failure, and refractory angina. It should be recognized that the results are mixed, with benefits ranging from absent to transient and, at most, marginal. However, lessons drawn from this first wave of clinical series and the experimental data that have been concomitantly collected are multiple and highly informative. They indicate that adult stem cells, whether muscular or bone marrow-derived, fail to generate new cardiomyocytes. They suggest that the potential benefits of cardiac cell therapy are thus mediated by alternate mechanisms such as limitation of left ventricular remodelling or paracrine activation of signalling pathways involved in angiogenesis. They highlight the fact that the therapeutic benefits of grafted cells will not be fully exploited until issues of cell transfer and postengraftment survival have not been adequately addressed. These observations thus allow us to better fine-tune upcoming research, which should specifically concentrate on the development of cells featuring a true regeneration potential. In this setting, the greatest promises are currently held by embryonic stem cells.

Background. Non-bacterial thrombotic endocarditis is a severe complication of cancer, rarely reported in gynecologic tumors. However, it can be inaugural and lead to complex diagnostic pathways. Case. A 40-year-old woman presented with a stroke, related to an endocarditis. The valvular vegetation was surgically removed, and a malignant node was resected. A PET-scan led to the diagnosis of a myometrial tumor, which was found to be a primitive neuroectodermal tumor (PNET). The patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy, and systemic chemotherapy which allowed a complete remission of tumoral and cardio-vascular symptoms. Conclusion. To our knowledge, this is the first case report of a PNET of the myometrium revealed by cardio-vascular symptoms.

Background— Severing a limited number of second-order chordae to the anterior leaflet can improve ischemic mitral regurgitation (MR). Some concerns have been raised regarding possible influence on regional and global left ventricle (LV) function. We evaluated changes in cardiac function in 5 normal sheep with cutting of pre-instrumented chords in the beating heart to maintain constant load. Methods and Results— Under cardiopulmonary bypass, wires were placed around the 2 central basal chordae and brought outside the heart, which was restarted. Hemodynamic and imaging data were collected before and after chordal cutting by radiofrequency ablation using those wires. Segmental contractility was assessed invasively using sonomicrometers and noninvasively using Doppler tissue velocity and strain rate (with strain rate viewed as less load-dependent than ejection fraction) at 6 sites: base, mid-ventricle, and apex along the anteroseptal and posterolateral walls. We found no changes from before to after chordal cutting in LV end-diastolic volume (47.2±3.3 after cutting versus 48.4±4.6 mL before cutting, P =0.66), end-systolic volume (21.5±1.2 versus 22.3±2.8 mL, P =0.68), ejection fraction (54.2±1.8 versus 54.2±2.7%, P =0.96), systolic ventricular elastance (7.28±1.68 versus 7.66±2.11 mm Hg/mL, P =0.64), preload-recruitable stroke work (46.6±7.7 versus 50.2±10.7 mm Hg, P =0.76), and LVdP/dt (1480±238 versus 1392±250 mm Hg/s, P =0.45). Doppler tissue velocities and longitudinal strain rates surrounding the papillary muscles were unchanged, as were sonomicrometer longitudinal and mediolateral absolute strains. No wall motion abnormalities were visible around the papillary muscles, and no MR developed. Conclusion— We find no evidence for acutely decreased global or segmental LV contractility with chordal cutting. This absence of adverse effects is consistent with long-term clinical experience with cutting these chords in valve repair.

Background— Skeletal myoblast (SM) transplantation (Tx) in a post-myocardial infarction (MI) scar experimentally improves left ventricular (LV) ejection fraction (EF). Short-term follow-up (FU) studies have suggested that a similar benefit could clinically occur despite an increased risk of LV arrhythmias. Methods and Results— We report the long-term FU of the first worldwide cohort of grafted patients (n =9, 61.8±11.6 years, previous MI, EF ≤35%) operated on (autologous SM Tx and bypass surgery) in 2000 to 2001 and evaluated before Tx, at 1 month (M1) and at a median FU of 52 (18 to 58) months after Tx (37 patient-years). NYHA class improved from 2.5±0.5 to 1.8±0.4 at M1 ( P =0.004 versus baseline) and 1.7±0.5 at FU ( P =not significant versus M1; P =0.0007 versus baseline). EF increased from 24.3±4% to 31±4.1% at M1 (+28%, P =0.001 versus baseline) and remained stable thereafter (28.7±8.1%, +18% versus baseline). There were 5 hospitalizations for heart failure in 3 patients at 28.6±9.9 months, allowing implant in 2 patients with a resynchronization pacemaker. An automatic cardiac defibrillator (ACD) was implanted in 5 patients for nonsustained (n =1) or sustained (n =4) ventricular tachycardia at 12.2±18.6 (1 to 45) months. Despite a beta-blocker/amiodarone combination therapy, there were 14 appropriate shocks for 3 arrhythmic storms in 3 patients at 6, 7, and 18 months after ACD implantation. Conclusions— In this cohort of severe heart failure patients both clinical status and EF stably improve over time with a strikingly low incidence of hospitalizations for heart failure (0.13/patient-years) and the arrhythmic risk can be controlled by medical therapy and/or on-request ACD implantation.

International audience; Objectives: This study was designed to assess whether post-myocardial infarction (MI) in-scar transplantation of skeletal myoblasts (SM) could reduce chronic ischemic mitral regurgitation (MR) by decreasing left ventricular (LV) remodeling.Background: Extensive work has confirmed the relationship between ischemic MR and post-myocardial infarction (MI) remodeling of the LV.Methods: An infero-posterior MI was created in 13 sheep, thereby resulting in increasing MR. Two months post-MI, the animals were randomized and in-scar injected with expanded autologous SM (n = 6, mean: 251 x 10(6) cells) or culture medium only (n = 7). Three-dimensional echocardiography was performed at baseline, before transplantation, and for two months thereafter (sacrifice), with measurements of LV end-diastolic and end-systolic volumes (ESV), ejection fraction (EF), MR stroke volume, and leaflet tethering distance; wall motion score index (WMSi) was assessed by two-dimensional echo.Results: Measurements were similar between groups at baseline and before transplantation. At sacrifice, transplantation was found to have reduced MR progression (regurgitant volume change: -1.83 +/- 0.32 ml vs. 5.9 +/- 0.7 ml in control group, p < 0.0001) and tethering distance (-0.41 +/- 0.09 cm vs. 0.44 +/- 0.12 cm in control group, p < 0.001), with significant improvement of EF (2.01 +/- 0.94% vs. -4.86 +/- 2.23%, p = 0.02), WMSi (-0.25 +/- 0.11 vs. 0.13 +/- 0.03 in controls, p < 0.01) and a trend to a lesser increase in ESV (23.3 +/- 3.5 ml vs. 35.4 +/- 4.2 ml in control group, p = 0.055).Conclusions: Autologous skeletal myoblast transplantation attenuates mild-to-moderate chronic ischemic MR, which otherwise is progressive, by decreasing tethering distance and improving EF and wall motion score, thereby enhancing valve coaptation. These data shed additional light on the mechanism by which skeletal myoblast transplantation may be cardioprotective.

