G-CSF-Based Stem Cell Therapy for the Heart?Unresolved Issues Part A: Paracrine Actions, Mobilization, and Delivery

Comparison of the Cytokine Profile in Mesenchymal Stem Cells from Human Adipose, Umbilical Cord, and Placental Tissues

Human mesenchymal stem cells (MSCs) can be isolated from various tissues. However, the cytokine profile in different MSC types remains unclear. In this study, MSCs were extracted from adipose, umbilical cord, and placental tissues. The surface marker expression, multilineage differentiation potential, and cytokine secretion of these cells were compared. The isolated MSCs exhibited similar morphology and surface marker expression. However, they differed with regard to their differentiation potential. Adipose-MSCs (A-MSCs) exhibited a higher potential for adipogenesis and osteogenic differentiation compared with umbilical cord-MSCs (UC-MSCs) and placental-MSCs (P-MSCs). The expression levels of 80 cytokines were detected, and the data demonstrated that the three MSC types abundantly secreted insulin-like growth factor-binding protein (IGFBP)-4, IGFBP-3, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, IGFBP-6, monocyte chemoattractant protein-1, and granulocyte colony-stimulating factor. However, the expression levels of vascular endothelial growth factor, tumor necrosis factor alpha, interleukin (IL)-6 receptor, and IL-13 in A-MSCs were higher compared with those of UC-MSCs and P-MSCs. Moreover, the expression levels of intercellular adhesion molecule-1 and growth differentiation factor 15 were lower in A-MSCs. Kyoto Encyclopedia of Genes and Genomes analysis indicated that the "adipocytokine" and the "PI3K/Akt pathways" were enriched in A-MSCs. Taken together, the results demonstrated that MSCs from different sources exhibited differences in the secretion of specific factors. A-MSCs were associated with the expression of several proangiogenic factors and may be an improved source for angiogenesis and tissue regeneration.

Application of G-CSF in Congestive Heart Failure Treatment

INTRODUCTION

Congestive Heart Failure (CHF) is a disorder in which the heart is unable to supply enough blood for body tissues. Since heart is an adaptable organ, it overcomes this condition by going under remodeling process. Considering cardiac myocytes are capable of proliferation after MI, stimulation of neovascularization as well as their regeneration might serve as a novel target in cardiac remodeling prevention and CHF treatment. Granulocyte Colony-Stimulating Factor (G-CSF), is a hematopoietic cytokine that promotes proliferation and differentiation of neutrophils and is involved in cardiac repair after MI. So far, this is the first review to focus on GCSF as a novel treatment for heart failure.

METHODS

We conducted a search of some databases such as PubMed for articles and reviews published between 2003 and 2017, with different keywords including "G-CSF", "congestive heart failure", "new therapies for CHF", "filgrastim", "in vivo study".

RESULTS

GCSF exerts its beneficial effects on cardiac repair through either stem cell mobilization or direct angiogenesis promotion. All of which are capable of promoting cardiac cell repair.

CONCLUSION

GCSF is a promising target in CHF-therapy by means of cardiac repair and remodeling prevention through multiple mechanisms, which are effective enough to be used in clinical practice.

Granulocyte-Colony Stimulating Factor-Overexpressing Mesenchymal Stem Cells Exhibit Enhanced Immunomodulatory Actions Through the Recruitment of Suppressor Cells in Experimental Chagas Disease Cardiomyopathy

