Cell therapy generates a favourable chemokine gradient for stem cell recruitment into the infarcted heart in rabbits

Therapeutic Potential of Mesenchymal Stem Cells versus Omega n − 3 Polyunsaturated Fatty Acids on Gentamicin-Induced Cardiac Degeneration

This study compared the cardioprotective action of mesenchymal stem cells (MSCs) and PUFAs in a rat model of gentamicin (GM)-induced cardiac degeneration. Male Wistar albino rats were randomized into four groups of eight rats each: group I (control group), group II (gentamicin-treated rats receiving gentamicin intraperitoneally (IP) at dose of 100 mg/kg/day for 10 consecutive days), group III (gentamicin and PUFA group receiving gentamicin IP at dose of 100 mg/kg/day for 10 consecutive days followed by PUFAs at a dose of 100 mg/kg/day for 4 weeks), and group IV (gentamicin and MSC group receiving gentamicin IP at dose of 100 mg/kg/day followed by a single dose of MSCs (1 × 10⁶)/rat IP). Cardiac histopathology was evaluated via light and electron microscopy. Immunohistochemical detection of proliferating cell nuclear antigen (PCNA), caspase-3 (apoptosis), Bcl2, and Bax expression was performed. Moreover, cardiac malonaldehyde (MDA) content, catalase activity, and oxidative stress parameters were biochemically evaluated. Light and electron microscopy showed that both MSCs and PUFAs had ameliorative effects. Their actions were mediated by upregulating PCNA expression, downregulating caspase-3 expression, mitigating cardiac MDA content, catalase activity, and oxidative stress parameters. MSCs and PUFAs had ameliorative effects against gentamicin-induced cardiac degeneration, with MSCs showing higher efficacy compared to PUFAs.

Emerging Trends in Mesenchymal Stem Cells Applications for Cardiac Regenerative Therapy: Current Status and Advances

Irreversible myocardium infarction is one of the leading causes of cardiovascular disease (CVD) related death and its quantum is expected to grow in coming years. Pharmacological intervention has been at the forefront to ameliorate injury-related morbidity and mortality. However, its outcomes are highly skewed. As an alternative, stem cell-based tissue engineering/regenerative medicine has been explored quite extensively to regenerate the damaged myocardium. The therapeutic modality that has been most widely studied both preclinically and clinically is based on adult multipotent mesenchymal stem cells (MSC) delivered to the injured heart. However, there is debate over the mechanistic therapeutic role of MSC in generating functional beating cardiomyocytes. This review intends to emphasize the role and use of MSC in cardiac regenerative therapy (CRT). We have elucidated in detail, the various aspects related to the history and progress of MSC use in cardiac tissue engineering and its multiple strategies to drive cardiomyogenesis. We have further discussed with a focus on the various therapeutic mechanism uncovered in recent times that has a significant role in ameliorating heart-related problems. We reviewed recent and advanced technologies using MSC to develop/create tissue construct for use in cardiac regenerative therapy. Finally, we have provided the latest update on the usage of MSC in clinical trials and discussed the outcome of such studies in realizing the full potential of MSC use in clinical management of cardiac injury as a cellular therapy module.

Differential roles of microtubules in the two formation stages of membrane nanotubes between human mesenchymal stem cells and neonatal mouse cardiomyocytes

Membrane nanotubes (MNTs) are a kind of novel way for communication between two distant cells. It was recently shown that MNTs can be formed between distressed cardiomyocytes (CMs) and mesenchymal stem cells (MSCs). As a cytoskeleton-containing structure, the role of microtubules in MNTs is not fully understood. Here, we investigated this question. By membrane dye staining, we found that the numbers of MNTs between human MSCs (hMSCs) and distressed neonatal mouse CMs (NMCMs) increased gradually from 3 to 16 h and remained constant from 16 to 30 h, which were identified as active formation stage (the 1st stage, ≤16 h in coculture), and mature and stable stage (the 2nd stage, >16 h in coculture), respectively. In the 1st stage, more MNTs originated from hMSCs, whereas more MNTs originated from NMCMs in the 2nd stage. The formation of MNTs was affected when microtubules were disrupted by nocodazole in the 1st stage, but not in the 2nd stage. MNTs became shorter and thinner when microtubules were disrupted in the 2nd stage. Immunofluorescence staining and flow cytometry showed that mitochondria in hMSCs were transported into distressed NMCMs, which was suppressed by nocodazole in the 2nd stage. Tunnel staining showed that hypoxia/reoxygenation-induced apoptosis of NMCMs only in the 2nd stage could be rescued by direct, but not indirect, coculture with hMSCs. This rescue function was weakened when the mitochondrial functions of cocultured hMSCs were disrupted by EtBr or microtubules in cocultures were disrupted by nocodazole. All these results suggested that there are two stages for MNT formation, and microtubules played differential roles in the two stages: During the 1st stage, microtubules were required for MNT formation, whereas during the 2nd stage, microtubules were related to the morphological features of MNTs and played a key role in anti-apoptosis of MNTs by mitochondrial transfer.