Objectives: To assess the functional effects of multipotent adult progenitor cells (MAPCs) transplanted in a rat model of chronic myocardial infarction. Methods: Forty-four rats underwent coronary ligation and, 14 days later, were randomly allocated to receive in-scar injections (5×106 cells/150 μL) of green fluorescent protein (eGFP)-transduced allogeneic MAPCs ( n =25) or culture medium (controls, n =19). Nine of the MAPC-treated hearts were employed for functional studies while the remaining 16 received cells co-labeled with Resovist™ and were only used for serial histological assessments. Left ventricular (LV) function was assessed echocardiographically before transplantation and 1 month thereafter in a blinded manner. Immunohistochemistry, electron microscopy and PCR were used to detect grafted cells. All data were compared by nonparametric tests. Results: Baseline ejection fractions (EF, median;[interquartile range]) did not differ significantly among the groups: 30% [0.23;0.37] and 37% [0.32;0.38] in control and rMAPC-transplanted hearts, respectively. One month later, LV function of control hearts was found to have deteriorated, as reflected by a decline in EF to 24% [0.21;0.30], and although EF tended to remain more stable after cell transplantation (37% [0.27;0.41]), the difference between the two groups failed to achieve statistical significance ( p =0.06). While MAPCs could be identified early post-transplant, no evidence of engraftment was further observed at 1 month by immunohistochemistry, electron microscopy or PCR. Conclusions: In this model, MAPCs did not improve global pump function, and although some of these cells expressed endothelial markers during the early post-transplant period, we could not detect any evidence for differentiation into cardiomyocytes and no engraftment was further identified beyond 2 weeks after cell injections.

The modalities of pharmacologically-induced preconditioning, although intellectually appealing, remain to be determined including the choice of the optimal agents and regimens. Benefits should be measured through clinical endpoints such as improved immediate or late myocardial function or perhaps improved survival in certain subgroups of patients such as those with problematic cardioplegia delivery or poor ventricular function. These considerations must be addressed before recommending the routine application of techniques or pharmacologic interventions. The only clinical situation in which the ischemic preconditioning remains logical would be “offpump” minimally invasive cardiac surgery as the occlusion of the target vessel during construction of the distal anastomosis most closely mimics the experimental scenario that has turned out to result in reduction of regionally-induced ischemic damage.

Background Prolonged cross-clamp time during cardiac surgery increases the risk of postoperative mortality and myocardial injury. This subanalysis from the pexelizumab for reduction of infarction and mortality in coronary artery bypass grafting surgery (PRIMO-CABG) trial, a phase III double-blind, placebo-controlled study of 3,099 patients undergoing on-pump coronary artery bypass graft surgery with or without valve surgery, assessed the impact of pexelizumab, an investigational C5 complement inhibitor, on postoperative outcomes after prolonged aortic cross-clamp time. Methods The composite endpoint of death or myocardial infarction through postoperative day 30 and death alone through days 30, 90, and 180 were examined in subpopulations of patients across different cross-clamp times. Results After prolonged cross-clamping (≥90 minutes), death, or myocardial infarction through day 30 and death through days 30, 90, and 180 were significantly increased in the intent-to-treat population and were even higher in patients with two or more prespecified risk factors, compared with all patients cross-clamped less than 90 minutes. Pexelizumab significantly reduced the incidence of death or myocardial infarction through day 30, and significantly reduced the incidence of mortality through day 180, in patients with two or more risk factors that required prolonged cross-clamp time. Pexelizumab also significantly reduced perioperative myocardial injury in all patients requiring prolonged cross-clamp time. Conclusions In this retrospective, subgroup analysis, pexelizumab reduced postoperative morbidity and myocardial injury in patients with multiple risk factors who underwent prolonged cross-clamp time during coronary artery bypass surgery. The clinical benefit of pexelizumab may be related to the effect of complement inhibition in the presence of potential ischemic-reperfusion injury associated with prolonged aortic cross-clamp time.

Objective(s) Even though the mechanism is not clearly understood, direct intramyocardial cell transplantation has demonstrated potential to treat patients with severe heart failure. We previously reported on the bioengineering of myoblast-based constructs. We investigate here the functional outcome of infarcted hearts treated by implantation of myoblast-seeded scaffolds. Methods Adult Lewis rats with echocardiography-confirmed postinfarction reduced ejection fraction (48.3% ± 1.1%) were randomized to (1) implantation of myoblast-seeded polyurethane patches at the site of infarction (PU-MyoB, n=11), (2) implantation of nonseeded polyurethane patches (PU, n=11), (3) sham operation (Sham, n=12), and (4) direct intramyocardial myoblast injection (MyoB, n=11). Four weeks later, the functional assessment by echocardiography was repeated, and we additionally performed left ventricular catheterization plus histologic studies. Results The ejection fraction significantly decreased in the PU (39.1% ± 2.3%; P = .02) and Sham (39.9% ± 3.5%; P = .04) groups, whereas it remained stable in the PU-MyoB (48.4% ± 3.1%) and MyoB (47.9% ± 3.0%) groups during the observation time. Similarly, left ventricular contractility was significantly higher in groups PU-MyoB (4960 ± 266 mm Hg/s) and MyoB (4748 ± 304 mm Hg/s) than in groups PU (3909 ± 248 mm Hg/s, P = .01) and Sham (4028 ± 199 mm Hg/s, P = .01). Immunohistology identified a high density of myoblasts within the seeded scaffolds without any migration toward the host cardiac tissue and no evidence of cardiac cell differentiation. Conclusions Myoblast-seeded polyurethane scaffolds prevent post–myocardial infarction progression toward heart failure as efficiently as direct intramyocardial injection. The immunohistologic analysis suggests that an indirect mechanism, potentially a paracrine effect, may be assumed.

Objective. Cell death remains a major limitation of skeletal myoblast (SM) transplantation but the patterns of cell survival and proliferation in heart and their potential modulation by thermic stresses like heat shock (HS) and cryopreservation (Cryo) are still incompletely characterized. Methods. To track SMs in situ, we developed a dual-marker system based on the semiconservative expression of the foreign soluble protein, β-Galactosidase (β-Gal) and the constitutive expression of the Y chromosome in a myocardial infarction model. Control medium or Lewis male rat SMs (fresh or subjected to Cryo or HS) were injected in Lewis female rats. Results. There was a massive cell loss early after transplantation in the fresh group, which was only partially compensated for by a subsequent proliferation. Conversely, both Cryo and HS significantly improved early cell survival but blunted subsequent proliferation so that, at 15 days posttransplantation, the total number of engrafted donor-derived Y-positive cells did not differ significantly between the three groups. Most of them expressed a skeletal muscle phenotype. Conclusions. These data confirm the high death rate of in-scar transplanted myoblasts, demonstrate the ability of those that survive to proliferate and differentiate along the myogenic pathway but do not support the efficacy of either Cryo or HS for increasing the ultimate magnitude of myoblast engraftment.