Genetic modification of mesenchymal stem cells (MSCs) is a promising strategy to improve their therapeutic effects. Granulocyte-colony stimulating factor (G-CSF) is a growth factor widely used in the clinical practice with known regenerative and immunomodulatory actions, including the mobilization of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). Here we evaluated the therapeutic potential of MSCs overexpressing G-CSF (MSC_G-CSF) in a model of inflammatory cardiomyopathy due to chronic Chagas disease. C57BL/6 mice were treated with wild-type MSCs, MSC_G-CSF, or vehicle (saline) 6 months after infection with Trypanosoma cruzi. Transplantation of MSC_G-CSF caused an increase in the number of circulating leukocytes compared to wild-type MSCs. Moreover, G-CSF overexpression caused an increase in migration capacity of MSCs to the hearts of infected mice. Transplantation of either MSCs or MSC_G-CSF improved exercise capacity, when compared to saline-treated chagasic mice. MSC_G-CSF mice, however, were more potent than MSCs in reducing the number of infiltrating leukocytes and fibrosis in the heart. Similarly, MSC_G-CSF-treated mice presented significantly lower levels of inflammatory mediators, such as IFNγ, TNFα, and Tbet, with increased IL-10 production. A marked increase in the percentage of Tregs and MDSCs in the hearts of infected mice was seen after administration of MSC_G-CSF, but not MSCs. Moreover, Tregs were positive for IL-10 in the hearts of T. cruzi-infected mice. In vitro analysis showed that recombinant hG-CSF and conditioned medium of MSC_G-CSF, but not wild-type MSCs, induce chemoattraction of MDSCs in a transwell assay. Finally, MDSCs purified from hearts of MSC_G-CSF transplanted mice inhibited the proliferation of activated splenocytes in a co-culture assay. Our results demonstrate that G-CSF overexpression by MSCs potentiates their immunomodulatory effects in our model of Chagas disease and suggest that mobilization of suppressor cell populations such as Tregs and MDSCs as a promising strategy for the treatment of chronic Chagas disease. Finally, our results reinforce the therapeutic potential of genetic modification of MSCs, aiming at increasing their paracrine actions.

Pathophysiological aldosterone levels modify the secretory activity of cardiac progenitor cells

Cardiac progenitor cells (CPCs) trigger regenerative processes via paracrine mechanisms in response to changes in their environment. In the present study we explored alterations in the secretory activity of CPCs induced by raised aldosterone levels symptomatic for heart failure. The cytokine profile of the supernatant of CPCs that were treated with the mineralocorticoid showed an induction of interleukin-6 secretion. Mass spectrometric analyses revealed an increase in the abundance of secreted proteins associated with regeneration and cell migration like gelsolin and galectin-1. Differential regulation of proteins associated with the extracellular matrix further points to an activation of cell migration. In response to supernatant, migration and proliferation were induced in CPCs, indicating a potential role of paracrine factors in the activation of CPCs from other regions of the heart or extra-cardiac sources. Changes in the secretory activity of CPCs might aim to compensate for the detrimental actions of aldosterone in heart failure.

Mobilization of endogenous bone marrow-derived stem cells in a thioacetamide-induced mouse model of liver fibrosis

The clinical significance of enhancing endogenous circulating haematopoietic stem cells is becoming increasingly recognized, and the augmentation of circulating stem cells using granulocyte-colony stimulating factor (G-CSF) has led to promising preclinical and clinical results for several liver fibrotic conditions. However, this approach is largely limited by cost and the infeasibility of maintaining long-term administration. Preclinical studies have reported that StemEnhance, a mild haematopoietic stem cell mobilizer, promotes cardiac muscle regeneration and remedies the manifestation of diabetes. However, the effectiveness of StemEnhance in ameliorating liver cirrhosis has not been studied. This study is the first to evaluate the beneficial effect of StemEnhance administration in a thioacetamide-induced mouse model of liver fibrosis. StemEnhance augmented the number of peripheral CD34-positive cells, reduced hepatic fibrosis, improved histopathological changes, and induced endogenous liver proliferation. In addition, VEGF expression was up-regulated, while TNF-α expression was down-regulated in thioacetamide-induced fibrotic livers after StemEnhance intake. These data suggest that StemEnhance may be useful as a potential therapeutic candidate for liver fibrosis by inducing reparative effects via mobilization of haematopoietic stem cells.

