Overexpression of phosphoinositide-3-kinase class II alpha enhances mesenchymal stem cell survival in infarcted myocardium

Role of PI3K/Akt signaling pathway in cardiac fibrosis

Heart failure (HF) is considered as a severe health problem worldwide, while cardiac fibrosis is one of the main driving factors for the progress of HF. Cardiac fibrosis was characterized by changes in cardiomyocytes, cardiac fibroblasts, ratio of collagen (COL) I/III, and the excessive production and deposition of extracellular matrix (ECM), thus forming a scar tissue, which leads to pathological process of cardiac structural changes and systolic as well as diastolic dysfunction. Cardiac fibrosis is a common pathological change of many advanced cardiovascular diseases including ischemic heart disease, hypertension, and HF. Accumulated studies have proven that phosphoinositol-3 kinase (PI3K)/Akt signaling pathway is involved in regulating the occurrence, progression and pathological formation of cardiac fibrosis via regulating cell survival, apoptosis, growth, cardiac contractility and even the transcription of related genes through a series of molecules including mammalian target of rapamycin (mTOR), glycogen synthase kinase 3 (GSK-3), forkhead box proteins O1/3 (FoxO1/3), and nitric oxide synthase (NOS). Thus, the review focuses on the role of PI3K/Akt signaling pathway in the cardiac fibrosis. The information reviewed here should be significant in understanding the role of PI3K/Akt in cardiac fibrosis and contribute to the design of further studies related to PI3K/Akt and the cardiac fibrotic response, as well as sought to shed light on a potential treatment for cardiac fibrosis.

Functional heterogeneity of mesenchymal stem cells from natural niches to culture conditions: implications for further clinical uses

Mesenchymal stem cells (MSC) are present in all organs and tissues. Several studies have shown the therapeutic potential effect of MSC or their derived products. However, the functional heterogeneity of MSC constitutes an important barrier for transferring these capabilities to the clinic. MSC heterogeneity depends on their origin (biological niche) or the conditions of potential donors (age, diseases or unknown factors). It is accepted that many culture conditions of the artificial niche to which they are subjected, such as O₂ tension, substrate and extracellular matrix cues, inflammatory stimuli or genetic manipulations can influence their resulting phenotype. Therefore, to attain a more personalized and precise medicine, a correct selection of MSC is mandatory, based on their functional potential, as well as the need to integrate all the existing information to achieve an optimal improvement of MSC features in the artificial niche.

Enhancing Therapeutic Efficacy and Reducing Cell Dosage in Stem Cell Transplantation Therapy for Ischemic Limb Diseases by Modifying the Cell Injection Site

In conventional stem cell transplantation therapies for ischemic limb diseases, stem cells are generally transplanted into the ischemic region (IR), and most of the transplanted cells undergo hypoxia-mediated cell death. Due to massive cell death, the therapeutic efficacy is reduced and a high dose of stem cells is necessitated for the therapies. In this study, we investigated whether the therapeutic efficacy can be improved and the cell dosage can be reduced in the therapy for limb ischemia simply by modifying the stem cell injection site to a site where cell engraftment is improved and blood vessel sprouting is efficiently stimulated. Human mesenchymal stem cells (hMSCs) cultured under hypoxic condition, which simulates cells transplanted to IR, underwent extensive cell death in vitro. Importantly, cell death was significantly attenuated when hMSCs adhered first under normoxic condition for 24 h and then were exposed to hypoxic condition, which simulates cells transplanted to the border zone (BZ) in the upper thigh and migrated to IR. hMSCs, at doses of 2 × 10(5) or 2 × 10(6) cells, were injected into the IR or BZ of 5-week-old female athymic mice after ischemic hindlimb induction. Compared with human mesenchymal stem cell (hMSC) transplantation to the IR of mouse ischemic limbs, transplantation to the BZ significantly enhanced cell engraftment and paracrine factor secretion, which effectively stimulated vessel sprouting, enhanced blood perfusion in IR, and enabled the cell dosage reduction. Therefore, modification of the stem cell transplantation site would improve the current stem cell therapies for ischemic limb diseases in terms of cell dosage reduction and therapeutic efficacy enhancement.

