Vasileios Karantalis

Transendocardial Mesenchymal Stem Cells and Mononuclear Bone Marrow Cells for Ischemic Cardiomyopathy: The TAC-HFT Randomized Trial

IMPORTANCE Whether culture-expanded mesenchymal stem cells or whole bone marrow mononuclear cells are safe and effective in chronic ischemic cardiomyopathy is controversial. OBJECTIVE To demonstrate the safety of transendocardial stem cell injection with autologous mesenchymal stem cells (MSCs) and bone marrow mononuclear cells (BMCs) in patients with ischemic cardiomyopathy. DESIGN, SETTING, AND PATIENTS A phase 1 and 2 randomized, blinded, placebo-controlled study involving 65 patients with ischemic cardiomyopathy and left ventricular (LV) ejection fraction less than 50% (September 1, 2009-July 12, 2013). The study compared injection of MSCs (n=19) with placebo (n = 11) and BMCs (n = 19) with placebo (n = 10), with 1 year of follow-up. INTERVENTIONS Injections in 10 LV sites with an infusion catheter. MAIN OUTCOMES AND MEASURES Treatment-emergent 30-day serious adverse event rate defined as a composite of death, myocardial infarction, stroke, hospitalization for worsening heart failure, perforation, tamponade, or sustained ventricular arrhythmias. RESULTS No patient had a treatment-emergent serious adverse events at day 30. The 1-year incidence of serious adverse events was 31.6% (95% CI, 12.6% to 56.6%) for MSCs, 31.6% (95% CI, 12.6%-56.6%) for BMCs, and 38.1% (95% CI, 18.1%-61.6%) for placebo. Over 1 year, the Minnesota Living With Heart Failure score improved with MSCs (-6.3; 95% CI, -15.0 to 2.4; repeated measures of variance, P=.02) and with BMCs (-8.2; 95% CI, -17.4 to 0.97; P=.005) but not with placebo (0.4; 95% CI, -9.45 to 10.25; P=.38). The 6-minute walk distance increased with MSCs only (repeated measures model, P = .03). Infarct size as a percentage of LV mass was reduced by MSCs (-18.9%; 95% CI, -30.4 to -7.4; within-group, P = .004) but not by BMCs (-7.0%; 95% CI, -15.7% to 1.7%; within-group, P = .11) or placebo (-5.2%; 95% CI, -16.8% to 6.5%; within-group, P = .36). Regional myocardial function as peak Eulerian circumferential strain at the site of injection improved with MSCs (-4.9; 95% CI, -13.3 to 3.5; within-group repeated measures, P = .03) but not BMCs (-2.1; 95% CI, -5.5 to 1.3; P = .21) or placebo (-0.03; 95% CI, -1.9 to 1.9; P = .14). Left ventricular chamber volume and ejection fraction did not change. CONCLUSIONS AND RELEVANCE Transendocardial stem cell injection with MSCs or BMCs appeared to be safe for patients with chronic ischemic cardiomyopathy and LV dysfunction. Although the sample size and multiple comparisons preclude a definitive statement about safety and clinical effect, these results provide the basis for larger studies to provide definitive evidence about safety and to assess efficacy of this new therapeutic approach. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00768066.

Autologous Mesenchymal Stem Cells Produce Concordant Improvements in Regional Function, Tissue Perfusion, and Fibrotic Burden When Administered to Patients Undergoing Coronary Artery Bypass Grafting The Prospective Randomized Study of Mesenchymal Stem Cell Therapy in Patients Undergoing Cardiac Surgery (PROMETHEUS) Trial

