Left ventricular systolic and diastolic function improve after acute myocardial infarction treated with acute percutaneous coronary intervention, but are not influenced by intracoronary injection of autologous mononuclear bone marrow cells: a 3 year serial echocardiographic sub-study of the randomized-controlled ASTAMI study

Mid- to long-term efficacy and safety of stem cell therapy for acute myocardial infarction: a systematic review and meta-analysis

BACKGROUND

This comprehensive systematic review and meta-analysis investigated the mid- to long-term efficacy and safety of stem cell therapy in patients with acute myocardial infarction (AMI).

METHODS

The study encompassed 79 randomized controlled trials with 7103 patients, rendering it the most up-to-date and extensive analysis in this field. This study specifically focused on the impact of stem cell therapy on left ventricular ejection fraction (LVEF), major adverse cardiac events (MACE), and infarct size.

RESULTS

Stem cell therapy significantly improved LVEF at 6, 12, 24, and 36 months post-transplantation compared to control values, indicating its potential for long-term cardiac function enhancement. A trend toward reduced MACE occurrence was observed in the intervention groups, suggesting the potential of stem cell therapy to lower the risk of cardiovascular death, reinfarction, and stroke. Significant LVEF improvements were associated with long cell culture durations exceeding 1 week, particularly when combined with high injected cell quantities (at least 108 cells). No significant reduction in infarct size was observed.

CONCLUSIONS

This review highlights the potential of stem cell therapy as a promising therapeutic approach for patients with AMI, offering sustained LVEF improvement and a potential reduction in MACE risk. However, further research is required to optimize cell culture techniques, determine the optimal timing and dosage, and investigate procedural variations to maximize the efficacy and safety of stem cell therapy in this context.

Peak early diastolic strain rate improves prediction of adverse cardiovascular outcomes in patients with ST-elevation myocardial infarction

BACKGROUND

The prognostic role of diastolic dysfunction measured by the circumferential peak early diastolic strain rate (PEDSR) on ST-elevation myocardial infarction (STEMI) is not completely established.

OBJECTIVES

We aimed to investigate the prognostic value of diastolic function by measuring PEDSR within 1 week after STEMI.

METHODS

The cardiac magnetic resonance (CMR) pictures of 420 subjects from a clinical registry study (NCT03768453) were analyzed and the composite major adverse cardiac events (MACEs) were followed up.

RESULTS

The PEDSR of patients was significantly lower compared with that of control subjects (P < 0.001). Within the median follow-up period of 52 months, PEDSR of patients who experienced MACEs deceased more significantly than that of patients without MACEs (P < 0.001). After adjusting with clinical or CMR indexes, per 0.1/s reduction of PEDSR increased the risks of MACEs to 1.402 or 1.376 fold and the risk of left ventricular (LV) remodeling to 1.503 or 1.369 fold. When PEDSR divided by best cutoff point, significantly higher risk of MACEs (P < 0.001) and more remarkable LV remodeling (P < 0.001) occurred in patients with PEDSR ≤ 0.485/s. Moreover, when adding the PEDSR to the conventional prognostic factors such as LV ejection fraction and infarction size, better prognostic risk classification models were created. Finally, aging, tobacco use, remarkable LV remodeling, and a low LV ejection fraction were factors related with the reduction of PEDSR.

CONCLUSIONS

Diastolic dysfunction has an important prognostic effect on patients with STEMI. Measurement of the PEDSR in the acute phase could serve as an effective index to predict the long-term risk of MACEs and cardiac remodeling.

Unlocking the Pragmatic Potential of Regenerative Therapies in Heart Failure with Next-Generation Treatments

Patients with chronic heart failure (HF) have a poor prognosis due to irreversible impairment of left ventricular function, with 5-year survival rates <60%. Despite advances in conventional medicines for HF, prognosis remains poor, and there is a need to improve treatment further. Cell-based therapies to restore the myocardium offer a pragmatic approach that provides hope for the treatment of HF. Although first-generation cell-based therapies using multipotent cells (bone marrow-derived mononuclear cells, mesenchymal stem cells, adipose-derived regenerative cells, and c-kit-positive cardiac cells) demonstrated safety in preclinical models of HF, poor engraftment rates, and a limited ability to form mature cardiomyocytes (CMs) and to couple electrically with existing CMs, meant that improvements in cardiac function in double-blind clinical trials were limited and largely attributable to paracrine effects. The next generation of stem cell therapies uses CMs derived from human embryonic stem cells or, increasingly, from human-induced pluripotent stem cells (hiPSCs). These cell therapies have shown the ability to engraft more successfully and improve electromechanical function of the heart in preclinical studies, including in non-human primates. Advances in cell culture and delivery techniques promise to further improve the engraftment and integration of hiPSC-derived CMs (hiPSC-CMs), while the use of metabolic selection to eliminate undifferentiated cells will help minimize the risk of teratomas. Clinical trials of allogeneic hiPSC-CMs in HF are now ongoing, providing hope for vast numbers of patients with few other options available.

Anterior STEMI associated with decreased strain in remote cardiac myocardium

To assess (1) global longitudinal strain (GLS) by feature tracking cardiac magnetic resonance (CMR) in the sub-acute and chronic phases after ST-elevation infarction (STEMI) and compare to GLS in healthy controls, and (2) the evolution of GLS and regional longitudinal strain (RLS) over time, and their relationship to infarct location and size. Seventy-seven patients from the CHILL-MI-trial (NCT01379261) who underwent CMR 2–6 days and 6 months after STEMI and 27 healthy controls were included for comparison. Steady state free precession (SSFP) long-axis cine images were obtained for GLS and RLS, and late gadolinium enhancement (LGE) images were obtained for infarct size quantifications. GLS was impaired in the sub-acute (− 11.8 ± 3.0%) and chronic phases (− 14.3 ± 2.9%) compared to normal GLS in controls (− 18.4 ± 2.4%; p < 0.001 for both). GLS improved from sub-acute to chronic phase (p < 0.001). GLS was to some extent determined by infarct size (sub-acute: r² = 0.2; chronic: r² = 0.2, p < 0.001). RLS was impaired in all 6 wall-regions in LAD infarctions in both the sub-acute and chronic phase, while LCx and RCA infarctions had preserved RLS in remote myocardium at both time points. Global longitudinal strain is impaired sub-acutely after STEMI and improvement is seen in the chronic phase, although not reaching normal levels. Global longitudinal strain is only moderately determined by infarct size. Regional longitudinal strain is most impaired in the infarcted region, and LAD infarctions have effects on the whole heart. This could explain why LAD infarcts are more serious than the other culprit vessel infarctions and more often cause heart failure.

Effects of deferred versus immediate stenting on left ventricular function in patients with ST elevation myocardial infarction

BACKGROUND

Previous studies have shown conflicting results on the benefits of deferred stenting (DS) in infarct size and the incidence of microvascular obstruction in patients with ST elevation myocardial infarction (STEMI). However, effect of DS on left ventricular (LV) function was not known. We aimed to evaluate whether DS improve LV function and relevant clinical outcomes after STEMI, using follow-up data from the INNOVATION study (NCT02324348).

METHODS

In total, 114 patients were randomly assigned to DS group or immediate stenting (IS) group at a 1:1 ratio. LV functional remodeling indices and MACE (major adverse cardiac events: a composite of death, non-fatal MI, unplanned target vessel revascularization, or hospitalization due to heart failure) were compared between DS and IS groups.

RESULTS

Serial echocardiographic analyses were completed in 89 subjects (78%). There were no significant changes in LV volume in either group. While LV ejection fraction and wall motion score index (WMSI) improved in both groups during follow-up, the increments were not statistically different between the 2 groups (4.3 ± 8.2 vs 3.2 ± 7.1, P = .504 for ΔLV ejection fraction; -0.16 ± 0.25 vs -0.16 ± 0.25, P = .99 for ΔWMSI). However, E/e'' was decreased and e' was increased only in the DS group (-3.31 ± 5.60 vs -0.46 ± 3.10, P = .005 for ΔE/e'; 0.77 ± 1.71 vs -0.22 ± 1.64, P = .009 for Δe'). The incidence of major adverse cardiac events was numerically lower in the DS group than in the IS group without a statistical significance at 1-year follow-up.