Circulating Stromal Cell-Derived Factor 1α Levels in Heart Failure: A Matter of Proper Sampling

Background

The chemokine Stromal cell-derived factor 1α (SDF1α, CXCL12) is currently under investigation as a biomarker for various cardiac diseases. The correct interpretation of SDF1α levels is complicated by the occurrence of truncated forms that possess an altered biological activity.

Methodology

We studied the immunoreactivities of SDF1α forms and evaluated the effect of adding a DPP4 inhibitor in sampling tubes on measured SDF1α levels. Using optimized sampling, we measured DPP4 activity and SDF1α levels in patients with varying degrees of heart failure.

Results

The immunoreactivities of SDF1α and its degradation products were determined with three immunoassays. A one hour incubation of SDF1α with DPP4 at 37°C resulted in 2/3 loss of immunoreactivity in each of the assays. Incubation with serum gave a similar result. Using appropriate sampling, SDF1α levels were found to be significantly higher in those heart failure patients with a severe loss of left ventricular function. DPP4 activity in serum was not altered in the heart failure population. However, the DPP4 activity was found to be significantly decreased in patients with high SDF1α levels

Conclusions

We propose that all samples for SDF1α analysis should be collected in the presence of at least a DPP4 inhibitor. In doing so, we found higher SDF1α levels in subgroups of patients with heart failure. Our work supports the need for further research on the clinical relevance of SDF1α levels in cardiac disease.

A new method of wound treatment: targeted therapy of skin wounds with reactive oxygen species-responsive nanoparticles containing SDF-1α

Objective

To accelerate wound healing through promoting vascularization by using reactive oxygen species (ROS)-responsive nanoparticles loaded with stromal cell-derived factor-1α(SDF-1α).

Methods

The ROS-reactive nanomaterial poly-(1,4-phenyleneacetone dimethylene thioketal) was synthesized, and its physical and chemical properties were characterized. ROS-responsive nanoparticles containing SDF-1α were prepared through a multiple emulsion solvent evaporation method. The loading capacity, stability, activity of the encapsulated protein, toxicity, and in vivo distribution of these nanoparticles were determined. These nanoparticles were administered by intravenous infusion to mice with full-thickness skin defects to study their effects on the directed chemotaxis of bone marrow mesenchymal stem cells, wound vascularization, and wound healing.

Results

The synthesized ROS-reactive organic polymer poly-(1,4-phenyleneacetone dimethylene thioketal) possessed a molecular weight of approximately 11.5 kDa with a dispersity of 1.97. ROS-responsive nanoparticles containing SDF-1α were prepared with an average diameter of 110 nm and a drug loading capacity of 1.8%. The encapsulation process showed minimal effects on the activity of SDF-1α, and it could be effectively released from the nanoparticles in the presence of ROS. Encapsulated SDF-1α could exist for a long time in blood. In mice with full-thickness skin defects, SDF-1α was effectively released and targeted to the wounds, thus promoting the chemotaxis of bone marrow mesenchymal stem cells toward the wound and its periphery, inducing wound vascularization, and accelerating wound healing.

Clinical trials update from the European Society of Cardiology-Heart Failure meeting 2015: AUGMENT-HF, TITRATION, STOP-HF, HARMONIZE, LION HEART, MOOD-HF, and renin-angiotensin inhibitors in patients with heart and renal failure

This article provides an overview on the key trials relevant to the pathophysiology, prevention, and treatment of heart failure (HF) presented at the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) annual meeting held in Seville, Spain in May 2015. Trials reported include AUGMENT-AF (myocardial injections of calcium-alginate hydrogel), a propensity score-matched study of renin-angiotensin system antagonists in patients with HF and severe renal dysfunction, HARMONIZE (sodium zirconium cyclosilicate used to bind potassium), TITRATION, comparing two regimes for introducing LCZ696, STOP-HF, a trial of intramyocardial stromal cell-derived factor-1, MOOD-HF (escitalopram for patients with heart failure and depression), and LION HEART, a trial of intermittent levosimendan therapy. Unpublished reports should be considered as preliminary, since analyses may change in the final publication.

