Autologous stem cell transplantation in acute myocardial infarction: The ASTAMI randomized controlled trial. Intracoronary transplantation of autologous mononuclear bone marrow cells, study design and safety aspects

Characterization of fetal microchimeric immune cells in mouse maternal hearts during physiologic and pathologic pregnancies

Introduction: During pregnancy, fetal cells can be incorporated into maternal tissues (fetal microchimerism), where they can persist postpartum. Whether these fetal cells are beneficial or detrimental to maternal health is unknown. This study aimed to characterize fetal microchimeric immune cells in the maternal heart during pregnancy and postpartum, and to identify differences in these fetal microchimeric subpopulations between normal and pregnancies complicated by spontaneous preterm induced by ascending infection. Methods: A Cre reporter mouse model, which when mated with wild-type C57BL/6J females resulted in cells and tissues of progeny expressing red fluorescent protein tandem dimer Tomato (mT+), was used to detect fetal microchimeric cells. On embryonic day (E)15, 104 colony-forming units (CFU) E. coli was administered intravaginally to mimic ascending infection, with delivery on or before E18.5 considered as preterm delivery. A subset of pregnant mice was sacrificed at E16 and postpartum day 28 to harvest maternal hearts. Heart tissues were processed for immunofluorescence microscopy and high-dimensional mass cytometry by time-of-flight (CyTOF) using an antibody panel of immune cell markers. Changes in cardiac physiologic parameters were measured up to 60 days postpartum via two-dimensional echocardiography. Results: Intravaginal E. coli administration resulted in preterm delivery of live pups in 70% of the cases. mT + expressing cells were detected in maternal uterus and heart, implying that fetal cells can migrate to different maternal compartments. During ascending infection, more fetal antigen-presenting cells (APCs) and less fetal hematopoietic stem cells (HSCs) and fetal double-positive (DP) thymocytes were observed in maternal hearts at E16 compared to normal pregnancy. These HSCs were cleared while DP thymocytes persisted 28 days postpartum following an ascending infection. No significant changes in cardiac physiologic parameters were observed postpartum except a trend in lowering the ejection fraction rate in preterm delivered mothers. Conclusion: Both normal pregnancy and ascending infection revealed distinct compositions of fetal microchimeric immune cells within the maternal heart, which could potentially influence the maternal cardiac microenvironment via (1) modulation of cardiac reverse modeling processes by fetal stem cells, and (2) differential responses to recognition of fetal APCs by maternal T cells.

The Progress of Stem Cell Therapy in Myocardial-Infarcted Heart Regeneration: Cell Sheet Technology

Various tissues, including the heart, cornea, bone, esophagus, bladder and liver, have been vascularized using the cell sheet technique. It overcomes the limitations of existing techniques by allowing small layers of the cell sheet to generate capillaries on their own, and it can also be used to vascularize tissue-engineered transplants. Cell sheets eliminate the need for traditional tissue engineering procedures such as isolated cell injections and scaffold-based technologies, which have limited applicability. While cell sheet engineering can eliminate many of the drawbacks, there are still a few challenges that need to be addressed. The number of cell sheets that can be layered without triggering core ischemia or hypoxia is limited. Even when scaffold-based technologies are disregarded, strategies to tackle this problem remain a substantial impediment to the efficient regeneration of thick, living three-dimensional cell sheets. In this review, we summarize the cell sheet technology in myocardial infarcted tissue regeneration.

Clinical-based Cell Therapies for Heart Disease-Current and Future State

Patients have an ongoing unmet need for effective therapies that reverse the cellular and functional damage associated with heart damage and disease. The discovery that ~1%-2% of adult cardiomyocytes turn over per year provided the impetus for treatments that stimulate endogenous repair mechanisms that augment this rate. Preclinical and clinical studies provide evidence that cell-based therapy meets these therapeutic criteria. Recent and ongoing studies are focused on determining which cell type(s) works best for specific patient population(s) and the mechanism(s) by which these cells promote repair. Here we review clinical and preclinical stem cell studies and anticipate future directions of regenerative medicine for heart disease.

Cell-Based Therapies for Cardiac Regeneration: A Comprehensive Review of Past and Ongoing Strategies

Despite considerable improvements in the treatment of cardiovascular diseases, heart failure (HF) still represents one of the leading causes of death worldwide. Poor prognosis is mostly due to the limited regenerative capacity of the adult human heart, which ultimately leads to left ventricular dysfunction. As a consequence, heart transplantation is virtually the only alternative for many patients. Therefore, novel regenerative approaches are extremely needed, and several attempts have been performed to improve HF patients’ clinical conditions by promoting the replacement of the lost cardiomyocytes and by activating cardiac repair. In particular, cell-based therapies have been shown to possess a great potential for cardiac regeneration. Different cell types have been extensively tested in clinical trials, demonstrating consistent safety results. However, heterogeneous efficacy data have been reported, probably because precise end-points still need to be clearly defined. Moreover, the principal mechanism responsible for these beneficial effects seems to be the paracrine release of antiapoptotic and immunomodulatory molecules from the injected cells. This review covers past and state-of-the-art strategies in cell-based heart regeneration, highlighting the advantages, challenges, and limitations of each approach.

