Cardiovascular Cell Therapy Research Network Research Articles

Microvascular obstruction identifies a subgroup of patients who benefit from stem cell therapy following ST-elevation myocardial infarction

Microvascular obstruction (MVO) is associated with greater infarct size, adverse left-ventricular (LV) remodeling and reduced ejection fraction following ST-elevation myocardial infarction (STEMI). We hypothesized that patients with MVO may constitute a subgroup of patients that would benefit from intracoronary stem cell delivery with bone marrow mononuclear cells (BMCs) given previous findings that BMCs tended to improve LV function only in patients with significant LV dysfunction. We analyzed the cardiac MRIs of 356 patients (303 M, 53 F) with anterior STEMIs who received autologous BMCs or placebo / control as part of 4 randomized clinical trials that included the Cardiovascular Cell Therapy Research Network (CCTRN) TIME trial and its pilot, the multicenter French BONAMI trial and SWISS-AMI trials. A total of 327 patients had paired imaging data at 1 year. All patients received 100 to 150 million intracoronary autologous BMCs or placebo / control 3 to 7 days following primary PCI and stenting. LV function, volumes, infarct size and MVO were assessed prior to infusion of BMCs and 1 year later. Patients with MVO (n = 210) had reduced LVEF and much greater infarct size and LV volumes compared to patients without MVO (n=146) (P < .01). At 12 months, patients with MVO who received BMCs had significantly greater recovery of LVEF compared to those patients with MVO who received placebo (absolute difference=2.7%; P < .05). Similarly, left-ventricular end-diastolic (LVEDVI) and end-systolic volume indices (LVESVI) demonstrated significantly less adverse remodeling in patients with MVO who received BMCs compared to placebo. In contrast, no improvement in LVEF or LV volumes was observed in those patients without MVO who received BMCs compared to placebo. The presence of MVO on cardiac MRI following STEMI identifies a subgroup of patients who benefit from intracoronary stem cell therapy.

Abstract 10915: Microvascular Obstruction Identifies a Subgroup of Patients Who Benefit From Intracoronary Stem Cell Delivery Following ST-Elevation Myocardial Infarction

Aims: Microvascular obstruction (MVO) following ST-elevation myocardial infarction (STEMI) is associated with greater infarct size, adverse left-ventricular (LV) remodeling and reduced ejection fraction. We hypothesized that patients with MVO may constitute a subgroup of patients that would benefit from intracoronary stem cell delivery with bone marrow mononuclear cells (BMCs) given previous findings that BMCs tended to improve LV function only in patients with significant LV dysfunction. Methods and Results: We analyzed the cardiac MRIs of 356 patients (303 M, 53 F) with anterior STEMIs who received autologous BMCs as part of 3 clinical trials that included the Cardiovascular Cell Therapy Research Network (CCTRN) TIME trial and its pilot (n=157), the multi-center French BONAMI trial (n=91) and the SWISS-AMI trial (n=108). All patients received 100 - 150 million intracoronary autologous BMCs or placebo / control 3 - 7 days following primary PCI and stenting. LV function, volumes, infarct size and MVO were assessed prior to infusion of BMCs and 1 year later. Patients with MVO (n=210) had reduced LVEF and much greater infarct size and LV volumes compared to patients without MVO (n=146) (all p &lt; 0.01) (TABLE). At 12 months, patients with MVO who received BMCs had significantly greater recovery of LVEF compared to those patients with MVO who received placebo (absolute difference = 2.7 %; p &lt; 0.05). Similarly, the changes in left-ventricular end-diastolic (LVEDV) and end-systolic volumes (LVESV) were consistent with significantly less adverse remodeling in patients with MVO who received BMCs compared to placebo ( % change; LVEDV = -9.7%; p &lt; 0.05 and LVESVI = -14.7 %; p = 0.006). In contrast, patients without MVO experienced no benefit of BMC administration compared to placebo. Conclusion: The presence of MVO on cardiac MRI following STEMI identifies a subgroup of patients who may benefit from intracoronary stem cell delivery of BMCs.

