C-Kit Promotes Growth and Migration of Human Cardiac Progenitor Cells via the PI3K-AKT and MEK-ERK Pathways

Bone marrow-derived c-kit positive stem cell administration protects against diabetes-induced nephropathy in a rat model by reversing PI3K/AKT/GSK-3β pathway and inhibiting cell apoptosis

Stem cell-based therapy has been proposed as a novel therapeutic strategy for diabetic nephropathy. This study was designed to evaluate the effect of systemic administration of rat bone marrow-derived c-kit positive (c-kit+) cells on diabetic nephropathy in male rats, focusing on PI3K/AKT/GSK-3β pathway and apoptosis as a possible therapeutic mechanism. Twenty-eight animals were randomly classified into four groups: Control group (C), diabetic group (D), diabetic group, intravenously received 50 μl phosphate-buffered saline (PBS) containing 3 × 105 c-kit- cells (D + ckit-); and diabetic group, intravenously received 50 μl PBS containing 3 × 105 c-Kit positive cells (D + ckit+). Control and diabetic groups intravenously received 50 μl PBS. C-kit+ cell therapy could reduce renal fibrosis, which was associated with attenuation of inflammation as indicated by decreased TNF-α and IL-6 levels in the kidney tissue. In addition, c-kit+ cells restored the expression levels of PI3K, pAKT, and GSK-3β proteins. Furthermore, renal apoptosis was decreased following c-kit+ cell therapy, evidenced by the lower apoptotic index in parallel with the increased Bcl-2 and decreased Bax and Caspase-3 levels. Our results showed that in contrast to c-kit- cells, the administration of c-kit+ cells ameliorate diabetic nephropathy and suggested that c-kit+ cells could be an alternative cell source for attenuating diabetic nephropathy.

The Metabolic Fingerprint of Doxorubicin-Induced Cardiotoxicity in Male CD-1 Mice Fades Away with Time While Autophagy Increases

The cardiotoxicity of doxorubicin (DOX) may manifest at the beginning/during treatment or years after, compromising patients' quality of life. We intended to study the cardiac pathways one week (short-term, control 1 [CTRL1] and DOX1 groups) or five months (long-term, CTRL2 and DOX2 groups) after DOX administration in adult male CD-1 mice. Control groups were given saline, and DOX groups received a 9.0 mg/Kg cumulative dose. In the short-term, DOX decreased the content of AMP-activated protein kinase (AMPK) while the electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) increased compared to CTRL1, suggesting the upregulation of fatty acids oxidation. Moreover, mitofusin1 (Mfn1) content was decreased in DOX1, highlighting decreased mitochondrial fusion. In addition, increased B-cell lymphoma-2 associated X-protein (BAX) content in DOX1 pointed to the upregulation of apoptosis. Conversely, in the long-term, DOX decreased the citrate synthase (CS) activity and the content of Beclin1 and autophagy protein 5 (ATG5) compared to CTRL2, suggesting decreased mitochondrial density and autophagy. Our study demonstrates that molecular mechanisms elicited by DOX are modulated at different extents over time, supporting the differences on clinic cardiotoxic manifestations with time. Moreover, even five months after DOX administration, meaningful heart molecular changes occurred, reinforcing the need for the continuous cardiac monitoring of patients and determination of earlier biomarkers before clinical cardiotoxicity is set.

Urokinase-Type Plasminogen Activator Receptor Regulates Prosurvival and Angiogenic Properties of Cardiac Mesenchymal Stromal Cells

One of the largest challenges to the implementation of cardiac cell therapy is identifying selective reparative targets to enhance stem/progenitor cell therapeutic efficacy. In this work, we hypothesized that such a target could be an urokinase-type plasminogen activator receptor (uPAR)-a glycosyl-phosphatidyl-inositol-anchored membrane protein, interacting with urokinase. uPAR is able to form complexes with various transmembrane proteins such as integrins, activating intracellular signaling pathway and thus regulating multiple cell functions. We focused on studying the CD117+ population of cardiac mesenchymal progenitor cells (MPCs), expressing uPAR on their surface. It was found that the number of CD117+ MPCs in the heart of the uPAR-/- mice is lower, as well as their ability to proliferate in vitro compared with cells from wild-type animals. Knockdown of uPAR in CD117+ MPCs of wild-type animals was accompanied by a decrease in survival rate and Akt signaling pathway activity and by an increase in the level of caspase activity in these cells. That suggests the role of uPAR in supporting cell survival. After intramyocardial transplantation of uPAR(-) MPCs, reduced cell retention and angiogenesis stimulation were observed in mice with myocardial infarction model compared to uPAR(+) cells transplantation. Taken together, the present results appear to prove a novel mechanism of uPAR action in maintaining the survival and angiogenic properties of CD117+ MPCs. These results emphasize the importance of the uPAR as a potential pharmacological target for the regulation of reparative properties of myocardial mesenchymal progenitor cells.

Ex Vivo Expansion and Homing of Human Cord Blood Hematopoietic Stem Cells

Cord blood (CB) has been proven to be an alternative source of haematopoietic stem cells (HSCs) for clinical transplantation and has multiple advantages, including but not limited to greater HLA compatibility, lower incidence of graft-versus-host disease (GvHD), higher survival rates and lower relapse rates among patients with minimal residual disease. However, the limited number of HSCs in a single CB unit limits the wider use of CB in clinical treatment. Many efforts have been made to enhance the efficacy of CB HSC transplantation, particularly by ex vivo expansion or enhancing the homing efficiency of HSCs. In this chapter, we will document the major advances regarding human HSC ex vivo expansion and homing and will also discuss the possibility of clinical translation of such laboratory work.

Multi-Omics-Based Autophagy-Related Untypical Subtypes in Patients with Cerebral Amyloid Pathology

Recent multi-omics analyses paved the way for a comprehensive understanding of pathological processes. However, only few studies have explored Alzheimer's disease (AD) despite the possibility of biological subtypes within these patients. For this study, unsupervised classification of four datasets (genetics, miRNA transcriptomics, proteomics, and blood-based biomarkers) using Multi-Omics Factor Analysis+ (MOFA+), along with systems-biological approaches following various downstream analyses are performed. New subgroups within 170 patients with cerebral amyloid pathology (Aβ+) are revealed and the features of them are identified based on the top-rated targets constructing multi-omics factors of both whole (M-TPAD) and immune-focused models (M-IPAD). The authors explored the characteristics of subtypes and possible key-drivers for AD pathogenesis. Further in-depth studies showed that these subtypes are associated with longitudinal brain changes and autophagy pathways are main contributors. The significance of autophagy or clustering tendency is validated in peripheral blood mononuclear cells (PBMCs; n = 120 including 30 Aβ- and 90 Aβ+), induced pluripotent stem cell-derived human brain organoids/microglia (n = 12 including 5 Aβ-, 5 Aβ+, and CRISPR-Cas9 apolipoprotein isogenic lines), and human brain transcriptome (n = 78). Collectively, this study provides a strategy for precision medicine therapy and drug development for AD using integrative multi-omics analysis and network modelling.