Paracrine mechanisms of mesenchymal stem cell-based therapy: current status and perspectives

Mesenchymal stem cells (MSCs) are one of a few stem cell types to be applied in clinical practice as therapeutic agents for immunomodulation and ischemic tissue repair. In addition to their multipotent differentiation potential, a strong paracrine capacity has been proposed as the principal mechanism that contributes to tissue repair. Apart from cytokine/chemokine secretion, MSCs also display a strong capacity for mitochondrial transfer and microvesicle (exosomes) secretion in response to injury with subsequent promotion of tissue regeneration. These unique properties of MSCs make them an invaluable cell type to repair damaged tissues/organs. Although MSCs offer great promise in the treatment of degenerative diseases and inflammatory disorders, there are still many challenges to overcome prior to their widespread clinical application. Particularly, their in-depth paracrine mechanisms remain a matter for debate and exploration. This review will highlight the discovery of the paracrine mechanism of MSCs, regulation of the paracrine biology of MSCs, important paracrine factors of MSCs in modulation of tissue repair, exosome and mitochondrial transfer for tissue repair, and the future perspective for MSC-based therapy.

Brown adipocytes, cardiac protection and a common adipo- and myogenic stem precursor in aged human hearts

New data on adult stem cells (ASCs) are continuously added by research for use in regenerative medicine. However organ-specific ASC markers are incompletely explored. It was demonstrated that in non-cardiac brown adipose tissue (BAT) CD133+ cells differentiate in cardiomyocytes, and such BAT-derived cells induce bone marrow-derived cells into cardiomyocytes, thus being a promising source for cardiac stem cell therapy. During embryogenesis the subepicardial fat derives from BAT. Although it was not specifically investigated in human adult or aged hearts, it is actually known that metabolically active BAT can be found in many adult humans, is related to antiobesity effects, and it may derive from stem/progenitor cells. Stro-1 can safely identify in situ cardiac stem cells (CSCs) with myogenic and adipogenic potential. It was therefore raised the hypothesis of subepicardial differentiation of CSCs in BAT in adult/aged hearts, which could be viewed, such as in infants, as a mechanism of protection. This could be determined by the reactivation of an embryologic differentiation pattern in which brown adipocytes and muscle cells derive from a common stem ancestor. Such quiescent common stem ancestors could be suggested in adult, or aged, human hearts, when subepicardial BAT is found, and if a Stro-1+/CD133+/Isl-1+ phenotype of CSCs is determined.

Bone marrow mesenchymal stem cell transplantation retards the natural senescence of rat hearts

Bone marrow mesenchymal stem cells (BMSCs) have been shown to offer a wide variety of cellular functions including the protective effects on damaged hearts. Here we investigated the antiaging properties of BMSCs and the underlying mechanism in a cellular model of cardiomyocyte senescence and a rat model of aging hearts. Neonatal rat ventricular cells (NRVCs) and BMSCs were cocultured in the same dish with a semipermeable membrane to separate the two populations. Monocultured NRVCs displayed the senescence-associated phenotypes, characterized by an increase in the number of β-galactosidase-positive cells and decreases in the degradation and disappearance of cellular organelles in a time-dependent manner. The levels of reactive oxygen species and malondialdehyde were elevated, whereas the activities of antioxidant enzymes superoxide dismutase and glutathione peroxidase were decreased, along with upregulation of p53, p21(Cip1/Waf1), and p16(INK4a) in the aging cardiomyocytes. These deleterious alterations were abrogated in aging NRVCs cocultured with BMSCs. Qualitatively, the same senescent phenotypes were consistently observed in aging rat hearts. Notably, BMSC transplantation significantly prevented these detrimental alterations and improved the impaired cardiac function in the aging rats. In summary, BMSCs possess strong antisenescence action on the aging NRVCs and hearts and can improve cardiac function after transplantation in aging rats. The present study, therefore, provides an alternative approach for the treatment of heart failure in the elderly population.