CONCLUSIONS

Routine DS improved LV diastolic function but not systolic function compared with IS in patients with STEMI.

Left Ventricular Twist and Untwist in Patients Undergoing Elective Percutaneous Coronary Intervention

BACKGROUND

Left ventricular (LV) twist and untwist plays important roles in physiological adaptation and development of clinically relevant cardiac diseases.

AIMS

To assess LV twist and untwist in patients undergoing elective percutaneous coronary intervention (PCI) by two-dimensional (2D) speckle tracking echocardiography (STE).

SUBJECTS AND METHODS

Fifty patients who had stable angina pectoris and/or abnormal result from noninvasive stress tests were enrolled after undergoing elective PCI. Conventional and 2D STE were performed before elective PCI and after 3 months.

RESULTS

There was no significant systolic improvement in conventional echocardiography. However, there was a significant diastolic improvement after elective PCI as higher E, E/A, e` and lower E/e` (P < 0.034, <0.042, 0.015, and 0.033, respectively). In addition, there was a statistically significant improvement of STE-derived systolic parameters as regard higher global longitudinal strain, peak twist, and torsion (P value 0.009, 0.009, and < 0.001, respectively). Furthermore, there was significant improvement of STE-derived diastolic parameters as higher peak untwist, recoil, and lower time to peak untwist (P value 0.013, 0.001, and 0.004, respectively).

CONCLUSIONS

LV and untwist parameters were improved before most of conventional echocardiographic parameters in postrevascularization of stable coronary artery disease.

Effect of cardiosphere-derived cells on segmental myocardial function after myocardial infarction: ALLSTAR randomised clinical trial

BACKGROUND

Most cell therapy trials failed to show an improvement in global left ventricular (LV) function measures after myocardial infarction (MI). Myocardial segments are heterogeneously impacted by MI. Global LV function indices are not able to detect the small treatment effects on segmental myocardial function which may have prognostic implications for cardiac events. We aimed to test the efficacy of allogeneic cardiosphere-derived cells (CDCs) for improving regional myocardial function and contractility.

METHODS

In this exploratory analysis of a randomised clinical trial, 142 patients with post-MI with LVEF <45% and 15% or greater LV scar size were randomised in 2:1 ratio to receive intracoronary infusion of allogenic CDCs or placebo, respectively. Change in segmental myocardial circumferential strain (Ecc) by MRI from baseline to 6 months was compared between CDCs and placebo groups.

RESULTS

In total, 124 patients completed the 6-month follow-up (mean (SD) age 54.3 (10.8) and 108 (87.1%) men). Segmental Ecc improvement was significantly greater in patients receiving CDC (-0.5% (4.0)) compared with placebo (0.2% (3.7), p=0.05). The greatest benefit for improvement in segmental Ecc was observed in segments containing scar tissue (change in segmental Ecc of -0.7% (3.5) in patients receiving CDC vs 0.04% (3.7) in the placebo group, p=0.04).

CONCLUSIONS

In patients with post-MI LV dysfunction, CDC administration resulted in improved segmental myocardial function. Our findings highlight the importance of segmental myocardial function indices as an endpoint in future clinical trials of patients with post-MI.

TRIAL REGISTRATION NUMBER

NCT01458405.

Stem Cell Therapy for Acute Myocardial Infarctions: A Systematic Review

Each year 790,000 people in the United States suffer from a myocardial infarction. This results in the permanent loss of cardiomyocytes and an irreversible loss of cardiac function. Current therapies lower mortality rates, but do not address the core pathology, which opens a pathway to step-wise heart failure. Utilizing stem cells to regenerate the dead tissue is a potential method to reverse these devastating effects. Several clinical trials have already demonstrated the safety of stem cell therapy. In this review, we highlight clinical trials, which have utilized various stem cell lineages, and discuss areas for future research.

Meta-analysis of short- and long-term efficacy of mononuclear cell transplantation in patients with myocardial infarction

BACKGROUND

Mononuclear cells (MNCs) have been tested in clinical trials across multiple cardiovascular pathologies with mixed results. Major adverse cardiac events (MACE) and markers of cardiovascular capacity have been particularly challenging to interpret because of small size. This meta-analysis is aimed to assess the efficacy of MNC therapy in randomized clinical trials to identify the markers of efficiency that could influence future trial design.

METHODS

PubMed, Embase, Cochrane library, and ClinicalTrials.gov were searched from inception through November 8, 2018. Changes in left ventricular ejection fraction (LVEF) and infarct size from baseline to follow-up were selected as primary outcomes. Changes in the left ventricular end-systolic volume, left ventricular end-diastolic volume, brain natriuretic peptide/N-terminal pro-B-type natriuretic peptide, 6-minute walk test, New York Heart Association class, and MACE incidences were considered secondary outcomes.

RESULTS

In short-term follow-up, patients treated with MNCs demonstrated a significant increase in absolute LVEF of 2.21% (95% CI 1.59-2.83; P < .001; I² = 32%) and 6.01% (95% CI 4.45-7.57; P < .001; I² = 0%) in acute myocardial infarction (AMI) and ischemic cardiomyopathy studies, respectively. This effect was sustained in long-term follow-up. MNC therapy significantly reduced left ventricular end-systolic volume; however, infarct size, 6-minute walk test, New York Heart Association class, and MACE rates were comparable.

CONCLUSIONS

MNC therapy may convey a modest but sustained increase in LVEF in ischemic cardiomyopathy patients, supporting further investigation. AMI trials, however, demonstrated minimal improvement in LVEF of unclear clinical significance, suggesting a limited role for MNC therapy in AMI.

Deformation imaging to assess global and regional effects of cardiac regenerative therapy in ischaemic heart disease: A systematic review

Currently, left ventricular ejection fraction (LVEF) is the most common endpoint in cardiovascular stem cell therapy research. However, this global measure of cardiac function might not be suitable to detect the regional effects sorted by this therapy and is hampered by high operator variability and loading dependency. Deformation imaging might be more accurate in detecting potential regional functional improvements by cardiac regenerative therapy. The aim of this systematic review is to provide a comprehensive overview of current literature on the value of deformation imaging in cardiac regenerative therapy. A systematic review of current literature available on PubMed, Embase, and Cochrane databases was performed regarding both animal and patient studies in which deformation imaging was used to study cardiac cell therapy. After critical appraisal, outcomes regarding study design, type of cell therapy, procedural characteristics, outcome measure, method for measuring strain, and efficacy on both LVEF and deformation parameters were depicted. A total of 30 studies, 15 preclinical and 15 clinical, were included for analysis. Deformation outcomes improved significantly in 14 out of 15 preclinical studies and in 10 out of 15 clinical studies, whereas LVEF improved in 12 and 4 articles, respectively. Study designs and used deformation outcomes varied significantly among the included papers. Six studies found a positive effect on deformation outcomes without LVEF improvement. Hence, deformation imaging seems at least equal, and perhaps superior, to LVEF measurement in the assessment of cardiac regenerative therapy. However, strategies varied substantially and call for a standardized approach.

Effects of bone marrow mononuclear cells delivered through a graft vessel in patients with previous myocardial infarction and chronic heart failure: An echocardiographic study of left ventricular dyssynchrony

OBJECTIVES

Several trials are investigating the delivery of stem cells to treat ischemic cardiomyopathy. The aim of this study was the echocardiographic evaluation of the effectiveness of isolated coronary artery bypass graft (CABG) combined with bone marrow mononuclear cells (BMMNC) delivered through the graft vessels to improve left ventricular dyssynchrony in patients with previous myocardial infarction and chronic heart failure.

METHODS

42 patients with previous myocardial infarction and chronic heart failure were randomly allocated to either the CABG only group (n = 18) or the CABG with BMMNC graft group (n = 24group). We used 2D strain imaging to measure the absolute difference in time-to-peak radial strain between the earliest and the latest activated segments on LV short-axis images at the apical (RSTa), at the mitral annulus (RSTb), and at the papillary muscle (RSTm) level.