Summary Background Heart failure develops after myocardial infarction and is a major cause of morbidity and mortality. The ability to direct differentiation of embryonic stem cells (ESC) towards a cardiomyogenic phenotype makes them an attractive therapeutic option for cardiac repair, but species-specific and individual-specific immunological imprinting remains a hurdle. Our aim was to ascertain whether the purported immune privilege of ESC allows for their cross-species engraftment in a clinically relevant large-animal model. Methods We studied engraftment and differentiation of cardiac-committed mouse ESC in 18 sheep in which a myocardial infarction had been induced; nine controls received medium and nine sheep (five of which were immunosuppressed) received ESC. The gain in myocardial function was measured by echocardiography 1 month after cell transplantation. Findings Cardiac-committed murine ESC engrafted in infarcted myocardium of immunosuppressed and immunocompetent sheep, and differentiated into mature cardiomyocytes that expressed connexins. Colonisation of the scar area by ESC was accompanied by a functional benefit of the damaged myocardium. Left-ventricular ejection fraction deteriorated in the control group by a median of 9·9% (range −20 to 0·3) relative to baseline (p=0·011) whereas in the treated group it improved by 6·6% (−5·7 to 50·8; comparison between groups p=0·002). Interpretation These findings obtained in a clinically relevant large-animal model of heart failure strengthen the potential therapeutic use of ESC to regenerate the severely dysfunctional myocardium and bring additional evidence for an immune privilege of these cells.

Skeletal myoblast transplantation has now entered the clinical arena as a potential means of restoring function to scarred myocardium. While the current experience derived from phase I trials suggests that cell implantation during coronary artery bypass operations is a straightforward and safe procedure, routine use of myoblast transplantation would certainly be premature. Two major issues have not yet been addressed: firstly, the risk–benefit ratio needs to be assessed, specifically whether the potential proarrhythmic risk associated with myoblast transplantation is supported by the results of an ongoing large, randomized study, and if so, whether this risk is offset by a benefit in terms of improvement of left ventricular function and patient outcome. Secondly, this putative benefit will then have to be weighed against the financial burden inherent to this type of procedure, to assess whether the cost–effectiveness ratio is favorably shifted and supports the expanded indication of myoblast transplantation during coronary artery revascularization in patients with severe ischemic heart failure.

Cell therapy is currently receiving growing interest as a new means of repairing infarcted myocardium. Despite the encouraging experimental results yielded by autologous skeletal myoblasts and bone marrow-derived hematopoietic and mesenchymal stem cells, there is increasing evidence that the plasticity of these adult cells is more limited than initially thought and that, consequently, their conversion into cardiomyocytes is unlikely or, at best, quantitatively very limited. As the engrafted cells should electromechanically interact with host cardiac cells to form a functional syncytium, attention is now increasingly focused on cells that feature a true cardiomyogenic differentiation potential, enabling them to connect with the neighboring cardiomyocytes. In this setting, embryonic stem cells are particularly attractive, since they can be precommitted towards a cardiac lineage and complete their full maturation in vivo, possibly under the influence of host tissue-associated paracrine signaling pathways. Although a potential clinical use of embryonic stem cells is still fraught with difficulty (amplification, purification and immunogenicity), available experimental data suggest a consistent efficacy in repairing infarcted myocardium, which has stimulated efforts to address these issues.

A completely asymptomatic 60-year-old man presented for a preventive calcium score screening. ECG-gated non–contrast-enhanced cardiac computed tomography showed a noncalcified hypodense oval mass in the right ventricle with a spontaneously hyperdense wall measuring 19×17 mm (Figure 1A). Echocardiography was performed and found a 16×18 mm egg-shaped hypoechoic mass with regular hyperechoic borders, suggestive of a cyst appended to the interventricular septum. Although he never traveled outside Western Europe, a hydatic cyst was suspected and a follow-up strategy was decided. Figure 1. Initial ECG-gated nonenhanced cardiac computed tomography performed for calcium scoring, axial …

Background— The benefits of skeletal myoblast (SM) transplantation on infarcted myocardium have been investigated extensively; however, little is known about its effects in nonischemic cardiomyopathy models. To address this issue, we tested SM transplantation in CHF147 Syrian hamsters, a strain characterized by a δ-sarcoglycan deficiency that phenotypically features the human setting of primary dilated cardiomyopathy. Methods and Results— Cell culture techniques were used to prepare ≈5×10 6 muscle cells from autologous tibialis anterior muscle, of which 50% were SMs (desmin staining). The cells were injected in 6 sites across the left ventricular wall (n=14). Control animals (n=12) received equivalent volumes of culture medium. Left ventricular systolic function was assessed in a blinded fashion from 2D echocardiographic left ventricular fractional area change, before transplantation, and 4 weeks later. Explanted hearts were processed for the detection of myotubes and quantification of fibrosis. Baseline functional data did not differ between the 2 groups. Four weeks after transplantation, 6 of the 10 surviving grafted hamsters were improved compared with 0 of the 8 survivors of the control group. This translated into a 6% decrease in fractional area change in controls compared with a 24% increase in cell-transplanted hamsters ( P =0.001). Engrafted myotubes were consistently detected in all SM transplanted hearts by immunohistochemistry, whereas fibrosis was not worsened by cell injections. Conclusions— These data suggest that the functional benefits of SM transplantation might extend to nonischemic cardiomyopathy.

Objective: This study was designed to assess whether the protective effects of Na C /H C exchange (NHE) inhibition, which have been largely demonstrated in normal hearts, are also manifest in a more surgically relevant model of hypertrophied myocardium subjected to cardioplegic arrest. Methods: Left ventricular hypertrophy was created in 3-week-old rats by coarctation of the ascending thoracic aorta with a hemoclip. Eight weeks later, hearts were excised, isovolumetrically perfused and subjected to 1 h of potassium cardioplegic arrest followed by 2 h of reperfusion. Hearts were allocated to one of the following four groups: sham-operated and aortic banding hearts without any treatment or treated with the NHE inhibitor cariporide (1 mmol/L) given as an additive to cardioplegia and over the first 15 min of reperfusion. Results: The major effect of cariporide was to reduce ischemic peak contacture and to improve post-ischemic diastolic function in both sham-operated and hypertrophied hearts. Total creatine kinase release over the first 45 min of reperfusion was significantly reduced in hypertrophied hearts treated with cariporide. The endothelium-dependent coronary vasodilation to 5-hydroxytryptamine was observed in all sham-operated hearts before cardiac arrest, however, it was significantly impaired following cardioplegic ischemia and reperfusion. Hypertrophied hearts demonstrated markedly impaired endothelium-dependent and -independent coronary vasodilations during both pre- and post-ischemic period that were not affected by the treatment with cariporide. Conclusions: The cardioprotective effects of the NHE inhibitor cariporide are also manifest in hypertrophied myocardium, which supports the potential usefulness of NHE inhibition in the setting of cardiac surgery. q 2004 Elsevier B.V. All rights reserved.