Local activation of cardiac stem cells for post-myocardial infarction cardiac repair

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite continuous advancements in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. The emergence of stem cell transplantation approaches has recently represented promising alternatives to stimulate myocardial regeneration. Regarding their tissue-specific properties, cardiac stem cells (CSCs) residing within the heart have advantages over other stem cell types to be the best cell source for cell transplantation. However, time-consuming and costly procedures to expanse cells prior to cell transplantation and the reliability of cell culture and expansion may both be major obstacles in the clinical application of CSC-based transplantation therapy after MI. The recognition that the adult heart possesses endogenous CSCs that can regenerate cardiomyocytes and vascular cells has raised the unique therapeutic strategy to reconstitute dead myocardium via activating these cells post-MI. Several strategies, such as growth factors, mircoRNAs and drugs, may be implemented to potentiate endogenous CSCs to repair infarcted heart without cell transplantation. Most molecular and cellular mechanism involved in the process of CSC-based endogenous regeneration after MI is far from understanding. This article reviews current knowledge opening up the possibilities of cardiac repair through CSCs activation in situ in the setting of MI.

Comparison of transendocardial and intracoronary CD34+ cell transplantation in patients with nonischemic dilated cardiomyopathy

BACKGROUND

In an open-label blinded study, we compared intracoronary and transendocardial CD34(+) cell transplantation in patients with nonischemic dilated cardiomyopathy.

METHODS AND RESULTS

Of the 40 patients with dilated cardiomyopathy, 20 were randomized to receive intracoronary injection and 20 received transendocardial CD34(+) cell delivery. In both groups, CD34(+) cells were mobilized by filgrastim, collected via apheresis, and labeled with technetium-99m radioisotope for single-photon emission computed tomographic imaging. In the intracoronary group, cells were injected intracoronarily in the artery supplying segments of greater perfusion defect on myocardial perfusion scintigraphy. In the transendocardial group, electroanatomic mapping was used to identify viable but dysfunctional myocardium, and transendocardial cell injections were performed. Nuclear single-photon emission computed tomographic imaging for quantification of myocardial retention was performed 18 hours thereafter. At baseline, groups did not differ in age, sex, left ventricular ejection fraction, or N-terminal pro-brain natriuretic peptide levels. The number of CD34(+) cells was also comparable (105 ± 31 × 10(6) in the transendocardial group versus 103 ± 27 × 10(6) in the intracoronary group, P=0.62). At 18 hours after procedure, myocardial retention was higher in the transendocardial group (19.2 ± 4.8%) than in the intracoronary group (4.4 ± 1.2%, P<0.01). At 6 months, left ventricular ejection fraction improved more in the transendocardial group (+8.1 ± 4.3%) than in the intracoronary group (+4.2 ± 2.3%, P=0.03). The same pattern was observed for the 6-minute walk test distance (+125 ± 33 m in the transendocardial group versus +86 ± 13 m in the intracoronary group, P=0.03) and N-terminal pro-brain natriuretic peptide (-628 ± 211 versus -315 ± 133 pg/mL, P=0.04).

CONCLUSIONS

In patients with dilated cardiomyopathy, transendocardial CD34(+) cell transplantation is associated with higher myocardial retention rates and greater improvement in ventricular function, N-terminal pro-brain natriuretic peptide, and exercise capacity compared with intracoronary route.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01350310.

Mesenchymal stem cells in tissue repairing and regeneration: Progress and future

The presence of mesenchymal progenitor cells within bone marrow has been known since the late nineteenth century. To date, mesenchymal stem cells (MSCs) have been isolated from several different connective tissues, such as adipose tissue, muscle, placenta, umbilical cord matrix, blood, liver, and dental pulp. Bone marrow, however, is still one of the major sources of MSCs for preclinical and clinical research. MSCs were first evaluated for regenerative applications and have since been shown to directly influence the immune system and to promote neovascularization of ischemic tissues. These observations have prompted a new era of MSC transplantation as a treatment for various diseases. In this review, we summarize the important studies that have investigated the use of MSCs as a therapeutic agent for regenerative medicine, immune disorders, cancer, and gene therapy. Furthermore, we discuss the mechanisms involved in MSC-based therapies and clinical-grade MSC manufacturing.

Cell transplantation as an initiator of endogenous stem cell-based tissue repair

PURPOSE OF REVIEW

The aim of this review is to summarize recent findings of endogenous cell-based tissue repair triggered by a multitude of approaches, especially stem cell therapy.