Stem cell therapies for myocardial infarction in clinical trials: bioengineering and biomaterial aspects

Cardiovascular disease remains the leading cause of death and disability in advanced countries. Stem cell transplantation has emerged as a promising therapeutic strategy for acute and chronic ischemic cardiomyopathy. The current status of stem cell therapies for patients with myocardial infarction is discussed from a bioengineering and biomaterial perspective in this review. We describe (a) the current status of clinical trials of human pluripotent stem cells (hPSCs) compared with clinical trials of human adult or fetal stem cells, (b) the gap between fundamental research and application of human stem cells, (c) the use of biomaterials in clinical and pre-clinical studies of stem cells, and finally (d) trends in bioengineering to promote stem cell therapies for patients with myocardial infarction. We explain why the number of clinical trials using hPSCs is so limited compared with clinical trials using human adult and fetal stem cells such as bone marrow-derived stem cells.

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.

Genome-wide epigenetic and proteomic analysis reveals altered Notch signaling in EPC dysfunction

Endothelial progenitor cells (EPCs) are bone-marrow-derived mononuclear cells that participate in tube formation in vitro and vessel formation in vivo. EPC transplantation, as a therapeutic approach in cardiovascular diseases, has produced mixed results likely due to underlying disease states and environmental factors affecting EPC function. In this study, we investigated the mechanisms by which a high-salt diet impairs EPC function. The number of endothelial progenitor cells (CD34(+), VEGFR2(+), CD133(+), and c-Kit(+)) was decreased in the bone marrow of Sprague-Dawley (SD) rats fed a high-salt diet (HSD; 4% NaCl) as compared to SD rats on a normal-salt diet (NSD; 0.4% NaCl). NSD EPCs augmented endothelial cell tube formation in vitro, whereas HSD EPCs did not. NSD EPCs were a potent therapeutic restoring electrical stimulation-induced angiogenesis in vivo. HSD EPCs were not able to restore angiogenesis in vivo. EPC DNA methylation was analyzed by reduced representative bisulfite sequencing and membrane proteins were analyzed using high accuracy liquid chromatography mass spectrometry. Differentially methylated genes and differentially abundant membrane proteins measured between the NSD and HSD EPCs, revealed a total of 886 gene-protein sets where reciprocal methylation and expression occurred. Based on stringent criteria, Notch4 was found to be hypermethylated in HSD EPCs and had corresponding decrease in protein expression. Suppression of Notch4 protein expression in EPCs using siRNA confirmed a role for Notch4 in EPC-mediated angiogenesis, suggesting Notch4 suppression as a mechanism by which high-salt diet inhibits EPC-mediated angiogenesis.

The Effect of Intracoronary Stem Cell Injection on Markers of Leukocyte Activation in Acute Myocardial Infarction

BACKGROUND

Beneficial effects of stem cell treatment during acute myocardial infarction (AMI) have been suggested, but the effects on inflammation are controversial. The neutrophil cell markers pentraxin 3 (PTX3) and myeloperoxidase (MPO) are both reported to be elevated during AMI. We studied the effects of stem cell treatment in ST-elevation myocardial infarction (STEMI) on PTX3 and MPO levels.

METHODS

Subjects with STEMI undergoing percutaneous coronary intervention (PCI) were randomized to intracoronary injection of bone marrow cells (mBMCs) (n = 50) or controls (n = 50). Blood samples were drawn 1 day before mBMC injection (baseline), after 1 day, 3 days, 2 - 3 weeks and 3 months. Enzyme-linked immunosorbent assay (ELISA) and RT-PCR were used for biochemical analysis. Myocardial necrosis was quantified by single photon emission computed tomography (SPECT) and creatine kinase MB (CKMB) levels.

RESULTS

PTX3 and MPO levels did not differ between the groups at any time points. Within the mBMC group, overall changes in both variables were observed (P < 0.01), with decreased levels from baseline throughout. Within the control group, similar patterns were observed. The relative reduction of PTX3 from baseline to day 1 was significantly less pronounced in the mBMC group compared to controls (P = 0.002), whereas no differences in relative changes from baseline were observed for MPO. Plasma and gene expression levels of PTX3 in leukocytes correlated significantly at all time points (r = 0.379 - 0.448, P < 0.01, all). MPO was significantly correlated to baseline left ventricular ejection fraction (LVEF) (r = -0.229, P = 0.025) and peak CKMB (r = 0.200, P = 0.05).

CONCLUSIONS

Stem cell treatment had limited effect on plasma levels of PTX3 and MPO. The initially high PTX3 and MPO levels, the genetic regulation of PTX3 and the association between MPO and myocardial injury support the importance of neutrophil cell activation in STEMI.

Clinical application of adult stem cells for therapy for cardiac disease

INTRODUCTION

Cardiovascular disease is a major cause of death worldwide. Different medical and surgical therapeutic options are well established, but a significant number of patients are not amenable to standard therapeutic options. Cell-based therapies after clinical application have shown different results in recent years. Here, we are giving a comprehensive overview on major available clinical data regarding cell therapy.

BACKGROUND

Cell-based therapies and tissue engineering provide new promising platforms to develop upcoming therapeutic options. Initial clinical trials were able to generate promising results. A variety of different stem cell types have been used for the clinical application. Different adult cardiac stem cells and progenitor cells, including mesenchymal, CD34(+) and CD133(+) autologous human bone marrow-derived stem cells (BMCs), human myoblasts, and peripheral blood-derived stem and progenitor cells (PBSCs) have been used for the therapy for end-stage heart failure. Future experiments will show the importance of novel cell populations and clarify the mechanism causing cell therapy-mediated observed effects.