RESULTS

The effective rate of LV dyssynchrony improvement was significantly higher in the CABG + BMMNC than in the CABG only group (RSTb: 91.7% vs 50%, P < .05; RSTm: 78.6% vs 35.7%, P < .05; RSTa: 92.3% vs 50%, P < .05). The deterioration rate of LV synchrony was significantly lower in the CABG + BMMNC than in the CABG only group for RSTb (8.3% vs 70%, P < .05;) and RSTm (0 vs 50%, P < .05), but not for RSTa (18.2% vs 37.5%, P > .05).

CONCLUSIONS

Combining CABG with BMMNC delivering provided a better improvement of left ventricular dyssynchrony than CABG only.

Bone Marrow Mononuclear Cells Transfer for Patients after ST-Elevated Myocardial Infarction: A Meta-Analysis of Randomized Control Trials

PURPOSE

Results on the clinical utility of cell therapy for ST-elevated myocardial infarction (STEMI) are controversial. This study sought to analyze the efficacy of treatment with intracoronary bone marrow mononuclear cells (BMMC) on left ventricular (LV) function and remodeling and LV diastolic and systolic function in patients with STEMI.

MATERIALS AND METHODS

Literature search of PubMed and EMBASE databases between 2004 and 2017 was performed for randomized controlled trials in STEMI patients who underwent successful percutaneous coronary intervention and received intracoronary BMMC therapy. The defined end points were left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV). Also, sensitivity analysis and several subgroup analyses based on follow-up duration, timing of injection, doses of cells, and imaging modalities were conducted to strengthen the statistic power of the study.

RESULTS

A total of 22 trials with 1360 patients were available for the current meta-analysis. The pooled statistics showed a significant improvement in LVEF {2.58 [95% confidence interval (CI), 1.32, 3.84]; p<0.001}, LVEDV [-3.73, (95% CI, -6.94, -0.52), p=0.02], and LVESV [?4.67, (95% CI, -7.07, -2.28), p<0.001] in the BMMC group, compared with the control group. However, in sensitivity analysis, a significant reduction in LVEDV disappeared, while the outcomes of LVEF and LVESV remained unchanged. The same results were presented in the subgroup analysis adjusting for imaging modalities and timing of cells injection.

CONCLUSION

BMMC transplantation in patients with STEMI was found to lead to improvement in LVEF, LVEDV, and LVESV parameters, indicating that cell therapy has a potential beneficial effect on LV remodeling and function.

Impact of bone marrow mononuclear cells therapy on left ventricular function in patients with ST-elevated myocardial infarction: A meta-analysis

BACKGROUND

Bone marrow mononuclear cell (BMMNC) therapy has been used as an adjunctive treatment in patients with ST-elevated myocardial infarction (STEMI). However, the therapeutic efficacy of this approach remains controversial. The present meta-analysis is aimed to evaluate the impact of cell therapy on left ventricular function after STEMI.

METHODS

We searched through PubMed and EMBASE databases till 2017 for all relevant publications using certain search terms. Randomized controlled trials investigating the effect of BMMNC therapy in patients with STEMI who underwent percutaneous coronary intervention were selected. Wall motion score index (WMSI), infarct size, wall thickening, and myocardial perfusion were our endpoints.

RESULTS

A total of 24 trials with 1536 patients were included in our study. Overall, as observed in our data, cell therapy reduced infarct size by -2.32 (95% confidence interval [CI] -4.03, -0.62; P = .007; I = 24%) and improved myocardial perfusion by -3.04 (95% CI -3.94, -2.15; P < .001; I = 0%). However, there was no significant difference between treatment group and control group in WMSI or wall thickening.

CONCLUSION

Intracoronary BMMNC infusion is safe for patients with STEMI. It is also associated with improvement of infarct size and myocardial perfusion. Further multicenter randomized trials should be conducted to validate the therapeutic efficacy of this treatment.

Pursuing meaningful end-points for stem cell therapy assessment in ischemic cardiac disease

Despite optimal interventional and medical therapy, ischemic heart disease is still an important cause of morbidity and mortality worldwide. Although not included in standard of care rehabilitation, stem cell therapy (SCT) could be a solution for prompting cardiac regeneration. Multiple studies have been published from the beginning of SCT until now, but overall no unanimous conclusion could be drawn in part due to the lack of appropriate end-points. In order to appreciate the impact of SCT, multiple markers from different categories should be considered: Structural, biological, functional, physiological, but also major adverse cardiac events or quality of life. Imaging end-points are among the most used - especially left ventricle ejection fraction (LVEF) measured through different methods. Other imaging parameters are infarct size, myocardial viability and perfusion. The impact of SCT on all of the aforementioned end-points is controversial and debatable. 2D-echocardiography is widely exploited, but new approaches such as tissue Doppler, strain/strain rate or 3D-echocardiography are more accurate, especially since the latter one is comparable with the MRI gold standard estimation of LVEF. Apart from the objective parameters, there are also patient-centered evaluations to reveal the benefits of SCT, such as quality of life and performance status, the most valuable from the patient point of view. Emerging parameters investigating molecular pathways such as non-coding RNAs or inflammation cytokines have a high potential as prognostic factors. Due to the disadvantages of current techniques, new imaging methods with labelled cells tracked along their lifetime seem promising, but until now only pre-clinical trials have been conducted in humans. Overall, SCT is characterized by high heterogeneity not only in preparation, administration and type of cells, but also in quantification of therapy effects.

Effects of timing on intracoronary autologous bone marrow-derived cell transplantation in acute myocardial infarction: a meta-analysis of randomized controlled trials

Background

Several cell-based therapies for adjunctive treatment of acute myocardial infarction have been investigated in multiple clinical trials, but the timing of transplantation remains controversial. We conducted a meta-analysis of randomized controlled trials to investigate the effects of timing on bone marrow-derived cell (BMC) therapy in acute myocardial infarction (AMI).

Methods

A systematic literature search of PubMed, MEDLINE, and Cochrane Evidence-Based Medicine databases from January 2000 to June 2017 was performed on randomized controlled trials with at least a 3-month follow-up for patients with AMI undergoing emergency percutaneous coronary intervention (PCI) and receiving intracoronary BMC transfer thereafter. The defined end points were left ventricular (LV) ejection fraction, LV end-diastolic and end-systolic index. The data were analyzed to evaluate the effects of timing on BMC therapy.

Results

Thirty-four RCTs comprising a total of 2,307 patients were included; the results show that, compared to the control group, AMI patients who received BMC transplantation showed significantly improved cardiac function. BMC transplantation 3–7 days after PCI (+3.32%; 95% CI, 1.91 to 4.74; P < 0.00001) resulted in a significant increase of left ventricular ejection fraction (LVEF). As for the inhibitory effect on ventricular remodeling, BMC transplantation 3–7 days after PCI reduced LV end-diastolic indexes (–4.48; 95% CI, −7.98 to –0.98; P = 0.01) and LV end-systolic indexes (–6.73; 95% CI, –11.27 to –2.19; P = 0.004). However, in the groups who received BMC transplantation either within 24 hours or later than 7 days there was no significant effect on treatment outcome. In subgroup analysis, the group with LVEF ≤ 50% underwent a significant decrease in LV end-diastolic index after BMC transplantation (WMD = –3.29, 95% CI, –4.49 to –2.09; P < 0.00001); the decrease was even more remarkable in the LV end-systolic index after BMC transplantation in the group with LVEF ≤ 50% (WMD = –5.25, 95% CI, –9.30 to –1.20; P = 0.01), as well as in patients who received a dose of 10^7–10^8 cells (WMD = –12.99, 95% CI, –19.07 to –6.91; P < 0.0001). In the group with a follow-up of more than 12 months, this beneficial effect was significant and increased to a more pronounced effect of +3.58% (95% CI, 1.55 to 5.61; P = 0.0006) when compared with control.

Conclusions

In this meta-analysis, BMC transfer at 3 to 7 days post-AMI was superior to transfer within 24 hours or more than 7 days after AMI in improving LVEF and decreasing LV end-systolic dimensions or LV end-diastolic dimensions. It is more effective in patients with lower baseline LVEF (≤50%) and the effect can last more than 12 months.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0680-5) contains supplementary material, which is available to authorized users.