RECENT FINDINGS

The emerging evidence has demonstrated that an important role of transplanted cells is to act as an initiator to trigger endogenous stem cell-mediated tissue repair after injury. Multiple approaches may orchestrate endogenous regeneration. The low efficacy of endogenous stem cells may be due to deficiency of cytokines to activate and induce endogenous stem cell homing, relatively insufficient endogenous stem cell pool, diseases or aging-related dysfunction of endogenous stem cells, and hostile microenvironments that limit the capacity of endogenous stem cells to repair damaged tissue. In certain situations, external stimulation and/or exogenous stem cells may be required to catalyze the repair.

SUMMARY

Endogenous stem cells are playing an important role in tissue repair. An important role of transplanted cells is to act as an initiator to trigger endogenous stem cell-based tissue repair.

Stroma cell-derived factor-1α signaling enhances calcium transients and beating frequency in rat neonatal cardiomyocytes

Stroma cell-derived factor-1α (SDF-1α) is a cardioprotective chemokine, acting through its G-protein coupled receptor CXCR4. In experimental acute myocardial infarction, administration of SDF-1α induces an early improvement of systolic function which is difficult to explain solely by an anti-apoptotic and angiogenic effect. We wondered whether SDF-1α signaling might have direct effects on calcium transients and beating frequency.

Primary rat neonatal cardiomyocytes were culture-expanded and characterized by immunofluorescence staining. Calcium sparks were studied by fluorescence microscopy after calcium loading with the Fluo-4 acetoxymethyl ester sensor. The cardiomyocyte enriched cellular suspension expressed troponin I and CXCR4 but was vimentin negative. Addition of SDF-1α in the medium increased cytoplasmic calcium release. The calcium response was completely abolished by using a neutralizing anti-CXCR4 antibody and partially suppressed and delayed by preincubation with an inositol triphosphate receptor (IP₃R) blocker, but not with a ryanodine receptor (RyR) antagonist. Calcium fluxes induced by caffeine, a RyR agonist, were decreased by an IP₃R blocker. Treatment with forskolin or SDF-1α increased cardiomyocyte beating frequency and their effects were additive. In vivo, treatment with SDF-1α increased left ventricular dP/dtmax.

These results suggest that in rat neonatal cardiomyocytes, the SDF-1α/CXCR4 signaling increases calcium transients in an IP₃-gated fashion leading to a positive chronotropic and inotropic effect.

Sustained therapeutic perfusion outside transplanted sites in chronic myocardial infarction after stem cell transplantation

This study aimed at comparing long-term variations in the perfusion of chronic myocardial infarction (MI) areas after local injections of autologous bone marrow stem cells (BMSCs). 14 coronary ligated rats with transmural chronic MI (4 months) were used: a control group (n = 7) versus a treated group (n = 7) in which (111)In labeled-BMSCs were directly engrafted on MI areas. By using (111)In/(99m)Tc SPECT and Sestamibi gated-SPECT,. left ventricle perfusion and function were monitored in all animals by serial (99m)Tc-Sestamibi pinhole gated-SPECT over a period of 6 months. Post-therapeutic myocardial perfusion improved as early as 48 h following injection in the 2 groups. This benefice was sustained during the 6-month follow-up in the non-engrafted MI-areas from treated rats (at 6-months: +10 ± 5 %), whereas the engrafted ones, as well as the MI areas from control rats, exhibited progressive deterioration over time (at 6-months: -9 ± 10 % and -5 ± 3 %, respectively). Perfusion enhancement of the chronic MI areas treated by BMSCs transplantation is: (1) marked in the following days, presumably because of an unspecific inflammatory reaction, and (2) sustained over the long term but only outside the sites of cell engraftment, suggesting a distant paracrine effect of transplanted cells.

Preservation of myocardial structure is enhanced by pim-1 engineering of bone marrow cells

RATIONALE

Bone marrow-derived cells to treat myocardial injury improve cardiac function and support beneficial cardiac remodeling. However, survival of stem cells is limited due to low proliferation of transferred cells.

OBJECTIVE

To demonstrate long-term potential of c-kit(+) bone marrow stem cells (BMCs) enhanced with Pim-1 kinase to promote positive cardiac remodeling.