Abstract 14080: A Phase II Randomized, Double-blind, Controlled Trial of Combined Mesenchymal Stromal Cells and C-kit+ Cardiac Progenitor Cells in Ischemic Heart Failure: The CCTRN CONCERT-HF Trial

Introduction: Although preclinical studies of cell delivery in models of ischemic heart failure (HF) suggest a beneficial interaction between mesenchymal stromal cells (MSCs) and c-kit+ cardiac progenitor cells (CPCs) resulting in additive therapeutic effects, no clinical trial has examined a combination of different cell types in ischemic HF. Furthermore, comparative studies of different cell products in humans are rare. CONCERT-HF (NCT02501811) is an NHLBI-sponsored, randomized, double-blind, placebo-controlled, Phase II trial of the Cardiovascular Cell Therapy Research Network (CCTRN) investigating feasibility, safety, and efficacy of MSCs and CPCs, alone and in combination, in patients with chronic ischemic HF. Objectives: To address the following questions: Is combined treatment with MSCs and CPCs feasible and safe in patients with ischemic HF? Do MSCs and CPCs, given alone or in combination, alleviate LV dysfunction, reduce scar size, improve quality of life, and/or augment functional capacity? Is either cell type more effective than the other? Is the combination of MSCs and CPCs more efficacious than MSCs alone or CPCs alone? Methods: Patients were randomized (1:1:1:1) to receive i) the combination of autologous bone marrow-derived MSCs and autologous CPCs, ii) MSCs alone, iii) CPCs alone, or iv) placebo. Target doses were 150 x 10 6 MSCs and 5 x 10 6 CPCs. All patients underwent bone marrow aspiration and right heart catheterization. Endomyocardial biopsy was performed only in the MSC + CPC and CPC alone groups; a “sham biopsy” was performed in the MSC alone and placebo groups. All patients underwent study product injection using the NOGA ® XP Mapping System and were followed for 12 months. Results: A total of 125 patients (116 M, 9 F), 62.5 ± 8.9 years old, were enrolled at 7 CCTRN centers between Nov 2016 and Oct 2018. Baseline LVEF (cardiac MRI) was 28.6 ± 6.1% with a mean scar size of 31.8 ± 10.9 g and NYHA class II (80%) or class III (15.2%). Conclusions: CONCERT-HF is the first cell therapy trial to assess a combination of different cell types and to directly compare two different cell products in patients with HF. All patients will complete follow-up by the end of June and final primary (12-month) safety and outcomes data will be available in August 2020.

Abstract 16882: Temporal Changes in the Peripheral Blood Mononuclear Cell Populations After Acute Myocardial Infarction and Prediction of Improvement in Left Ventricular Function in the Cardiovascular Cell Therapy Research Network (CCTRN) TIME and Late-TIME Trials

Background: Despite many cell-mediated attempts to promote myocardial repair after myocardial infarction (MI), no cell treatments are currently available. Instead, cell therapy clinical results remain mixed. We hypothesized that by evaluating changes in circulating cells in improvers and non-improvers in an MI cell therapy study, we could identify cells associated with repair that might be candidates for future cell therapy studies. Methods: In this study, peripheral blood (PB) was evaluated by flow cytometry at baseline and days 1, 30, 90 and 180 after bone marrow mononuclear cell (BMMNC) or placebo therapy from 207 consented patients in the CCTRN TIME (n=120) and Late-TIME (n=87) studies. A linear mixed model was used to determine changes over time in cell frequency. Multiple regression and discriminatory analyses were used to identify if changes in circulating cells predict changes in left ventricular ejection fraction (LVEF). Results: Changes in circulating cells were observed independent of treatment group. In TIME, a progressive decrease of CD11b+ cells started at day 30 (91.69±4.57 vs. 93.23±3.97%, p&lt;0.05) and CD14+ cells began at day 90 (73.53±10.82 vs. 79.17±10.97%, p&lt;0.05) compared to baseline. In Late-TIME, there was an increase in CD11b+ (94.01±3.82 vs. 92.81±3.98%, p&lt;0.05) and CD14+ (81.70±6.64 vs. 77.94±9.29%, p&lt;0.05) cells at day 1 when compared to baseline followed by a progressive decrease in the follow-up visits. A progressive decline in CXCR4+ cells started at day 30 in TIME (35.39 ±14.81 vs. 42.86±13.83%, p&lt;0.05) and at day 1 in Late-TIME (42.81±14.33 vs. 47.74±15.13%, p&lt;0.05). In TIME, a decrease of CXCR4+ cells at day 90 was a negative predictor of changes in LVEF from baseline to six months. Conclusion: Although multiple cell frequencies changed after treatment, only one cell frequency predicted changes in LVEF from baseline to six months. A significant reduction in CXCR4+ circulatory cells at day 90 after treatment is associated with improvement in LVEF. Further studies will be necessary to confirm the changes in circulatory cells and its impact on the regenerative capacity of patients with AMI.