Molecular imaging in stem cell-based therapies of cardiac diseases

In the past 15years, despite that regenerative medicine has shown great potential for cardiovascular diseases, the outcome and safety of stem cell transplantation has shown controversial results in the published literature. Medical imaging might be useful for monitoring and quantifying transplanted cells within the heart and to serially characterize the effects of stem cell therapy of the myocardium. From the multiple available noninvasive imaging techniques, magnetic resonance imaging and nuclear imaging by positron (PET) or single photon emission computer tomography (SPECT) are the most used clinical approaches to follow the fate of transplanted stem cells in vivo. In this article, we provide a review on the role of different noninvasive imaging modalities and discuss their advantages and disadvantages. We focus on the different in-vivo labeling and reporter gene imaging strategies for stem cell tracking as well as the concept and reliability to use imaging parameters as noninvasive surrogate endpoints for the evaluation of the post-therapeutic outcome.

Endothelial and cardiac progenitor cells for cardiovascular repair: A controversial paradigm in cell therapy

Stem cells have the potential to differentiate into cardiovascular cell lineages and to stimulate tissue regeneration in a paracrine/autocrine manner; thus, they have been extensively studied as candidate cell sources for cardiovascular regeneration. Several preclinical and clinical studies addressing the therapeutic potential of endothelial progenitor cells (EPCs) and cardiac progenitor cells (CPCs) in cardiovascular diseases have been performed. For instance, autologous EPC transplantation and EPC mobilization through pharmacological agents contributed to vascular repair and neovascularization in different animal models of limb ischemia and myocardial infarction. Also, CPC administration and in situ stimulation of resident CPCs have been shown to improve myocardial survival and function in experimental models of ischemic heart disease. However, clinical studies using EPC- and CPC-based therapeutic approaches have produced mixed results. In this regard, intracoronary, intra-myocardial or intramuscular injection of either bone marrow-derived or peripheral blood progenitor cells has improved pathological features of tissue ischemia in humans, despite modest or no clinical benefit has been observed in most cases. Also, the intriguing scientific background surrounding the potential clinical applications of EPC capture stenting is still waiting for a confirmatory proof. Moreover, clinical findings on the efficacy of CPC-based cell therapy in heart diseases are still very preliminary and based on small-size studies. Despite promising evidence, widespread clinical application of both EPCs and CPCs remains delayed due to several unresolved issues. The present review provides a summary of the different applications of EPCs and CPCs for cardiovascular cell therapy and underlies their advantages and limitations.

Cell-Based Therapy for Myocardial Dysfunction After Fontan Operation in Hypoplastic Left Heart Syndrome

Myocardial dysfunction after Fontan palliation for univentricular congenital heart disease is a challenging clinical problem. The medical treatment has a limited impact, with cardiac transplant being the ultimate management step. Cell-based therapies are evolving as a new treatment for heart failure. Phase 1 clinical trials using regenerative therapeutic strategies in congenital heart disease are ongoing. We report the first case of autologous bone marrow-derived mononuclear cell administration for ventricular dysfunction, 23 years after Fontan operation in a patient with hypoplastic left heart syndrome. The cells were delivered into the coronary circulation by cardiac catheterization. Ventricular size decreased and several parameters reflecting ventricular function improved, with maximum change noted 3 months after cell delivery. Such regenerative therapeutic options may help in delaying and preventing cardiac transplant.

Cell therapy for heart disease after 15 years: Unmet expectations

Over the past two decades cardiac cell therapy (CCT) has emerged as a promising new strategy to cure heart diseases at high unmet need. Thousands of patients have entered clinical trials for acute or chronic heart conditions testing different cell types, including autologous or allogeneic bone marrow (BM)-derived mononuclear or selected cells, BM- or adipose tissue-derived mesenchymal cells, or cardiac resident progenitors based on their potential ability to regenerate scarred or dysfunctional myocardium. Nowadays, the original enthusiasm surrounding the regenerative medicine field has been cushioned by a cumulative body of evidence indicating an inefficient or modest efficacy of CCT in improving cardiac function, along with the continued lack of indisputable proof for long-term prognostic benefit. In this review, we have firstly comprehensively outlined the positive and negative results of cell therapy studies in patients with acute myocardial infarction, refractory angina and chronic heart failure. Next, we have discussed cell therapy- and patient-related variables (e.g. cell intrinsic and extrinsic characteristics as well as criteria of patient selection and proposed methodologies) that might have dampened the efficacy of past cell therapy trials. Finally, we have addressed critical factors to be considered before embarking on further clinical trials.

Cell Therapies in Cardiomyopathy: Current Status of Clinical Trials

Because the human heart has limited potential for regeneration, the loss of cardiomyocytes during cardiac myopathy and ischaemic injury can result in heart failure and death. Stem cell therapy has emerged as a promising strategy for the treatment of dead myocardium, directly or indirectly, and seems to offer functional benefits to patients. The ideal candidate donor cell for myocardial reconstitution is a stem-like cell that can be easily obtained, has a robust proliferation capacity and a low risk of tumour formation and immune rejection, differentiates into functionally normal cardiomyocytes, and is suitable for minimally invasive clinical transplantation. The ultimate goal of cardiac repair is to regenerate functionally viable myocardium after myocardial infarction (MI) to prevent or heal heart failure. This review provides a comprehensive overview of treatment with stem-like cells in preclinical and clinical studies to assess the feasibility and efficacy of this novel therapeutic strategy in ischaemic cardiomyopathy.

The Effect of Metformin on Diastolic Function in Patients Presenting with ST-Elevation Myocardial Infarction

Introduction

Diastolic dysfunction is an important predictor of poor outcome after myocardial infarction. Metformin treatment improved diastolic function in animal models and patients with diabetes. Whether metformin improves diastolic function in patients presenting with ST-segment elevation myocardial infarction (STEMI) is unknown.

Methods

The GIPS-III trial randomized STEMI patients, without known diabetes, to metformin or placebo initiated directly after PCI. The previously reported primary endpoint was left ventricular ejection fraction at 4 months, which was unaffected by metformin treatment. This is a predefined substudy to determine an effect of metformin on diastolic function. For this substudy trans-thoracic echocardiography was performed during hospitalization and after 4 months. Diastolic dysfunction was defined as having the combination of a functional alteration (i.e. decreased tissue velocity: mean of septal e’ and lateral e’) and a structural alteration (i.e. increased left atrial volume index (LAVI)). In addition, left ventricular mass index and transmitral flow velocity (E) to mean e' ratio (E/e’) were measured to determine an effect of metformin on individual echocardiographic markers of diastolic function.

Results

In 237 (63%) patients included in the GIPS-III trial diastolic function was measured during hospitalization as well as at 4 months. Diastolic dysfunction was present in 11 (9%) of patients on metformin and 11 (9%) patients on placebo treatment (P = 0.98) during hospitalization. After 4 months 22 (19%) of patients with metformin and 18 (15%) patients with placebo (P = 0.47) had diastolic dysfunction. In addition, metformin did not improve any of the individual echocardiographic markers of diastolic function.

Conclusions

In contrast to experimental and observational data, our randomized placebo controlled trial did not suggest a beneficial effect of short-term metformin treatment on diastolic function in STEMI patients.

Stem Cell Therapy and Congenital Heart Disease

For more than a decade, stem cell therapy has been the focus of intensive efforts for the treatment of adult heart disease, and now has promise for treating the pediatric population. On the basis of encouraging results in the adult field, the application of stem cell-based strategies in children with congenital heart disease (CHD) opens a new therapy paradigm. To date, the safety and efficacy of stem cell-based products to promote cardiac repair and recovery in dilated cardiomyopathy and structural heart disease in infants have been primarily demonstrated in scattered clinical case reports, and supported by a few relevant pre-clinical models. Recently the TICAP trial has shown the safety and feasibility of intracoronary infusion of autologous cardiosphere-derived cells in children with hypoplastic left heart syndrome. A focus on preemptive cardiac regeneration in the pediatric setting may offer new insights as to the timing of surgery, location of cell-based delivery, and type of cell-based regeneration that could further inform acquired cardiac disease applications. Here, we review the current knowledge on the field of stem cell therapy and tissue engineering in children with CHD, and discuss the gaps and future perspectives on cell-based strategies to treat patients with CHD.

