Right ventricular effects of intracoronary delivery of mesenchymal stem cells (MSC) in an animal model of pressure overload heart failure

Impact of cardiosphere-derived cells on the maladapted right ventricular muscle in a rat sugen/hypoxia model of pulmonary hypertension with right ventricular dysfunction

BACKGROUND AND AIMS

With pulmonary arterial hypertension (PAH), right ventricular (RV) function is a major determinant of survival. Despite current therapies, maladaptive changes ensue in the RV muscle of PAH patients, culminating in RV dysfunction and failure. The aims of the study were to evaluate the impact of intra-coronary (IC) cardiosphere-derived cells (CDCs) in attenuating the maladaptive pathobiology in the RV muscle and evaluating mechanisms underlying improvements in RV function.

METHODS

Two groups of the Sugen/Hypoxia rat model of PAH, exhibiting significantly reduced RV function, via TAPSE measurements, received either intracoronary infusion of CDCs or PBS placebo. Immunohistochemistry methods were used to assess RV pathobiological changes. Additionally, advanced proteomics were employed to examine protein signaling pathways and upstream regulators.

RESULTS

RV muscle capillarity was significantly reduced in the PAH rats while RV muscle fibrosis was increased. IC CDCs significantly increased RV muscle capillarity back to levels noted in healthy rats and reduced RV free wall fibrosis. Further, a significant reduction in iNOS+ (M1) macrophages was also observed within the RV free wall in CDC-treated animals. Proteomic analysis of RV muscle in CDC- or PBS-treated PAH rats showed alterations in protein pathways related to inflammation, fibrosis, autophagy, cell vitality, and angiogenesis. These changes were consistent with putative coordination by a small number of key upstream regulators (MYC, TP53, HNF4A, TGFB1, and KRAS). TAPSE was significantly reduced in PBS-treated animals but was maintained at or above baseline levels in CDC-treated animals.

CONCLUSIONS

CDC therapy can significantly impact the maladaptive milieu of the RV myocardium in advanced PAH, by altering several pathobiological pathways. Such adjunctive therapy, in addition to those employed to reduce pulmonary vascular resistance, would be a great advance in managing RV failure, for which no effective current approved therapies exist.

CXCR4-Expressing Mesenchymal Stem Cells Derived Nanovesicles for Rheumatoid Arthritis Treatment

Cell membrane camouflage technology, which a demonstrated value for the bionic replication of natural cell membrane properties, is an active area of ongoing research readily applicable to nanomedicine. How to realize immune evasion, slow down the clearance from the body, and improve targeting are still worth great efforts for this technology. Herein, novel cell membrane-mimicked nanovesicles from genetically engineered mesenchymal stem cells (MSCs) are presented as a potential anti-inflammatory platform for rheumatoid arthritis (RA) management. Utilizing the synthetic biology approach, the biomimetic nanoparticles are constructed by fusing C-X-C motif chemokine receptor4 (CXCR4)-anchored MSC membranes onto drug-loaded polymeric cores (MCPNs), which make them ideal decoys of stromal cell-derived factor-1 (SDF-1)-targeted arthritis. These resulting nanocomplexes function to escape from the immune system and enhance accumulation in the established inflamed joints via the CXCR4/SDF-1 chemotactic signal axis, thereby achieving an affinity to activated macrophages and synovial fibroblasts. It is further demonstrated that the MCPNs can significantly suppress synovial inflammation and relieve pathological conditions with favorable safety properties in collagen-induced arthritis mice. These findings indicate the clinical value of MCPNs as biomimetic nanodrugs for RA therapy and related diseases.

The Role of Stem Cells in the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death and include several vascular and cardiac disorders, such as atherosclerosis, coronary artery disease, cardiomyopathies, and heart failure. Multiple treatment strategies exist for CVDs, but there is a need for regenerative treatment of damaged heart. Stem cells are a broad variety of cells with a great differentiation potential that have regenerative and immunomodulatory properties. Multiple studies have evaluated the efficacy of stem cells in CVDs, such as mesenchymal stem cells and induced pluripotent stem cell-derived cardiomyocytes. These studies have demonstrated that stem cells can improve the left ventricle ejection fraction, reduce fibrosis, and decrease infarct size. Other studies have investigated potential methods to improve the survival, engraftment, and functionality of stem cells in the treatment of CVDs. The aim of the present review is to summarize the current evidence on the role of stem cells in the treatment of CVDs, and how to improve their efficacy.

Stem cell therapy targeting the right ventricle in pulmonary arterial hypertension: is it a potential avenue of therapy?