Meet the First Authors.

Meet the First Authors.

Spiny mouse is protected from ischemia induced cardiac injury: leading role of microRNAs

Introduction and hypothesisDespite advances in drug therapy, revascularization and surgical interventions, mortality and morbidity from heart failure in ischemic heart disease remains high and a breakthrough in our understanding of this disorder is needed. Spiny mouse (Acomys cahirinus) has evolved a remarkable capacity to regenerate full thickness skin tissue without scarring. Here we tested the hypothesis that the lack of scarring and resulting regeneration in adult Acomys skin also applies to the heart.Methods and ResultsAdult Acomys and CD1 mice had either left anterior descending coronary artery ligation or sham surgery. Proliferative cells were identified by nuclear incorporation of 5‐bromodeoxyuridine (BrdU, 50mg/kg, daily, i.p.) with injections from 3d post myocardial infarction (MI) for 2wks and cardiac function was assessed by echocardiography. Following MI, Acomys infarct size was one‐fourth (18.6±3.4%) vs CD1 (76.2±3.4%, p&lt;0.05) with 3.2 fold better systolic function (ejection fraction 77.1±6.5 vs CD1 24.6±4.6%, p&lt;0.05). Post‐MI, Acomys had 2.2‐fold more proliferating cardiomyocytes (BrdU+ cells) in their left ventricle vs CD1 mice (Acomys‐sham 16±9.8 vs Acomys‐MI 101.1±30.9: CD1‐sham 11±3.5 vs CD1‐MI 44±9.1, p&lt;0.05). We also measured the expression of miRNAs in the border zone of the infarcted hearts for both CD1 and Acomys and the corresponding zone in sham‐operated animals using small RNA‐Sequencing. We found four miRNAs that have been shown to stimulate/promote cardiomyocyte proliferation and cardiac regeneration were significantly changed in the Acomys‐MI hearts: miR410‐3p (5.2‐fold increase in Acomys‐MI relative to Acomys‐Sham, Q value=&lt;0.03), miR‐199a (miR‐199a‐3p:4.6‐fold increase in Acomys‐MI relative to Acomys‐Sham, Q value=0.0003; miR‐199a‐5p:3.5‐fold increase in Acomys‐MI relative to Acomys‐Sham, Q value=0.0088), miR‐214(miR‐214‐3p: 4.3‐fold increase in Acomys‐MI relative to Acomys‐Sham Q value=0.005; miR‐214‐5p: 4.0‐fold increase in Acomys‐MI relative to Acomys‐Sham, Q value=0.01, and let‐7f‐5p (2.0‐fold decrease in Acomys‐MI relative to Acomys‐Sham, Q value=0.02 &lt;0.05). However, these miRNAs were not different between CD1 groups. Associated with this there was a dramatic increase in coronary microvasculature in the infarct region in Acomys.ConclusionsWe conclude that the Acomys heart responds to severe ischemia‐induced cardiac damage by increasing the number of proliferating cardiomyocytes. A possible mechanism is suggested by the upregulation of expression of microRNAs known to stimulate cardiomyocyte proliferation and cardiac regeneration (miR410, −199a, −214, let‐7f), These processes regenerated cardiac cells and vastly reduced scarring and hence preserved cardiac function.Support or Funding InformationNational Institute of Health grants HL33610(M.K.R), UM1 HL087366 to the Cardiovascular Cell Therapy Research Network (C.J. Pepine). Florida Heart Foundation Stop Heart Disease (Y.F. Qi).