Epicardial progenitor cells in cardiac regeneration and neovascularisation

While cardiovascular diseases remain the major worldwide cause of mortality and morbidity, there is an urgent need to tackle the clinical and economic burden of heart failure. Since the mammalian heart is unable to adequately regenerate beyond early postnatal stages, individuals surviving acute myocardial infarction are at risk of heart failure. Understanding the embryonic mechanisms of vasculogenesis and cardiogenesis, as well as the mechanisms retained for regeneration in species such as the zebrafish, will inform on strategies for human myocardial repair. Due to their fundamental role in heart development, epicardium-derived cells (EPDCs) have emerged as a population with potential to restore myocardium and coronary vasculature. The ability to revive ordinarily dormant EPDCs lies in the identification of key molecular cues used in the embryo to orchestrate cardiovascular development. One such stimulatory factor, Thymosin β4 (Tβ4), restores the quiescent adult epicardium to its pluripotent embryonic state. Tβ4 treatment of infarcted hearts induces dramatic EPDC proliferation and formation of a network of perfused, functional vessels to enhance blood flow to the ischaemic myocardium. Moreover, Tβ4 facilitates an epicardial contribution of mature de novo cardiomyocytes, structurally and functionally coupled with resident myocardium, which may contribute towards the functional improvement of Tβ4-treated hearts post-MI.

Challenges for heart disease stem cell therapy

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. The use of stem cells to improve recovery of the injured heart after myocardial infarction (MI) is an important emerging therapeutic strategy. However, recent reviews of clinical trials of stem cell therapy for MI and ischemic heart disease recovery report that less than half of the trials found only small improvements in cardiac function. In clinical trials, bone marrow, peripheral blood, or umbilical cord blood cells were used as the source of stem cells delivered by intracoronary infusion. Some trials administered only a stem cell mobilizing agent that recruits endogenous sources of stem cells. Important challenges to improve the effectiveness of stem cell therapy for CVD include: (1) improved identification, recruitment, and expansion of autologous stem cells; (2) identification of mobilizing and homing agents that increase recruitment; and (3) development of strategies to improve stem cell survival and engraftment of both endogenous and exogenous sources of stem cells. This review is an overview of stem cell therapy for CVD and discusses the challenges these three areas present for maximum optimization of the efficacy of stem cell therapy for heart disease, and new strategies in progress.

The Bone Marrow Derived Adult Stem Cells for Dilated Cardiomyopathy (REGENERATE-DCM) trial: study design

The field of autologous stem/progenitor cell therapy for cardiovascular diseases has moved rapidly from bench to bedside. In particular, a small number of pilot studies have demonstrated the safety and efficacy of this treatment in dilated cardiomyopathy (DCM), but this has to be validated in large randomized trials. Here we introduce the Bone Marrow Derived Adult Stem Cells for Dilated Cardiomyopathy (REGENERATE-DCM) trial, which to our knowledge, is the first randomized, double-blind, placebo-controlled trial worldwide to investigate the role of granulocyte-colony stimulating factor and autologous bone marrow-derived stem/progenitor cells to improve cardiac function in patients with DCM.

Hydrogels as a platform for stem cell delivery to the heart

Stem cell therapy offers great promise to repair the injured or failing heart. The outcomes of clinical trials to date, however, have shown that the actual benefit realized falls far short of the promise. A number of factors may explain why that is the case, but poor stem cell retention and engraftment in the hostile environment of the injured heart would seem to be a major factor. Improving stem cell retention and longevity once delivered would seem a logical means to enhance their reparative function. One way to accomplish this goal may be injectable hydrogels, which would serve to fix stem cells in place while providing a sheltering environment. Hydrogels also provide a means to allow for the paracrine factors produced by encapsulated stem cells to diffuse into the injured myocardium. Alternatively, hydrogels themselves can be used for the sustained delivery of reparative factors. Here the authors discuss chitosan-based hydrogels.

Bone marrow-derived aldehyde dehydrogenase-bright stem and progenitor cells for ischemic repair

Adult stem cell populations selected for use in cardiovascular clinical trials typically are mononuclear cell fractions of bone marrow and peripheral blood or cells of specific cell lineages selected by surface markers such as CD34 or CD133. This article describes a potent stem and progenitor cell population identified by an intracellular marker of "stemness" that crosses multiple lineages. Aldehyde dehydrogenase (ALDH)-bright (ALDH(br)) populations isolated from bone marrow contain potent stem and progenitor cells representing all cell types thought to be needed for ischemic repair and include hematopoietic, endothelial, mesenchymal, and neural progenitor cells. An animal model of hindlimb ischemia demonstrated that the ALDH(br) population was highly effective in restoring blood flow to ischemic limbs. Based upon the accumulating evidence for a potential therapeutic effect of bone marrow-derived cells in ischemic disease in humans and the vascular regenerative potential of ALDH(br) cells in the hindlimb model, clinical trials to investigate the use of autologous bone marrow-derived ALDH(br) cells in patients with ischemic heart failure and critical limb ischemia were initiated. Study designs are described. Results of the completed study in patients with critical limb ischemia (CLI) are encouraging and are summarized. Results of 6-month follow-up for the study in ischemic heart failure are pending.