Cardiac Function in Children and Young Adults Treated with MEK Inhibitors: A Retrospective Cohort Study

MEK inhibitors (MEKi) have shown efficacy in pediatric low-grade glioma as well as plexiform neurofibroma. MEKi have been associated with acute cardiac dysfunction in adults. Cardiac consequences in children are unknown. We performed a single center retrospective cohort study evaluating cardiac function by echocardiography (echo) in children and young adults < 21 years receiving MEKi between October 2013 and May 2018. Blinded assessment of left ventricular function by fractional shortening (FS) and ejection fraction (EF) was performed on all available echocardiograms performed before, during, and following therapy, as well as after re-initiation of therapy. Twenty-six patients underwent MEKi therapy with echo follow-up during the study period. Twenty-four of these had complete echo data. Median follow-up was 12 months. Borderline EF (EF 53-57.9%) occurred in 12 (50%) patients; and 3 (12.5%) progressed to abnormal EF (EF < 53%). Cardiac dysfunction, when it occurred, was mild (lowest documented EF was 45%, and lowest FS was 24.4%). EF abnormalities typically fluctuated during therapy, resolved off therapy, and recurred with MEKi re-initiation. No clinical or demographic differences were detected between those who maintained normal cardiac function and those who developed borderline or overt cardiac dysfunction. Symptomatic heart failure did not occur. In this cohort of children and young adults, MEKi use was associated with a high (50%) incidence of borderline or mildly decreased left ventricular function. There was no evidence of permanent cardiac dysfunction. Further evaluation in larger prospective trials is needed.

'Youthful' phenotype of c-Kit+ cardiac fibroblasts

Cardiac fibroblast (CF) population heterogeneity and plasticity present a challenge for categorization of biological and functional properties. Distinct molecular markers and associated signaling pathways provide valuable insight for CF biology and interventional strategies to influence injury response and aging-associated remodeling. Receptor tyrosine kinase c-Kit mediates cell survival, proliferation, migration, and is activated by pathological injury. However, the biological significance of c-Kit within CF population has not been addressed. An inducible reporter mouse detects c-Kit promoter activation with Enhanced Green Fluorescent Protein (EGFP) expression in cardiac cells. Coincidence of EGFP and c-Kit with the DDR2 fibroblast marker was confirmed using flow cytometry and immunohistochemistry. Subsequently, CFs expressing DDR2 with or without c-Kit was isolated and characterized. A subset of DDR2+ CFs also express c-Kit with coincidence in ~ 8% of total cardiac interstitial cells (CICs). Aging is associated with decreased number of c-Kit expressing DDR2+ CFs, whereas pathological injury induces c-Kit and DDR2 as well as the frequency of coincident expression in CICs. scRNA-Seq profiling reveals the transcriptome of c-Kit expressing CFs as cells with transitional phenotype. Cultured cardiac DDR2+ fibroblasts that are c-Kit+ exhibit morphological and functional characteristics consistent with youthful phenotypes compared to c-Kit- cells. Mechanistically, c-Kit expression correlates with signaling implicated in proliferation and cell migration, including phospho-ERK and pro-caspase 3. The phenotype of c-kit+ on DDR2+ CFs correlates with multiple characteristics of 'youthful' cells. To our knowledge, this represents the first evaluation of c-Kit biology within DDR2+ CF population and provides a fundamental basis for future studies to influence myocardial biology, response to pathological injury and physiological aging.

Receptor tyrosine kinase inhibitors negatively impact on pro-reparative characteristics of human cardiac progenitor cells

Receptor tyrosine kinase inhibitors improve cancer survival but their cardiotoxicity requires investigation. We investigated these inhibitors’ effects on human cardiac progenitor cells in vitro and rat heart in vivo. We applied imatinib, sunitinib or sorafenib to human cardiac progenitor cells, assessing cell viability, proliferation, stemness, differentiation, growth factor production and second messengers. Alongside, sunitinib effects were assessed in vivo. Inhibitors decreased (p < 0.05) cell viability, at levels equivalent to ‘peak’ (24 h; imatinib: 91.5 ± 0.9%; sunitinib: 83.9 ± 1.8%; sorafenib: 75.0 ± 1.6%) and ‘trough’ (7 days; imatinib: 62.3 ± 6.2%; sunitinib: 86.2 ± 3.5%) clinical plasma levels, compared to control (100% viability). Reduced (p < 0.05) cell cycle activity was seen with imatinib (29.3 ± 4.3% cells in S/G2/M-phases; 50.3 ± 5.1% in control). Expression of PECAM-1, Nkx2.5, Wnt2, linked with cell differentiation, were decreased (p < 0.05) 2, 2 and 6-fold, respectively. Expression of HGF, p38 and Akt1 in cells was reduced (p < 0.05) by sunitinib. Second messenger (p38 and Akt1) blockade affected progenitor cell phenotype, reducing c-kit and growth factor (HGF, EGF) expression. Sunitinib for 9 days (40 mg/kg, i.p.) in adult rats reduced (p < 0.05) cardiac ejection fraction (68 ± 2% vs. baseline (83 ± 1%) and control (84 ± 4%)) and reduced progenitor cell numbers. Receptor tyrosine kinase inhibitors reduce cardiac progenitor cell survival, proliferation, differentiation and reparative growth factor expression.

The roles of interleukin-1 receptor accessory protein in certain inflammatory conditions

Interleukin-1 receptor accessory protein (IL-1RAcP) is a member of the immunoglobulin superfamily proteins consisting of soluble and membranous isoforms. IL-1RAcP plays an essential role in the signaling of the IL-1 family cytokines such as IL-1, IL-33, and IL-36, as well as tyrosine kinases FLT3 and C-Kit. IL-1RAcP generally initiate inflammatory signaling pathway through the recruitment of signaling mediators, including MYD88 and IRAK. Chronic inflammation following prolonged signaling of cytokine receptors is a critical process in the pathogenesis of many inflammatory disorders, including autoimmunity, obesity, psoriasis, type 1 diabetes, endometriosis, preeclampsia and Alzheimer's disease. Recently IL-1RAcP aberrant signaling has been considered to play a central role in the pathogenesis of these chronic inflammatory diseases. Targeting IL-1RAcP signaling pathway that was recently considered in clinical trials related to malignancies, also indicates its potential as therapeutic target for the inflammatory and autoimmune diseases. This review summarizes the molecular structure, components associated with IL-1RAcP signaling pathways, and their involvement in the pathogenesis of different inflammatory diseases. We will also discuss the effect of IL-1RAcP inhibition for treatment proposes.

A holistic view on c-Kit in cancer: Structure, signaling, pathophysiology and its inhibitors

Receptor tyrosine kinases play an important role in many cellular processes, and their dysregulation leads to diseases, most importantly cancer. One such receptor tyrosine kinase is c-Kit, a type-III receptor tyrosine kinase, which is involved in various intracellular signaling pathways. The role of different mutant isoforms of c-Kit has been established in several types of cancers. Accordingly, promising c-Kit inhibition results have been reported for the treatment of different cancers (e.g., gastrointestinal stromal tumors, melanoma, acute myeloid leukemia, and other tumors). Therefore, lots of effort has been put to target c-Kit for the treatment of cancer. Here, we provide a comprehensive compilation to provide an insight into c-Kit inhibitor discovery. This compilation provides key information regarding the structure, signaling pathways related to c-Kit, and, more importantly, pharmacophores, binding modes, and SAR analysis for almost all small-molecule heterocycles reported for their c-Kit inhibitory activity. This work could be used as a guide in understanding the basic requirements for targeting c-Kit, and how the selectivity and efficacy of the molecules have been achieved till today.