Baseline assessment and comparison of arterial anatomy, hyperemic flow, and skeletal muscle perfusion in peripheral artery disease: The Cardiovascular Cell Therapy Research Network “Patients with Intermittent Claudication Injected with ALDH Bright Cells” (CCTRN PACE) study

Peripheral artery disease (PAD) is important to public health as a major contributor to cardiovascular morbidity and mortality. Recent developments in magnetic resonance imaging (MRI) techniques permit improved assessment of PAD anatomy and physiology, and may serve as surrogate end points after proangiogenic therapies. The PACE study is a randomized, double-blind, placebo-controlled clinical trial designed to assess the physiologic impact and potential clinical efficacy of autologous bone marrow-derived ALDHbr stem cells. The primary MRI end points of the study are as follows: (1) total collateral count, (2) calf muscle plasma volume (a measure of capillary perfusion) by dynamic contrast-enhanced MRI, and (3) peak hyperemic popliteal flow by phase-contrast MRI (PC-MRI). The interreader and intrareader and test-retest results demonstrated good-to-excellent reproducibility (interclass correlation coefficient range 0.61-0.98) for all magnetic resonance measures. The PAD participants (n=82) had lower capillary perfusion measured by calf muscle plasma volume (3.8% vs 5.6%) and peak hyperemic popliteal flow (4.1 vs 13.5mL/s) as compared with the healthy participants (n=16), with a significant level of collateralization. Reproducibility of the MRI primary end points in PACE was very good to excellent. The PAD participants exhibited decreased calf muscle capillary perfusion as well as arterial flow reserve when compared with healthy participants. The MRI tools used in PACE may advance PAD science by enabling accurate measurement of PAD microvascular anatomy and perfusion before and after stem cell or other PAD therapies.

UK research paper of the year

The UK Research Paper of the Year category recognises outstanding research by one or more UK authors that has potential to considerably improve health and healthcare. Nigel Hawkes describes the...

Abstract 12445: A Detailed Analysis of Peripheral Blood Cytokines 2-3 weeks After Acute Myocardial Infarction: IL-6-Related Impairment of Bone Marrow Function

Background: Intracoronary infusion of bone marrow (BM) mononuclear cells (BM-MNCs) late after acute myocardial infarction (AMI) has shown no improvement in global or regional left ventricular (LV) function (LateTIME and SWISS-AMI). Studies in experimental AMI models suggest a possible cytokine-related depression of progenitor cell function. Furthermore, BM cell content is correlated with the LV functional response. Accordingly, we hypothesize that inflammatory cytokines associated with the late phase of AMI may impair BM function and alter progenitor cell subsets. Method: Patients with previous AMI (n=87) were recruited in a multicenter cell therapy trial by the Cardiovascular Cell Therapy Research Network (CCTRN LateTIME, NCT00684060). BM and peripheral blood (PB) were collected 2-3 weeks after AMI and examined for cell phenotypes and progenitor capacities as well as PB inflammatory and angiogenic cytokines in a core laboratory. Multiple regression analyses were conducted and correlations between cytokine levels and cell phenotypes, cell functions, and post-MI cardiac function were determined. BM from healthy donors, handled in the same manner, was used as a reference. Result: Of 26 cytokines analyzed, IL-6 showed a negative correlation with ECFC colony maximum in BM (estimate±SE (SEE) -0.13±0.04 P=0.007, multivariableR2: 0.59) and Healthy BM showed decreased ECFC colony outgrowth in the presence of IL-6 (P &lt;0.05), in a dose-dependent manner. PDGF-BB positively correlated with CFU-EC colony maximum in BM (SEE 0.006± 0.002, P=0.023, R2: 0.22), MSC colony maximum in BM (SEE 0.006±0.002, P=0.023, R2: 0.17) and MSC colony maximum in PB (SSE 0.018±0.005, P=0.00005, R2:0.24). No significant correlations were found between cardiac function after AMI and PB cytokine levels. Conclusions: At 2-3 weeks after AMI, PB levels of the angiogenic cytokine, PDGF-BB and the pro-inflammatory cytokine, IL-6, were associated with BM cell phenotype and function. IL-6 has the potential to impair endothelial progenitor cell capacity; inhibiting IL-6 may be a target for improving the regenerative capacity of BM cells after AMI.

