Autologous CD34+ Stem Cell Therapy Increases Coronary Flow Reserve and Reduces Angina in Patients With Coronary Microvascular Dysfunction.

Background: Coronary microvascular dysfunction results in angina and adverse outcomes in patients with evidence of ischemia and nonobstructive coronary artery disease; however, no specific therapy exists. CD34+ cell therapy increases microvasculature in preclinical models and improves symptoms, exercise tolerance, and mortality in refractory angina patients with obstructive coronary artery disease. The objective of this research was to evaluate the safety, tolerability, and efficacy of intracoronary CD34+ cell therapy in patients with coronary microvascular dysfunction.

CD34 cell therapy significantly reduces adverse cardiac events, health care expenditures, and mortality in patients with refractory angina.

Patients with refractory angina who are suboptimal candidates for further revascularization have improved exercise time, decreased angina frequency, and reduced major adverse cardiac events with intramyocardial delivery of CD34 cells. However, the effect of CD34 cell therapy on health care expenditures before and after treatment is unknown. We determined the effect of CD34 cell therapy on cardiac-related hospital visits and costs during the 12 months following stem cell injection compared with the 12 months prior to injection.

Autologous CD34+ Cell Therapy for Ischemic Tissue Repair.

In 1997, the seminal manuscript by Asahara, Murohara, Isner et al outlined the evidence for the existence of circulating, bone marrow-derived cells capable of stimulating and contributing to the formation of new blood vessels. Consistent with the paradigm shift that this work represented, it triggered much scientific debate and controversy, some of which persists 2 decades later. In contrast, the clinical application of autologous CD34 cell therapy has been marked by a track record of consistent safety and clinical benefit in multiple ischemic conditions.

A Path Forward for Regenerative Medicine.

Although clinical trials of cell-based approaches to cardiovascular disease have yielded some promising results, no cell-based therapy has achieved regulatory approval for a cardiovascular indication. To broadly assess the challenges to regulatory approval and identify strategies to facilitate this goal, the Cardiac Safety Research Consortium sponsored a session during the Texas Heart Institute International Symposium on Cardiovascular Regenerative Medicine in September 2017. This session convened leaders in cardiovascular regenerative medicine, including participants from academia, the pharmaceutical industry, the US Food and Drug Administration, and the Cardiac Safety Research Consortium, with particular focus on treatments closest to regulatory approval.

Endothelial smoothened-dependent hedgehog signaling is not required for sonic hedgehog induced angiogenesis or ischemic tissue repair.

Sonic Hedgehog (Shh) signaling induces neovascularization and angiogenesis. It is not known whether the hedgehog signaling pathway in endothelial cells is essential to angiogenesis. Smoothened (Smo) transduces hedgehog signaling across the cell membrane.

E2F1 Suppresses Oxidative Metabolism and Endothelial Differentiation of Bone Marrow Progenitor Cells.

Rationale: The majority of current cardiovascular cell therapy trials use bone marrow progenitor cells (BM PCs) and achieve only modest efficacy; the limited potential of these cells to differentiate into endothelial-lineage cells is one of the major barriers to the success of this promising therapy. We have previously reported that the E2F transcription factor 1 (E2F1) is a repressor of revascularization after ischemic injury.

Objective: We sought to define the role of E2F1 in the regulation of BM PC function.

Autologous CD34+ cell therapy improves exercise capacity, angina frequency and reduces mortality in no-option refractory angina: a patient-level pooled analysis of randomized double-blinded trials.

Aims: Autologous CD34+ (auto-CD34+) cells represent an attractive option for the treatment of refractory angina. Three double-blinded randomized trials (n = 304) compared intramyocardial (IM) auto-CD34+ cells with IM placebo injections to affect total exercise time (TET), angina frequency (AF), and major adverse cardiac events (MACE). Patient-level data were pooled from the Phase I, Phase II ACT-34, ACT-34 extension, and Phase III RENEW trials to determine the efficacy and safety of auto-CD34+ cells.

Navigating the Future of Cardiovascular Drug Development-Leveraging Novel Approaches to Drive Innovation and Drug Discovery: Summary of Findings from the Novel Cardiovascular Therapeutics Conference.