Rationale: Although accumulating data support the efficacy of intramyocardial cell-based therapy to improve left ventricular (LV) function in patients with chronic ischemic cardiomyopathy undergoing CABG, the underlying mechanism and impact of cell injection site remain controversial. Mesenchymal stem cells (MSCs) improve LV structure and function through several effects including reducing fibrosis, neoangiogenesis, and neomyogenesis. Objective: To test the hypothesis that the impact on cardiac structure and function after intramyocardial injections of autologous MSCs results from a concordance of prorecovery phenotypic effects. Methods and Results: Six patients were injected with autologous MSCs into akinetic/hypokinetic myocardial territories not receiving bypass graft for clinical reasons. MRI was used to measure scar, perfusion, wall thickness, and contractility at baseline, at 3, 6, and 18 months and to compare structural and functional recovery in regions that received MSC injections alone, revascularization alone, or neither. A composite score of MRI variables was used to assess concordance of antifibrotic effects, perfusion, and contraction at different regions. After 18 months, subjects receiving MSCs exhibited increased LV ejection fraction (+9.4±1.7%, P=0.0002) and decreased scar mass (−47.5±8.1%; P<0.0001) compared with baseline. MSC-injected segments had concordant reduction in scar size, perfusion, and contractile improvement (concordant score: 2.93±0.07), whereas revascularized (0.5±0.21) and nontreated segments (−0.07±0.34) demonstrated nonconcordant changes (P<0.0001 versus injected segments). Conclusions: Intramyocardial injection of autologous MSCs into akinetic yet nonrevascularized segments produces comprehensive regional functional restitution, which in turn drives improvement in global LV function. These findings, although inconclusive because of lack of placebo group, have important therapeutic and mechanistic hypothesis-generating implications. Clinical Trial Registration: URL: http://clinicaltrials.gov/show/NCT00587990. Unique identifier: NCT00587990.

Use of Mesenchymal Stem Cells for Therapy of Cardiac Disease

Despite substantial clinical advances over the past 65 years, cardiovascular disease remains the leading cause of death in America. The past 15 years has witnessed major basic and translational interest in the use of stem and precursor cells as a therapeutic agent for chronically injured organs. Among the cell types under investigation, adult mesenchymal stem cells are widely studied, and in early stage, clinical studies show promise for repair and regeneration of cardiac tissues. The ability of mesenchymal stem cells to differentiate into mesoderm- and nonmesoderm-derived tissues, their immunomodulatory effects, their availability, and their key role in maintaining and replenishing endogenous stem cell niches have rendered them one of the most heavily investigated and clinically tested type of stem cell. Accumulating data from preclinical and early phase clinical trials document their safety when delivered as either autologous or allogeneic forms in a range of cardiovascular diseases, but also importantly define parameters of clinical efficacy that justify further investigation in larger clinical trials. Here, we review the biology of mesenchymal stem cells, their interaction with endogenous molecular and cellular pathways, and their modulation of immune responses. Additionally, we discuss factors that enhance their proliferative and regenerative ability and factors that may hinder their effectiveness in the clinical setting.

Cell-based therapy for prevention and reversal of myocardial remodeling

Although pharmacological and interventional advances have reduced the morbidity and mortality of ischemic heart disease, there is an ongoing need for novel therapeutic strategies that prevent or reverse progressive ventricular remodeling following myocardial infarction, the process that forms the substrate for ventricular failure. The development of cell-based therapy as a strategy to repair or regenerate injured tissue offers extraordinary promise for a powerful anti-remodeling therapy. In this regard, the field of cell therapy has made major advancements in the past decade. Accumulating data from preclinical studies have provided novel insights into stem cell engraftment, differentiation, and interactions with host cellular elements, as well as the effectiveness of various methods of cell delivery and accuracy of diverse imaging modalities to assess therapeutic efficacy. These findings have in turn guided rationally designed translational clinical investigations. Collectively, there is a growing understanding of the parameters that underlie successful cell-based approaches for improving heart structure and function in ischemic and other cardiomyopathies.

Myocardial infarction and intramyocardial injection models in swine

Sustainable and reproducible large animal models that closely replicate the clinical sequelae of myocardial infarction (MI) are important for the translation of basic science research into bedside medicine. Swine are well accepted by the scientific community for cardiovascular research, and they represent an established animal model for preclinical trials for US Food and Drug Administration (FDA) approval of novel therapies. Here we present a protocol for using porcine models of MI created with a closed-chest coronary artery occlusion-reperfusion technique. This creates a model of MI encompassing the anteroapical, lateral and septal walls of the left ventricle. This model infarction can be easily adapted to suit individual study design and enables the investigation of a variety of possible interventions. This model is therefore a useful tool for translational research into the pathophysiology of ventricular remodeling and is an ideal testing platform for novel biological approaches targeting regenerative medicine. This model can be created in approximately 8–10 h.