Efficacy of stem cell in improvement of left ventricular function in acute myocardial infarction--MI3 Trial

Background & objectives:

Acute myocardial infarction (AMI) is characterized by irreparable and irreversible loss of cardiac myocytes. Despite major advances in the management of AMI, a large number of patients are left with reduced left ventricular ejection fraction (LVEF), which is a major determinant of short and long term morbidity and mortality. A review of 33 randomized control trials has shown varying improvement in left ventricular (LV) function in patients receiving stem cells compared to standard medical therapy. Most trials had small sample size and were underpowered. This phase III prospective, open labelled, randomized multicenteric trial was undertaken to evaluate the efficacy in improving the LVEF over a period of six months, after injecting a predefined dose of 5-10 × 10⁸ autologous mononuclear cells (MNC) by intra-coronary route, in patients, one to three weeks post ST elevation AMI, in addition to the standard medical therapy.

Methods:

In this phase III prospective, multicentric trial 250 patients with AMI were included and randomized into stem cell therapy (SCT) and non SCT groups. All patients were followed up for six months. Patients with AMI having left ventricular ejection fraction (LVEF) of 20-50 per cent were included and were randomized to receive intracoronary stem cell infusion after successfully completing percutaneous coronary intervention (PCI).

Results:

On intention-to-treat analysis the infusion of MNCs had no positive impact on LVEF improvement of ≥ 5 per cent. The improvement in LVEF after six months was 5.17 ± 8.90 per cent in non SCT group and 4.82 ± 10.32 per cent in SCT group. The adverse effects were comparable in both the groups. On post hoc analysis it was noted that the cell dose had a positive impact when infused in the dose of ≥ 5 × 10⁸(n=71). This benefit was noted upto three weeks post AMI. There were 38 trial deviates in the SCT group which was a limitation of the study.

Interpretation & conclusions:

Infusion of stem cells was found to have no benefit in ST elevation AMI. However, the procedure was safe. A possible benefit was seen when the predefined cell dose was administered which was noted upto three weeks post AMI, but this was not significant and needs confirmation by larger trials.

Position Paper of the European Society of Cardiology Working Group Cellular Biology of the Heart: cell-based therapies for myocardial repair and regeneration in ischemic heart disease and heart failure

Despite improvements in modern cardiovascular therapy, the morbidity and mortality of ischaemic heart disease (IHD) and heart failure (HF) remain significant in Europe and worldwide. Patients with IHD may benefit from therapies that would accelerate natural processes of postnatal collateral vessel formation and/or muscle regeneration. Here, we discuss the use of cells in the context of heart repair, and the most relevant results and current limitations from clinical trials using cell-based therapies to treat IHD and HF. We identify and discuss promising potential new therapeutic strategies that include ex vivo cell-mediated gene therapy, the use of biomaterials and cell-free therapies aimed at increasing the success rates of therapy for IHD and HF. The overall aim of this Position Paper of the ESC Working Group Cellular Biology of the Heart is to provide recommendations on how to improve the therapeutic application of cell-based therapies for cardiac regeneration and repair.

Circulating annexin A5 predicts mortality in patients with heart failure

BACKGROUND

Natriuretic peptides are currently used to predict mortality in patients with heart failure (HF). However, novel independent biomarkers are needed to improve risk stratification in these patients. We hypothesized that annexin A5 (anxA5) would be highly expressed by organs which are generally affected by HF and that circulating anxA5 levels would predict mortality in HF patients.

METHODS

We prospectively determined the diagnostic value of anxA5, N-terminal pro-B-type natriuretic peptide (NT-proBNP), C-reactive protein (CRP) and estimated glomerular filtration rate (eGFR) to predict mortality in 180 HF patients during a median follow-up of 3.6 years. Studies were conducted with anxA5(-/-) mice to investigate the underlying mechanisms.

RESULTS

AnxA5 levels were significantly elevated in HF patients compared to healthy control subjects. Cox regression analysis demonstrated that anxA5, NT-proBNP and eGFR all predict mortality independently. AnxA5 significantly improved the diagnostic efficiency of NT-proBNP alone (improvement of c-statistic from 0.662 to 0.705, P < 0.001) and also combined with eGFR and CRP (improvement of c-statistic from 0.675 to 0.738, P < 0.001) to predict mortality in the Cox regression model. Receiver operating characteristic curve analysis showed that anxA5 predicted 3-year survival (area under curve 0.708) with an optimal cut-off value of 2.24 ng mL(-1) . Using anxA5(-/-) mice, we demonstrated that anxA5 is highly expressed in organs that are often affected by HF including lung, kidney, liver and spleen. Lysis of these organs in vitro resulted in a marked and significant increase in anxA5 concentrations.

CONCLUSION

AnxA5 improves the diagnostic efficiency of conventional biomarkers to predict mortality in HF patients. Whereas natriuretic peptides originate from the myocardium, high circulating anxA5 levels in patients with HF are likely to reflect peripheral organ damage secondary to HF.

Stem cell treatment for acute myocardial infarction

BACKGROUND

Cell transplantation offers a potential therapeutic approach to the repair and regeneration of damaged vascular and cardiac tissue after acute myocardial infarction (AMI). This has resulted in multiple randomised controlled trials (RCTs) across the world.

OBJECTIVES

To determine the safety and efficacy of autologous adult bone marrow stem cells as a treatment for acute myocardial infarction (AMI), focusing on clinical outcomes.

SEARCH METHODS

This Cochrane review is an update of a previous version (published in 2012). We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 2), MEDLINE (1950 to March 2015), EMBASE (1974 to March 2015), CINAHL (1982 to March 2015) and the Transfusion Evidence Library (1980 to March 2015). In addition, we searched several international and ongoing trial databases in March 2015 and handsearched relevant conference proceedings to January 2011.

SELECTION CRITERIA

RCTs comparing autologous bone marrow-derived cells with no cells in patients diagnosed with AMI were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references, assessed the risk of bias of the included trials and extracted data. We conducted meta-analyses using random-effects models throughout. We analysed outcomes at short-term (less than 12 months) and long-term (12 months or more) follow-up. Dichotomous outcomes are reported as risk ratio (RR) and continuous outcomes are reported as mean difference (MD) or standardised MD (SMD). We performed sensitivity analyses to evaluate the results in the context of the risk of selection, performance and attrition bias. Exploratory subgroup analysis investigated the effects of baseline cardiac function (left ventricular ejection fraction, LVEF) and cell dose, type and timing of administration, as well as the use of heparin in the final cell solution.

MAIN RESULTS

Forty-one RCTs with a total of 2732 participants (1564 cell therapy, 1168 controls) were eligible for inclusion. Cell treatment was not associated with any changes in the risk of all-cause mortality (34/538 versus 32/458; RR 0.93, 95% CI 0.58 to 1.50; 996 participants; 14 studies; moderate quality evidence), cardiovascular mortality (23/277 versus 18/250; RR 1.04, 95% CI 0.54 to 1.99; 527 participants; nine studies; moderate quality evidence) or a composite measure of mortality, reinfarction and re-hospitalisation for heart failure (24/262 versus 33/235; RR 0.63, 95% CI 0.36 to 1.10; 497 participants; six studies; moderate quality evidence) at long-term follow-up. Statistical heterogeneity was low (I(2) = 0% to 12%). Serious periprocedural adverse events were rare and were generally unlikely to be related to cell therapy. Additionally, cell therapy had no effect on morbidity, quality of life/performance or LVEF measured by magnetic resonance imaging. Meta-analyses of LVEF measured by echocardiography, single photon emission computed tomography and left ventricular angiography showed evidence of differences in mean LVEF between treatment groups although the mean differences ranged between 2% and 5%, which are accepted not to be clinically relevant. Results were robust to the risk of selection, performance and attrition bias from individual studies.

AUTHORS' CONCLUSIONS

The results of this review suggest that there is insufficient evidence for a beneficial effect of cell therapy for AMI patients. However, most of the evidence comes from small trials that showed no difference in clinically relevant outcomes. Further adequately powered trials are needed and until then the efficacy of this intervention remains unproven.

Effect of Percutaneous Coronary Intervention on Left Ventricular Diastolic Function in Patients With Coronary Artery Disease

BACKGROUND

There is considerable disagreement over the effects of percutaneous coronary intervention (PCI) on left ventricular diastolic function that has necessitated the investigation of diastolic indices. The present study was conducted to evaluate left ventricular diastolic function and its indices, three months after performing the PCI procedure in patients with coronary artery disease (CAD).