Bone marrow characteristics associated with changes in infarct size after STEMI: a biorepository evaluation from the CCTRN TIME trial.

Despite significant interest in bone marrow mononuclear cell (BMC) therapy for ischemic heart disease, current techniques have resulted in only modest benefits. However, selected patients have shown improvements after autologous BMC therapy, but the contributing factors are unclear. The purpose of this study was to identify BMC characteristics associated with a reduction in infarct size after ST-segment-elevation-myocardial infarction. This prospective study comprised patients consecutively enrolled in the CCTRN TIME (Cardiovascular Cell Therapy Research Network Timing in Myocardial Infarction Evaluation) trial who agreed to have their BMCs stored and analyzed at the CCTRN Biorepository. Change in infarct size between baseline (3 days after percutaneous coronary intervention) and 6-month follow-up was measured by cardiac MRI. Infarct-size measurements and BMC phenotype and function data were obtained for 101 patients (mean age, 56.5 years; mean screening ejection fraction, 37%; mean baseline cardiac MRI ejection fraction, 45%). At 6 months, 75 patients (74.3%) showed a reduction in infarct size (mean change, -21.0±17.6%). Multiple regression analysis indicated that infarct size reduction was greater in patients who had a larger percentage of CD31(+) BMCs (P=0.046) and in those with faster BMC growth rates in colony-forming unit Hill and endothelial-colony forming cell functional assays (P=0.033 and P=0.032, respectively). This study identified BMC characteristics associated with a better clinical outcome in patients with segment-elevation-myocardial infarction and highlighted the importance of endothelial precursor activity in regenerating infarcted myocardium. Furthermore, it suggests that for these patients with segment-elevation-myocardial infarction, myocardial repair was more dependent on baseline BMC characteristics than on whether the patient underwent intracoronary BMC transplantation. http://www.clinicaltrials.gov. Unique identifier: NCT00684021.

A training program in cardiovascular cell-based therapy: from the NHLBI Cardiovascular Cell Therapy Research Network.

Stem/progenitor cell-based therapies offer novel treatment for many prevalent diseases. However, most physicians are not trained or introduced to cell therapy. We describe a model of a training program aimed at empowering physician-scientists with the knowledge and skills necessary for advancing the field of cardiovascular cell therapy. To date, five full-time scholars have completed this training program, obtained a full-time academic appointment in Cardiovascular Disease, and continue to actively contribute to the advancement of cell therapy applications. Another has returned to his parent institution to complete his PhD and several part-time scholars have continued in scholarly activities in other academic programs.

Rationale and Design for PACE: Patients with Intermittent Claudication Injected with ALDH Bright Cells

Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.

Bone marrow mononuclear cell therapy for acute myocardial infarction: a perspective from the cardiovascular cell therapy research network.

To understand the role of bone marrow mononuclear cells in the treatment of acute myocardial infarction, this overview offers a retrospective examination of strengths and limitations of 3 contemporaneous trials with attention to critical design features and provides an analysis of the combined data set and implications for future directions in cell therapy for acute myocardial infarction.

Abstract 295: The Stem Cell Therapy to Prevent Expansion of Abdominal Aortic Aneurysm (STOP-AAA) Trial: Rationale and Design