Pulmonary arterial hypertension (PAH) is an incurable disease characterized by an increase in pulmonary arterial pressure due to pathological changes to the pulmonary vascular bed. As a result, the right ventricle (RV) is subject to an increased afterload and undergoes multiple changes, including a decrease in capillary density. All of these dysfunctions lead to RV failure. A number of studies have shown that RV function is one of the main prognostic factors for PAH patients. Many stem cell therapies targeting the left ventricle are currently undergoing development. The promising results observed in animal models have led to clinical trials that have shown an improvement of cardiac function. In contrast to left heart disease, stem cell therapy applied to the RV has remained poorly studied, even though it too may provide a therapeutic benefit. In this review, we discuss stem cell therapy as a treatment for RV failure in PAH. We provide an overview of the results of preclinical and clinical studies for RV cell therapies. Although a large number of studies have targeted the pulmonary circulation rather than the RV directly, there are nonetheless encouraging results in the literature that indicate that cell therapies may have a direct beneficial effect on RV function. This cell therapy strategy may therefore hold great promise and warrants further studies in PAH patients.

Prolonged intra-myocardial growth hormone administration ameliorates post-infarction electrophysiologic remodeling in rats

Experimental studies indicate improved ventricular function after treatment with growth hormone (GH) post-myocardial infarction, but its effect on arrhythmogenesis is unknown. Here, we assessed the medium-term electrophysiologic remodeling after intra-myocardial GH administration in (n = 33) rats. GH was released from an alginate scaffold, injected around the ischemic myocardium after coronary ligation. Two weeks thereafter, ventricular tachyarrhythmias were induced by programmed electrical stimulation. Monophasic action potentials were recorded from the infarct border, coupled with evaluation of electrical conduction and repolarization from a multi-electrode array. The arrhythmia score was lower in GH-treated rats than in alginate-treated rats or controls. The shape and the duration of the action potential at the infarct border were preserved, and repolarization-dispersion was attenuated after GH; moreover, voltage rise was higher and activation delay was shorter. GH normalized also right ventricular parameters. Intra-myocardial GH preserved electrical conduction and repolarization-dispersion at the infarct border and decreased the incidence of induced tachyarrhythmias in rats post-ligation. The long-term antiarrhythmic potential of GH merits further study.

Comparison of Magnetic Intensities for Mesenchymal Stem Cell Targeting Therapy on Ischemic Myocardial Repair: High Magnetic Intensity Improves Cell Retention but Has no Additional Functional Benefit

Magnetic targeting has the potential to enhance the therapeutic effects of stem cells through increasing retention of transplanted cells. To investigate the effects of magnetic targeting intensities on cell transplantation, we performed different magnetic intensities for mesenchymal stem cell (MSC)-targeting therapy in a rat model of ischemia/reperfusion. Rat MSCs labeled with superparamagnetic oxide nanoparticles (SPIOs) were injected into the left ventricular (LV) cavity of rats during a brief aorta and pulmonary artery occlusion. The 0.15 Tesla (T), 0.3 T, and 0.6 T magnets were placed 0∼1 mm above the injured myocardium during and after the injection of 1 × 10(6) MSCs. Fluorescence imaging and quantitative PCR revealed that magnetic targeting enhanced cell retention in the heart at 24 h in a magnetic field strength-dependent manner. Compared with the 0 T group, three magnetic targeting groups enhanced varying cell engraftment at 3 weeks, at which time LV remodeling was maximally attenuated, and the therapeutic benefit (LV ejection fraction) was also highest in the 0.3 T groups. Interestingly, due to the low MSC engraftment resulting from microvascular embolisms, the 0.6 T group failed to translate into additional therapeutic outcomes, though it had the highest cell retention. Magnetic targeting enhances cell retention in a magnetic field strength-dependent manner. However, too high of a magnetic intensity may result in microembolization and consequently undermine the functional benefits of cell transplantation.

The effect of nonuniform magnetic targeting of intracoronary-delivering mesenchymal stem cells on coronary embolisation

Magnetic targeting has been recently introduced to enhance cell retention in animals with acute myocardial infarction. However, it is unclear whether the magnetic accumulation of intravascular cells increases the risk of coronary embolism. Upon finite element analysis, we found that the permanent magnetic field was nonuniform, manifestated as attenuation along the vertical axis and polarisation along the horizontal axis. In the in vitro experiments, iron-labelled mesenchymal stem cells (MSCs) were accumulated in layers predominantly at the edge of the magnet. In an ischaemic rat model subjected to intracavitary MSCs injection, magnetic targeting induced unfavourable vascular embolisation and an inhomogeneous distribution of the donor cells, which prevented the enhanced cell retention from translating into additional functional benefit. These potential complications of magnetic targeting should be thoroughly investigated and overcome before clinical application.