METHODS

In a quasi-experimental clinical trial study (before and after), 51 patients with CAD scheduled for elective PCI were investigated provided that their Ejection Fraction (EF) was > 30%. Before and three months after PCI, echocardiography was carried out to evaluate left ventricular diastolic indices including the E/Ea as the most important criteria for diagnosis of diastolic heart failure (DHF).

RESULTS

Based on the E/Ea indices and after PCI, the number of patients with DHF decreased significantly: 40 patients (78.4%) before PCI versus 28 patients (54.9%) after PCI (p<0.05). The Mean and Standard error of deceleration time (DT), isovolumic relaxation time (IVRT), early diastolic mitral annulus velocity; Ea (E'), E/Ea and left ventricular ejection function (LVEF) indices underwent significant changes. In addition, MVA dur/PVA dur, PVs/PVd, and E/Ea indices had changed significantly after PCI in both genders. However, no significant difference was reported for the other indices.

CONCLUSION

The E/Ea ratio as an important criterion for diagnosis of DHF was improved after PCI. Improvement of several other diastolic indices was observed after the PCI procedure. It can be concluded that PCI can be an effective treatment modality in patients with left ventricular diastolic indices.

Effects of Bone Marrow Mononuclear Cells Delivered through a Graft Vessel for Patients with Previous Myocardial Infarction and Chronic Heart Failure: An Echocardiographic Study of Left Atrium Function

OBJECTIVES

The graft of stem cells to treat ischemic cardiomyopathy is popular in many clinical trials. The aim of this study was to evaluate the effectiveness of isolated coronary artery bypass graft combined with bone marrow mononuclear cells (BMMNC) delivered through the graft vessels to improve left atrium (LA) function of patients with previous myocardial infarction and chronic heart failure using echocardiography.

METHODS

Forty-two patients with previous myocardial infarction and chronic heart failure were randomly allocated to one of the two groups: coronary artery bypass graft (CABG) only (18 in CABG group) or CABG with BMMNC transplantation (24 in CABG + BMMNC group). Echocardiographic parameters were measured on two-dimensional (2D) imaging, three-dimensional imaging, 2D strain, and strain rate imaging, eight parameters were measured totally.

RESULTS

Postoperative LA global strain (LAGS) versus Preoperative LAGS were 24.875 ± 1.588% versus 14.250 ± 1.281% (P < 0.05) in CABG + BMMMNC group and 17.556 ± 1.834% versus 13.111 ± 1.479% (P < 0.05) in CABG group, LVEF was 49.083 ± 1.914% versus 36.042 ± 1.185% (P < 0.05) in CABG + BMMMNC group and 41.389 ± 2.210% versus 34.667 ± 1.369% (P < 0.05) in CABG group, and LA volume (LAV) was 15.651 ± 0.631 mL versus 23.894 ± 0.831 mL (P < 0.05) in CABG + BMMMNC group and 21.429 ± 0.707 mL versus 22.379 ± 0.959 mL (P < 0.05) in CABG group. LAGS, LVEF, and LAV were significantly improved postoperatively in both groups. The degree of the improvement was significantly different between the two groups with the CABG + BMMNC group improved more versus the group of CABG only (P < 0.05). Postoperative LVEDV and LVESV were significantly improved compared with those obtained prior to operation in CABG + BMMNC group (P < 0.05).

CONCLUSIONS

The improvement of LA function in CABG + BMMNC group is better than CABG group. 2D strain imaging is a more sensitive tool to evaluate LA function.

Effects of Bone Marrow Mononuclear Cells Delivered through a Graft Vessel for Patients with Previous Myocardial Infarction and Chronic Heart Failure: An Echocardiographic Study of Left Ventricular Function

OBJECTIVES

The graft of stem cells to treat ischemic cardiomyopathy is popular in many clinical trials. The aim of this study was to evaluate the effectiveness of isolated coronary artery bypass graft combined with bone marrow mononuclear cells (BMMNC) delivered through graft vessels to improve left ventricular function of patients with previous myocardial infarction and chronic heart failure using echocardiography.

METHODS

Forty-two patients with previous myocardial infarction and chronic heart failure were randomly allocated to one of the two groups: CABG only (18 in CABG group), or CABG with BMMNC transplantation (24 in CABG + BMMNC group). Echocardiographic parameters of systolic function were measured on B-mode imaging, tissue Doppler imaging (TDI), two-dimensional (2D) strain imaging, and 8 parameters were measured totally. Echocardiographic parameters of diastolic function were measured on pulsed-wave Doppler imaging, TDI, and 2D strain rate imaging; 17 parameters were measured totally.

RESULTS

Postoperative left ventricular ejection fraction (LVEF) versus preoperative LVEF were 49.083 ± 1.914% versus 36.042 ± 1.185% (P < 0.05) in CABG + BMMMNC group and 41.389 ± 2.210% versus 34.667 ± 1.369% (P < 0.05) in CABG group, global longitudinal strain were -12.542 ± 0.512% versus -7.083 ± 0.583% (P < 0.05) in CABG + BMMMNC group and -9.278 ± 0.591% versus -7.000 ± 0.673% (P < 0.05) in CABG group, mLsr1 were -0.108 ± 0.018/sec versus -0.039 ± 0.017/sec (P < 0.05) in CABG+BMMMNC group and -0.048 ± 0.021/sec versus 0.004 ± 0.020/sec (P < 0.05) in CABG group, mLsr2 were -0.055 ± 0.013/sec versus -0.009 ± 0.015/sec (P < 0.05) in CABG + BMMMNC group and 0.004 ± 0.015/sec versus 0.024 ± 0.017/sec (P < 0.05) in CABG group, and Aa1 were 7.303 ± 0.479 cm/sec versus 5.131 ± 0.381 cm/sec (P < 0.05) in CABG + BMMMNC group and 7.908 ± 0.553 cm/sec versus 6.764 ± 0.440 cm/sec (P < 0.05) in CABG group. Parameters above were significantly improved postoperatively in both groups. The degree of the improvement was significantly different between the two groups with the CABG + BMMNC group improved more versus the group of CABG only (P < 0.05).

CONCLUSIONS

The improvement of left ventricular function in CABG + BMMNC group is better than CABG group. 2D strain and strain rate imaging is a more sensitive tool to evaluate left ventricular function.

In vivo magnetic resonance imaging tracking of transplanted superparamagnetic iron oxide-labeled bone marrow mesenchymal stem cells in rats with myocardial infarction

Superparamagnetic iron oxide (SPIO) nanoparticles generate superparamagnetism, thereby resulting in an inhomogeneous local magnetic field, which shortens the T2 value on magnetic resonance imaging (MRI). The purpose of the present study was to use MRI to track bone marrow mesenchymal stem cells (BMSCs) labeled with SPIO in a rat model of myocardial infarction. The BMSCs were isolated from rats and labeled with SPIO. The anterior descending branch of the coronary artery was ligated under anesthesia. Two weeks later, the rats received, at random, 5×10⁷ SPIO-labeled BMSCs, 5×10⁷ unlabeled BMSCs or a vehicle (100 μl phosphate-buffered saline) via direct injection into the ischemic area (20 animals/group). MRI was used to track the SPIO-labeled BMSCs and the rats were then sacrificed to verify the presence of BMSCs using immunohistochemistry with an anti-CD90 antibody. The procedure labeled 99% of the BMSCs with SPIO, which exhibited low-intensity signals on T2 and T2* MRI imaging. At 24 h post-BMSC transplantation, low-intensity MRI signals were detected on the T2 and T2* sequences at the infarction margins. After 3 weeks following transplantation, low-intensity signals started to appear within the infarcted area; however, the signal intensity subsequently decreased and became indistinct. Immunohistochemistry revealed that the SPIO-labeled BMSCs migrated from the margin into the infarcted region. In conclusion, the BMSCs were readily labeled with SPIO and in vivo and MRI tracking demonstrated that the SPIO-labeled BMSCs established and grew in the infarcted myocardium.