Hypoxia regulates human mast cell adhesion to fibronectin via the PI3K/AKT signaling pathway

A decrease in oxygen concentration is a hallmark of inflammatory reactions resulting from infection or homeostasis disorders. Mast cells interact with extracellular matrix and other cells by adhesion receptors. We investigated the effect of hypoxia on integrin-mediated mast cell adhesion to fibronectin. We found that it was mediated by the α5/β1 receptor and that hypoxia significantly upregulated this process. Hypoxia-mediated increases in mast cell adhesion occurred without increased surface expression of integrins, suggesting regulation by inside-out integrin signaling. Hypoxia also mediated an increase in phosphorylation of Akt, and PI3’kinase inhibitors abolished hypoxia-mediated mast cell adhesion. Hypoxia upregulates the function of integrin receptors by PI3’ kinase-dependent signaling. This process might be important for the location of mast cells at inflammatory sites

Pathophysiological Basis for Nutraceutical Supplementation in Heart Failure: A Comprehensive Review

There is evidence demonstrating that heart failure (HF) occurs in 1-2% of the global population and is often accompanied by comorbidities which contribute to increasing the prevalence of the disease, the rate of hospitalization and the mortality. Although recent advances in both pharmacological and non-pharmacological approaches have led to a significant improvement in clinical outcomes in patients affected by HF, residual unmet needs remain, mostly related to the occurrence of poorly defined strategies in the early stages of myocardial dysfunction. Nutritional support in patients developing HF and nutraceutical supplementation have recently been shown to possibly contribute to protection of the failing myocardium, although their place in the treatment of HF requires further assessment, in order to find better therapeutic solutions. In this context, the Optimal Nutraceutical Supplementation in Heart Failure (ONUS-HF) working group aimed to assess the optimal nutraceutical approach to HF in the early phases of the disease, in order to counteract selected pathways that are imbalanced in the failing myocardium. In particular, we reviewed several of the most relevant pathophysiological and molecular changes occurring during the early stages of myocardial dysfunction. These include mitochondrial and sarcoplasmic reticulum stress, insufficient nitric oxide (NO) release, impaired cardiac stem cell mobilization and an imbalanced regulation of metalloproteinases. Moreover, we reviewed the potential of the nutraceutical supplementation of several natural products, such as coenzyme Q10 (CoQ10), a grape seed extract, Olea Europea L.-related antioxidants, a sodium-glucose cotransporter (SGLT2) inhibitor-rich apple extract and a bergamot polyphenolic fraction, in addition to their support in cardiomyocyte protection, in HF. Such an approach should contribute to optimising the use of nutraceuticals in HF, and the effect needs to be confirmed by means of more targeted clinical trials exploring the efficacy and safety of these compounds.

Cardiotoxic effects of angiogenesis inhibitors

The development of new therapies for cancer has led to dramatic improvements in survivorship. Angiogenesis inhibitors represent one such advancement, revolutionising treatment for a wide range of malignancies. However, these drugs are associated with cardiovascular toxicities which can impact optimal cancer treatment in the short-term and may lead to increased morbidity and mortality in the longer term. Vascular endothelial growth factor inhibitors (VEGFIs) are associated with hypertension, left ventricular systolic dysfunction (LVSD) and heart failure as well as arterial and venous thromboembolism, QTc interval prolongation and arrhythmia. The mechanisms behind the development of VEGFI-associated LVSD and heart failure likely involve the combination of a number of myocardial insults. These include direct myocardial effects, as well as secondary toxicity via coronary or peripheral vascular damage. Cardiac toxicity may result from the 'on-target' effects of VEGF inhibition or 'off-target' effects resulting from inhibition of other tyrosine kinases. Similar mechanisms may be involved in the development of VEGFI-associated right ventricular (RV) dysfunction. Some VEGFIs can be associated with QTc interval prolongation and an increased risk of ventricular and atrial arrhythmia. Further pre-clinical and clinical studies and trials are needed to better understand the impact of VEGFI on the cardiovascular system. Once mechanisms are elucidated, therapies can be investigated in clinical trials and surveillance strategies for identifying VEGFI-associated cardiovascular complications can be developed.

Cell Sheet Comprised of Mesenchymal Stromal Cells Overexpressing Stem Cell Factor Promotes Epicardium Activation and Heart Function Improvement in a Rat Model of Myocardium Infarction

Cell therapy of the post-infarcted myocardium is still far from clinical use. Poor survival of transplanted cells, insufficient regeneration, and replacement of the damaged tissue limit the potential of currently available cell-based techniques. In this study, we generated a multilayered construct from adipose-derived mesenchymal stromal cells (MSCs) modified to secrete stem cell factor, SCF. In a rat model of myocardium infarction, we show that transplantation of SCF producing cell sheet induced activation of the epicardium and promoted the accumulation of c-kit positive cells in ischemic muscle. Morphometry showed the reduction of infarct size (16%) and a left ventricle expansion index (0.12) in the treatment group compared to controls (24-28%; 0.17-0.32). The ratio of viable myocardium was more than 1.5-fold higher, reaching 49% compared to the control (28%) or unmodified cell sheet group (30%). Finally, by day 30 after myocardium infarction, SCF-producing cell sheet transplantation increased left ventricle ejection fraction from 37% in the control sham-operated group to 53%. Our results suggest that, combining the genetic modification of MSCs and their assembly into a multilayered construct, we can provide prolonged pleiotropic effects to the damaged heart, induce endogenous regenerative processes, and improve cardiac function.

PIM1 Promotes Survival of Cardiomyocytes by Upregulating c-Kit Protein Expression

Enhancing cardiomyocyte survival is crucial to blunt deterioration of myocardial structure and function following pathological damage. PIM1 (Proviral Insertion site in Murine leukemia virus (PIM) kinase 1) is a cardioprotective serine threonine kinase that promotes cardiomyocyte survival and antagonizes senescence through multiple concurrent molecular signaling cascades. In hematopoietic stem cells, PIM1 interacts with the receptor tyrosine kinase c-Kit upstream of the ERK (Extracellular signal-Regulated Kinase) and Akt signaling pathways involved in cell proliferation and survival. The relationship between PIM1 and c-Kit activity has not been explored in the myocardial context. This study delineates the interaction between PIM1 and c-Kit leading to enhanced protection of cardiomyocytes from stress. Elevated c-Kit expression is induced in isolated cardiomyocytes from mice with cardiac-specific overexpression of PIM1. Co-immunoprecipitation and proximity ligation assay reveal protein–protein interaction between PIM1 and c-Kit. Following treatment with Stem Cell Factor, PIM1-overexpressing cardiomyocytes display elevated ERK activity consistent with c-Kit receptor activation. Functionally, elevated c-Kit expression confers enhanced protection against oxidative stress in vitro. This study identifies the mechanistic relationship between PIM1 and c-Kit in cardiomyocytes, demonstrating another facet of cardioprotection regulated by PIM1 kinase.