METHODS AND RESULTS

Lentiviral modification of c-kit(+) BMCs to express Pim-1 (BMCeP) increases proliferation and expression of prosurvival proteins relative to BMCs expressing green fluorescent protein (BMCe). Intramyocardial delivery of BMCeP at time of infarction supports improvements in anterior wall dimensions and prevents left ventricle dilation compared with hearts treated with vehicle alone. Reduction of the akinetic left ventricular wall was observed in BMCeP-treated hearts at 4 and 12 weeks after infarction. Early recovery of cardiac function in BMCeP-injected hearts facilitated modest improvements in hemodynamic function up to 12 weeks after infarction between cell-treated groups. Persistence of BMCeP is improved relative to BMCe within the infarct together with increased recruitment of endogenous c-kit(+) cells. Delivery of BMC populations promotes cellular hypertrophy in the border and infarcted regions coupled with an upregulation of hypertrophic genes. Thus, BMCeP treatment yields improved structural remodeling of infarcted myocardium compared with control BMCs.

CONCLUSIONS

Genetic modification of BMCs with Pim-1 may serve as a therapeutic approach to promote recovery of myocardial structure. Future approaches may take advantage of salutary BMC actions in conjunction with other stem cell types to increase efficacy of cellular therapy and improve myocardial performance in the injured myocardium.

Mesenchymal stem cells and cardiovascular disease: a bench to bedside roadmap

In recent years, the incredible boost in stem cell research has kindled the expectations of both patients and physicians. Mesenchymal progenitors, owing to their availability, ease of manipulation, and therapeutic potential, have become one of the most attractive options for the treatment of a wide range of diseases, from cartilage defects to cardiac disorders. Moreover, their immunomodulatory capacity has opened up their allogenic use, consequently broadening the possibilities for their application. In this review, we will focus on their use in the therapy of myocardial infarction, looking at their characteristics, in vitro and in vivo mechanisms of action, as well as clinical trials.

Repair mechanisms of bone marrow mesenchymal stem cells in myocardial infarction

The prognosis of patients with myocardial infarction (MI) and resultant chronic heart failure remains extremely poor despite advances in optimal medical therapy and interventional procedures. Animal experiments and clinical trials using adult stem cell therapy following MI have shown a global improvement of myocardial function. Bone marrow-derived mesenchymal stem cells (MSCs) hold promise for cardiac repair following MI, due to their multilineage, self-renewal and proliferation potential. In addition, MSCs can be easily isolated, expanded in culture, and have immunoprivileged properties to the host tissue. Experimental studies and clinical trials have revealed that MSCs not only differentiate into cardiomyocytes and vascular cells, but also secrete amounts of growth factors and cytokines which may mediate endogenous regeneration via activation of resident cardiac stem cells and other stem cells, as well as induce neovascularization, anti-inflammation, anti-apoptosis, anti-remodelling and cardiac contractility in a paracrine manner. It has also been postulated that the anti-arrhythmic and cardiac nerve sprouting potential of MSCs may contribute to their beneficial effects in cardiac repair. Most molecular and cellular mechanisms involved in the MSC-based therapy after MI are still unclear at present. This article reviews the potential repair mechanisms of MSCs in the setting of MI.

Exercise training improves cardiac function in infarcted rabbits: involvement of autophagic function and fatty acid utilization

AIMS

To explore whether exercise can improve cardiac function in a post-myocardial infarction (MI) rabbit model and to determine contributing factors in the left ventricle (LV).

METHODS AND RESULTS

Adult male New Zealand White rabbits (2.5-3 kg) underwent MI by ligation of the left anterior descending coronary artery. For 8 weeks after surgery, sham-operated, and post-MI rabbits were housed under sedentary conditions or assigned to a 4-week treadmill exercise protocol at a speed of 1.0 km/h for 30 min 5 days per week, then sacrificed. The non-infarcted region of the LV was harvested for further analysis. MI decreased left ventricular ejection fraction (LVEF) and increased thiobarbituric acid reactive substances (TBARS) generation in the LV. Exercise improved the cardiac function of MI rabbits. Left ventricular LC3II/LC3I (microtubule-associated protein light chain 3) in the MI group was 2.1-fold higher than that of the sham group, exercise significantly decreased LC3II/LC3I in the MI group. MI down-regulated the expression of heart-type fatty acid binding protein (h-FABP), and exercise up-regulated h-FABP. In addition, LVEF had a significantly positive correlation with h-FABP and a negative correlation with LC3II/LC3I.

CONCLUSION

Exercise induced change in autophagic function and fatty acid utilization may contribute to the improvement in ventricular function in the infarcted heart.