CONCLUSION

Several clinical trials have reported on sole therapy, as well as combined application of autologous adult stem cells with conventional revascularization. The reported promising findings encourage further research in the field of the translational research.

The influence of autologous bone marrow stem cell transplantation on matrix metalloproteinases in patients treated for acute ST-elevation myocardial infarction

Background. Matrix metalloproteinase-9 (MMP-9), regulated by tissue inhibitor of metalloproteinase-9 (TIMP-1) and the extracellular matrix metalloproteinase inducer (EMMPRIN), contributes to plaque instability. Autologous stem cells from bone marrow (mBMC) treatment are suggested to reduce myocardial damage; however, limited data exists on the influence of mBMC on MMPs. Aim. We investigated the influence of mBMC on circulating levels of MMP-9, TIMP-1, and EMMPRIN at different time points in patients included in the randomized Autologous Stem-Cell Transplantation in Acute Myocardial Infarction (ASTAMI) trial (n = 100). Gene expression analyses were additionally performed. Results. After 2-3 weeks we observed a more pronounced increase in MMP-9 levels in the mBMC group, compared to controls (P = 0.030), whereas EMMPRIN levels were reduced from baseline to 2-3 weeks and 3 months in both groups (P < 0.0001). Gene expression of both MMP-9 and EMMPRIN was reduced from baseline to 3 months. MMP-9 and EMMPRIN were significantly correlated to myocardial injury (CK: P = 0.005 and P < 0.001, resp.) and infarct size (SPECT: P = 0.018 and P = 0.008, resp.). Conclusion. The results indicate that the regulation of metalloproteinases is important during AMI, however, limited influenced by mBMC.

Impact of short-term liquid storage on human CD133(+) stem cells

Stem cell transplantation is a viable strategy for regenerative medicine. However, it is inevitable to have cells undergo storage for several hours or days due to processing and transportation. Therefore, it is crucial to have rigidly controlled conditions ensuring the therapeutic benefit of isolated stem cells. In the present study, we investigated the impact of short-term storage on human CD133(+) cells. CD133(+) cells were isolated from human bone marrow and kept at standardized nonfreezing storage conditions for up to 72 h. Cell viability (apoptosis/necrosis) and expression of CD133 and CXCR4 were analyzed by flow cytometry. Metabolic activity was determined using an MTT assay; colony-forming ability, as well as endothelial-like differentiation, was further evaluated. A qRT-PCR array was employed to investigate the expression of stemness genes. CD133 and CXCR4 expressions were preserved at all time points. After 30 h, cell number and metabolic activity decreased, although no significant changes were detected in cell viability and proliferation as well as endothelial-like differentiation. Cell viability and proliferation decreased significantly only after 72 h of storage. Our results indicate that storage of isolated human CD133(+) bone marrow stem cells in liquid allows for high viability and functionality. However, storage time should be limited in order to avoid cell loss.

Resident cardiac stem cells and their role in stem cell therapies for myocardial repair

Despite advances in treatment, heart failure remains one of the top killers in Canada. This recognition motivated a new research focus to harness the fundamental repair properties of the human heart. Since then, cardiac stem cells (CSCs) have emerged as a promising cell candidate to regenerate damaged hearts. The rationale of this approach is simple with ex vivo amplification of CSCs from clinical-grade biopsies, followed by delivery to areas of injury, where they engraft and regenerate the heart. In this review we will summarize recent advances and discuss future developments in CSC-mediated cardiac repair to treat the growing number of Canadians living with and dying from heart failure.

The Reverse Remodeling Effect of Mesenchymal Stem Cells is Independent from the Site of Epimyocardial Cell Transplantation

Objective

The transplantation of mesenchymal stem cells (MSCs) represents a promising approach for treating the ischemic and the nonischemic diseased heart. The positive effects of transplanting these cells could be shown, but the exact mechanisms remain unknown. We evaluated whether the injection site affects the improvement in left ventricular (LV) ejection fraction (EF) and angiogenesis in doxorubicin (Dox)–induced failing hearts.

Methods

Heart failure was induced in New Zealand white rabbits by doxorubicin treatment, followed by right ventricular MSC transplantation (RV-MSC, n = 6), LV MSC transplantation (LV-MSC, n = 6), sham treatment (sham group, n = 6), or no therapy (Dox group, n = 5). Healthy rabbits were used as control group (n = 8). Cells were isolated after bone marrow aspiration and transplanted locally into the ventricular myocardium. After 4 weeks, cardiac function and capillary density (CD31 staining) were measured.

Results

The transplantation of MSCs increased the EF significantly (LV-MSC, 39.0% ± 1.4%, and RV-MSC, 39.2% ± 2.6%, vs sham group, 29.8% ± 3.7%; P < 0.001), without significance between the MSC groups ( P = 0.858). Neither the evidence of a transdifferentiation nor any signs of cell engraftment of transplanted cells could be found. The capillary density (capillaries/high-power field) increased in both MSC groups compared with the sham group (LV-MSC by 8.3% ± 3.4%; and RV-MSC, 8.1% ± 2.2%; P < 0.05), without significance between the two MSC groups ( P = 0.927).

Conclusions

Injection of autologous MSCs in doxorubicin-induced cardiomyopathic rabbit hearts improves EF and enhances angiogenesis. Despite local application, we observed global effects on heart function and capillary density without significant difference between right and LV injection. The paracrine mechanism might be one possible explanation for these findings.