PURPOSE OF REVIEW The last few years have witnessed a growing interest in regenerative therapy of the failing heart by cell transplantation. Special emphasis has been put on skeletal myoblasts and bone marrow-derived stem cells, with a flurry of experimental studies generating overall positive but occasionally conflicting results. It is thus appropriate to review the most important of these studies in light of the major issues that still impede widespread clinical use of cell therapy. RECENT FINDINGS Recent laboratory data demonstrate the ability of autologous skeletal myoblasts to engraft into scarred myocardium and improve its function. Equally successful results have been reported with bone marrow-derived cells which, in contrast to myoblasts, are credited with a plasticity that might allow their transdifferentiation into cardiac or endothelial cells in response to organ-specific cues. However, some major questions remain unanswered; they include the choice of the optimal cell type in relation with the target patient population, the strategies for enhancing cell survival and functional integration, the clarification of the mechanisms of improvement, and the means of reducing invasiveness of cell delivery. SUMMARY Although laboratory research attempts to overcome these persisting hurdles, the accumulated body of evidence warrants implementation of clinical trials. The earliest ones have now documented the feasibility of cell therapy. It is now appropriate to conduct safety and efficacy studies which, if carefully done, should allow assessment of the extent to which this concept of regenerative therapy can be made a clinical reality.

In conclusion, myoblast transfer has now reached a stage where large randomized trials such as the one we are initiating (300 patients) are mandatory to thoroughly assess the efficacy of the procedure. It is important that the design of these studies complies with the stringent methodologic guidelines commonly used in drug trials, as this is the only means of accurately assessing whether and to what extent skeletal myoblast transfer can really impact the outcome of patients with advanced left-ventricular ischemic dysfunction.

Background— Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Leaflet closure is restricted by tethering to displaced papillary muscles, and is, therefore, incompletely treated by annular reduction. In an acute ischemic model, we reduced such MR by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. Whether this is effective without prolapse, recurrent MR, or left ventricular (LV) failure in chronic persistent ischemic MR, despite greater LV remodeling, remains to be established. Therefore, we studied 7 sheep with chronic inferobasal infarcts known to produce progressive MR over 2 months. In all of those sheep, after a mean of 4.1 months, the 2 central basal (intermediate) chordae were cut at the chronic ischemic MR stage. 3-Dimensional echo quantified MR, LV function, and valve geometry. Five other sheep were followed for a mean of 7.8±1.2 months after inferobasal infarction with chordal cutting. Results— All 7 of the sheep with chronic ischemic MR (increased from 1.4±0.4 to 11.1±0.5 mL/beat, regurgitant fraction=39.0±4.2%, P P P =not significant [NS]). The five sheep with long-term follow-up showed no prolapse or MR, and no significant post-infarct decrease in LV ejection fraction (EF; 38.9±2.4% to 41.4±1.2%, P =NS). Conclusion— Cutting a minimum number of basal (intermediate) chordae can improve coaptation and reduce chronic persistent ischemic MR without impairing LVEF. No adverse effects were noted long-term after chordal cutting at the time of infarction.

Cell transplantation is emerging as a new treatment designed tot improve the poor outcome of patients with cardiac failure. Its rationale is that implantation of contractile cells into postinfarction scars can functionally rejuvenate these areas. Primarily for practical reasons, autologous skeletal myoblasts have been the first to be tested clinically but bone marrow stromal and hematopoietic stem cells may represent an interesting alternative in select situations because of their autologous origin and their purported plasticity. However, several key issues still need to be addressed including (1) the optimal type of cells, (2) the mechanism by which cell engraftment improves cardiac function, i.e., increased contractility or limitation of remodeling, (3) the most effective strategies for optimizing cell survival, and (4) the potential benefits of cell transplantation in nonischemic heart failure. In parallel to the experimental studies designed to address these issues, initial clinical trials are underway and should hopefully allow to know whether the hopes raised by cellular therapy are met by clinically meaningful improvements in function and outcome in patients with severe left ventricular ischemic dysfunction.

Survival and differentiation of myogenic cells grafted into infarcted myocardium have raised the hope that cell transplantation becomes a new therapy for cardiovascular diseases. The approach was further supported by transplantation of skeletal myoblasts, which was shown to improve cardiac performance in several animal species. Despite the success of myoblast transplantation and its recent trial in human, the mechanism responsible for the functional improvement remains unclear. Here, we used intracellular recordings coupled to video and fluorescence microscopy to establish whether myoblasts, genetically labeled with enhanced GFP and transplanted into rat infarcted myocardium, retain excitable and contractile properties, and participate actively to cardiac function. Our results indicate that grafted myoblasts differentiate into peculiar hyperexcitable myotubes with a contractile activity fully independent of neighboring cardiomyocytes. We conclude that mechanisms other than electromechanical coupling between grafted and host cells are involved in the improvement of cardiac function.

Cell transplantation is currently gaining a growing interest as a potential new means of improving the prognosis of patients with cardiac failure. The basic assumption is that left ventricular dysfunction is primarily caused by the loss of a critical number of cardiomyocytes and that their replacement by new contractile cells could functionally ‘regenerate’ postinfarction scars in which these cells are implanted. Primarily for practical reasons, autologous skeletal myoblasts have been the first to undergo clinical trials but other cell types are also considered, particularly bone marrow stem cells which are attractive because of their autologous origin and their purported cardiomyocyte/endothelial transdifferentiation potential in response to cues present in the target organ. However, several key issues still need to be addressed including (1) the optimal type of donor cells, (2) the mechanism by which cell engraftment improves cardiac function, (3) the optimization of cell survival, and (4) the potential benefits of cell transplantation in nonischemic dilated cardiomyopathies. In parallel to the experimental studies designed to address these issues, clinical trials are underway and their results should hopefully allow the assessment of to what extent cellular therapy may improve the outcome of patients with heart failure.

International audience; Objectives: This phase I trial was designed to assess the feasibility and safety of autologous skeletal myoblast transplantation in patients with severe ischemic cardiomyopathy.Background: Experimentally, myoblast grafting into postinfarction myocardial scars improves left ventricular function.Methods: Ten patients were included on the basis of the following criteria: 1) severe left ventricular dysfunction (ejection fraction < or = 35%); 2) the presence of a postinfarction akinetic and nonviable scar, as assessed by dobutamine echocardiography and 18-fluorodeoxyglucose positron emission tomography; and 3) an indication of coronary bypass in remote areas. Skeletal myoblasts were grown from a biopsy taken at the thigh.Results: An average of 871 x 10(6) cells (86% of myoblasts) were obtained after a mean period of 16 days and implanted uneventfully across the scar at the time of bypass. Except for one patient whose early death was unrelated to the cell transplantation, all patients had an uncomplicated postoperative course. Four patients showed delayed episodes of sustained ventricular tachycardia and were implanted with an internal defibrillator. At an average follow-up of 10.9 months, the mean New York Heart Association functional class improved from 2.7 +/- 0.2 preoperatively to 1.6 +/- 0.1 postoperatively (p < 0.0001), and the ejection fraction increased from 24 +/- 1% to 32 +/- 1% (p < 0.02). A blinded echocardiographic analysis showed that 63% of the cell-implanted scars (14 of 22) demonstrated improved systolic thickening. One noncardiac death occurred 17.5 months after transplantation.Conclusions: These preliminary data suggest the feasibility and safety of autologous skeletal myoblast transplantation in severe ischemic cardiomyopathy, with the caveat of an arrhythmogenic potential. New-onset contraction of akinetic and nonviable segments suggests a functional efficacy that requires confirmation by randomized studies.