Isolation, growth kinetics, and immunophenotypic characterization of adult human cardiac progenitor cells

The discovery of cardiac progenitor cells (CPCs) has raised expectations for the development of cell-based therapy of the heart. Although cell therapy is emerging as a novel treatment for heart failure, several issues still exist concerning an unambiguous definition of the phenotype of CPC types. There is a need to define and validate the methods for the generation of quality CPC populations used in cell therapy applications. Considering the critical roles of cardiac cell progenitors in cellular therapy, we speculate that long term culture might modulate the immunophenotypes of CPCs. Hence, a strategy to validate the isolation and cell culture expansion of cardiac cell populations was devised. Isolation of three subpopulations of human CPCs was done from a single tissue sample using explant, enzymatic isolation, and c-kit⁺ immunomagnetic sorting methods. The study assessed the effects of ex vivo expansion on proliferation, immunophenotypes, and differentiation of CPCs. Additionally, we report that an explant culture can take over 2 months to achieve similar cell yields, and cell sorting requires a much larger starting population to match this expansion time frame. In comparison, an enzymatic method is expected to yield equivalent quantities of CPCs in 2-3 weeks, notably at a significantly lower cost, which may intensify their use in therapeutic approaches. We determined that ex vivo expansion caused changes in cellular characteristics, and hence propose validated molecular signatures should be established to evaluate the impact of ex vivo expansion for a safe cell therapy product.

C-Kit+ progenitors restore rat asthmatic lung function by modulation of T-bet and GATA-3 expression

NEW FINDINGS

What is the central question of this study? The aim of the experiment was to highlight the regenerative capacity of bone marrow Kit⁺ cells in the restoration of asthmatic pulmonary function in the rat model. What is the main finding and its importance? Data showed that these cells were recruited successfully to the asthmatic niche after intratracheal administration and accelerated the regeneration of asthmatic lungs by the modulation of inflammation via the control of Gata3 and Tbx21 expression, leading to decreased tracheal responsiveness to methacholine and reduction of pathological remodelling.

ABSTRACT

Allergic asthma is a T helper (Th) 2 immunological disorder with consequential uncontrolled inflammatory responses. There is an increasing demand to use new methods for the treatment of asthma based on modulation of the Th2-to-Th1 ratio in favour of the Th1 population. Accordingly, we decided to evaluate the effects of intratracheal administration of Kit⁺ bone marrow cells on tracheal responsiveness and the expression of Gata3 and Tbx21 genes. Forty male Wistar rats were allocated  randomly  into four experimental groups: healthy rats (control group), sensitized rats (OVA group), sensitized rats receiving Kit^- cells (OVA+Kit^- group) and sensitized rats receiving Kit⁺ cells (OVA+Kit⁺ group). Total and differential white blood cell counts, tracheal responsiveness to cumulative methacholine concentrations and histopathological analysis were evaluated. The results showed a statistically significant increase in total white blood cell, eosinophil and neutrophil counts, tracheal contractility, Gata3 expression and prototypical histopathology of asthma. Along with these conditions, we found that the number of lymphocytes was decreased and expression of Tbx21 diminished in sensitized rats compared with control animals. Monitoring of labelled tagged cells confirmed successful engraftment of transplanted cells in pulmonary tissue. Juxtaposition of Kit⁺ cells changed the blood leucogram closer to the control values. Kit⁺ cells increased the expression of Tbx21 and suppressed Gata3 (P < 0.05). In the OVA+Kit⁺ group, tracheal responsiveness was improved coincident with increased pulmonary regeneration. In conclusion, this study showed that intratracheal administration of bone marrow-derived Kit⁺ cells, but not Kit^- cells, could be effective in the alleviation of asthma, presumably by the modulation of Gata3 and Tbx21.

An overview of the myocardial regeneration potential of cardiac c-Kit+ progenitor cells via PI3K and MAPK signaling pathways

In recent years, several studies have investigated cell transplantation as an innovative strategy to restore cardiac function following heart failure. Previous studies have also shown cardiac progenitor cells as suitable candidates for cardiac cell therapy compared with other stem cells. Cellular kit (c-kit) plays an important role in the survival and migration of cardiac progenitor cells. Like other types of cells, in the heart, cellular responses to various stimuli are mediated via coordinated pathways. Activation of c-kit⁺ cells leads to subsequent activation of several downstream mediators such as PI3K and the MAPK pathways. This review aims to outline current research findings on the role of PI3K/AKT and the MAPK pathways in myocardial regeneration potential of c-kit⁺.

Paneth Cells Respond to Inflammation and Contribute to Tissue Regeneration by Acquiring Stem-like Features through SCF/c-Kit Signaling

IBD syndromes such as Crohn's disease and ulcerative colitis result from the inflammation of specific intestinal segments. Although many studies have reported on the regenerative response of intestinal progenitor and stem cells to tissue injury, very little is known about the response of differentiated lineages to inflammatory cues. Here, we show that acute inflammation of the mouse small intestine is followed by a dramatic loss of Lgr5⁺ stem cells. Instead, Paneth cells re-enter the cell cycle, lose their secretory expression signature, and acquire stem-like properties, thus contributing to the tissue regenerative response to inflammation. Stem cell factor secretion upon inflammation triggers signaling through the c-Kit receptor and a cascade of downstream events culminating in GSK3β inhibition and Wnt activation in Paneth cells. Hence, the plasticity of the intestinal epithelium in response to inflammation goes well beyond stem and progenitor cells and extends to the fully differentiated and post-mitotic Paneth cells.

Human CardioChimeras: Creation of a Novel "Next-Generation" Cardiac Cell

Background

CardioChimeras produced by fusion of murine c‐kit⁺ cardiac interstitial cells with mesenchymal stem cells promote superior structural and functional recovery in a mouse model of myocardial infarction compared with either precursor cell alone or in combination. Creation of human CardioChimeras (hCCs) represents the next step in translational development of this novel cell type, but new challenges arise when working with c‐kit⁺ cardiac interstitial cells isolated and expanded from human heart tissue samples. The objective of the study was to establish a reliable cell fusion protocol for consistent optimized creation of hCCs and characterize fundamental hCC properties.

Methods and Results

Cell fusion was induced by incubating human c‐kit⁺ cardiac interstitial cells and mesenchymal stem cells at a 2:1 ratio with inactivated Sendai virus. Hybrid cells were sorted into 96‐well microplates for clonal expansion to derive unique cloned hCCs, which were then characterized for various cellular and molecular properties. hCCs exhibited enhanced survival relative to the parent cells and promoted cardiomyocyte survival in response to serum deprivation in vitro.

Conclusions

The generation of hCC is demonstrated and validated in this study, representing the next step toward implementation of a novel cell product for therapeutic development. Feasibility of creating human hybrid cells prompts consideration of multiple possibilities to create novel chimeric cells derived from cells with desirable traits to promote healing in pathologically damaged myocardium.

Cardiac Progenitor Cells from Stem Cells: Learning from Genetics and Biomaterials

Cardiac Progenitor Cells (CPCs) show great potential as a cell resource for restoring cardiac function in patients affected by heart disease or heart failure. CPCs are proliferative and committed to cardiac fate, capable of generating cells of all the cardiac lineages. These cells offer a significant shift in paradigm over the use of human induced pluripotent stem cell (iPSC)-derived cardiomyocytes owing to the latter's inability to recapitulate mature features of a native myocardium, limiting their translational applications. The iPSCs and direct reprogramming of somatic cells have been attempted to produce CPCs and, in this process, a variety of chemical and/or genetic factors have been evaluated for their ability to generate, expand, and maintain CPCs in vitro. However, the precise stoichiometry and spatiotemporal activity of these factors and the genetic interplay during embryonic CPC development remain challenging to reproduce in culture, in terms of efficiency, numbers, and translational potential. Recent advances in biomaterials to mimic the native cardiac microenvironment have shown promise to influence CPC regenerative functions, while being capable of integrating with host tissue. This review highlights recent developments and limitations in the generation and use of CPCs from stem cells, and the trends that influence the direction of research to promote better application of CPCs.