Background: Abdominal aortic aneurysm (AAA) is the 13 th leading cause of death in the United States. The only options for treatment at present for AAA are open surgical and endovascular repair, both of which are associated with significant morbidity, mortality, and expense.Thus AAA represents an unmet medical need. AAA pathogenesis is a multifactorial inflammatory process characterized by activation of T-cells,macrophages and neutrophils resulting in degradation of the aortic wall. Mesenchymal stromal cells (MSCs) suppress T-cell and macrophage activation, inhibit matrix metalloproteinases and have been shown to decrease aneurysm expansion in murine models. Methods: The STOP-AAA trial, from the NHLBI funded Cardiovascular Cell Therapy Research Network, is a randomized, double-blind, placebo-controlled trial evaluating the safety and efficacy of autologous bone marrow derived MSCs in suppressing expansion of small AAA (35-50mm).Forty patients will be randomized in a 1:1 fashion to receive systemic administration of placebo or 3 doses of 2x10 6 MSC/kg. at baseline, 24, and 52 weeks. The primary endpoint will be change in AAA diameter at 18 months as measured by a single blinded observer using contrast enhanced helical computed tomographic angiography (CTA).The secondary endpoints include time to elective repair, incidence of AAA related deaths and rupture,change in aortic mural inflammation at 18 months as quantified by F18-fluorodeoxyglucose (FDG) uptake with integrated positron emission tomography and computed tomography (PET/CT), changes in circulating mRNA, microRNA, and inflammatory cell profiles, changes in serum cytokine levels, and major adverse cardiac events. Conclusion: The STOP-AAA will be the first in man study to assess the efficacy of autologous bone marrow derived MSCs to suppress AAA expansion. Furthermore the data collected from this novel trial will provide unique mechanistic insights in the immunomodulatory properties of this stem cell population.

Dr. Sonia Skarlatos—Leader, Colleague, and Friend: From Vascular Biology to Gene Therapy and the Cardiovascular Cell Therapy Research Network

Dr. Sonia Skarlatos—Leader, Colleague, and Friend: From Vascular Biology to Gene Therapy and the Cardiovascular Cell Therapy Research Network

TCT-823 Results from LateTIME: A Randomized, Placebo Controlled Trial of Intracoronary Stem Cell Delivery Two to Three Weeks Following Acute Myocardial Infarction from the Cardiovascular Cell Therapy Research Network

Meta-analysis suggest that intracoronary (IC) administration of autologous bone marrow mononuclear cells (BMCs) delivered early after acute myocardial infarction (MI) may improve left ventricular (LV) function. However, many patients early post MI are unstable or present to sites without cell

Bone Marrow–Derived Cell Therapy After Myocardial Infarction

We would like to clarify several points in the editorial (1) accompanying our publication of the TIME report (2). First, the automated system for extracting bone marrow-derived mononuclear cells (MNCs) used for Cardiovascular Cell Therapy Research Network (CCTRN) clinical trials (2,3,4) employs Ficoll gradient centrifugation, similar to the manual method used for REPAIR AMI (5). Thus, the difference lies in improved reproducibility and standardization by the automated system, not some other fundamental characteristic. Second, our original publication erroneously listed the heparin concentration at 0.1 units/ml. In fact, no heparin was added to the automated system, and cells used in all CCTRN studies contained only residual heparin from bone marrow aspiration, estimated to be not more than 0.01 units per ml (Data Correction 6). This is five times below the lowest concentration evaluated (7) in a stromal cell-derived factor-1- (SDF-1)-stimulated invasion capacity assay, and 200-2000 times lower than heparin concentrations used in other functional assays reported by this group. Accordingly, the statement: “… the cell product used in TIME contained heparin at a dose that has been shown to impair the migratory capacity of MNCs” is no longer supported by the facts. We regret the confusion caused by our error. Third, the statement, “MNCs isolated by the automated system used in this study have not been tested in an animal model of MI, and cell bioactivity has not been verified in any human studies of heart disease” should be considered in view of the following: (a) MNCs from automated and manual preparations were found to have similar reperfusion activity in a murine hind-limb ischemia model (2); (b) A Cochrane review of stem cell studies (8) reported ten clinical trials cells were administered in a solution of “standard saline containing heparin.” Of these ten studies, we note that seven disclosed positive results (e.g., increased left ventricular ejection fraction, LVEF);(c) in the CCTRN FOCUS trial we found that LVEF increased 2.7% in patients receiving MNCs versus placebo, and that this increase was associated with higher percentages of CD34+ and CD133+ MNCs (3). Additionally, pre-clinical studies by CCTRN investigators demonstrated retention of SDF-1 migration and CFU-activity when MNCs isolated by the automated system were compared with MNCs from the manual method (unpublished observations). Thus, cell bioactivity was observed not only in one CCTRN trial (with miniscule residual heparin) but also in seven other trials in which cells were re-suspended in heparin. One explanation for this retention of bioactivity is that “…the effects of heparin can be ameliorated by excessive serum in vitro…” (7). Summarizing, the available evidence does not support the contention that bioactivity of cells administered in the TIME study was impaired by processing techniques or exposure to heparin. We believe that the TIME results are consistent with a limited effect of bone marrow cells on recovery of LV function, and support previous findings (9) demonstrating that MNCs have reduced cytokine and growth factor production compared to other bone marrow-derived stem and progenitor cells.