JAK redux: a second look at the regulation and role of JAKs in the heart

A number of type 1 receptor cytokine family members protect the heart from acute and chronic oxidative stress. This protection involves activation of two intracellular signaling cascades: the reperfusion injury salvage kinase (RISK) pathway, which entails activation of phosphatidylinositol 3-kinase (PI3-kinase) and ERK1/2, and JAK-STAT signaling, which involves activation of transcription factor signal transducer and activator of transcription 3 (STAT3). Obligatory for activation of both RISK and STAT3 by nearly all of these cytokines are the kinases JAK1 and JAK2. Yet surprisingly little is known about how JAK1 and JAK2 are regulated in the heart or how they couple to PI3-kinase activation. Although the JAKs are linked to antioxidative stress programs in the heart, we recently reported that these kinases are inhibited by oxidative stress in cardiac myocytes. In contrast, others have reported that cardiac JAK2 is activated by acute oxidative stress by an undefined process. Here we summarize recent insights into the regulation of JAK1 and JAK2. Besides oxidative stress, inhibitory regulation involves phosphorylation, nitration, and intramolecular restraints. Stimulatory regulation involves phosphorylation and adaptor proteins. The net effect of stress on JAK activity in the heart likely represents the sum of both inhibitory and stimulatory processes, along with their dynamic interaction. Thus the regulation of JAKs in the heart, once touted as the paragon of simplicity, is proving rather complicated indeed, requiring a second look. It is our contention that a better understanding of the regulation of this kinase family that is implicated in cardiac protection could translate into effective therapeutic strategies for preventing myocardial damage or repairing the injured heart.

Mesenchymal stem cell: present challenges and prospective cellular cardiomyoplasty approaches for myocardial regeneration

Myocardial ischemia and cardiac dysfunction have been known to follow ischemic heart diseases (IHDs). Despite a plethora of conventional treatment options, their efficacies are associated with skepticism. Cell therapies harbor a promising potential for vascular and cardiac repair, which is corroborated by adequate preclinical evidence. The underlying objectives behind cardiac regenerative therapies subsume enhancing angiomyogenesis in the ischemic myocardium, ameliorating cellular apoptosis, regenerating the damaged myocardium, repopulating the lost resident myocardial cells (smooth muscle, cardiomyocyte, and endothelial cells), and finally, decreasing fibrosis with a consequent reduction in ventricular remodeling. Although-cell based cardiomyoplasty approaches have an immense potential, their clinical utilization is limited owing to the increased need for better candidates for cellular cardiomyoplasty, better routes of delivery, appropriate dose for efficient engraftment, and better preconditioning or genetic-modification strategies for the progenitor and stem cells. Mesenchymal stem cells (MSCs) have emerged as powerful candidates in mediating myocardial repair owing to their unique properties of multipotency, transdifferentiation, intercellular connection with the resident cardiomyocytes via connexin 43 (Cx43)-positive gap junctions in the myocardium, and most important, immunomodulation. In this review, we present an in-depth discussion on the complexities associated with stem and progenitor cell therapies, the potential of preclinical approaches involving MSCs for myocardial repair, and an account of the past milestones and ongoing MSC-based trials in humans.

Coronary vessel development and insight towards neovascular therapy

Formation of the coronary arteries consists of a precisely orchestrated series of morphogenetic and molecular events which can be divided into three distinct processes: vasculogenesis, angiogenesis and arteriogenesis (Risau 1997; Carmeliet 2000). Even subtle perturbations in this process may lead to congenital coronary artery anomalies, as occur in 0.2-1.2% of the general population (von Kodolitsch et al. 2004). Contrary to the previously held dogma, the process of vasculogenesis is not limited to prenatal development. Both vasculogenesis and angiogenesis are now known to actively occur within the adult heart. When the need for regeneration arises, for example in the setting of coronary artery disease, a reactivation of embryonic processes ensues, redeploying many of the same molecular regulators. Thus, an understanding of the mechanisms of embryonic coronary vasculogenesis and angiogenesis may prove invaluable in developing novel strategies for cardiovascular regeneration and therapeutic coronary angiogenesis.