In situ mechanotransduction via vinculin regulates stem cell differentiation

Human mesenchymal stem cell (hMSC) proliferation, migration, and differentiation have all been linked to extracellular matrix stiffness, yet the signaling pathway(s) that are necessary for mechanotransduction remain unproven. Vinculin has been implicated as a mechanosensor in vitro, but here we demonstrate its ability to also regulate stem cell behavior, including hMSC differentiation. RNA interference-mediated vinculin knockdown significantly decreased stiffness-induced MyoD, a muscle transcription factor, but not Runx2, an osteoblast transcription factor, and impaired stiffness-mediated migration. A kinase binding accessibility screen predicted a cryptic MAPK1 signaling site in vinculin which could regulate these behaviors. Indeed, reintroduction of vinculin domains into knocked down cells indicated that MAPK1 binding site-containing vinculin constructs were necessary for hMSC expression of MyoD. Vinculin knockdown does not appear to interfere with focal adhesion assembly, significantly alter adhesive properties, or diminish cell traction force generation, indicating that its knockdown only adversely affected MAPK1 signaling. These data provide some of the first evidence that a force-sensitive adhesion protein can regulate stem cell fate.

Stem cell-derived endothelial cells for cardiovascular disease: a therapeutic perspective

Stem cell therapy and organ regeneration are therapeutic approaches that will, we suggest, become mainstream for the treatment of human disease. Endothelial cells, which line the luminal surface of every vessel in the body, are essential components in any organ regeneration programme. There are a number of potentially therapeutic endothelial cell types, including embryonic, adult progenitor and induced pluripotent stem cell-derived endothelial cells, as well as host vascular cells. The features (benefits as well as disadvantages) of each cell type that make them potentially useful in therapy are important to consider. The field of stem cell biology is well developed in terms of protocols for generating endothelium. However, where there is a distinct and urgent unmet need for knowledge concerning how the endothelial cells from these different sources function as endothelium and how susceptible they may be to inflammation and atherosclerosis. Furthermore, where stem cells have been used in clinical trials there is little commonality in protocols for deriving the cells (and thereby the specific phenotype of cells used), administering the cells, dosing the cells and/or in assessing efficacy attributed to the cells themselves. This review discusses these and other issues relating to stem cell-derived endothelial cells in cell therapy for cardiovascular disease.

In vivo response to dynamic hyaluronic acid hydrogels

Tissue-specific elasticity arises in part from developmental changes in extracellular matrix over time, e.g. ~10-fold myocardial stiffening in the chicken embryo. When this time-dependent stiffening has been mimicked in vitro with thiolated hyaluronic acid (HA-SH) hydrogels, improved cardiomyocyte maturation has been observed. However, host interactions, matrix polymerization, and the stiffening kinetics remain uncertain in vivo, and each plays a critical role in therapeutic applications using HA-SH. Hematological and histological analysis of subcutaneously injected HA-SH hydrogels showed minimal systemic immune response and host cell infiltration. Most importantly, subcutaneously injected HA-SH hydrogels exhibited time-dependent porosity and stiffness changes at a rate similar to hydrogels polymerized in vitro. When injected intramyocardially host cells begin to actively degrade HA-SH hydrogels within 1week post-injection, continuing this process while producing matrix to nearly replace the hydrogel within 1month post-injection. While non-thiolated HA did not degrade after injection into the myocardium, it also did not elicit an immune response, unlike HA-SH, where visible granulomas and macrophage infiltration were present 1month post-injection, likely due to reactive thiol groups. Altogether these data suggest that the HA-SH hydrogel responds appropriately in a less vascularized niche and stiffens as had been demonstrated in vitro, but in more vascularized tissues, in vivo applicability appears limited.

Current status of myocardial regeneration therapy

Myocardial regeneration therapy has emerged as an alternative therapy for heart failure and is expected to replace current conventional therapies. As a cell source, the presence of resident cardiac stem cells (RCSC) in the heart has been reported by many researchers. These RCSC show multi-potency and are considered to differentiate into myocytes. On the other hand, bone marrow stem cells have received the greatest attention as a source of cell transplantation therapy in the current era, with a larger number of clinical applications reported because of their ease and safety. Myoblasts have also emerged as a possible cell source for clinical applications. We previously found that myoblast-cell-sheet implantation improved cardiac function and ventricle thickness in a rat MI model. Furthermore, we conducted a pre-clinical large animal study using porcine MI and dog DCM models, and confirmed the effectiveness of skeletal myoblast sheets. Thereafter, we conducted clinical applications of skeletal myoblast implantation. It may eventually be possible to perform regeneration therapy as a routine therapeutic method.

Periprocedural adverse events in cell therapy trials in myocardial infarction and cardiomyopathy: a systematic review

BACKGROUND

Cell therapy (CTh) is a promising novel therapy for myocardial infarction (MI) and ischemic cardiomyopathy (iCMP). Recognizing adverse events (AE) is important for safety evaluation, harm prevention and may aid in the design of future trials.

OBJECTIVE

To define the prevalence of periprocedural AE in CTh trials in MI and iCMP.

METHODS

A literature search was conducted using the MEDLINE database from January 1990 to October 2010. Controlled clinical trials that compared CTh with standard treatment in the setting of MI and/or iCMP were selected. AE related to CTh were analyzed.