Serum level of stem cell factor and its soluble receptor in aspirin-exacerbated respiratory disease

Aim: Stem cell factor (SCF) may be associated with inflammatory processes leading to aspirin-induced asthma. This study evaluated the relationship between serum level of SCF and its soluble receptor with aspirin-induced asthma. Methods & materials: Twenty-five patients and 25 healthy controls were enrolled in this study. The concentration of SCF and mast/stem cell growth factor receptor (C-kit) was determined in serum samples. Spirometry and rhinometry were performed to determine the severity of the disease. p < 0.05 were considered significant. Results: The serum levels of SCF and C-kit receptor were significantly higher in the case group. The serum SCF and C-kit level had a significant positive correlation with the severity of asthma, disease duration and nasal obstruction. Conclusion: Our findings suggest that SCF and C-kit receptors have a direct effect on the severity of aspirin-induced asthma.

KIF15 promotes bladder cancer proliferation via the MEK-ERK signaling pathway

Background

Bladder cancer (BC) is the most common cancer of the urinary tract and invariably predicts a poor prognosis. In this study, we found a reliable gene signature and potential biomarker for predicting clinical prognosis.

Methods

The gene expression profiles were obtained from the GEO database. By performing GEO2R analysis, numerous differentially expressed genes (DEGs) were found. Three different microarray datasets were integrated in order to more precisely identify up-expression genes. Functional analysis revealed that these genes were mainly involved in cell cycle, DNA replication and metabolic pathways.

Results

Based on protein-protein interactome (PPI) networks that were identified in the current study and previous studies, we focused on KIF15 for further study. The results showed that KIF15 promotes BC cell proliferation via the MEK -ERK pathway, and Kaplan‐Meier survival analysis revealed that KIF15 expression was an independent prognostic risk factor in BC patients.

Conclusion

KIF15 may represent a promising prognostic biomarker and a potential therapeutic option for BC.

Spaceflight/microgravity inhibits the proliferation of hematopoietic stem cells by decreasing Kit-Ras/cAMP-CREB pathway networks as evidenced by RNA-Seq assays

Exposure to spaceflight and microgravity causes physiologic and psychologic changes including bone loss, cardiovascular dysfunction, and immune dysfunction. Anemia and hematopoietic disorders are observed in astronauts after spaceflight. Hematopoietic stem and progenitor cells (HSPCs), which can self-renew and give rise to all blood cells, play vital roles in hematopoiesis and homeostasis; however, the molecular mechanisms responsible for the impacts of microgravity on the proliferation of HSPCs remain unclear. We maintained mouse bone marrow HSPCs in the presence of stem cell factor for 12 d under spaceflight and simulated microgravity conditions, respectively, and analyzed cell proliferation and gene expression. Both spaceflight and simulated microgravity significantly decreased the number of HSPCs, mainly by blocking cell cycle at G₁/S transition, but did not affect their differentiation abilities. RNA-sequencing data indicated that genes related to cell proliferation were down-regulated, whereas the genes related to cell death were up-regulated under microgravity. Among the gene signatures, we identified that the Kit-Ras/cAMP-cAMP response element-binding protein pathway might be one of the major microgravity-regulated pathways during HSPC proliferation. Furthermore, the quantification of notable genes was validated at the mRNA levels under simulated microgravity condition. Overall, these results would help us to understand the intracellular molecular mechanisms regulating microgravity-inhibited proliferation of HSPCs.-Wang, P., Tian, H., Zhang, J., Qian, J., Li, L., Shi, L., Zhao, Y. Spaceflight/microgravity inhibits the proliferation of hematopoietic stem cells by decreasing Kit-Ras/cAMP-CREB pathway networks as evidenced by RNA-Seq assays.

Role of c-Kit in Myocardial Regeneration and Aging

c-Kit, a type III receptor tyrosine kinase (RTK), is involved in multiple intracellular signaling whereby it is mainly considered a stem cell factor receptor, which participates in vital functions of the mammalian body, including the human. Furthermore, c-kit is a necessary yet not sufficient marker to detect and isolate several types of tissue-specific adult stem cells. Accordingly, c-kit was initially used as a marker to identify and enrich for adult cardiac stem/progenitor cells (CSCs) that were proven to be clonogenic, self-renewing and multipotent, being able to differentiate into cardiomyocytes, endothelial cells and smooth muscle cells in vitro as well as in vivo after myocardial injury. Afterwards it was demonstrated that c-kit expression labels a heterogenous cardiac cell population, which is mainly composed by endothelial cells while only a very small fraction represents CSCs. Furthermore, c-kit as a signaling molecule is expressed at different levels in this heterogenous c-kit labeled cardiac cell pool, whereby c-kit low expressers are enriched for CSCs while c-kit high expressers are endothelial and mast cells. This heterogeneity in cell composition and expression levels has been neglected in recent genetic fate map studies focusing on c-kit, which have claimed that c-kit identifies cells with robust endothelial differentiation potential but with minimal if not negligible myogenic commitment potential. However, modification of c-kit gene for Cre Recombinase expression in these Cre/Lox genetic fate map mouse models produced a detrimental c-kit haploinsufficiency that prevents efficient labeling of true CSCs on one hand while affecting the regenerative potential of these cells on the other. Interestingly, c-kit haploinsufficiency in c-kit-deficient mice causes a worsening myocardial repair after injury and accelerates cardiac aging. Therefore, these studies have further demonstrated that adult c-kit-labeled CSCs are robustly myogenic and that the adult myocardium relies on c-kit expression to regenerate after injury and to counteract aging effects on cardiac structure and function.

KIT as a therapeutic target for non-oncological diseases

KIT is a receptor tyrosine kinase that after binding to its ligand stem cell factor activates signaling cascades linked to biological processes such as proliferation, differentiation, migration and cell survival. Based on studies performed on SCF and/or KIT mutant animals that presented anemia, sterility, and/or pigmentation disorders, KIT signaling was mainly considered to be involved in the regulation of hematopoiesis, gametogenesis, and melanogenesis. More recently, novel animal models and ameliorated cellular and molecular techniques have led to the discovery of a widen repertoire of tissue compartments and functions that are being modulated by KIT. This is the case for the lung, heart, nervous system, gastrointestinal tract, pancreas, kidney, liver, and bone. For this reason, the tyrosine kinase inhibitors that were originally developed for the treatment of hemato-oncological diseases are being currently investigated for the treatment of non-oncological disorders such as asthma, rheumatoid arthritis, and alzheimer's disease, among others. The beneficial effects of some of these tyrosine kinase inhibitors have been proven to depend on KIT inhibition. This review will focus on KIT expression and regulation in healthy and pathologic conditions other than cancer. Moreover, advances in the development of anti-KIT therapies, including tyrosine kinase inhibitors, and their application will be discussed.