Prompt bone marrow-derived mesenchymal stem cell therapy enables early porcine heart function recovery from acute myocardial infarction

Impact of early bone marrow-derived mesenchymal stem cell (BMDMSC) implantation on left ventricular (LV) function after AMI was studied.Twelve mini-pigs were equally divided into placebo (AMI through left coronary artery ligation) and cell-treated groups [BMDMSCs (3.0 × 10(7)) implanted into infarct area (IA)] with myocardium harvested by post-AMI day 90. Six healthy animals served as controls.On post-AMI day 90, magnetic resonance imaging showed a lower LV ejection fraction but higher LV dimensions in the placebo group (P < 0.003) that also had increased IAs but reduced wall thickness (P < 0.005). Pro-apoptotic gene expressions (Bax, caspase-3) and apoptotic nucleus number in IAs and peri-IAs were highest in the placebo group (P < 0.001). Inflammatory biomarker expressions (MMP-9, oxidized protein, CD40+ cells) were highest, whereas those of angiogenesis (VEGF, CD31+ cells, SDF-1α, CXCR4) and myocardium-preservation (connexin43, troponin-I, cytochrome-C) were lowest in the placebo group (P < 0.01).BMDMSC implantation preserved LV function and alleviated remodeling at post-AMI day 90.

Intracoronary stem cell infusion after acute myocardial infarction: a meta-analysis and update on clinical trials

BACKGROUND

Several cell-based therapies for adjunctive treatment of acute myocardial infarction have been investigated in multiple clinical trials, but the benefits still remain controversial. This meta-analysis aims to evaluate the efficacy of bone marrow-derived mononuclear cell (BMMNC) therapy in patients with acute myocardial infarction, but also explores the effect of newer generations of stem cells.

METHODS AND RESULTS

A random-effects meta-analysis was performed on randomized controlled trials investigating the effects of stem cell therapy in patients with acute myocardial infarction that were published between January 2002 and September 2013. The defined end points were left ventricular (LV) ejection fraction, LV end-systolic and end-diastolic volumes, infarct size, and major adverse cardiac and cerebrovascular event rates. Also, several subgroup analyses were performed on BMMNC trials. Overall, combining the results of 22 randomized controlled trials (RCTs), LV ejection fraction increased by +2.10% (95% confidence interval [CI], 0.68-3.52; P=0.004) in the BMMNC group as compared with controls, evoked by a preservation of LV end-systolic volume (-4.05 mL; 95% CI, -6.91 to -1.18; P=0.006) and a reduction in infarct size (-2.69%; 95% CI, -4.83 to -0.56; P=0.01). However, there is no effect on cardiac function, volumes, or infarct size, when only RCTs (n=9) that used MRI-derived end points were analyzed. Moreover, no beneficial effect could be detected on major adverse cardiac and cerebrovascular event rates after BMMNC infusion after a median follow-up duration of 6 months.

CONCLUSIONS

Intracoronary infusion of BMMNC is safe, but does not enhance cardiac function on MRI-derived parameters, nor does it improve clinical outcome. New and possibly more potent stem cells are emerging in the field, but their clinical efficacy still needs to be defined in future trials.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

A critical analysis of clinical outcomes reported in stem cell trials for acute myocardial infarction: some thoughts for design of future trials

The purpose of stem cell therapy for myocardial infarction is to improve clinical outcomes, and detailed information on clinical outcomes is critical to appropriate planning of phase III trials. We have examined data from select phase II trials using autologous bone-marrow-derived stem cells in patients with acute myocardial infarction. We have extracted available definitions and outcome data, and have generated standardized estimates of events to permit summary comparisons. Nine trials (1,040 patients) with results for 6 months to 5 years were evaluated. Adverse outcomes differed widely, and there was a general lack of details in the definitions of these outcomes. Heart-failure-related hospitalizations occurred in only 16 patients (1.5 %) and death occurred in only 43 patients (4.1 %). Ischemia-related outcomes outnumbered heart failure outcomes more than tenfold. Uniform criteria need to be developed to better define clinical outcomes of interest. Furthermore, a refocus from heart failure outcomes to ischemia-related outcomes seems appropriate.

In vitro biological and mechanical evaluation of various scaffold materials for myocardial tissue engineering

A cardiac patch is a construct devised in regenerative medicine to replace necrotic heart tissue after myocardial infarctions. The cardiac patch consists of a scaffold seeded with stem cells. To identify the best scaffold for cardiac patch construction we compared polyurethane, Collagen Cell Carriers, ePTFE, and ePTFE SSP1-RGD regarding their receptiveness to seeding with mesenchymal stem cells isolated from umbilical cord tissue. Seeding was tested at an array of cell seeding densities. The bioartificial patches were cultured for up to 35 days and evaluated by scanning electron microscopy, microscopy of histological stains, fluorescence microscopy, and mitochondrial assays. Polyurethane was the only biomaterial which resulted in an organized multilayer (seeding density: 0.750 × 10(6) cells/cm(2)). Cultured over 35 days at this seeding density the mitochondrial activity of the cells on polyurethane patches continually increased. There was no decrease in the E Modulus of polyurethane once seeded with cells. Seeding of CCC could only be realized at a low seeding density and both ePTFE and ePTFE SSP1-RGD were found to be unreceptive to seeding. Of the tested scaffolds polyurethane thus crystallized as the most appropriate for seeding with mesenchymal stem cells in the framework of myocardial tissue engineering.

Perfusion MRI at rest in subacute and chronic myocardial infarct

BACKGROUND

Perfusion magnetic resonance imaging (MRI) and delayed contrast-enhanced MRI (DE-MRI) serve as tools for tissue characterization.

PURPOSE

To assess and compare semi-quantitative parameters of myocardial infarct (MI) in the subacute and chronic phase, and to correlate these parameters with qualitative enhancement analysis.

MATERIAL AND METHODS

Perfusion MRI at rest and DE-MRI were performed in 63 patients with anterior wall MI at 2-3 weeks after revascularization and repeated after 6 months. Descriptive enhancement parameters of contrast arrival time, initial upslope, enhancement at normal tissue peak (TTPn) and wash-out slope, and kinetic tissue parameters rBF, K (trans), k ep and v e were calculated. Subacute infarct tissue was compared to normal myocardium and chronic infarct tissue. Patients were stratified at baseline according to a qualitative grading of hypoenhancement based on first-pass enhancement and presence of microvascular obstruction (MO) at perfusion MRI and on persistent MO at DE-MRI. The qualitative grade was correlated to semi-quantitative perfusion MRI parameters.

RESULTS

Initial upslope, enhancement at TTPn, rBF, and k ep were decreased and wash-out slope and v e were increased in infarct tissue (P < 0.001 for all analyses). Infarct tissue v e decreased from baseline to 6 months (P = 0.045). At baseline infarct tissue with persistent MO revealed decreased K (trans) and delayed contrast arrival, and more pronounced decrease of enhancement at TTPn, rBF and k ep compared to other enhancement groups (P < 0.008 for pairwise analyses).

CONCLUSION

Perfusion is decreased in subacute reperfused infarct tissue compared to normal tissue. K (trans) is not decreased, consistent with increased surface area of the vascular bed of the subacute infarct. Infarct tissue v e is increased, and decreases with scarring. The presence of persistent MO correlates to more pronounced perfusion reduction and results in delayed contrast arrival, indicating microvascular collateral circulation.

Cardiospheres and cardiosphere-derived cells as therapeutic agents following myocardial infarction

Heart disease is a major cause of morbidity and mortality. Cellular therapies hold significant promise for patients with heart disease. Heart-derived progenitor cells are capable of repairing a diseased heart through modulation of growth factor milieu and temporary engraftment leading to endogenous repair. The proof-of-concept CADUCEUS clinical trial using cardiosphere-derived cells has shown evidence of therapeutic cardiac tissue regeneration. Future clinical trials are now being planned to generate additional safety and efficacy data in the hopes of building toward an approved cellular therapy for heart disease.