RESULTS

A total of 2,472 patients from 35 trials were included. There were 26 trials including 1,796 patients that used CTh in MI and 9 trials including 676 patients that used CTh in iCMP. Periprocedural arrhythmia monitoring protocols were heterogeneous and follow-up was short in most of the trials. In MI trials, the incidence of periprocedural adverse events (AE) related to intracoronary cell transplantation was 7.5 % (95 % CI 6.04-8.96 %). AE related to granulocyte colony-stimulating factor (GCS-F) used for cell mobilization for peripheral apheresis was 16 % (95 % CI 9.44-22.56 %). During intracoronary transplantation in iCMP, the incidence of periprocedural AE incidence was 2.6 % (95 % CI 0.53-4.67 %). There were no AE reported during transepicardial transplantation and AE were rare during transendocardial transplantation.

CONCLUSIONS

The majority of periprocedural AE in CTh trials in MI occurred during intracoronary transplantation and GCS-F administration. In iCMP, periprocedural AE were uncommon. Avoiding intracoronary route for CTh implantation may decrease the burden of periprocedural AE. Standardization of AE definition in CTh trials is needed.

A new heart: somatic stem cells and myocardial regeneration

End-stage heart failure is a global scourge. Current therapies merely delay its inexorable progression. Heart transplantation is resource-intensive and limited by organ availability. Bone marrow-derived and cardiac-specific stem cells have demonstrated potential for cardiac regeneration and repair, but the magnitude and durability of these promising findings are inconsistent. The purpose of this review is to (1) describe cells currently being investigated, (2) outline the status of current trials, and (3) discuss key objectives of future research.

Potential for stem cell use in congenital heart disease

This article reports on the evolving field of stem cell therapy and its impact on the management of cardiac pathology, in particular congenital heart disease. To date, stem cell therapy has focused on cardiomyoplasty for heart muscle disease, stem cell therapies are already in clinical use for these disorders. Research is now also supporting the potential role of stem cell therapy for congenital heart disease. In the future it may be possible to use stem cells to create cellular grafts and structures that may be surgically implanted into the disordered heart using bioengineering technology. Different types of stem cells have been evaluated and the identification of specific cardiac stem cells offers great potential. Preliminary animal studies investigating fetal cardiac therapies are also underway. These new directions for stem cell research provide exciting potential for the future management of congenital heart disease.

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.

Cardiac regeneration therapy: connections to cardiac physiology

Without heart transplantation, a large number of patients with failing hearts worldwide face poor outcomes. By means of cardiomyocyte regeneration, cardiac regeneration therapy is emerging with great promise as a means for restoring loss of cardiac function. However, the limited success of clinical trials using bone marrow-derived cells and myoblasts with heterogeneous constituents, transplanted at a wide range of cell doses, has led to disagreement on the efficacy of cell therapy. It is therefore essential to reevaluate the evidence for the efficacy of cell-based cardiac regeneration therapy, focusing on targets, materials, and methodologies. Meanwhile, the revolutionary innovation of cardiac regeneration therapy is sorely needed to help the millions of people who suffer heart failure from acquired loss of cardiomyocytes. Cardiac regeneration has been used only in limited species or as a developing process in the rodent heart; now, the possibility of cardiomyocyte turnover in the human heart is being revisited. In the pursuit of this concept, the use of cardiac stem/progenitor stem cells in the cardiac niche must be focused to usher in a second era of cardiac regeneration therapy for the severely injured heart. In addition, tissue engineering and cellular reprogramming will advance the next era of treatment that will enable current cell-based therapy to progress to "real" cardiac regeneration therapy. Although many barriers remain, the prevention of refractory heart failure through cardiac regeneration is now becoming a realistic possibility.

Tracking stem cells for cardiovascular applications in vivo: focus on imaging techniques

Despite rapid translation of stem cell therapy into clinical practice, the treatment of cardiovascular disease using embryonic stem cells, adult stem and progenitor cells or induced pluripotent stem cells has not yielded satisfactory results to date. Noninvasive stem cell imaging techniques could provide greater insight into not only the therapeutic benefit, but also the fundamental mechanisms underlying stem cell fate, migration, survival and engraftment in vivo. This information could also assist in the appropriate choice of stem cell type(s), delivery routes and dosing regimes in clinical cardiovascular stem cell trials. Multiple imaging modalities, such as MRI, PET, SPECT and CT, have emerged, offering the ability to localize, monitor and track stem cells in vivo. This article discusses stem cell labeling approaches and highlights the latest cardiac stem cell imaging techniques that may help clinicians, research scientists or other healthcare professionals select the best cellular therapeutics for cardiovascular disease management.

In vivo imaging and monitoring of transplanted stem cells: clinical applications

Regenerative medicine using stem cells has appeared as a potential therapeutic alternative for coronary artery disease, and stem cell clinical studies are currently on their way. However, initial results of these studies have provided mixed information, in part because of the inability to correlate organ functional information with the presence/absence of transplanted stem cells. Recent advances in molecular biology and imaging have allowed the successful noninvasive monitoring of transplanted stem cells in the living subject. In this article, different imaging strategies (direct labeling, indirect labeling with reporter genes) to study the viability and biology of stem cells are discussed. In addition, the limitations of each approach and imaging modality (eg, single photon emission computed tomography, positron emission tomography, and MRI) and their requirements for clinical use are addressed. Use of these strategies will be critical as the different regenerative therapies are being tested for clinical use.