Does Transendocardial Injection of Mesenchymal Stem Cells Improve Myocardial Function Locally or Globally? An Analysis From the Percutaneous Stem Cell Injection Delivery Effects on Neomyogenesis (POSEIDON) Randomized Trial

Rationale: Transendocardial stem cell injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the effect of the injection site remains unknown. Objective: To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in noninjected segments. Methods and Results: Biplane ventriculographic and endocardial tracings were recorded. TESI was guided to 10 sites in infarct-border zones. Sites were mapped according to the 17-myocardial segment model. As a result, 510 segments were analyzed in 30 patients before and 13 months after TESI. Segmental early enhancement defect (a measure of scar size) was reduced by TESI in both injected (−43.7±4.4%; n=95; P<0.01) and noninjected segments (−25.1±7.8%; n=148; P<0.001; between-group comparison P<0.05). Conversely, segmental ejection fraction (a measure of contractile performance) improved in injected scar segments (19.9±3.3–26.3±3.5%; P=0.003) but not in noninjected scar segments (21.3±2.6–23.5±3.2%; P=0.20; between-group comparison P<0.05). Furthermore, segmental ejection fraction in injected scar segments improved to a greater degree in patients with baseline segmental ejection fraction <20% (12.1±1.2–19.9±2.7%; n=18; P=0.003), versus <20% (31.7±3.4–35.5±3.3%; n=12; P=0.33, between-group comparison P<0.0001). Conclusions: These findings illustrate a dichotomy in regional responses to TESI. Although scar size reduction was evident in all scar segments, scar size reduction and ventricular functional responses preferentially occurred at the sites of TESI versus non-TESI sites. Furthermore, improvement was greatest when segmental left ventricular dysfunction was severe.Rationale: Transendocardial stem cell injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the effect of the injection site remains unknown. Objective: To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in noninjected segments. Methods and Results: Biplane ventriculographic and endocardial tracings were recorded. TESI was guided to 10 sites in infarct-border zones. Sites were mapped according to the 17-myocardial segment model. As a result, 510 segments were analyzed in 30 patients before and 13 months after TESI. Segmental early enhancement defect (a measure of scar size) was reduced by TESI in both injected (−43.7±4.4%; n=95; P <0.01) and noninjected segments (−25.1±7.8%; n=148; P <0.001; between-group comparison P <0.05). Conversely, segmental ejection fraction (a measure of contractile performance) improved in injected scar segments (19.9±3.3–26.3±3.5%; P =0.003) but not in noninjected scar segments (21.3±2.6–23.5±3.2%; P =0.20; between-group comparison P <0.05). Furthermore, segmental ejection fraction in injected scar segments improved to a greater degree in patients with baseline segmental ejection fraction <20% (12.1±1.2–19.9±2.7%; n=18; P =0.003), versus <20% (31.7±3.4–35.5±3.3%; n=12; P =0.33, between-group comparison P <0.0001). Conclusions: These findings illustrate a dichotomy in regional responses to TESI. Although scar size reduction was evident in all scar segments, scar size reduction and ventricular functional responses preferentially occurred at the sites of TESI versus non-TESI sites. Furthermore, improvement was greatest when segmental left ventricular dysfunction was severe. # Novelty and Significance {#article-title-37}

Does Transendocardial Injection of Mesenchymal Stem Cells Improve Myocardial Function Locally or Globally? An Analysis From the POSEIDON Randomized Trial