The role of class I, II and III PI 3-kinases in platelet production and activation and their implication in thrombosis

Blood platelets play a pivotal role in haemostasis and are strongly involved in arterial thrombosis, a leading cause of death worldwide. Besides their critical role in pathophysiology, platelets represent a valuable model to investigate, both in vitro and in vivo, the biological roles of different branches of the phosphoinositide metabolism, which is highly active in platelets. While the phospholipase C (PLC) pathway has a crucial role in platelet activation, it is now well established that at least one class I phosphoinositide 3-kinase (PI3K) is also mandatory for proper platelet functions. Except class II PI3Kγ, all other isoforms of PI3Ks (class I α, β, γ, δ; class II α, β and class III) are expressed in platelets. Class I PI3Ks have been extensively studied in different models over the past few decades and several isoforms are promising drug targets to treat cancer and immune diseases. In platelet activation, it has been shown that while class I PI3Kδ plays a minor role, class I PI3Kβ has an important function particularly in thrombus growth and stability under high shear stress conditions found in stenotic arteries. This class I PI3K is a potentially interesting target for antithrombotic strategies. The role of class I PI3Kα remains ill defined in platelets. Herein, we will discuss our recent data showing the potential impact of inhibitors of this kinase on thrombus formation. The role of class II PI3Kα and β as well as class III PI3K (Vps34) in platelet production and function is just emerging. Based on our data and those very recently published in the literature, we will discuss the impact of these three PI3K isoforms in platelet production and functions and in thrombosis.

Periostin is critical for improving the therapeutic properties of adipocyte-derived stem cells

Periostin is a matricellular protein that is reactivated during tissue damage and repair and has been shown to be a critical regulator of multiple biological pathways involved in the repair of tissue after myocardial infarction, peripheral vascular disease, and skin wounds. The tissue repair properties attributed to periostin make it an ideal candidate to enhance the therapeutic properties of donor cells such as mesenchymal stem cells from adipocyte tissue. In a recent article in Stem Cell Research & Therapy, Qin et al. demonstrated enhanced therapeutic properties of adipocyte-derived stem cells by genetically engineering them to express periostin.

Genetic Engineering of Mesenchymal Stem Cells for Regenerative Medicine

Mesenchymal stem cells (MSCs), which can be obtained from various organs and easily propagated in vitro, are one of the most extensively used types of stem cells and have been shown to be efficacious in a broad set of diseases. The unique and highly desirable properties of MSCs include high migratory capacities toward injured areas, immunomodulatory features, and the natural ability to differentiate into connective tissue phenotypes. These phenotypes include bone and cartilage, and these properties predispose MSCs to be therapeutically useful. In addition, MSCs elicit their therapeutic effects by paracrine actions, in which the metabolism of target tissues is modulated. Genetic engineering methods can greatly amplify these properties and broaden the therapeutic capabilities of MSCs, including transdifferentiation toward diverse cell lineages. However, cell engineering can also affect safety and increase the cost of therapy based on MSCs; thus, the advantages and disadvantages of these procedures should be discussed. In this review, the latest applications of genetic engineering methods for MSCs with regenerative medicine purposes are presented.

Multivariate analysis of subjective responses to d-amphetamine in healthy volunteers finds novel genetic pathway associations

RATIONALE

Researchers studying behavioral and physiologic effects of d-amphetamine have explored individual response differences to the drug. Concurrently, genome-wide analyses have identified several single-nucleotide polymorphisms (SNPs) associated with these traits. Univariate methods can identify SNPs associated with behavioral and physiological traits, but multivariate analyses allow identification of clusters of related biologically relevant SNPs and behavioral components.

OBJECTIVES

The aim of the study was to identify clusters of related biologically relevant SNPs and behavioral components in the responses of healthy individuals to d-amphetamine using multivariate analysis.

METHODS

Individuals (N = 375) without substance abuse histories completed surveys and detailed cardiovascular monitoring during randomized, blinded sessions: d-amphetamine (10 and 20 mg) and placebo. We applied parallel independent component analysis (Para-ICA) to data previously analyzed with univariate approaches, revealing new associations between genes and behavioral responses to d-amphetamine.

RESULTS

Three significantly associated (p < .001) phenotype-genotype pairs emerged. The first component included physiologic measures of systolic and diastolic blood pressure (BP) and mean arterial pressure (MAP) along with SNPs in calcium and glutamatergic signaling pathways. The second associated components included the "Anger" items from the Profile of Mood States (POMS) questionnaire and the marijuana effects from the Addiction Research Center Inventory (Cuyas, Verdejo-Garcia et al.), with enriched genetic pathways involved in cardiomyopathy and MAPK signaling. The final pair included "Anxious," "Fatigue," and "Confusion" items from the POMS questionnaire, plus functional pathways related to cardiac muscle contraction and cardiomyopathy.