International audience; Background: Several studies have demonstrated the short-term benefits of autologous skeletal muscle cell transplantation on postinfarction left ventricular function. The present experiments were designed to assess the long-term effects of the procedure.Methods and results: Thirteen Wistar rats that had undergone skeletal muscle cell transplantation (n=6) or injection of control culture medium (n=7) in isoforms areas after myocardial infarction created by coronary artery ligation and survived for 1 year were functionally assessed by combining echocardiography and pressure-volume loops. At 1 year after transplantation, both contractile and relaxation indices were significantly improved in the skeletal muscle cell-grafted group compared with controls. One-year echocardiographic measurements of ejection fraction were similar to those recorded 2 months after the procedure. The stability of the functional outcome contrasted with a decrease in the number of histologically detectable skeletal myotubes over time. However, the proportion of the slow and composite (fast and slow) myosin isoforms expressed by skeletal muscle fibers still present after 1 year was greater than that found in animals sacrificed after 2 months.Conclusion: The functional benefits of autologous skeletal muscle cell transplantation are sustained over time and are associated with either selection, preservation or an increased expression of slow myosin heavy chain isoforms. The discrepancy between maintenance of this improvement and the decay in the engrafted myotubes suggests protective mechanisms operative from the early post-transplantation stage and possibly involving modulation of extracellular matrix remodelling or paracrinally induced maturation of putative cardiac resident stem cells.

The prevention of postoperative adhesions to make sternal re-entry safer and to avoid its potentially associated lifethreatening complications has been a longstanding endeavor in cardiac surgery. The multiplicity of the proposed strategies, which range from the topical application of agents stimulating the pericardial fibrinolytic function by mesothelial cells to the placement of resorbable or nonresorbable pericardial substitutes, clearly demonstrates that none of these strategies has proven convincing enough to gain wide clinical acceptance. On the basis of the study of Lassaletta, Chu, and Sellke, it would seem that this list of compounds and devices can now be completed by.vodka. In this provocative study, the authors first subjected swine to a 4-week hypercholesterolemic diet before inducing chronic myocardial ischemia by placement of an ameroid constrictor around the circumflex coronary artery. While the hypercaloric regimen was continued, the animals were then given either red wine or vodka to drink, and a third group served as control. After 7 weeks of these regimens, the animals were reoperated on and those that had received vodka were then found to have much less severe pericardial adhesions than their counterparts in the 2 other groups, as assessed by a macroscopic grading system. Histologically, vodka intake was also associated with a reduction in fibrosis and transmural collagen expression whereas there were no significant between-group differences in the expression of several proteins involved in focal adhesion. This study is certainly original at least for 2 reasons. First, it has usually been considered that a local problem, that is, the formation of pericardial adhesions, needed to be fixed by a local solution. The present study challenges this concept by suggesting a potential benefit of a systemic intervention. In that, its findings are consistent with those of Meisel and coworkers, who have shown, in a rabbit model, that the systemic administration of the tyrosine kinase receptor inhibitor sunitinib could effectively reduce

Cardiac transplantation still remains the only radical treatment of end-stage heart failure but organ shortage results in the lengthening of the waiting period during which hemodynamic decompensation may occur and then require temporary circulatory support. Improvement in these assist devices now allows to permanently implant some of them which then appear as true alternatives to cardiac transplantation when this technique is contra-indicated. In parallel to these "mechanical" options, "biological" strategies have been designed, which are primarily based on cell therapy. Thus, autologous skeletal myoblast transplantation has yet entered the clinical arena, on the basis of experimental data suggesting the functional efficacy of these cells once implanted into infarcted myocardium. However, the clinical benefits of this approach still need to be validated by randomized trials. Gene therapy appears more complex to implement clinically, because of the multiplicity of candidate genes and the persisting issues associated with vectors and gene transfection systems.

Transplantation of autologous skeletal muscle cells (myoblasts) into post-infarction scars is intended to restore some functionality in these akinetic areas. This concept is now validated by a large number of experimental studies and the preliminary results of a phase 1 human trial. Several issues however still need to be addressed: critical analysis of myoblasts in comparison with other cell types, in particular bone marrow stem cells; optimization of delivery techniques and cell survival following engraftment; mechanisms by which transplanted cells may affect overall cardiac function and possible extension of the indications to non ischemic cardiomyopathies. Only carefully controlled clinical studies, based on sound experimental data, will allow to address these questions and to define the place cell therapy may have within our armamentarium of techniques designed to ameliorate the prognosis of patients with severe heart failure.

Along with angiogenesis and gene therapy, cell transplantation is one of the newest treatment modalities proposed to improve the outcome of patients with cardiac failure. Both experimental and clinical data have now established that implantation of contractile cells into fibrous postinfarction scars can allow them to regain some functionality. Primarily for practical reasons, autologous skeletal myoblasts have been the first to be tested in a clinical trial, but other cell types can be considered among which bone marrow stromal and hematopoietic stem cells are of particular interest because of their presumed pluripotentiality and the possibility to use them as autografts. However, several key issues still need to be addressed including: (1) the advantages and disadvantages of these different donor cells; (2) the extent to which cell engraftment affects cardiac function actively (ie, by increasing contractility) or passively (ie, by limiting infarct expansion and remodeling); (3) the development of strategies targeted at enhancing cell survival; and (4) the identification of cardiac diseases for which cell engraftment may be most beneficial. In parallel to the numerous experimental studies designed to address these issues, initial clinical trials are underway or in preparation and it is mandatory to design and conduct them in a careful manner so as to ultimately know whether cellular transplantation holds its promise as a means of improving the outcomes of patients with heart failure. Copyright 2002, Elsevier Science (USA). All rights reserved.

A recent survey of outcomes in 8,641 patients who underwent coronary artery bypass grafting (CABG) operations in northern New England indicates an overall mortality of 4.48%. (1) Importantly, 65% of all deaths could be directly attributed to postoperative heart failure. These data indicate that in spite of the dramatic improvements in myocardial protection that have been accomplished over the past decades, there is still room for improvement, in particular in high-risk patients who may poorly tolerate superimposition of perioperative ischemic damage on their underlying critical hemodynamic status. This paper reviews the major techniques in current clinical use with more emphasis on recent advances and possible perspectives. From a practical standpoint, a distinction can be made between strategies directly targeted at the myocardium and strategies that can indirectly enhance cardioprotection by attenuating the systemic inflammatory effects of cardiopulmonary bypass (CPB). These different approaches will thus be reviewed consecutively.