Rationale: Transendocardial stem cell injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the effect of the injection site remains unknown. Objective: To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in noninjected segments. Methods and Results: Biplane ventriculographic and endocardial tracings were recorded. TESI was guided to 10 sites in infarct-border zones. Sites were mapped according to the 17-myocardial segment model. As a result, 510 segments were analyzed in 30 patients before and 13 months after TESI. Segmental early enhancement defect (a measure of scar size) was reduced by TESI in both injected (−43.7±4.4%; n=95; P<0.01) and noninjected segments (−25.1±7.8%; n=148; P<0.001; between-group comparison P<0.05). Conversely, segmental ejection fraction (a measure of contractile performance) improved in injected scar segments (19.9±3.3–26.3±3.5%; P=0.003) but not in noninjected scar segments (21.3±2.6–23.5±3.2%; P=0.20; between-group comparison P<0.05). Furthermore, segmental ejection fraction in injected scar segments improved to a greater degree in patients with baseline segmental ejection fraction <20% (12.1±1.2–19.9±2.7%; n=18; P=0.003), versus <20% (31.7±3.4–35.5±3.3%; n=12; P=0.33, between-group comparison P<0.0001). Conclusions: These findings illustrate a dichotomy in regional responses to TESI. Although scar size reduction was evident in all scar segments, scar size reduction and ventricular functional responses preferentially occurred at the sites of TESI versus non-TESI sites. Furthermore, improvement was greatest when segmental left ventricular dysfunction was severe.Rationale: Transendocardial stem cell injection (TESI) with mesenchymal stem cells improves remodeling in chronic ischemic cardiomyopathy, but the effect of the injection site remains unknown. Objective: To address whether TESI exerts its effects at the site of injection only or also in remote areas, we hypothesized that segmental myocardial scar and segmental ejection fraction improve to a greater extent in injected than in noninjected segments. Methods and Results: Biplane ventriculographic and endocardial tracings were recorded. TESI was guided to 10 sites in infarct-border zones. Sites were mapped according to the 17-myocardial segment model. As a result, 510 segments were analyzed in 30 patients before and 13 months after TESI. Segmental early enhancement defect (a measure of scar size) was reduced by TESI in both injected (−43.7±4.4%; n=95; P <0.01) and noninjected segments (−25.1±7.8%; n=148; P <0.001; between-group comparison P <0.05). Conversely, segmental ejection fraction (a measure of contractile performance) improved in injected scar segments (19.9±3.3–26.3±3.5%; P =0.003) but not in noninjected scar segments (21.3±2.6–23.5±3.2%; P =0.20; between-group comparison P <0.05). Furthermore, segmental ejection fraction in injected scar segments improved to a greater degree in patients with baseline segmental ejection fraction <20% (12.1±1.2–19.9±2.7%; n=18; P =0.003), versus <20% (31.7±3.4–35.5±3.3%; n=12; P =0.33, between-group comparison P <0.0001). Conclusions: These findings illustrate a dichotomy in regional responses to TESI. Although scar size reduction was evident in all scar segments, scar size reduction and ventricular functional responses preferentially occurred at the sites of TESI versus non-TESI sites. Furthermore, improvement was greatest when segmental left ventricular dysfunction was severe. # Novelty and Significance {#article-title-37}

Effect of Aging on Human Mesenchymal Stem Cell Therapy in Ischemic Cardiomyopathy Patients

BACKGROUND The role of patient age in the efficacy of mesenchymal stem cell (MSC) therapy in ischemic cardiomyopathy (ICM) is controversial. OBJECTIVES This study sought to determine whether the therapeutic effect of culture-expanded MSCs persists, even in older subjects. METHODS Patients with ICM who received MSCs via transendocardial stem cell injection (TESI) as part of the TAC-HFT (Transendocardial Autologous Cells in Ischemic Heart Failure) (n = 19) and POSEIDON (Percutaneous Stem Cell Injection Delivery Effects on Neomyogenesis) (n = 30) clinical trials were divided into 2 age groups: younger than 60 and 60 years of age and older. Functional capacity was measured by 6-min walk distance (6MWD) and quality of life using the Minnesota Living With Heart Failure Questionnaire (MLHFQ) score, measured at baseline, 6 months, and 1 year post-TESI. Various cardiac imaging parameters, including absolute scar size, were compared at baseline and 1 year post-TESI. RESULTS The mean 6MWD was similar at baseline and increased at 1 year post-TESI in both groups: 48.5 ± 14.6 m (p = 0.001) for the younger and 35.9 ± 18.3 m (p = 0.038) for the older participants (p = NS between groups). The older group exhibited a significant reduction in MLHFQ score (-7.04 ± 3.54; p = 0.022), whereas the younger than 60 age group had a borderline significant reduction (-11.22 ± 5.24; p = 0.058) from baseline (p = NS between groups). Although there were significant reductions in absolute scar size from baseline to 1 year post-TESI, the effect did not differ by age. CONCLUSIONS MSC therapy with TESI in ICM patients improves 6MWD and MLHFQ score and reduces myocardial infarction size. Importantly, older individuals did not have an impaired response to MSC therapy.