(+)-Usnic Acid Inhibits Migration of c-KIT Positive Cells in Human Colorectal Cancer

Inhibition of tumor cell migration is a treatment strategy for patients with colorectal cancer (CRC). SCF-dependent activation of c-KIT is responsible for migration of c-KIT positive [c-KIT(+)] cells of CRC. Drug resistance to Imatinib Mesylate (c-KIT inhibitor) has emerged. Inhibition of mTOR can induce autophagic degradation of c-KIT. (+)-usnic acid [(+)-UA], isolated from lichens, has two major functions including induction of proton shuttle and targeting inhibition of mTOR. To reduce hepatotoxicity, the treatment concentration of (+)-UA should be lower than 10 μM. HCT116 cells and LS174 cells were employed to investigate the inhibiting effect of (+)-UA (<10 μM) on SCF-mediated migration of c-KIT(+) CRC cells. HCT116 cells were employed to investigate the molecular mechanisms. The results indicated that firstly, 8 μM (+)-UA decreased ATP content via uncoupling; secondly, 8 μM (+)-UA induced mTOR inhibition, thereby mediated activation suppression of PKC-A, and induced the autophagy of the completed autophagic flux that resulted in the autophagic degradation and transcriptional inhibition of c-KIT and the increase in LDH release; ultimately, 8 μM (+)-UA inhibited SCF-mediated migration of CRC c-KIT(+) cells. Taken together, 8 μM could be determined as the effective concentration for (+)-UA to inhibit SCF-mediated migration of CRC c-KIT(+) cells.

Insights from molecular signature of in vivo cardiac c-Kit(+) cells following cardiac injury and β-catenin inhibition

There is much interest over resident c-Kit(+) cells in tissue regeneration. Their role in cardiac regeneration has been controversial. In this study we aim to understand the in vivo behavior of cardiac c-Kit(+) cells at baseline and after myocardial infarction and in response to Sfrp2. This approach can accurately study the in vivo transcript expressions of these cells in temporal response to injury and overcomes the limitations of the in vitro approach. RNA-seq was performed with c-Kit(+) cells and cardiomyocytes from healthy non-injured mice as well as c-Kit(+) cells from 1 day post-MI and 12 days post-MI mice. When compared to in vivo c-Kit(+) cells isolated from a healthy non-injured mouse heart, cardiomyocytes were enriched in transcripts that express anion channels, cation channels, developmental/differentiation pathway components, as well as proteins that inhibit canonical Wnt/β-catenin signaling. Myocardial infarction (MI) induced in vivo c-Kit(+) cells to transiently adopt the cardiomyocyte-specific signature: expression of a number of cardiomyocyte-specific transcripts was maximal 1 day post-MI and declined by 12 days post-MI. We next studied the effect of β-catenin inhibition on in vivo c-Kit(+) cells by administering the Wnt inhibitor Sfrp2 into the infarct border zone. Sfrp2 both enhanced and sustained cardiomyocyte-specific gene expression in the in vivo c-Kit(+) cells: expression of cardiomyocyte-specific transcripts was higher and there was no decline in expression by 12 days post-MI. Further analysis of the biology of c-Kit(+) cells identified that culture induced a significant and irreversible change in their molecular signature raising questions about reliability of in vitro studies. Our findings provide evidence that MI induces in vivo c-Kit(+) cells to adopt transiently a cardiomyocyte-specific pattern of gene expression, and Sfrp2 further enhances and induces sustained gene expression. Our approach is important for understanding c-Kit(+) cells in cardiac regeneration and also has broad implications in the investigation of in vivo resident stem cells in other areas of tissue regeneration.

Expression of AMHR2 and C-KIT in cervical lesions in Uyghur Women of Xinjiang, China

BACKGROUND

Cervical cancer is one of the most common malignant tumors in women. Anti-Müllerian hormone receptor 2 (AMHR2) and C-Kit were two members of protein kinase which were reported increased in some cancers like ovarian carcinoma and breast cancer. The present study aimed to assess the expression of AMHR2 and c-Kit in cervical cancer of different differentiated degrees as well as in cervicitis sections.

METHODS

All the lesions were collected randomly during clinical observations in hospitals located in Xinjiang, China. Polymerase chain reaction (PCR) and immunohistochemical staining were used to detect AMHR2 and c-Kit expression in cervical samples from women who had been infected with human papilloma virus (HPV)16. The expression rate was compared between cervical cancer of well, moderately and poorly differentiated and cervicitis.

RESULTS

The average age of the patients was 45 years; ranged from 23 to 80. For AMHR2, all 17 cervicitis samples ranged from (++) to (++++), while cervical cancer showed 11 (+), 9 (++), 15 (+++),9 (++++), and 8 (-), which showed AMHR2 expression was lessen with the poorer of differentiation degree of cervical cancer (P < .05). For c-Kit, 18 cervicitis samples mainly expressed as (-) with none showed (+++) or (++++), while cervical cancer samples showed 7 (-), 6 (+), 1 (++), 2 (+++), and 8 (++++), which indicated c-Kit's expression increased with the reduction of cervical cancer's differentiation degree (P < .05).

CONCLUSION

AMHR2 might have some correlation with self defense of our body, while c-Kit might link with the potential invasive capacity of cervical cancer.

Cardiac c-Kit Biology Revealed by Inducible Transgenesis

RATIONALE

Biological significance of c-Kit as a cardiac stem cell marker and role(s) of c-Kit+ cells in myocardial development or response to pathological injury remain unresolved because of varied and discrepant findings. Alternative experimental models are required to contextualize and reconcile discordant published observations of cardiac c-Kit myocardial biology and provide meaningful insights regarding clinical relevance of c-Kit signaling for translational cell therapy.

OBJECTIVE

The main objectives of this study are as follows: demonstrating c-Kit myocardial biology through combined studies of both human and murine cardiac cells; advancing understanding of c-Kit myocardial biology through creation and characterization of a novel, inducible transgenic c-Kit reporter mouse model that overcomes limitations inherent to knock-in reporter models; and providing perspective to reconcile disparate viewpoints on c-Kit biology in the myocardium.

METHODS AND RESULTS

In vitro studies confirm a critical role for c-Kit signaling in both cardiomyocytes and cardiac stem cells. Activation of c-Kit receptor promotes cell survival and proliferation in stem cells and cardiomyocytes of either human or murine origin. For creation of the mouse model, the cloned mouse c-Kit promoter drives Histone2B-EGFP (enhanced green fluorescent protein; H2BEGFP) expression in a doxycycline-inducible transgenic reporter line. The combination of c-Kit transgenesis coupled to H2BEGFP readout provides sensitive, specific, inducible, and persistent tracking of c-Kit promoter activation. Tagging efficiency for EGFP+/c-Kit+ cells is similar between our transgenic versus a c-Kit knock-in mouse line, but frequency of c-Kit+ cells in cardiac tissue from the knock-in model is 55% lower than that from our transgenic line. The c-Kit transgenic reporter model reveals intimate association of c-Kit expression with adult myocardial biology. Both cardiac stem cells and a subpopulation of cardiomyocytes express c-Kit in uninjured adult heart, upregulating c-Kit expression in response to pathological stress.

CONCLUSIONS

c-Kit myocardial biology is more complex and varied than previously appreciated or documented, demonstrating validity in multiple points of coexisting yet heretofore seemingly irreconcilable published findings.

Beyond cardiomyocyte loss: Role of Notch in cardiac aging

The knowledge of the cellular events occurring in the aging heart has dramatically expanded in the last decade and is expected to further grow in years to come. It is now clear that impaired function and loss of cardiomyocytes are major features of cardiac aging, but other events are likewise important. In particular, accumulating experimental evidence highlights the importance of fibroblast and cardiac progenitor cell (CPC) dysfunction. The Notch pathway regulates cardiomyocyte, fibroblast, and CPC activity and, thus, may be critically involved in heart disease associated with advanced age, especially heart failure. In a translational perspective, thorough investigation of the Notch system in the aging myocardium may lead to the identification of molecular targets for novel therapies for age-related cardiac disease.