Composite scaffold provides a cell delivery platform for cardiovascular repair

Control over cell engraftment, survival, and function remains critical for heart repair. We have established a tissue engineering platform for the delivery of human mesenchymal progenitor cells (MPCs) by a fully biological composite scaffold. Specifically, we developed a method for complete decellularization of human myocardium that leaves intact most elements of the extracellular matrix, as well as the underlying mechanical properties. A cell-matrix composite was constructed by applying fibrin hydrogel with suspended cells onto decellularized sheets of human myocardium. We then implanted this composite onto the infarct bed in a nude rat model of cardiac infarction. We next characterized the myogenic and vasculogenic potential of immunoselected human MPCs and demonstrated that in vitro conditioning with a low concentration of TGF-β promoted an arteriogenic profile of gene expression. When implanted by composite scaffold, preconditioned MPCs greatly enhanced vascular network formation in the infarct bed by mechanisms involving the secretion of paracrine factors, such as SDF-1, and the migration of MPCs into ischemic myocardium, but not normal myocardium. Echocardiography demonstrated the recovery of baseline levels of left ventricular systolic dimensions and contractility when MPCs were delivered via composite scaffold. This adaptable platform could be readily extended to the delivery of other reparative cells of interest and used in quantitative studies of heart repair.

Downregulation of the CXC chemokine receptor 4/stromal cell-derived factor 1 pathway enhances myocardial neovascularization, cardiomyocyte survival, and functional recovery after myocardial infarction

OBJECTIVES

Although adequate numbers of hematopoietic progenitor cells reside in the human bone marrow, the extent of endogenous neovascularization after myocardial infarction remains insufficient. The aim of this study was to identify the role of the CXC chemokine receptor 4/stromal cell-derived factor 1 axis in the mobilization and homing of hematopoietic progenitor cells in the ischemic heart.

METHODS

Human bone marrow-derived hematopoietic progenitor cells or saline were injected systemically into athymic nude rats 48 hours after myocardial infarction. Myocardial and bone marrow expression of stromal cell-derived factor 1 and chemotaxis of hematopoietic progenitor cells were measured in vitro in the presence or absence of stromal cell-derived factor 1. The role of the CXC chemokine receptor 4/stromal cell-derived factor 1 axis was investigated by means of antibody blockade or systemic administration of granulocyte colony-stimulating factor. Morphologic analysis included measurement of the infarct area, capillary density, and apoptosis, whereas left ventricular function was measured by means of echocardiographic analysis.

RESULTS

Expression of postinfarct stromal cell-derived factor 1 was increased by 67% in the bone marrow and decreased by 43% in myocardium. Disruption of bone marrow stromal cell-derived factor 1/CXC chemokine receptor 4 interactions by antibody blockade resulted in a redirection of human hematopoietic progenitor cells from the bone marrow to the ischemic heart and augmented neovascularization and cardiomyocyte survival. Similarly, systemic administration of granulocyte colony-stimulating factor to block CXC chemokine receptor 4/stromal cell-derived factor 1 interaction resulted in increased mobilization and homing of hematopoietic progenitor cells to the ischemic heart, which translated to augmented myocardial neovascularization, prevention of apoptosis, and improved cardiac function.

CONCLUSIONS

Bone marrow stromal cell-derived factor 1 upregulation after myocardial ischemia prevents mobilization of endogenous hematopoietic progenitor cells. We provide evidence that disruption of stromal cell-derived factor 1/CXC chemokine receptor 4 interactions allows redirection of hematopoietic progenitor cells to ischemic myocardium and enhances recovery of left ventricular function.

Functional recovery following intracoronary infusion of autologous mononuclear bone marrow cells in patients with chronic anterior myocardial infarction and severely depressed ventricular function

INTRODUCTION AND OBJECTIVES

Studies have shown that intracoronary infusion of mononuclear bone marrow cells improves ventricular function in patients with acute myocardial infarction. However, less information is available about the use of this therapy during the chronic phase of a myocardial infarction. This study involved an analysis of the clinical, echocardiographic and angiographic changes observed in 19 patients with a revascularized chronic anterior myocardial infarction and depressed ventricular function who were treated by cell therapy.

METHODS

A series of patients were monitored during treatment and 6 months and 1 year after treatment. Autologous bone marrow was obtained by needle aspiration of the iliac crest and mononuclear cells were isolated by density-gradient centrifugation. An in vitro biological study of a sample of the infused cells was performed using fluorocytometry, phenotype marking and an analysis of the chemotactic properties of the cells.