D URING THE first 3 months following mitral valve replacement (MVR) with a bioprosthetic valve, moderate anticoagulation is required. Sodium warfarin is usually the drug of choice. Most of the time, heparin is used during the first postoperative week before an adequate anticoagulation lcvcl is obtained with sodium warfarin. Recently, a low molecular weight heparin (LMWH) became clinically available; it has good antithrombotic properties along with a reduced risk of hemorrhagic complications and is more conveniently and practically administered than unfractionated heparin. Reports have detailed its successful use in the prevention of thrombosis following general or orthopedic surgery.‘,’ Others have demonstrated its safe and effective use in hemodialysis and hemofiltration patients.” Encouraged by these results, the authors extended its use for prophylaxis against atria1 thrombosis in the immediate postoperative period following valve replacement. This is the first report of the use of LMWH in this clinical setting. Unfortunately, an acute massive left atrial thrombosis occurred in the early postoperative period after MVR with a bioprosthesis in the patient.

Objectif Une limite importante en chirurgie cardiaque pediatrique est le manque de materiaux de remplacement de la voie de sortie ventriculaire droite (RVOT), doues de croissance et evitant les reoperations. Objectif : restaurer une RVOT fonctionnelle autologue a l’aide d’un patch en polydioxanone (PDO) biodegradable valve, ensemence de cellules souches mesenchymateuses (CSMs) autologues, dans un modele ovin en croissance. Methodes Des patchs en PDO biodegradables valves ensemences de CSMs autologues marquees par quantum dots ont ete implantes en position transannulaire sur la RVOT de 6 agneaux (suivi : 8 mois). Des patchs non ensemences ( n = 2) ou en pericarde autologue ( n = 2) constituaient les groupes controle. Resultats Echocardiographie et IRM demontrent l’absence de stenose et d’anevrysme de la neo-RVOT et son potentiel de croissance. Histologie et immunohistochimie objectivent moins de fibrose et de calcifications (0,08 % ± 0,03 % Ca2+), une degradation complete du polymere, l’apparition d’un neo-tissu organise et endothelialise avec matrice extracellulaire de type natif. Conclusion Un patch en PDO valve transannulaire ensemence de CSMs autologues restaure une RVOT vivante et fonctionnelle, et pourrait ameliorer le pronostic des cardiopathies droites congenitales.

Background—Autologous skeletal myoblast (SM) transplantation improves function of infarcted myocardium, but pretransplantation cultures remain a complex process. This study assessed whether it could be optimized by muscle preconditioning with the local anesthetic bupivacaine or even bypassed with the use of the so-called mince technique.Methods and Results—Muscle preconditioning consisted of intramuscular injections of the tibialis anterior of rats, 2 days before harvest. After 7 days of culture, the number of available myoblasts was significantly increased compared with nonconditioned controls (1 683 147 versus 85 300,P=0.0013). The mince technique was then assessed. A myocardial infarction was created in 66 rats by coronary artery ligation. One week later, rats were reoperated on and intramyocardially injected with culture medium alone (controls, n=23), autologous cultured SM (3.5×106, n=21), or autologous muscle minced into a fine slurry, which was immediately transplanted (n=22). All muscles had been preconditioned. Left ventricular function was assessed by 2D echocardiography. Whereas end-diastolic volumes expanded over time in all groups, left ventricular ejection fraction (%, mean±SEM) was increased only in the cultured SM–transplanted group at 1 (P=0.0006) and 2 months (P=0.0008) versus baseline (37.52±1.92 and 40.92±2.17 versus 30.34±1.74), with a significant additional benefit between 1 and 2 months (P=0.0069).Conclusions—Cell culture remains mandatory for SM transplantation to be successful but, in a clinical perspective, this process can be made more expeditious by preharvest muscle conditioning with bupivacaine, which greatly enhances the baseline cell yield.

Background This study was designed to assess the protective effects of the mitochondrial adenosine triphosphate-sensitive potassium channel (K ATP ) opener diazoxide as an additive to heart preservation solution. Methods. Forty isolated isovolumic buffer-perfused rat hearts were divided into four groups. Groups I and III hearts were arrested with and cold-stored in Celsior solution for 4 hr and 10 hr, respectively. In Groups II and IV, hearts underwent a protocol similar to that used in Group I and III, respectively, except that Celsior was supplemented with 100 μmol/L of diazoxide. Results. The protective effects of diazoxide were primarily manifest as a better preservation of diastolic function and a reduction of myocardial edema. The improvement of postischemic systolic function was observed only after prolonged exposure to diazoxide in Group IV, compared with Group III. The endothelium-dependent and endothelium-independent coronary flow postischemic responses were not affected by the supplementation of Celsior with diazoxide. Conclusions. Pharmacologic activation of mitochondrial K ATP channels seems to be an effective means of improving preservation of cold-stored hearts, which is consistent with the presumed role of these channels as end effectors of the cardioprotective preconditioning pathway.

Background —Recent studies have implicated mitochondrial ATP-sensitive potassium (K ATP ) channels in the cardioprotective effects of ischemic preconditioning. The present study used a model of prolonged cold heart storage to assess whether the mitochondrial K ATP opener diazoxide could reproduce the protection conferred by ischemic preconditioning. Methods and Results —Fifty-four isolated rat hearts were arrested with and stored in Celsior at 4°C for 10 hours before a 2-hour reperfusion. They were divided into 5 groups. Group 1 hearts served as controls. In group 2, hearts were preconditioned by two 5-minute episodes of global ischemia, each separated by 5 minutes of reperfusion before arrest. In group 3, hearts received a 15-minute infusion of the mitochondrial K ATP opener diazoxide (30 μmol/L) followed by 5 minutes of washout before arrest. In groups 4 and 5, hearts underwent a protocol similar to that used in groups 2 and 3, respectively, except that the preconditioning was preceded by a 10-minute infusion of the mitochondrial K ATP blocker 5-hydroxydecanoate (5-HD, 100 μmol/L). Both ischemic and diazoxide preconditioning provided a similar degree of cardioprotection demonstrated by a significantly better preservation of left ventricular compliance, reduced leakage of creatine kinase, and smaller degree of myocardial edema compared with control hearts. These beneficial effects were abolished by 5-HD pretreatment. Postischemic left ventricular contractility and endothelium-dependent coronary response to 5-hydroxytryptamine and acetylcholine were not different among groups. However, the endothelium-independent vasodilatory postischemic response to papaverine was better preserved after ischemic and diazoxide preconditioning than in the other groups. Conclusions —These data support the concept that the cardioprotective effects of ischemic preconditioning can be duplicated by a mitochondrial K ATP opener and suggest that activation of these channels could be an effective means of improving the preservation of globally ischemic cold-stored hearts, as occurs during cardiac transplantation.