Insulin-like growth factor-1-mediated regulation of miR-193a expression promotes the migration and proliferation of c-kit-positive mouse cardiac stem cells

Background

C-kit-positive cardiac stem cells (CSCs) have been shown to be a promising candidate treatment for myocardial infarction and heart failure. Insulin-like growth factor (IGF)-1 is an anabolic growth hormone that regulates cellular proliferation, differentiation, senescence, and death in various tissues. Although IGF-1 promotes the migration and proliferation of c-kit-positive mouse CSCs, the underlying mechanism remains unclear.

Methods

Cells were isolated from adult mouse hearts, and c-kit-positive CSCs were separated using magnetic beads. The cells were cultured with or without IGF-1, and c-kit expression was measured by Western blotting. IGF-1 induced CSC proliferation and migration, as measured through Cell Counting Kit-8 (CCK-8) and Transwell assays, respectively. The miR-193a expression was measured by quantitative real-time PCR (qPCR) assays.

Results

IGF-1 enhanced c-kit expression in c-kit-positive CSCs. The activities of the phosphoinositol 3-kinase (PI3K)/AKT signaling pathway and DNA methyltransferases (DNMTs) were enhanced, and their respective inhibitors LY294002 and 5-azacytidine (5-AZA) blunted c-kit expression. Based on the results of quantitative real-time PCR (qPCR) assays, the expression of miR-193a, which is embedded in a CpG island, was down-regulated in the IGF-1-stimulated group and negatively correlated with c-kit expression, whereas c-kit-positive CSCs infected with lentivirus carrying micro-RNA193a displayed reduced c-kit expression, migration and proliferation.

Conclusions

IGF-1 upregulated c-kit expression in c-kit-positive CSCs resulting in enhanced CSC proliferation and migration by activating the PI3K/AKT/DNMT signaling pathway to epigenetically silence miR-193a, which negatively modifies the c-kit expression level.

Electronic supplementary material

The online version of this article (10.1186/s13287-017-0762-4) contains supplementary material, which is available to authorized users.

c-kit Positive Cardiac Outgrowth Cells Demonstrate Better Ability for Cardiac Recovery Against Ischemic Myopathy

Objective

Resident cardiac stem cells are expected to be a therapeutic option for patients who suffer from severe heart failure. However, uncertainty remains over whether sorting cells for c-kit, a stem cell marker, improves therapeutic outcomes.

Materials and methods

Cardiac outgrowth cells cultured from explants of rat heart atrium were sorted according to their positivity (+) or negativity (−) for c-kit. These cells were exposed to hypoxia for 3 d, and subsequently harvested for mRNA expression measurement. The cell medium was also collected to assess cytokine secretion. To test for a functional benefit in animals, myocardial infarction (MI) was induced in rats, and c-kit+ or c-kit− cells were injected. The left ventricular ejection fraction (LVEF) was measured for up to 4 weeks, after which the heart was harvested for biological and histological analyses.

Results and conclusion

Expression of the angiogenesis-related genes, VEGF and ANGPTL2, was significantly higher in c-kit+ cells after 3 d of hypoxic culture, although we found no such difference prior to hypoxia. Secretion of VEGF and ANGPTL2 was greater in the c-kit+ group than in the c-kit− group, while hypoxia tended to increase cytokine expression in both groups. In addition, IGF-1 was significantly increased in the c-kit+ group, consistent with the relatively low expression of cleaved-caspase 3 revealed by western blot assay, and the relatively low count of apoptotic cells revealed by histochemical analysis. Administration of c-kit+cells into the MI heart improved the LVEF and increased neovascularization. These results indicate that c-kit+cells may be useful in cardiac stem cell therapy.

Imatinib mesylate-induced cardiomyopathy involves resident cardiac progenitors

Cardiovascular complications are included among the systemic effects of tyrosine kinase inhibitor (TKI)-based therapeutic strategies. To test the hypothesis that inhibition of Kit tyrosine kinase that promotes cardiac progenitor cell (CPC) survival and function may be one of the triggering mechanisms of imatinib mesylate (IM)-related cardiovascular effects, the anatomical, structural and ultrastructural changes in the heart of IM-treated rats were evaluated. Cardiac anatomy in IM-exposed rats showed a dose-dependent, restrictive type of remodeling and depressed hemodynamic performance in the absence of remarkable myocardial fibrosis. The effects of IM on rat and human CPCs were also assessed. IM induced rat CPC depletion, reduced growth and increased cell death. Similar effects were observed in CPCs isolated from human hearts. These results extend the notion that cardiovascular side effects are driven by multiple actions of IM. The identification of cellular mechanisms responsible for cardiovascular complications due to TKIs will enable future strategies aimed at preserving concomitantly cardiac integrity and anti-tumor activity of advanced cancer treatment.

Platelet Derived Growth Factor Alpha (PDGFRα) Induces the Activation of Cardiac Fibroblasts by Activating c-Kit

Background

Enhanced platelet-derived growth factor receptor α (PDGFRα) signaling pathway activity leads to cardiac fibrosis. However, because of the pleiotropic effects of PDGFR signaling, its role in mediating the cardiac fibrotic response remains poorly understood. This study aimed to investigate the regulatory effect of c-Kit in cardiac fibroblasts activated by PDGFRα signaling.

Material/Methods

A cardiac fibrosis mice model was induced using isoproterenol, and the heart tissues of mice were tested through western blotting and real-time quantitative PCR (RT-qPCR). The cardiac fibroblasts of neonatal mice were treated with PDGF-AA or transfected with small interfering RNAs (siRNAs) specific for the mouse c-Kit gene. The levels of collagen I, collagen III, and alpha-smooth muscle actin (α-SMA) were analyzed using western blotting and RT-qPCR.

Results

In the heart of the cardiac fibrosis mice model, the activity of c-Kit was enhanced. PDGF-AA treatment accelerated the activity of c-Kit in cardiac fibroblasts. In addition, imatinib inhibited the activity of c-Kit in vivo and in vitro. Moreover, inhibition of c-Kit by siRNAs reduced the expression of α-SMA and collagens in the activated cardiac fibroblasts. Furthermore, PDGFRα directly bound c-Kit in cardiac fibroblasts and stimulated the expression of stem cell factor (SCF).

Conclusions

Our data demonstrated that PDGF/PDGFRα induced the activation of cardiac fibroblasts by activating c-Kit. This study indicated that c-Kit could be used as a potential therapeutic target for treatment of cardiac fibrosis.

Electrotaxis of cardiac progenitor cells, cardiac fibroblasts, and induced pluripotent stem cell-derived cardiac progenitor cells requires serum and is directed via PI3'K pathways

BACKGROUND

The limited regenerative capacity of cardiac tissue has long been an obstacle to treating damaged myocardium. Cell-based therapy offers an enormous potential to the current treatment paradigms. However, the efficacy of regenerative therapies remains limited by inefficient delivery and engraftment. Electrotaxis (electrically guided cell movement) has been clinically used to improve recovery in a number of tissues but has not been investigated for treating myocardial damage.

OBJECTIVE

The purpose of this study was to test the electrotactic behaviors of several types of cardiac cells.

METHODS

Cardiac progenitor cells (CPCs), cardiac fibroblasts (CFs), and human induced pluripotent stem cell-derived cardiac progenitor cells (hiPSC-CPCs) were used.