CONCLUSIONS

Multifactorial genetic networks related to calcium signaling, glutamatergic and dopaminergic synapse function, and amphetamine addiction appear to mediate common behavioral and cardiovascular responses to d-amphetamine.

Periostin enhances adipose-derived stem cell adhesion, migration, and therapeutic efficiency in Apo E deficient mice with hind limb ischemia

Introduction

Therapeutic angiogenesis by transplantation of autologous/allogeneic adipose-derived stem cells (ADSCs) is a potential approach for severe ischemic diseases. However, poor viability, adhesion, migration and differentiation limit the therapeutic efficiency after the cells were transplanted into the targeted area. Periostin, an extracellular matrix protein, exhibits a critical role in wound repair as well as promotes cell adhesion, survival, and angiogenesis.

Method

ADSCs were obtained and genetically engineered with periostin gene (P-ADSCs). The viability, proliferation, migration, and apoptosis of P-ADSCs under hypoxia were analyzed. Moreover, P-ADSCs were implanted into Apo E deficient mice with hind limb ischemia. The Laser Doppler perfusion index, immunofluorescence, and histological pathology assay were tested to evaluate the therapeutic effects. The associated molecular mechanism of periostin on the proliferation, adhesion, migration, and differentiation of ADSCs was also analyzed.

Results

The in vitro studies have shown that periostin-transfected ADSCs (P-ADSCs) promoted viability, proliferation, and migration of ADSCs. Apoptosis of ADSCs was inhibited under hypoxic conditions. The Laser Doppler perfusion index was significantly higher in the P-ADSCs group compared with that in the ADSC and control groups after 4 weeks. Immunofluorescence and histological pathology assay showed that the P-ADSCs were in and around the ischemic sites, and some cells differentiated into capillaries and endothelium. Microvessel densities were significantly improved in P-ADSCs group compared with those in the control group. The molecular mechanisms that provide the beneficial effects of periostin were connected with the upregulated expression of integrinβ1/FAK/PI3K/Akt/eNOS signal pathway and the increased secretion of growth factors.

Conclusion

Overexpression of periostin by gene transfection on ADSCs promotes survival, migration, and therapeutic efficiency, which will bring new insights into the treatment of critical limb ischemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0126-x) contains supplementary material, which is available to authorized users.

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.

The caspase-8 shRNA-modified mesenchymal stem cells improve the function of infarcted heart

The beneficial effects of mesenchymal stem cells (MSCs) in cardiac cell therapy are greatly limited due to poor survival after transplantation into ischemic hearts. Here, we investigated whether caspase 8 small hairpin RNA (shRNA) modification enhance human MSCs (hMSCs) survival and improve infarcted heart function. Recombinant adenovirus encoding pre-miRNA-155-designed caspase 8 shRNA was prepared to inhibit caspase 8 expression in hMSCs. The effect of caspase 8 shRNA modification on protecting hMSCs from apoptosis under the conditions of serum deprivation and hypoxia was tested by Annexin V/PI staining and caspase 8 activity assay. The caspase 8 shRNA-modified and superparamagnetic iron oxide (SPIO)-labeled hMSCs were injected into the border zone of the infarcted region of rat heart. Echocardiography and Masson trichrome staining were performed to assess heart function and cardiac fibrosis. Our results showed that adenovirus-mediated caspase 8 shRNA could efficiently inhibit caspase 8 expression in hMSCs. Knock-down of caspase 8 expression lead to inhibition of hMSCs apoptosis, reduction of caspase 8 activity and up-regulations of HGF, IGF-1 and Bcl-2. Transplantation of caspase 8 shRNA-modified hMSCs could significantly improve infracted heart function, attenuate cardiac fibrosis. Consistently, the rate of cardiomyocyte apoptosis and caspase 8 activity were significantly decreased, and the survival rate of transplanted hMSCs was markedly elevated in the myocardium receiving caspase 8 shRNA-modified hMSCs transplantation. Together, our findings implicated the therapeutic potential of caspase 8 shRNA-modified hMSCs in improving the infarcted heart function.

Suicide gene reveals the myocardial neovascularization role of mesenchymal stem cells overexpressing CXCR4 (MSC(CXCR4))

Background

Our previous studies indicated that MSC^CXCR4 improved cardiac function after myocardial infarction (MI). This study was aimed to investigate the specific role of MSC^CXCR4 in neovascularization of infarcted myocardium using a suicide gene approach.