Background —Experimentally, isoflurane, a commonly used volatile anesthetic agent, mimics the cardioprotective effects of ischemic preconditioning via a mechanism that could involve the activation of protein kinase C. The present study was designed to assess the clinical relevance of this observation in patients undergoing elective CABG. Methods and Results —Twenty patients were included in the study. In 10 of them, preconditioning was elicited after the onset of cardiopulmonary bypass via a 5-minute exposure to isoflurane (2.5 minimum alveolar concentration), followed by a 10-minute washout before aortic cross-clamping and cardioplegic arrest. Ten case-matched control patients underwent an equivalent period (15 minutes) of prearrest isoflurane-free bypass. Outcome measurements included troponin I and creatine kinase–MB isoenzyme (until the third postoperative day) levels and the activity of ecto-5′-nucleotidase, which contributes to adenosine production and is considered to be a reporter of protein kinase C activation, as assessed in right atrial biopsy samples taken before bypass and at the end of the preconditioning protocol (or after 15 minutes of bypass in control patients). Aortic cross-clamping times did not differ between the 2 groups: 52±14 and 48±14 minutes (mean±SD) in control and isoflurane-preconditioned patients, respectively. Likewise, prebypass values of ecto-5′-nucleotidase were similar in control (3.54±0.86 nmol · mg protein −1 · min −1 ) and isoflurane-treated (2.98±1.08 nmol · mg protein −1 · min −1 ) patients. The values subsequently remained unchanged in control patients (3.62±0.94 nmol · mg protein −1 · min −1 ), whereas they significantly increased after isoflurane preconditioning (4.74±0.50 nmol · mg protein −1 · min −1 ; P P −1 · min −1 and 3.98±2.83 ng/mL, respectively, versus 284±136 ng · mL −1 · min −1 and 5.88±3.64 ng/mL, respectively, in control patients. The release of creatine kinase–MB featured a similar pattern. There were no adverse effects related to isoflurane. Conclusions —These data support a cardioprotective effect of isoflurane and, more generally, demonstrate the feasibility of pharmacologically preconditioning the human heart during cardiac surgery.

Background —The tolerance of hibernating mammals to cold hypoxia is related to a factor similar to agonists of δ-opioid receptors. This study was designed to assess whether activation of these receptors could reproduce the protection conferred by ischemic preconditioning and whether such cardioprotection was similarly mediated by an opening of ATP-sensitive potassium (K ATP ) channels. Methods and Results —Thirty-two isolated rat hearts were arrested with and stored in Celsior at 4°C for 5 hours before being reperfused for 2 hours. They were divided into 4 equal groups. Group 1 hearts served as controls. In group 2, ischemic preconditioning was elicited by two 5-minute global ischemia periods interspersed with 5 minutes of reperfusion before arrest. In group 3, hearts were pharmacologically preconditioned with a 15-minute infusion of the δ-opioid receptor agonist d -Ala2- d -Leu5-enkephalin (DADLE; 200 μmol/L). In group 4, the protocol was similar to group 3 except that infusion of DADLE was preceded by infusion of the K ATP blocker glibenclamide (50 μmol/L). The salutary effects of both forms of preconditioning were primarily manifest as a better preservation of diastolic function, a reduced myocardial edema, and reduced creatine kinase leakage. This protection was abolished by administration of glibenclamide before DADLE. Conclusions —These data suggest that activation of δ-opioid receptors improves recovery of cold-stored hearts to a similar extent as ischemic preconditioning, most likely through an opening of K ATP channels. This provides a rationale for improving the preservation of hearts for transplantation by pharmacologically duplicating the common pathway to natural hibernation and preconditioning.

Background A key role of endothelial dysfunction in the pathogenesis of early low coronary flow of heart transplants and late cardiac allograft vasculopathy indicates the importance of optimal coronary endothelial preservation during cold heart storage. We designed this study to investigate the effect of prolonged cold storage on endothelial and smooth muscle function of proximal (epicardial) and distal (intramyocardial) coronary arteries. Methods Four groups of isolated rat hearts were subjected to cold cardioplegic perfusion and immersed in storage medium at 4°C. In groups 1, 2, and 3, hearts were perfused with and stored in Celsior solution for 10, 15, and 30 hours, respectively. In group 4, hearts were perfused with Plegisol and stored in saline for 15 hours. At the end of cold heart storage, arterial segments were taken from the proximal and distal parts of the left coronary artery and mounted on an isometric wire myograph for functional studies. In fifth group, proximal and distal segments of coronary artery isolated from fresh hearts were used as controls. At the end of control measurements, these vessels were used for storage in vitro at 4°C for 15 hours in saline (group 5A) or Celsior (group 5B). Results The endothelium-dependent relaxation to acetylcholine was reduced in distal coronary arteries in group 1, and in both proximal and distal coronary artery segments in groups 2, 3, 4, and 5A. Endothelial function was significantly more impaired in both proximal and distal coronary arteries in group 4, as compared with group 2. The impairment of relaxation to acetylcholine was more pronounced following cold storage of the heart than after a similarly long storage of the isolated vessels. The endothelium-independent relaxations to isoprenaline did not differ among all groups. The basal myogenic tone was increased in distal coronary arteries in group 1, and in both proximal and distal coronary arteries in groups 2, 3, 4, and 5A. The sensitivity to the vasoconstricting action of 5-hydroxytryptamine was increased in distal coronary arteries in group 2, and in both proximal and distal coronary arteries in groups 3, 4, and 5A. Conclusions: Prolonged ischemic cold heart storage induces coronary endothelial dysfunction that is more pronounced in distal than in proximal arteries and is related to the duration of heart storage and the composition of storage medium.

Celsior is a new preservation solution for heart transplants that recently has been shown also to improve protection of pulmonary grafts. As these data were obtained in isolated lung preparations, we sought to perform further tests with an in vivo model of allogeneic lung transplantation.The left lungs of 41 rats were either transplanted immediately after harvest (controls) or flushed with and cold stored in Celsior or the blood-based Wallwork solution for 5 or 12 hours. Lungs were then reperfused for 30 minutes, after which ligation of the contralateral pulmonary artery and bronchus made the recipient rat exclusively dependent on the transplanted lung. Assessment of preservation was made on functional (blood gases, pulmonary hemodynamics) and structural (dry-to-weight ratio, light microscopy, myeloperoxidase [MPO] content) end points.The protective effects of Celsior were primarily manifest, once the contralateral lung had been functionally excluded, as a better preservation of oxygen tensions in the 5-hour storage experiments (416 +/- 52 mm Hg vs 406 +/- 59 mm Hg in controls [p = NS] and vs 239 +/- 34 mm Hg in Wallwork [p0.05 vs the 2 other groups]) and a smaller increase in pulmonary vascular resistance in the 12-hour storage experiments (10.2 +/- 4.1 mm Hg/mL/minute vs 3.2 +/- 1.1 mm Hg/mL/minute in controls [p = NS] and vs 23.1 +/- 4.3 mm Hg/mL/minute in Wallwork [p0.02 vs Celsior, p0.002 vs controls]). Survival was also longer in the 12-hour preserved Celsior group. Other end points were not significantly different between the two preservative solutions.These data support the efficacy of Celsior as a flush-out and storage solution for pulmonary grafts. Given its previously documented ability to adequately preserve heart transplants, Celsior might provide a unified "solution" to thoracic organ preservation.