Allogeneic Cell Therapy: A New Paradigm in Therapeutics

Cell-based therapy is at the forefront of clinical investigation for cardiovascular disease, backed by over a decade of rigorous preclinical study of cell biology, mechanism(s) of action, immunology, and phenotypic efficacy.1 After early proof-of-concept and safety clinical trials,2–5 the field is entering the next phase of clinical evaluation to delineate clinical efficacy. However, several questions still need to be addressed, namely the optimal cell delivery method, cell dosage range, and cell characteristics. Importantly, translating cell therapy into standard clinical practice requires the ability to readily administer a safe and efficacious product at the optimal dosage. An opportunity that greatly enhances the ability to develop such a product is the use of allogeneic therapy, which offers an efficient way to achieve both immediate availability of product and the appropriate number of cells. Article, see p 80 Allogeneic therapy is clearly a disruptive concept in biology. Standard immunologic dogma holds that any foreign tissue will elicit an immune reaction.6 This concept is clearly evident in solid organ and hematopoietic transplantation, in which aggressive immunosuppression is the norm to protect allografts from rejection.6 As the field of cell-based therapy evolves, it has become evident that various cell types—mesenchymal stem cells (MSCs) being the prototype—have sufficient ability to evade7 or suppress8 the immune system to the extent that they may be used as allografts without requiring concomitant immunosuppression. ### Preclinical Studies More than 10 years ago, it was suggested that MSCs act as immune system modulators.9 Bartholomew et al10 performed a mixed lymphocyte reaction in which baboon MSCs were cocultured with stimulated allogeneic peripheral blood leukocytes and demonstrated that the MSCs suppressed leukocyte proliferation. Extensive studies have subsequently revealed that MSCs evade the immune system via multiple mechanisms, which include having moderate levels of human leukocyte antigen …

Nitroso-Redox Imbalance Affects Cardiac Structure and Function*

Cardiovascular diseases (CVDs) and their treatment pose a huge economic and social burden in Western societies and in the developing world (1). Thus, there is significant interest in developing new therapeutic targets, and it is of particular interest that an old class of drugs, inhibitors of xanthine oxidoreductase (XO), may be repositioned to treat heart failure and left ventricular (LV) dysfunction. In this context, there is growing awareness that nitroso-redox balance may represent a new therapeutic target for heart failure (2). However, whether or not XO inhibitors fully address nitroso-redox imbalance in all patients remains controversial. The hypothesis that XO inhibition could treat heart failure was tested in the OPT-CHF trial (3). In that study, the primary endpoint was not statistically different in the population of symptomatic heart failure patients enrolled; however patients with hyperuricemia appeared to be a responsive population. While hyperuricemia is classically associated with gout and nephropathy, it is clearly also a biomarker in heart failure populations (4-6). Uric acid (UA) is the end product of purine metabolism, involving the conversion of hypoxanthine to xanthine and then to UA in reactions catalyzed by XO (Figure 1) (7). In most mammals including rodents, UA is further degraded to allantoin via the enzyme urate oxidase (UO), resulting in low UA serum levels. In humans and great apes, however, this final step does not occur because of a single point mutation inactivating UO, resulting in substantially higher serum UA levels. Whether UA plays beneficial or deleterious roles remains controversial, and some arguments can be made that the impact of UA on vascular tone have played an evolutionary role (4). However, in hypertension, type 2 diabetes mellitus, coronary artery disease (CAD), heart failure, and chronic kidney disease (CKD), high UA levels correlate with an increased risk of stroke and CVDs (4,6,8-10) Figure 1 Increased xanthine oxidase activity and nitroso-redox imbalance As UA levels represent a biomarker of XO activity, the OPT-CHF results suggest that patients with elevated XO activity responded preferentially (3). XO is a key oxidase participating in nitroso-redox imbalance in the heart, producing superoxide as a byproduct of purine metabolism (Figure 1). Thus, the epidemiological association of high UA levels with worse prognosis in a wide cohort of patients with CVDs likely reflects the fact that UA levels rise with increased XO activity (4-10).