Mesenchymal chondroprogenitor cell origin and therapeutic potential

Mesenchymal progenitor cells, a multipotent adult stem cell population, have the ability to differentiate into cells of connective tissue lineages, including fat, cartilage, bone and muscle, and therefore generate a great deal of interest for their potential use in regenerative medicine. During development, endochondral bone is formed from a template of cartilage that transforms into bone; however, mature articular cartilage remains in the articulating joints, where its principal role is reducing friction and dispersing mechanical load. Articular cartilage is prone to damage from sports injuries or ageing, which regularly progresses to more serious joint disorders, such as osteoarthritis. Osteoarthritis is a degenerative joint disease characterized by the thinning and eventual wearing of articular cartilage, and affects millions of people worldwide. Due to low chondrocyte motility and proliferative rates, and complicated by the absence of blood vessels, cartilage has a limited ability to self-repair. Current pharmaceutical and surgical interventions fail to generate repair tissue with the mechanical and cellular properties of native host cartilage. The long-term success of cartilage repair will therefore depend on regenerative methodologies resulting in the restoration of articular cartilage that closely duplicates the native tissue. For cell-based therapies, the optimal cell source must be readily accessible with easily isolated, abundant cells capable of collagen type II and sulfated proteoglycan production in appropriate proportions. Although a cell source with these therapeutic properties remains elusive, mesenchymal chondroprogenitors retain their expansion capacity with the promise of reproducing the structural or biomechanical properties of healthy articular cartilage. As current knowledge regarding chondroprogenitors is relatively limited, this review will focus on their origin and therapeutic application.

Randomized controlled trials on the therapeutic effects of adult progenitor cells for myocardial infarction: meta-analysis

OBJECTIVE

We performed a systematic meta-analysis to assess the therapeutic effects of progenitor cell therapy after myocardial infarction (MI).

RESEARCH DESIGN/METHODS

Randomized controlled trials of progenitor cell therapy for MI were extracted from MEDLINE. We performed a prospective comparison of progenitor cell therapy versus placebo after acute or chronic MI, with changes in left ventricular ejection fraction (LVEF) as the primary endpoint. We conducted random-effects meta-analyses to pool these outcomes across the studies.

RESULTS

A total of 980 patients from 18 studies were analysed. Seventeen trials used bone marrow-derived cells (BMCs). Overall, BMCs significantly increased LVEF, left ventricular end systolic volume and left ventricular end diastolic volume within six months of treatment, and the effect was sustained one year later. Following BMC transplantation regional myocardial anatomy displayed statistically and clinically significant improvements compared with controls, albeit without functional changes. Similar results were observed in the subgroup of patients with impaired LVEF at the baseline. The subgroup analysis suggested a benefit of BMCs on LVEF in acute but not chronic MI. LVEF enhancement seemed to correlate positively with dose and inversely with the storage duration of the BMCs.

CONCLUSIONS

BMC transplantation for MI was able to deliver benefits over regular therapy even at an 18-month follow-up, particularly when used to treat acute MI. CD34(+) cell therapy holds promise for MI treatment in the future.

Role of the renin angiotensin system on bone marrow-derived stem cell function and its impact on skeletal muscle angiogenesis

Autologous bone marrow cell (BMC) transplantation has been shown as a potential approach to treat various ischemic diseases. However, under many conditions BMC dysfunction has been reported, leading to poor cell engraftment and a failure of tissue revascularization. We have previously shown that skeletal muscle angiogenesis induced by electrical stimulation (ES) is impaired in the SS/Mcwi rats and that this effect is related to a dysregulation of the renin angiotensin system (RAS) that is normalized by the replacement of chromosome 13 derived from the Brown Norway rat (SS-13(BN)/Mcwi consomic rats). The present study explored bone marrow-derived endothelial cell (BM-EC) function in the SS/Mcwi rat and its impact on skeletal muscle angiogenesis induced by ES. SS/Mcwi rats were randomized to receive BMC from: SS/Mcwi; SS-13(BN)/Mcwi; SS/Mcwi rats infused with saline or ANG II (3 ng kg(-1) min(-1)). BMC were injected in the stimulated tibialis anterior muscle of SS/Mcwi rats. Vessel density was evaluated in unstimulated and stimulated muscles after 7 days of ES. BMC isolated from SS/Mcwi or SS/Mcwi rats infused with saline failed to restore angiogenesis induced by ES. However, BMC isolated from SS-13(BN)/Mcwi and SS/Mcwi rats infused with ANG II effectively restored the angiogenesis response in the SS/Mcwi recipient. Furthermore, ANG II infusion increased the capacity of BM-EC to induce endothelial cell tube formation in vitro and slightly increased VEGF protein expression. This study suggests that dysregulation of the RAS in the SS/Mcwi rat contributes to impaired BM-EC function and could impact the angiogenic therapeutic potential of BMC.

Acute homing of bone marrow-derived mononuclear cells in intramyocardial vs. intracoronary transplantation

OBJECTIVES

Cell homing optimisation after transplantation is critical in myocardial infarction (MI) cell therapy.