Autologous bone marrow-derived stem cells for ischemic heart failure: REGENERATE-IHD trial

The field of autologous stem/progenitor cell transplantation for cardiovascular diseases has moved rapidly from basic science research to clinical trials. To date, only a handful of pilot studies have reported the use of this novel strategy for heart failure patients. Most of these studies have demonstrated encouraging safety and efficacy data. However, this will need to be validated in large, randomized trials. Here, we introduce the ongoing REGENERATE-IHD trial, which is the largest randomized, placebo-controlled trial in the UK investigating the use of granulocyte-colony stimulating factor and autologous bone marrow-derived stem/progenitor cells to improve cardiac function and symptoms in heart failure patients.

Differentiation of two types of mobilized peripheral blood stem cells by microRNA and cDNA expression analysis

Background

Mobilized-peripheral blood hematopoietic stem cells (HSCs) have been used for transplantation, immunotherapy, and cardiovascular regenerative medicine. Agents used for HSC mobilization include G-CSF and the CXCR4 inhibitor AMD3100 (plerixafor). The HSCs cells mobilized by each agent may contain different subtypes and have different functions. To characterize mobilized HSCs used for clinical applications, microRNA (miRNA) profiling and gene expression profiling were used to compare AMD3100-mobilized CD133+ cells from 4 subjects, AMD3100 plus G-CSF-mobilized CD133+ cells from 4 subjects and G-CSF-mobilized CD34+ cells from 5 subjects. The HSCs were compared to peripheral blood leukocytes (PBLs) from 7 subjects.

Results

Hierarchical clustering of miRNAs separated HSCs from PBLs. miRNAs up-regulated in all HSCs included hematopoiesis-associated miRNA; miR-126, miR-10a, miR-221 and miR-17-92 cluster. miRNAs up-regulated in PBLs included miR-142-3p, -218, -21, and -379. Hierarchical clustering analysis of miRNA expression separated the AMD3100-mobilized CD133+ cells from G-CSF-mobilized CD34+ cells. Gene expression analysis of the HSCs naturally segregated samples according to mobilization and isolation protocol and cell differentiation status.

Conclusion

HSCs and PBLs have unique miRNA and gene expression profiles. miRNA and gene expression microarrays maybe useful for assessing differences in HSCs.

The stem cell movement

Stem or progenitor cell-based strategies to combat ischemic heart disease and myocardial infarction, whether autologous transplantation or stimulation of resident populations, not only require detailed insight into transdifferentiation potential and functional coupling, but the efficacy of this approach is underpinned by the need to induce appropriate migration and homing to the site of injury. This review focuses on existing insights into the trafficking of stem cells in the context of cardiac regenerative therapy, with particular focus on the wide variety of potential sources of cells, critical factors that may regulate their migration, and how extrapolating from embryonic stem/progenitor cell behavior during cardiogenesis may reveal pathways implicit in the adult heart postinjury.

G-CSF-based stem cell therapy for the heart--unresolved issues part B: Stem cells, engraftment, transdifferentiation, and bioengineering

The authors extend their coverage of recent developments in stem cell-based therapy for repairing the heart to cover the basic questions of what stem cells should be used and how best to favor their survivability within the injured heart. The authors focus their attention on those adult stem/progenitor cells that have been best investigated in animal studies for repairing the infarcted heart and are the focus of completed or ongoing clinical trials. In addition, they discuss the promise that resident cardiac stem cells offer and the recent identification of specialized architecturally defined niches within the heart to nurse their development. Bioengineering approaches employing off-the-shelf mesenchymal stem cell patches may soon provide a way to recreate these niches in the scarred heart. Conceivably, these patches might also be seeded with prescribed mixtures of culturally expanded autologous stem/progenitor cells that would lead to new blood vessel and cardiac myocyte formation. The convergence of bioengineering and molecular biology on stem cell therapy would seem to make what was once unimaginable, cardiac regeneration, a clinical reality in less than one generation.