Purpose: The need for novel approaches to cardiovascular drug development served as the impetus to convene an open meeting of experts from the pharmaceutical industry and academia to assess the challenges and develop solutions for drug discovery in cardiovascular disease.

Methods: The Novel Cardiovascular Therapeutics Summit first reviewed recent examples of ongoing or recently completed programs translating basic science observations to targeted drug development, highlighting successes (protein convertase sutilisin/kexin type 9 [PCSK9] and neprilysin inhibition) and targets still under evaluation (cholesteryl ester transfer protein [CETP] inhibition), with the hope of gleaning key lessons to successful drug development in the current era. Participants then reviewed the use of innovative approaches being explored to facilitate rapid and more cost-efficient evaluations of drug candidates in a short timeframe.

Angiogenic Mechanisms of Human CD34 Stem Cell Exosomes in the Repair of Ischemic Hindlimb.

Rationale: Paracrine secretions seem to mediate therapeutic effects of human CD34 stem cells locally transplanted in patients with myocardial and critical limb ischemia and in animal models. Earlier, we had discovered that paracrine secretion from human CD34 cells contains proangiogenic, membrane-bound nanovesicles called exosomes (CD34Exo).

Objective: Here, we investigated the mechanisms of CD34Exo-mediated ischemic tissue repair and therapeutic angiogenesis by studying their miRNA content and uptake.

PreSERVE-AMI: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial of Intracoronary Administration of Autologous CD34+ Cells in Patients With Left Ventricular Dysfunction Post STEMI.

Rationale: Despite direct immediate intervention and therapy, ST-segment-elevation myocardial infarction (STEMI) victims remain at risk for infarct expansion, heart failure, reinfarction, repeat revascularization, and death.

Objective: To evaluate the safety and bioactivity of autologous CD34+ cell (CLBS10) intracoronary infusion in patients with left ventricular dysfunction post STEMI.

Methods And Results: Patients who underwent successful stenting for STEMI and had left ventricular dysfunction (ejection fraction≤48%) ≥4 days poststent were eligible for enrollment.

The RENEW Trial: Efficacy and Safety of Intramyocardial Autologous CD34(+) Cell Administration in Patients With Refractory Angina.

Objectives: This study tested whether intramyocardial (IM) administration of mobilized, purified autologous CD34(+) cells would improve total exercise time (TET) and angina frequency in patients with refractory angina.

Background: IM administration of autologous CD34(+) cells has been associated consistently with improvements in functional capacity and angina symptoms in early phase clinical trials.

Methods: RENEW (Efficacy and Safety of Targeted Intramyocardial Delivery of Auto CD34+ Stem Cells for Improving Exercise Capacity in Subjects With Refractory Angina) was a randomized, double-blind, multicenter trial comparing IM CD34(+) administration with no intervention (open-label standard of care) or IM placebo injections (active control).

Autologous CD34 Cell Therapy for Refractory Angina: 2-Year Outcomes From the ACT34-CMI Study.

An increasing number of patients have refractory angina despite optimal medical therapy and are without further revascularization options. Preclinical studies indicate that human CD34 stem cells can stimulate new blood vessel formation in ischemic myocardium, improving perfusion and function. In ACT34-CMI (N = 167), patients treated with autologous CD34 stem cells had improvements in angina and exercise time at 6 and 12 months compared to placebo; however, the longer-term effects of this treatment are unknown.

Wnt11 Gene Therapy with Adeno-associated Virus 9 Improves Recovery from Myocardial Infarction by Modulating the Inflammatory Response.

Acute myocardial infarction induces activation of the acute phase response and infiltration of leukocytes to the infarcted area. Moreover, myocardium that is remote from ischemic area also becomes inflamed. Inflammatory reaction clears dead cells and matrix debris, while prolongation or expansion of the inflammatory response results in dysfunction following myocardial infarction.

IL-10 Accelerates Re-Endothelialization and Inhibits Post-Injury Intimal Hyperplasia following Carotid Artery Denudation.

The role of inflammation on atherosclerosis and restenosis is well established. Restenosis is thought to be a complex response to injury, which includes early thrombus formation, acute inflammation and neo-intimal growth. Inflammatory cells are likely contributors in the host response to vascular injury, via cytokines and chemokines secretion, including TNF-alpha (TNF).