RESULTS

Six months and 1 year after cell therapy, a modest improvement was observed in clinical status and ventricular function, which was most pronounced in the group of patients who responded. Characteristically, these patients were revascularized close to the time of cell therapy. There was an inverse relationship between functional recovery and biological parameters that reflected a state conducive to cell migration.

CONCLUSIONS

The intracoronary infusion of mononuclear bone marrow cells into patients with chronic anterior myocardial infarction appeared to result in a modest clinical and functional improvement after 6 months which was sustained up to 1 year after treatment.

Human mesenchymal stem cells and their use in cell-based therapies

The human population is increasingly facing various diseases, including types of cancer, that cannot be cured with conventional drugs. Advanced drug targeting of tumor cells is also often impossible when treating highly invasive and infiltrative tumors such as glioblastoma or pulmonary cancer, because of tumor cells' high migration and invasiveness. Pluripotent human mesenchymal stem cells (hMSCs) have been extensively studied, and strategies are being proposed for treating "incurable" cancers and injury/disease-affected organs. Because of their own intrinsic properties, involving homing and immunomodulatory potency, hMSCs could be used as an excellent cell/drug delivery vehicle in those cell-based therapies. Their unprecedented use has been shadowed, however, by their spontaneous transformation, which links them to cancer-initiating cells during tumor development. How malignant initiation proceeds in vivo, and what are the exact characteristics of the cancer-initiating cells, still remain to be investigated. In the present review, the authors summed up the most recent knowledge about hMSC characteristics, their malignant transformation, and outlined the possibilities of their safe use in novel cell-based therapies.

More insight into mesenchymal stem cells and their effects inside the body

IMPORTANCE OF THE FIELD

The pan-tissue existence and multipotency of differentiation make mesenchymal stem cells (MSCs) an attractive source of cells as tissue repair cells, seeds of engineered tissue, vehicles for gene therapy or in combination to promote tissue regeneration in wound healing and disease recovery.

AREAS COVERED IN THIS REVIEW

This review focuses on recent understanding on MSC's basic biological characteristics and the mechanisms underlying the therapeutic effects of MSCs in vivo.

WHAT THE READER WILL GAIN

The gene expression profiles for mRNA, protein, microRNA and cell surface marker of MSCs are summarized. Special attention is given to miRNA expression and its relationship with the characteristics of MSCs. The mechanisms of therapeutic effects of MSCs are attributed to their ability to migrate along chemokine gradients, differentiate into tissue-specific cells, enhance angiogenesis of wound tissue and regulate immune response. As examples, a detailed description is given on the regeneration of functional sweat glands on burned skin as well as neural cells in middle cerebral artery occlusion (MCAO) animals upon MSC transplantation.

TAKE HOME MESSAGE

Based on current data, although limited, the mesenchymal-epithelial transition is proposed to be one of the important ways for MSCs to participate tissue repair.

Progenitor Cells for the Treatment of Acute Myocardial Infarction

BACKGROUND: Left ventricular remodeling after myocardial infarction (MI) results in ventricular dilation, fibroplasia, and decline in cardiac function. There is significant morbidity and mortality associated with this process, often leading to heart failure despite medical management. New therapies aimed at altering ventricular remodeling after MI are needed, and cytotherapy utilizing progenitor cells is a current area of investigation. THE PROBLEM: Many variables need to be considered to maximize the therapeutic benefit of cytotherapy, including the cell type, the method of delivery, the timing, and patient selection. Investigation into progenitor cell biology will continue to identify novel treatment strategies that then must be tested clinically to demonstrate safety, feasibility, and ultimately therapeutic benefit. BASIC/CLINICAL SCIENCE ADVANCES: Although progenitor cells have the potential to affect ventricular remodeling through multiple mechanisms, their major effect is likely due to actions of secreted factors. Hepatocyte growth factor, stromal-derived growth factor-1 alpha, and stem cell factor affect the mobilization of progenitor cells, which makes it possible to develop treatment strategies based on recruitment of endogenous progenitor cells. CLINICAL CARE RELEVANCE: There have been a number of randomized controlled trials demonstrating modest improvements in cardiac function using progenitor cell therapies after MI. In addition, clinical trials have used granulocyte-colony-stimulating factor as a treatment aimed at increasing progenitor cell mobilization. CONCLUSION: Progenitor cell therapy after MI has been shown to be safe and feasible with some improvements in cardiac function and clinical outcomes. Further investigation is needed to better understand the biology of progenitor cells and the effects of progenitor cell-based therapies.