Michelle R. Santoso

Magnetic Nanoparticles for Targeting and Imaging of Stem Cells in Myocardial Infarction

Stem cell therapy has broad applications in regenerative medicine and increasingly within cardiovascular disease. Stem cells have emerged as a leading therapeutic option for many diseases and have broad applications in regenerative medicine. Injuries to the heart are often permanent due to the limited proliferation and self-healing capability of cardiomyocytes; as such, stem cell therapy has become increasingly important in the treatment of cardiovascular diseases. Despite extensive efforts to optimize cardiac stem cell therapy, challenges remain in the delivery and monitoring of cells injected into the myocardium. Other fields have successively used nanoscience and nanotechnology for a multitude of biomedical applications, including drug delivery, targeted imaging, hyperthermia, and tissue repair. In particular, superparamagnetic iron oxide nanoparticles (SPIONs) have been widely employed for molecular and cellular imaging. In this mini-review, we focus on the application of superparamagnetic iron oxide nanoparticles in targeting and monitoring of stem cells for the treatment of myocardial infarctions.

Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery Disease: The CCTRN PACE Trial (Patients with Intermittent Claudication Injected with ALDH Bright Cells)

Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P=0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P=0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P =0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P =0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P =0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: . Unique identifier: [NCT01774097][1]. # Clinical Perspective {#article-title-36} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01774097&atom=%2Fcirculationaha%2F135%2F15%2F1417.atom

Paracrine Effects of the Pluripotent Stem Cell-Derived Cardiac Myocytes Salvage the Injured MyocardiumNovelty and Significance

Rationale: Cardiac myocytes derived from pluripotent stem cells have demonstrated the potential to mitigate damage of the infarcted myocardium and improve left ventricular ejection fraction. However, the mechanism underlying the functional benefit is unclear. Objective: To evaluate whether the transplantation of cardiac-lineage differentiated derivatives enhance myocardial viability and restore left ventricular ejection fraction more effectively than undifferentiated pluripotent stem cells after a myocardial injury. Herein, we utilize novel multimodality evaluation of human embryonic stem cells (hESCs), hESC-derived cardiac myocytes (hCMs), human induced pluripotent stem cells (iPSCs), and iPSC-derived cardiac myocytes (iCMs) in a murine myocardial injury model. Methods and Results: Permanent ligation of the left anterior descending coronary artery was induced in immunosuppressed mice. Intramyocardial injection was performed with (1) hESCs (n=9), (2) iPSCs (n=8), (3) hCMs (n=9), (4) iCMs (n=14), and (5) PBS control (n=10). Left ventricular ejection fraction and myocardial viability, measured by cardiac magnetic resonance imaging and manganese-enhanced magnetic resonance imaging, respectively, was significantly improved in hCM- and iCM-treated mice compared with pluripotent stem cell- or control-treated mice. Bioluminescence imaging revealed limited cell engraftment in all treated groups, suggesting that the cell secretions may underlie the repair mechanism. To determine the paracrine effects of the transplanted cells, cytokines from supernatants from all groups were assessed in vitro. Gene expression and immunohistochemistry analyses of the murine myocardium demonstrated significant upregulation of the promigratory, proangiogenic, and antiapoptotic targets in groups treated with cardiac lineage cells compared with pluripotent stem cell and control groups. Conclusions: This study demonstrates that the cardiac phenotype of hCMs and iCMs salvages the injured myocardium effectively than undifferentiated stem cells through their differential paracrine effects.

Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery Disease: The CCTRN Patients with Intermittent Claudication Injected with ALDH Bright Cells (PACE) Trial

Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P=0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P=0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P =0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P =0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P =0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: . Unique identifier: [NCT01774097][1]. # Clinical Perspective {#article-title-36} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01774097&atom=%2Fcirculationaha%2F135%2F15%2F1417.atom

Molecular Imaging of Stem Cells and Exosomes for Myocardial Regeneration

Purpose of ReviewStem cell therapy is studied for the treatment of ischemic heart disease. Despite high expectations, investigation has yielded mixed results. For further advancement of this field, it is essential to understand the fate of the transplanted stem cells in living subjects. A myriad of tools has been developed to allow for the immediate and longitudinal monitoring of stem cells in vivo. In this review, we outline the most reliable techniques and their implications for cardiac regenerative medicine.Recent FindingsDirect (e.g., PET/SPECT, MRI) and indirect labeling (e.g., reporter gene) techniques have existed for decades prior to their use in stem cell imaging. In this review, we describe some of the key developments in the context of stem cell therapy for cardiac ischemia, including new contrast agents (MRI, SPECT) and novel reporter genes (e.g., near-infrared fluorescent protein). Furthermore, we discuss innovative techniques that integrate direct and indirect labeling, such as PET reporter gene systems. Finally, we examine the potential of exosomes, a component of the stem cell secretome, which has recently garnered much attention for its potential in myocardial regeneration, and how they may be imaged in vivo.SummaryThis review outlines the most reliable techniques for stem cell imaging in cardiac injury animal models, new and notable advancements in the field, and possible directions for cardiac regenerative medicine.

EXOSOMES FROM INDUCED PLURIPOTENT STEM CELL-DERIVED CARDIOMYOCYTES SALVAGE THE INJURED MYOCARDIUM BY MODULATION OF AUTOPHAGY

Induced pluripotent stem cells and their differentiated cardiomyocytes (iCMs) have tremendous potential as patient-specific therapy for myocardial injury (MI). Our previous work showed that iCMs secrete paracrine factors, modulating apoptotic pathways to restore the murine peri-infarct region (PIR

Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery DiseaseClinical Perspective: The CCTRN PACE Trial (Patients With Intermittent Claudication Injected With ALDH Bright Cells)

Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P=0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P=0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P =0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P =0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P =0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: . Unique identifier: [NCT01774097][1]. # Clinical Perspective {#article-title-36} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01774097&atom=%2Fcirculationaha%2F135%2F15%2F1417.atom

Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery DiseaseClinical Perspective

Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P=0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P=0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.Background: Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute–sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow–derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms. Methods: All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety. Results: A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] −0.6 to 2.5; P =0.238), collateral count (0.9±0.6 arteries; 95% CI, −0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, −0.8 to 0.8; P =0.978), and capillary perfusion (−0.2±0.6%; 95% CI, −1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1–2.9; P =0.047) in participants with completely occluded femoral arteries. Conclusions: ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights. Clinical Trial Registration: URL: . Unique identifier: [NCT01774097][1]. # Clinical Perspective {#article-title-36} [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT01774097&atom=%2Fcirculationaha%2F135%2F15%2F1417.atom