Mixed Results for Bone Marrow–Derived Cell Therapy for Ischemic Heart Disease

TWO EARLY-PHASE STUDIES REPORTED IN JAMA 1,2 ADdress the same general question: what is the effect of bone marrow–derived cell therapy on safety and surrogate end points in patients after myocardial infarction (MI)? Other than this thematic similarity, the Timing In Myocardial infarction Evaluation (TIME) trial and the POSEIDON trial have little in common. The TIME trial examined 120 patients with a recent (3-7 days) acute MI (AMI) and autologous mononuclear cells (MNCs) delivered via the intracoronary route with the intervention on day 3 (n=67) or on day 7 (n=53). This was a placebocontrolled, multicenter trial with a fixed dose of MNCs. The major motivation was to test the concept that timing of MNC therapy within the first week after MI influences outcome. The POSEIDON trial involved patients with ischemic cardiomyopathy after distant MIs (years earlier) and used autologous or allogeneic mesenchymal cells (MSCs) administered transendocardially via injection catheters. Two centers recruited 30 patients and randomly assigned them into 1 of 6 permutations of cell origin (self or donor) and dosage (n=5 patients each), with no controls. The goal of the trial was to compare the safety and efficacy of self-derived MSCs with donor MSCs in chronic ischemic cardiomyopathy. TIME is the latest in a series of studies from the Cardiovascular Cell Therapy Research Network (CCTRN), a consortium funded by the National Institutes of Health, which was mandated to conduct and complete trials of cell therapy within its initial 5-year funding period. Three trials (LateTIME, FOCUS-CCTRN, and now TIME) of autologous MNCs have been conducted. The goal of these trials has been to follow up on earlier positive phase 1 and 2 studies of MNCs; however, the CCTRN studies (including TIME) have all had negative results. The CCTRN used a convenient automated system for extracting MNCs from bone marrow aspirates. The older motivating studies, including the Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) multicenter trial of MNC therapy, relied instead on laborious manual Ficoll gradient centrifugation of bone marrow aspirates. TIME followed up on the subgroup analysis of REPAIR-AMI, hinting at superior functional outcomes in patients who had received MNCs more than 4 days after MI vs those who received therapy earlier. However, in TIME no significant incremental treatment effects on function, volumes, or infarct size were observed in patients treated with MNCs either 3 or 7 days after MI. The lack of benefit of MNC therapy in TIME and in the other CCTRN studies raises 2 possibilities: MNCs do not work, in which case the previous positive clinical studies were red herrings, or the CCTRN trials used an inactive cell product. The latter possibility cannot be discounted because MNCs isolated by the automated system used in this study have not been tested in an animal model of MI, and cell bioactivity has not been verified in any human studies of heart disease. In addition, the cell product used in TIME contained heparin at a dose that has been shown to impair the migratory capacity of MNCs. Such details of cell manufacturing are known to influence MNC potency substantially. Given these uncertainties, TIME (and the other 2 CCTRN studies) are well-intentioned, nicely designed, and impeccably executed, but difficult to interpret. POSEIDON, on the other hand, follows a more conventional development pathway, with ample preclinical validation and early proof-of-concept data in patients. The patients with chronic ischemic cardiomyopathy included in POSEIDON have a compelling clinical need. Their functional status is depressed and their ventricles have undergone extensive deleterious structural remodeling. The major finding of POSEIDON is that therapy with allogeneic (ie, donor-derived) MSCs appears to be safe and at least as active as therapy with autologous (ie, selfderived) MSCs. Allogeneic (but not autologous) MSCs reduced end-diastolic volume, whereas both allogeneic and autologous MSCs reduced early enhancement defect (a controversial measure of infarct size derived from computed tomography). The apparent changes in myocardial structure were not matched by improvements in global ventricular function; neither allogeneic nor autologous MSCs showed any significant increase in ejection fraction when analyzed individually or pooled together.