Background . The safe development of minimally invasive coronary artery bypass operations might require alternatives to conventional suture-based anastomotic techniques. In this setting, nonpenetrating stapling is an attractive option because of its simplicity of use and potential for improved endothelial preservation. Methods and Results . In the experimental part of this study, porcine internal mammary arteries were anastomosed to left anterior descending coronary arteries using either an 8-0 polypropylene running suture or nonpenetrating microclips (7 anastomoses in each group). The endothelium-dependent relaxations to bradykinin of the arterial rings bearing the anastomosis and of noninstrumented rings were compared in organ chamber experiments. There were no significant differences in maximal relaxations (mean ± SEM) between the microclipped and sutured anastomoses (81% ± 7% versus 74% ± 10%), which were both significantly lower than those of control coronary rings (98% ± 2%, p = 0.001 versus the two anastomosed groups). Histologic examination showed a comparable preservation of the coronary and graft endothelium with both techniques. The clinical part of the study comprised 7 patients in whom the left internal mammary artery was conventionally sutured to the left anterior descending whereas 13 saphenous vein grafts were anastomosed to their target vessels by nonpenetrating staples. There were no clip-related complications. An angiographic assessment of the venous grafts was performed within 10 days postoperatively in all patients. One graft is presumably occluded. The 12 remaining conduits were patent with stapled anastomoses featuring a widely open "shark-mouth" configuration. Conclusions . These preliminary data suggest that nonpenetrating stapling is an easy-to-use technique that competes well with conventional suturing, at least in terms of immediate results. Further studies are warranted to better define its potential place within the armamentarium of minimally invasive coronary artery bypass techniques.

The plasticity of adult bone marrow cells remains a controversial topic. The initial enthusiastic claims that these cells could “regenerate” the infarcted myocardium by converting into new cardiomyocytes1 have subsequently been dampened by reports that such an outcome was unlikely.2,3,4 Indeed, the purported transdifferentiation of bone marrow cells has most often been based on immunohistochemical data, which are known to be potentially misleading because of the autofluorescence of infarcted tissue. More reliable cell-tracking methods, based on genetic tags, have led to the opposite conclusion—that bone marrow cells are in fact lineage-restricted.2,3,4 Scherschel et al.,5 using two-photon laser scanning microscopy (TPLSM), provide compelling evidence in this issue of Molecular Therapy that bone marrow cells actually lack a fundamentally important attribute of cardiomyocytes: the ability to develop cytosolic calcium transients in response to membrane depolarization.

It is now widely accepted that the putative benefits of cell transplantation are hampered by the high rate of cell death that occurs shortly after the procedure. While this event may not be so relevant to bone-marrow-derived cellular grafts whose efficacy seems to depend on cell functionality rather than on the absolute numbers of delivered cells,1 such is not the case for skeletal myoblasts for which a dose-effect relationship has been demonstrated.2 It thus appears to be sound to speculate that outcomes of myoblast transplantation could be improved if cell survival was enhanced. Although post-delivery cell death is a complex phenomenon which involves several intricate factors, three of them have been clearly identified: inflammation due to needle-induced tissue disruption, apoptosis due to detachment of anchorage-dependent cells from their extracellular matrix, and ischaemia due to both the delivery of cells deprived from their own vascular supply and the poor vascularization of the target areas of injection. Several studies have already provided evidence for the role of these three factors by showing that tackling any one of them usually improves cell engraftment and left ventricular function. In the present issue of Cardiovascular Research , Aharinejad et al. 3 present data that further support the importance of specifically addressing the ischaemic component of post-injection myoblast cell death. Using the classical rat model of myocardial infarction, … *Corresponding author. Tel: +33 1 56 09 29 62; fax: +33 1 56 09 22 19. E-mail address: philippe.menasche{at}hop.egp.ap-hop-paris.fr

Current cardioplegic techniques do not consistently avoid myocardial ischemic damage in high-risk patients undergoing coronary artery bypass grafting. Alternatively, revascularization without cardiopulmonary bypass is not always technically feasible. We investigated whether an intermediary approach based on maintenance of a beating heart with cardiopulmonary bypass support but without aortic cross-clamping might be an acceptable trade-off.Thirty-seven consecutive patients underwent coronary artery bypass grafting (with an average of two grafts per patient) in a pump-supported, non-cross-clamped beating heart. Inclusion criteria were poor left ventricular function (18 patients; mean ejection fraction, 0.25), evolving myocardial ischemia or infarction (11 patients, 5 of whom were in cardiogenic shock), and advanced age (3 patients; mean age 79.5 years) with comorbidities. Results were assessed primarily on the basis of clinical outcome. In addition, measurements of plasma levels of markers of myocardial damage (troponin Ic) and systemic inflammation (interleukin-6, interleukin-10, elastase) were done in 9 patients before and after bypass. In 6 patients, right atrial biopsy specimens were taken before and after bypass and processed by Northern blotting for the expression of messenger ribonucleic acid coding for the cardioprotective heat-shock protein 70. These biologic data were compared with those from control patients who underwent warm cardioplegic arrest within the same time span.There was one cardiac-related death (2.7%), one Q-wave myocardial infarction, and no strokes. Four other deaths occurred from noncardiac causes, yielding an overall mortality rate of 13.5%. Limitation of myocardial injury was demonstrated by the minimal increase in postoperative troponin Ic levels (3.3 +/- 1.0 micrograms/L versus 6.6 +/- 1.5 micrograms/L in controls; p0.05) and the finding that heat-shock protein 70 messenger ribonucleic acid levels (expressed as a percentage of an internal standard) were significantly increased after bypass compared with pre-bypass values (279% +/- 80% versus 97% +/- 21%; p0.05). In the control group (cardioplegia), end-arrest values of heat-shock protein 70 messenger ribonucleic acid were not significantly changed from baseline (148% +/- 49% versus 91% +/- 29%), a finding suggesting a defective adaptive response to surgical stress. Conversely, peak levels of inflammatory mediators were not significantly different between the two groups. The eight grafts to the left anterior descending coronary artery that were assessed angiographically, by transthoracic Doppler echocardiography, or both methods were patent with satisfactory anastomoses.In select high-risk patients, on-pump, beating-heart coronary artery bypass grafting may be an acceptable trade-off between conventional cardioplegia and off-pump operations. It is still associated with the potentially detrimental effects of cardiopulmonary bypass but eliminates intraoperative global myocardial ischemia.

BACKGROUND Endothelial dysfunction can play a key role in early no reflow and late accelerated cardiac graft arteriosclerosis. We studied the direct effect of reduced glutathione (GSH) on the preservation of endothelial function of coronary arteries subjected to prolonged cold storage. METHODS Ring preparations were dissected from rat left coronary arteries and mounted on an isometric wire myograph. After control measurements, artery segments were exposed to 15 hr of hypothermic (+4 degrees C) incubation in either normal saline (group 1), GSH-free Celsior solution (a new heart preservation solution) (group 2), or Celsior solution with 3 mmol/L of GSH (group 3). RESULTS After storage, the basal tone was increased in groups 1 and 2, but it did not change in group 3. The endothelium-dependent relaxation to acetylcholine was reduced in groups 1 and 2, but it was not affected in group 3. The sensitivity to acetylcholine was decreased in group 1, and there were no changes in groups 2 and 3. CONCLUSIONS Our data suggest that fresh GSH in Celsior solution improves preservation of coronary endothelial function.