Negative Regulation of miR-375 by Interleukin-10 Enhances Bone Marrow-Derived Progenitor Cell-Mediated Myocardial Repair and Function After Myocardial Infarction.

Poor survival and function of transplanted cells in ischemic and inflamed myocardium likely compromises the functional benefit of stem cell-based therapies. We have earlier reported that co-administration of interleukin (IL)-10 and BMPAC enhances cell survival and improves left ventricular (LV) functions after acute myocardial infarction (MI) in mice. We hypothesized that IL-10 regulates microRNA-375 (miR-375) signaling in BMPACs to enhance their survival and function in ischemic myocardium after MI and attenuates left ventricular dysfunction after MI.

Reprint of: Development of bioactive peptide amphiphiles for therapeutic cell delivery.

There is great clinical interest in cell-based therapies for ischemic tissue repair in cardiovascular disease. However, the regenerative potential of these therapies is limited due to poor cell viability and minimal retention following application. We report here the development of bioactive peptide amphiphile nanofibers displaying the fibronectin-derived RGDS cell adhesion epitope as a scaffold for therapeutic delivery of bone marrow derived stem and progenitor cells.

Modulating the vascular response to limb ischemia: angiogenic and cell therapies.

The age-adjusted prevalence of peripheral arterial disease in the US population has been estimated to approach 12%. The clinical consequences of occlusive peripheral arterial disease include pain on walking (claudication), pain at rest, and loss of tissue integrity in the distal limbs; the latter may ultimately lead to amputation of a portion of the lower extremity. Surgical bypass techniques and percutaneous catheter-based interventions may successfully reperfuse the limbs of certain patients with peripheral arterial disease.

A critical role of Src family kinase in SDF-1/CXCR4-mediated bone-marrow progenitor cell recruitment to the ischemic heart.

The G protein-coupled receptor CXCR4 and its ligand stromal-cell derived factor 1 (SDF-1) play a crucial role in directing progenitor cell (PC) homing to ischemic tissue. The Src family protein kinases (SFK) can be activated by, and serve as effectors of, G proteins. In this study we sought to determine whether SFK play a role in SDF-1/CXCR4-mediated PC homing.

Genetic deletion of TNFR2 augments inflammatory response and blunts satellite-cell-mediated recovery response in a hind limb ischemia model.

We have previously shown that TNF-tumor necrosis factor receptor-2/p75 (TNFR2/p75) signaling plays a critical role in ischemia-induced neovascularization in skeletal muscle and heart tissues. To determine the role of TNF-TNFR2/p75 signaling in ischemia-induced inflammation and muscle regeneration, we subjected wild-type (WT) and TNFR2/p75 knockout (p75KO) mice to hind limb ischemia (HLI) surgery. Ischemia induced significant and long-lasting inflammation associated with considerable decrease in satellite-cell activation in p75KO muscle tissue up to 10 d after HLI surgery.

E2F1 suppresses cardiac neovascularization by down-regulating VEGF and PlGF expression.

Aims: The E2F transcription factors are best characterized for their roles in cell-cycle regulation, cell growth, and cell death. Here we investigated the potential role of E2F1 in cardiac neovascularization.

Methods And Results: We induced myocardial infarction (MI) by ligating the left anterior descending artery in wild-type (WT) and E2F1(-/-) mice.

Enhanced potency of cell-based therapy for ischemic tissue repair using an injectable bioactive epitope presenting nanofiber support matrix.

The translation of cell-based therapies for ischemic tissue repair remains limited by several factors, including poor cell survival and limited target site retention. Advances in nanotechnology enable the development of specifically designed delivery matrices to address these limitations and thereby improve the efficacy of cell-based therapies. Given the relevance of integrin signaling for cellular homeostasis, we developed an injectable, bioactive peptide-based nanofiber matrix that presents an integrin-binding epitope derived from fibronectin, and evaluated its feasibility as a supportive artificial matrix for bone marrow-derived pro-angiogenic cells (BMPACs) used as a therapy in ischemic tissue repair.