DESIGN

Eight pigs were randomized to receiving autologous purified (111)indium-labeled bone marrow mononuclear cells (BMMCs) (10(8) cells/2 ml) by intramyocardial (IM) (n=4) or by intracoronary (IC) (n=4) transplantation after 90 minutes occlusion of the CX-coronary artery. Dual isotope SPECT imaging was performed 2 and 24 hours postoperatively. Two animals were additionally analyzed on the sixth postoperative day. Tissue samples from the major organs were analyzed.

RESULTS

In SPECT imaging revealed that BMMCs administered using IM injection remained in the injured area. In contrast, minor proportion of IC transplanted cells remained in the myocardium, as most of the cells showed homing in the lungs. Analysis of the biopsies showed a seven-fold greater number of cells in the myocardium for the IM method and a 10-fold greater number of cells in the lungs in the IC group (p < 0.001).

CONCLUSIONS

In producing persistently high cell homing at the infarction site, the IM transplantation is superior to the IC transplantation. However, the IC administration might be more specific in targeting injured capillaries and epithelial cells within the infarcted myocardium.

Predifferentiated Adult Stem Cells and Matrices for Cardiac Cell Therapy

Stem cell therapy is a major field of research worldwide, with increasing clinical application, especially in cardiovascular pathology. However, the best stem cell source and type with optimal safety for functional engraftment remains unclear. An intermediate cardiac precommitted phenotype expressing some of the key proteins of a mature cardiomyocyte would permit better integration into the cardiac environment. The predifferentiated cells would receive signals from the environment, thus achieving gradual and complete differentiation. In cell transplantation, survival and engraftment within the environment of the ischemic myocardium represents a challenge for all types of cells, regardless of their state of differentiation. An alternative strategy is to embed cells in a 3-dimensional structure replicating the extracellular matrix, which is crucial for full tissue restoration and prevention of ventricular remodeling. The clinical translation of cell therapy requires avoidance of potentially harmful drugs and cytokines, and rapid off-the-shelf availability of cells. The combination of predifferentiated cells with a functionalized scaffold, locally releasing molecules tailored to promote in-situ completion of differentiation and improve homing, survival, and function, could be an exciting approach that might circumvent the potential undesired effects of growth factor administration and improve tissue restoration.

Endothelial progenitor cells and cardiovascular cell-based therapies

Since their initial discovery more than a decade ago, bone marrow (BM)-derived circulating endothelial progenitor cells (EPC) have been reported to play a role in postnatal vasculogenesis through vessel regeneration and remodeling. These cells have been reported to mobilize into the blood stream in response to vascular injury, and differentiate into cells expressing a host of endothelial cell (EC) markers in vitro. Because of demonstrable regenerative capacity in animal models of human disease, EPC are thought to represent a novel treatment option for problematic cardiovascular conditions such as myocardial infarction (MI) and peripheral vascular disease (PVD). Various studies have been performed to test the clinical efficacy of EPC in patients with cardiovascular disease (CVD), including the mobilization of EPC with pharmacologic agents in patients with heart disease, and harvesting of cells from the circulation and BM for autologous reinfusion in affected patients. The outcomes of these trials have been mixed and not as robust as predicted from the animal models, partly because of the variation in the definition of human EPC and the resulting heterogeneity in cell populations used in the treatments. This review will decipher a number of published studies that have been conducted to examine cell therapies for treatment of CVD, will attempt to explain why efficacy of treatment with putative EPC has been inconsistent, and predict which aspects of these trials may need to be redesigned for future successful treatment of CVD.

Stem cell therapy for cardiac repair: benefits and barriers

Cardiovascular disease remains the leading cause of death worldwide. Acute ischaemic injury and chronic cardiomyopathies lead to permanent loss of cardiac tissue and ultimately heart failure. Current therapies aim largely to attenuate the pathological remodelling that occurs after injury and to reduce risk factors for cardiovascular disease. Studies in animal models indicate that transplantation of mesenchymal stem cells, bone-marrow-derived haematopoietic stem cells, skeletal myoblasts, or embryonic stem cells has the potential to improve the function of ventricular muscle after ischaemic injury. Clinical trials using primarily bone-marrow-derived cells and skeletal myoblasts have also produced some encouraging results. However, the current experimental evidence suggests that the benefits of cell therapy are modest, the generation of new cardiac tissue is low, and the predominant mechanisms of action of transplanted stem cells involve favourable paracrine effects on injured myocardium. Recent studies show that the adult heart possesses various pools of putative resident stem cells, raising the hope that these cells can be isolated for therapy or manipulated in vivo to improve the healing of cardiac muscle after injury. This article reviews the properties and potential of the various stem cell populations for cardiac repair and regeneration as well as the barriers that might lie ahead.

Cell tracking and therapy evaluation of bone marrow monocytes and stromal cells using SPECT and CMR in a canine model of myocardial infarction

BACKGROUND

The clinical application of stem cell therapy for myocardial infarction will require the development of methods to monitor treatment and pre-clinical assessment in a large animal model, to determine its effectiveness and the optimum cell population, route of delivery, timing, and flow milieu.

OBJECTIVES

To establish a model for a) in vivo tracking to monitor cell engraftment after autologous transplantation and b) concurrent measurement of infarct evolution and remodeling.

METHODS

We evaluated 22 dogs (8 sham controls, 7 treated with autologous bone marrow monocytes, and 7 with stromal cells) using both imaging of 111Indium-tropolone labeled cells and late gadolinium enhancement CMR for up to12 weeks after a 3 hour coronary occlusion. Hearts were also examined using immunohistochemistry for capillary density and presence of PKH26 labeled cells.