Support for Cardiovascular Cell Therapy Research at the National Heart, Lung, and Blood Institute

Heart failure (HF) exerts an enormous burden both in the United States and worldwide, compounded by the lack of effective therapies for patients with end-stage HF. Current options other than medical management are limited to cardiac transplantation, severely limited by the lack of donor availability, and ventricular assist device (VAD) implantation. Although the introduction of newer VADs has reduced complications such as thrombosis and infection, mortality in patients with VADs is still significant (≈25% in the first year1). Since the capacity of the heart to repair itself after myocardial infarction (MI) is very limited, effective regenerative therapies for patients with large acute MI to prevent progression to HF would be highly beneficial in decreasing the morbidity and mortality associated with end-stage HF. Regenerative therapies to repair failing hearts have the potential to provide new options for patients with advanced HF who currently face low quality of life as well as poor prognosis. ### National Heart, Lung, and Blood Institute Cardiovascular Cell Therapy Research Network Clinical trials to test the ability of cell therapy to treat patients after MI were initiated a decade ago in Europe with injection of autologous skeletal myoblasts in patients undergoing coronary artery bypass surgery,2 followed rapidly by trials using other cell types and delivery routes. In response to the proliferation of non-US cell therapy trials, the National Heart, Lung, and Blood Institute (NHLBI) held a working group in August 2004 to assess the status of clinical studies of cell-based therapies for cardiovascular disease, to determine the gaps in knowledge and barriers that prevent the implementation of well-designed and safe clinical studies. Another charge to the working group was to identify the areas of opportunity to apply cell-based therapies for cardiovascular disease.3 The primary recommendation of the working group was the formation of a cardiovascular cell therapy research network, consisting of a clinical research network component …

Effect of Transendocardial Delivery of Autologous Bone Marrow Mononuclear Cells on Functional Capacity, Left Ventricular Function, and Perfusion in Chronic Heart Failure

Previous studies using autologous bone marrow mononuclear cells (BMCs) in patients with ischemic cardiomyopathy have demonstrated safety and suggested efficacy. To determine if administration of BMCs through transendocardial injections improves myocardial perfusion, reduces left ventricular end-systolic volume (LVESV), or enhances maximal oxygen consumption in patients with coronary artery disease or LV dysfunction, and limiting heart failure or angina. A phase 2 randomized double-blind, placebo-controlled trial of symptomatic patients (New York Heart Association classification II-III or Canadian Cardiovascular Society classification II-IV) with a left ventricular ejection fraction of 45% or less, a perfusion defect by single-photon emission tomography (SPECT), and coronary artery disease not amenable to revascularization who were receiving maximal medical therapy at 5 National Heart, Lung, and Blood Institute-sponsored Cardiovascular Cell Therapy Research Network (CCTRN) sites between April 29, 2009, and April 18, 2011. Bone marrow aspiration (isolation of BMCs using a standardized automated system performed locally) and transendocardial injection of 100 million BMCs or placebo (ratio of 2 for BMC group to 1 for placebo group). Co-primary end points assessed at 6 months: changes in LVESV assessed by echocardiography, maximal oxygen consumption, and reversibility on SPECT. Phenotypic and functional analyses of the cell product were performed by the CCTRN biorepository core laboratory. Of 153 patients who provided consent, a total of 92 (82 men; average age: 63 years) were randomized (n = 61 in BMC group and n = 31 in placebo group). Changes in LVESV index (-0.9 mL/m(2) [95% CI, -6.1 to 4.3]; P = .73), maximal oxygen consumption (1.0 [95% CI, -0.42 to 2.34]; P = .17), and reversible defect (-1.2 [95% CI, -12.50 to 10.12]; P = .84) were not statistically significant. There were no differences found in any of the secondary outcomes, including percent myocardial defect, total defect size, fixed defect size, regional wall motion, and clinical improvement. Among patients with chronic ischemic heart failure, transendocardial injection of autologous BMCs compared with placebo did not improve LVESV, maximal oxygen consumption, or reversibility on SPECT. clinicaltrials.gov Identifier: NCT00824005.