RESULTS

CPCs and CFs electrotax toward the anode of a direct current electric field, whereas hiPSC-CPCs electrotax toward the cathode. The voltage-dependent electrotaxis of CPCs and CFs requires the presence of serum in the media. Addition of soluble vascular cell adhesion molecule to serum-free media restores directed migration. We provide evidence that CPC and CF electrotaxis is mediated through phosphatidylinositide 3-kinase signaling. In addition, very late antigen-4, an integrin and growth factor receptor, is required for electrotaxis and localizes to the anodal edge of CPCs in response to direct current electric field. The hiPSC-derived CPCs do not express very late antigen-4, migrate toward the cathode in a voltage-dependent manner, and, similar to CPCs and CFs, require media serum and phosphatidylinositide 3-kinase activity for electrotaxis.

CONCLUSION

The electrotactic behaviors of these therapeutic cardiac cells may be used to improve cell-based therapy for recovering function in damaged myocardium.

Chasing c-Kit through the heart: Taking a broader view

Stem cell mediated cardiac repair is an exciting and controversial area of cardiovascular research that holds the potential to produce novel, revolutionary therapies for the treatment of heart disease. Extensive investigation to define cell types contributing to cardiac formation, homeostasis and regeneration has produced several candidates, including adult cardiac c-Kit+ expressing stem and progenitor cells that have even been employed in a Phase I clinical trial demonstrating safety and feasibility of this therapeutic approach. However, the field of cardiac cell based therapy remains deeply divided due to strong disagreement among researchers and clinicians over which cell types, if any, are the best candidates for these applications. Research models that identify and define specific cardiac cells that effectively contribute to heart repair are urgently needed to resolve this debate. In this review, current c-Kit reporter models are discussed with respect to myocardial c-Kit cell biology and function, and future designs imagined to better represent endogenous myocardial c-Kit expression.

KIF15 promotes pancreatic cancer proliferation via the MEK-ERK signalling pathway

Background:

Pancreatic cancer is highly malignant and characterised by rapid and uncontrolled growth. While some of the important regulatory networks involved in pancreatic cancer have been determined, the cancer relevant genes have not been fully identified.

Methods:

We screened genes that may control proliferation in pancreatic cancer in seven pairs of matched pancreatic cancer and normal pancreatic tissue samples. We examined KIF15 expression in pancreatic cancer tissues and the effect of KIF15 on cell proliferation in vitro and in vivo. The mechanisms underlying KIF15 promotion of cell proliferation were investigated.

Results:

mRNA microarray and functional analysis identified 22 genes that potentially play an important role in the proliferation of pancreatic cancer. High-content siRNA screening evaluated whether silencing these 22 genes affected proliferation of pancreatic cancer. Notably, silencing KIF15 exhibited the most potent inhibition of proliferation compared with the rest of the 22 genes. KIF15 was upregulated in human pancreatic cancer tissues, and higher KIF15 expression levels correlated with shorter patient survival times. Upregulation KIF15 promoted pancreatic cancer growth. KIF15 upregulated cyclin D1, CDK2, and phospho-RB and also promoted G1/S transition in pancreatic cancer cells. KIF15 upregulation activated MEK–ERK signalling by increasing p-MEK and p-ERK levels. MEK–ERK inhibitors successfully inhibited cell cycle progression, and PD98059 blocked KIF15-mediated pancreatic cancer proliferation in vivo and in vitro.

Conclusions:

This study identified KIF15 as a critical regulator that promotes pancreatic cancer proliferation, broadening our understanding of KIF15 function in tumorigenesis.

Resveratrol improves urinary dysfunction in rats with chronic prostatitis and suppresses the activity of the stem cell factor/c-Kit signaling pathway

Chronic prostatitis (CP) is a common urological disorder, with bladder voiding dysfunction being the primary clinical manifestation. Resveratrol is polyphenolic compound isolated from numerous plants, with widely‑reported anti-inflammatory properties. The present study aimed to investigate whether resveratrol may improve overactive bladder in rats with CP and to investigate the underlying molecular mechanisms. Furthermore, the potential pharmacological synergy between resveratrol and solifenacin was also investigated as a potential treatment for CP. Following the successful establishment of a rat model of CP by subcutaneously injecting DPT vaccine, rats were treated with resveratrol or a combination of resveratrol + solifenacin. Bladder pressure and volume tests were performed to investigate the effect of resveratrol and solifenacin on urinary dysfunction in rats with chronic prostatitis. Western blot analysis and immunohistochemical staining were used to examine the expression of c‑Kit receptor, stem cell factor (SCF), AKT and phosphorylated‑AKT (p‑AKT) in the bladder tissue. The results of the bladder pressure and volume test indicated that the maximum capacity of the bladder, residual urine volume and maximum voiding pressure in the control group were 0.57 ml, 0.17 ml and 29.62 cm H2O, respectively. These values were increased by 71, 27 and 206% in rats in the CP group compared with the control group. Following treatment with resveratrol, the results in the resveratrol group were reduced by 25.77, 44.23 and 13.32% compared with the CP group. The results of western blot analysis, immunohistochemical staining and immunofluorescence labeling demonstrate that the protein expression of SCF, c‑Kit and p‑AKT in the bladder of rats in the CP group was 4.32, 6.13 and 6.31 times higher compared with the control group, respectively. Following treatment with resveratrol, protein expression was significantly reduced. However, no significant differences were observed between the protein expression of the SCF, c‑Kit and p‑AKT in the bladder between the resveratrol and combination groups. In conclusion, resveratrol may improve overactive bladder by downregulating the protein expression of SCF, c‑Kit and p‑AKT in the bladder of rats with CP. Furthermore, a combination of resveratrol and solifenacin may have potential pharmacological synergy as a treatment for patients with CP.

G9a histone methyltransferase inhibitor BIX01294 promotes expansion of adult cardiac progenitor cells without changing their phenotype or differentiation potential

OBJECTIVES

As a follow-up to our previous reports showing that the G9a histone methyltransferase-specific inhibitor BIX01294 enhances bone marrow cell cardiac potential, this drug was examined for its effects on cardiomyocytes and mouse cardiac progenitor cells (CPCs).

MATERIALS AND METHODS

Cardiomyocytes and cardiac explants were cultured ± BIX01294, and examined for changes in cardiac function, protein and gene expression. Additionally, enriched populations of CPCs, contained in the 'phase bright cell' component of explants, were harvested from non-treated and BIX01294-treated cardiac tissue, and assayed for differences in cell phenotype and differentiation potential. Mouse CPCs were cultured with rat cardiomyocytes to allow differentiation of the progenitors to be assayed using species-specific PCR primers.

RESULTS

While BIX01294 had no discernible effect on myocyte function and sarcomeric organization, treatment with this drug significantly increased CPC proliferation, as indicated by enhanced MTT metabolization and BrdUrd incorporation (4.1- and 2.0-fold, respectively, P < 0.001) after 48 h labelling, and increased Ki67 expression (4.8-fold, P < 0.001) after 7 days culture. Heart explants exposed to BIX01294 generated 3.6-fold (P < 0.005) greater yields of CPCs by 2 weeks culture. Importantly, CPCs obtained from non-treated and BIX01294-treated cultures did not differ in phenotype or differentiation potential.

CONCLUSIONS

These data indicate that BIX01294 can expand CPCs without undermining their capacity as cardiac progenitors, and suggest that this drug may have utility for generating large numbers of CPCs for cardiac repair.