RESULTS

In vivo Indium imaging demonstrated an effective biological clearance half-life from the injection site of ~5 days. CMR demonstrated a pattern of progressive infarct shrinkage over 12 weeks, ranging from 67-88% of baseline values with monocytes producing a significant treatment effect. Relative infarct shrinkage was similar through to 6 weeks in all groups, following which the treatment effect was manifest. There was a trend towards an increase in capillary density with cell treatment.

CONCLUSION

This multi-modality approach will allow determination of the success and persistence of engraftment, and a correlation of this with infarct size shrinkage, regional function, and left ventricular remodeling. There were overall no major treatment effects with this particular model of transplantation immediately post-infarct.

Metabolic modulation and cellular therapy of cardiac dysfunction and failure

At present the prevalence of heart failure rises along with aging of the population. Current heart failure therapeutic options are directed towards disease prevention via neurohormonal antagonism (β-blockers, angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers and aldosterone antagonists), symptomatic treatment with diuretics and digitalis and use of biventricular pacing and defibrillators in a special subset of patients. Despite these therapies and device interventions heart failure remains a progressive disease with high mortality and morbidity rates. The number of patients who survive to develop advanced heart failure is increasing. These patients require new therapeutic strategies. In this review two of emerging therapies in the treatment of heart failure are discussed: metabolic modulation and cellular therapy. Metabolic modulation aims to optimize the myocardial energy utilization via shifting the substrate utilization from free fatty acids to glucose. Cellular therapy on the other hand has the goal to achieve true cardiac regeneration. We review the experimental data that support these strategies as well as the available pharmacological agents for metabolic modulation and clinical application of cellular therapy.

Age and stress related phenotypical changes in bone marrow CD34+ cells

OBJECTIVE

Phenotypical changes in the human bone marrow (BM) due to age and stress have not so far been properly addressed in the literature. In the present study, we compared CD34(+) BM cells between older and young volunteers. The influence of stress on CD34(+) cell phenotype in older patients was investigated in an age-matched group with acute myocardial infarction (AMI). Cytokines thought to influence BM CD34(+) cell homeostasis were also analysed.

MATERIAL AND METHODS

BM mononuclear cells of 10 older volunteers and of 7 young volunteers (18-25 years), as well as 22 AMI patients, were analysed by flow cytometry for the following markers: CD34, CD38, CD117 (c-kit) and CD133. Blood samples were analysed for CRP, IL-6, MCP-1, IL-8, MMP-9, TIMP-1 and TNFalpha by ELISA methods.

RESULTS

Significantly higher numbers of CD34(+) CD38(-) cells (both absolute and relative) were observed in older volunteers than in young volunteers and AMI patients. Higher numbers of immature progenitors, namely CD34(+)CD38(-) cells and CD34(+)CD38(-)CD117(+)CD133(+) cells, were observed among older volunteers compared to the other groups. However, the relative number of CD34(+) cells lacking CD38 expression or expressing CD133 was higher in the old volunteers and AMI patients. None of the circulating factors investigated correlated with any of the cell population yields.

CONCLUSION

In this study, we found that the absolute and relative numbers of BM CD34(+)CD38(-) progenitor cells increase with age. The increment is attenuated in patients with AMI.

Recovery and functional activity of mononuclear bone marrow and peripheral blood cells after different cell isolation protocols used in clinical trials for cell therapy after acute myocardial infarction

AIMS

Clinical trials showed contradictory results in functional recovery after intracoronary infusion of autologous mononuclear (bone marrow) cells in patients with acute myocardial infarction. A recent study suggests that this might be related to the isolation protocol used. In The Netherlands, a comparable randomised multicentre trial (HEBE) was designed. To validate the isolation method of bone marrow and peripheral blood-derived mononuclear cells, we compared our processing protocol with methods comparable to the ASTAMI (no beneficial effect) and the REPAIR-AMI study (beneficial effect).

METHODS AND RESULTS

The effect of several factors (density gradient, washing buffer and centrifugation speed) has been studied on recovery and function (migration and clonogenic capacity) of mononuclear cells. Significantly lower cell recoveries were found at a centrifugation speed of 250 g, compared to 600 or 800 g, respectively. Furthermore, washing buffer without supplemented human serum albumin and heparin resulted in significantly lower cell recovery and functional impairment as measured by clonogenic capacity.

CONCLUSIONS

The results of our study justify the cell-processing protocol as applied in the HEBE trial (600 g, human serum albumin supplemented washing buffer). This protocol results in viable and functional cells of which the quantity and quality is at least comparable to a successful study like the REPAIR-AMI.

Cardiogenesis and the complex biology of regenerative cardiovascular medicine

The heart is a complex organ system composed of a highly diverse set of muscle and nonmuscle cells. Understanding the pathways that drive the formation, migration, and assembly of these cells into the heart muscle tissue, the pacemaker and conduction system, and the coronary vasculature is a central problem in developmental biology. Efforts to unravel the biological complexity of in vivo cardiogenesis have identified a family of closely related multipotent cardiac progenitor cells. These progenitors must respond to non-cell-autonomous signaling cues to expand, differentiate, and ultimately integrate into the three-dimensional heart structures. Coupling tissue-engineering technologies with patient-specific cardiac progenitor biology holds great promise for the development of human cell models of human disease and may lay the foundation for novel approaches in regenerative cardiovascular medicine.