Janus-like role of fibroblast growth factor 2 in arteriosclerotic coronary artery disease: atherogenesis and angiogenesis

Angiogenic stimulation is a promising new strategy for treating patients with arteriosclerotic coronary artery disease. This strategy aims to ameliorate cardiac function by improving myocardial perfusion and lowering the risk of myocardial infarction. However, angiogenesis may contribute to the growth of atherosclerotic lesions. Atherogenesis is also a potential side effect of angiogenic therapy. Early clinical trials were performed using fibroblast growth factor 2 (FGF2) protein, which enhances the formation of new collateral vessels to reduce ischaemic symptoms. Conversely, angiogenic stimulation by FGF2 is a dilemma because it could cause negative angiogenic effects, such as atherosclerosis. Thus far, clinical trials in patients with recombinant FGF2 protein therapy have not yet yielded undisputable beneficial effects. Future trials should determine whether an improvement can be obtained in patients with coronary artery disease using a combination of FGF2 and other growth factors or a combination of the FGF2 gene and stem cell therapy. This review summarises the multiple roles of FGF2 in the progression of atherosclerosis, its effect on pro-angiogenesis and improvement of cardiac function in coronary artery disease, and the potentially unfavourable effect of angiogenesis on the prevention and treatment of atherogenesis.

Four-dimensional speckle tracking for assessing improvement in left ventricular contractility after coronary angioplasty

The objective of the study was to identify and quantify the potential improvement of left ventricular contractility after percutaneous transluminal coronary angioplasty (PTCA) using 4-dimensional (4D) speckle tracking echocardiography (4D STE). We investigated 41 patients with coronary disease by 4D STE pre- and 24 hours postcoronarography with (n = 18) or without (n = 23) PTCA. The 4D STE visualizes in real time the myocardium strain on 2- and 4-chamber apical views and on 3 transverse views of the left ventricle. Average and total strain of the left ventricle were measured. Of the 18 PTCA patients, 15 showed significant increase in left ventricle mean (+15 ± 6) and total strain (240 ± 100), which corresponded to an increase of 93% ± 55% from precoronarography, whereas the remainder showed no change. The total strain corresponded to 33% ± 10% (before PTCA) and 59% ± 11% (post PTCA) of the estimated normal strain for each patient. Strain improved in 70% of the segment downstream from the stent, and there was a negative correlation between the amplitude of the mean and total strain improvements after 24 hours and the mean and total strain values before PTCA. In the non-PTCA group, 21 of the 23 patients showed no changes in strain, whereas 2 showed improvement. The 4D STE showed significant improvements in left ventricular contractility in more than 70% of the areas downstream from the PTCA segment. This corresponded to an increase in the initial contractility by approximately 93% ± 55%; however, the myocardium contractility remained approximately 59% of normal level. No changes were seen in patients without PTCA.

Stem cell transplantation in cardiovascular disease: an update

Despite the development of novel therapeutic strategies, cardiovascular diseases remain the main cause of morbidity and mortality worldwide. Many phase 1 and 2 clinical trials have reported the safety, feasibility and promising potential of stem cell transplantation, however, the optimal cell types, timing of infusion, cell dosage and routes of administration remain to be determined. This paper reviews the findings of various clinical studies and discusses the challenges facing the delivery of stem cell therapy in cardiovascular diseases.

The effect of bone marrow-derived cells on diastolic function and exercise capacity in patients after acute myocardial infarction

BACKGROUND

The early- to mid-term impact of bone-marrow-derived stem cells (BMC) on diastolic function and exercise capacity after acute myocardial infarction (AMI) remains controversial. We performed a systematic analysis to assess whether BMC transfer is related to an early improvement in diastolic function and exercise capacity after AMI.

METHODS

Randomized controlled trials (RCTs) of BMC therapy after AMI were extracted from MEDLINE, EMBASE and CENTRAL and analyzed for a change in tissue Doppler annular early (Ea) and late diastolic (Aa) velocities, mitral inflow E velocity to tissue Doppler Ea (E/Ea) ratio, exercise time and exercise capacity.

RESULTS

A total of 365 patients were included from 6 trials. A greater improvement was observed in the E/Ea ratio after 1 year in the BMC group compared to the control group. Additionally, the BMC-treated patients had a larger improvement in exercise time, ventilation/CO₂ production (VE/VCO₂ slope) and respiratory exchange ratio (RER) after 1 year.

CONCLUSION

The results indicate that intracoronary BMC treatment in AMI patients leads to a mid-term improvement in diastolic function and exercise capacity.

Quantification of myocardial segmental function in acute and chronic ischemic heart disease and implications for cardiovascular cell therapy trials: a review from the NHLBI-Cardiovascular Cell Therapy Research Network

Global left ventricular (LV) ejection fraction (LVEF) has been used as a measure of improvement in LV function following cell therapy. Although the impact of cell therapy on LVEF in short- and long-term follow-up has been generally positive, there is concern that research evaluating regional therapeutics (e.g., cell or gene therapy) may require analysis of regional LV function localized to the site of intervention. Regional LV assessment is traditionally performed with qualitative or quantitative analysis of wall thickening within 16 myocardial segments, but advances in noninvasive imaging permit an increasingly more detailed and accurate evaluation of LV function. Wall-thickness measurements can now include evaluation of over 1,000 myocardial segments. In addition to higher resolution measures of wall thickening, automated assessments of myocardial segment deformation, such as strain imaging, exist. Strain imaging allows for direct evaluation of the mechanical properties that may improve following regional therapeutic intervention. Improvements in regional LV function may also be assessed by determining regional ejection fraction (EF). Regional EF offers the advantage of summarizing the end result of all of the complex deformations in the adjacent myocardial segments. Although regional EF and strain imaging, as compared with wall thickening, enhance detection of improvement in complex measures of regional myocardial function, it remains unclear whether such measures are better able to predict meaningful improvement in clinical outcomes.

Stem cell treatment for acute myocardial infarction

BACKGROUND

Stem cell therapy offers a promising approach to the regeneration of damaged vascular and cardiac tissue after acute myocardial infarction (AMI). This has resulted in multiple randomised controlled trials (RCTs) worldwide.

OBJECTIVES

To critically evaluate evidence from RCTs on the effectiveness of adult bone marrow-derived stem cells (BMSC) to treat acute myocardial infarction (AMI).

SEARCH METHODS

This Cochrane review is an update of a previous one (published in 2008). MEDLINE (1950 to January 2011), EMBASE (1974 to January 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 1, 2011), CINAHL (1982 to January 2011) and the Transfusion Evidence Library (1980 to January 2011) were searched. In addition, several international and ongoing trial databases were searched and handsearching of relevant conference proceedings undertaken to January 2011.

SELECTION CRITERIA

RCTs comparing autologous stem/progenitor cells with no autologous stem/progenitor cells in patients diagnosed with AMI were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently screened all references, assessed trial quality and extracted data. Meta-analyses using a random-effects model were conducted and heterogeneity was explored for the primary outcome using sub-group analyses.

MAIN RESULTS

Thirty-three RCTs (1765 participants) were eligible for inclusion. Stem/progenitor cell treatment was not associated with statistically significant changes in the incidence of mortality (RR 0.70, 95% CI 0.40 to 1.21) or morbidity (the latter measured by re-infarction, hospital re-admission, restenosis and target vessel revascularisation). A considerably high degree of heterogeneity has been observed among the included trials. In short-term follow up, stem cell treatment was observed to improve left ventricular ejection fraction (LVEF) significantly (WMD 2.87, 95% CI 2.00 to 3.73). This improvement in LVEF was maintained over long-term follow up of 12 to 61 months (WMD 3.75, 95% CI 2.57 to 4.93). With certain measurements and at certain times, stem cell treatment was observed to reduce left ventricular end systolic and end diastolic volumes (LVESV & LVEDV) and infarct size significantly in long-term follow up. There was a positive correlation between mononuclear cell dose infused and the effect on LVEF measured by magnetic resonance imaging. A correlation between timing of stem cell treatment and effect on LVEF measured by left ventricular angiography was also observed.

AUTHORS' CONCLUSIONS

Despite the high degree of heterogeneity observed, the results of this systematic review suggest that moderate improvement in global heart function is significant and sustained long-term. However, because mortality rates after successful revascularization of the culprit arteries are very low, larger number of participants would be required to assess the full clinical effect of this treatment. Standardisation of methodology, cell dosing and cell product formulation, timing of cell transplantation and patient selection may also be required in order to reduce the substantial heterogeneity observed among the included studies.