Methods

MSCs were transduced with either lentivirus-null vector/GFP (MSC^Null as control) or vector encoding for overexpressing CXCR4/GFP. The MSC derived-endothelial cell (EC) differentiation was assessed by a tube formation assay, Dil-ac-LDL uptake, EC marker expression, and VE-cadherin promoter activity assay. Gene expression was analyzed by quantitative RT-PCR or Western blot. The suicide gene approach was under the control of VE-cadherin promoter. In vivo studies: Cell patches containing MSC^Null or MSC^CXCR4 were transduced with suicide gene and implanted into the myocardium of MI rat. Rats received either ganciclovir (GCV) or vehicle after cell implantation. After one month, the cardiac functional changes and neovascularization were assessed by echocardiography, histological analysis, and micro-CT imaging.

Results

The expression of VEGF-A and HIF-1α was significantly higher in MSC^CXCR4 as compared to MSC^Null under hypoxia. Additionally, MSC^CXCR4 enhanced new vessel formation and EC differentiation, as well as STAT3 phosphorylation under hypoxia. STAT3 participated in the transcription of VE-cadherin in MSC^CXCR4 under hypoxia, which was inhibited by WP1066 (a STAT3 inhibitor). In addition, GCV specifically induced death of ECs with suicide gene activation. In vivo studies: MSC^CXCR4 implantation promoted cardiac functional restoration, reduced infarct size, improved cardiac remodeling, and enhanced neovascularization in ischemic heart tissue. New vessels derived from MSC^CXCR4 were observed at the injured heart margins and communicated with native coronary arteries. However, the derived vessel networks were reduced by GCV, reversing improvement of cardiac function.

Conclusion

The transplanted MSC^CXCR4 enhanced neovascularization after MI by boosting release of angiogenic factors and increasing the potential of endothelial differentiation.

Phorbol myristate acetate differentiates human adipose-derived mesenchymal stem cells into functional cardiogenic cells

To achieve effective regeneration of injured myocardium, it is important to find physiological way of improving the cardiogenic differentiation of stem cells. Previous studies demonstrated that cardiomyocytes from bone marrow-derived mesenchymal stem cells (BMSCs) activated with phorbolmyristate acetate (PMA), a protein kinase C (PKC) activator, restore electromechanical function in infarcted rat hearts. In this study, we investigated the effect of PMA on cardiogenic differentiation of adipose-derived MSCs (ASCs) for clinical applications. To confirm the effect of PMA, ASCs treated with 1μM PMA were grown for nine days. The expression of cardiac-specific markers (cardiac troponin T, myosin light chain, myosin heavy chain) in PMA-treated MSCs was demonstrated by immunocytochemistry. Alhough few α(1A) receptors exist in ASCs, α(1)-adrenergic receptor subtypes were preferentially expressed in PMA-treated ASCs. Moreover, expression of the β-adrenergic and muscarinic receptors increased in PMA-treated ASCs compared to normal cells. The mRNA levels of Ca(2+)-related factors (SERCA 2a; sarcoplasmic reticulum Ca(2+)-ATPase, LTCC; L-type Ca(2+) channel) in treated ASCs were similar to the levels in cardiomyocytes. Following the transplantation of chemically activated cardiogenic ASCs into infarcted myocardium, histological analysis showed that infarct size, interstitial fibrosis, and apoptotic index were markedly decreased and cardiac function was restored. In conclusion, PMA might induce the cardiogenic differentiation of human ASCs as well as BMSCs. This result suggests successful use of human ASCs in cardiac regeneration therapy.

Regulation and cellular functions of class II phosphoinositide 3-kinases

Class II isoforms of PI3K (phosphoinositide 3-kinase) are still the least investigated and characterized of all PI3Ks. In the last few years, an increased interest in these enzymes has improved our understanding of their cellular functions. However, several questions still remain unanswered on their mechanisms of activation, their specific downstream effectors and their contribution to physiological processes and pathological conditions. Emerging evidence suggests that distinct PI3Ks activate different signalling pathways, indicating that their functional roles are probably not redundant. In the present review, we discuss the recent advances in our understanding of mammalian class II PI3Ks and the evidence suggesting their involvement in human diseases.

Therapeutic applications of mesenchymal stromal cells: paracrine effects and potential improvements

Among the various types of cell-to-cell signaling, paracrine signaling comprises those signals that are transmitted over short distances between different cell types. In the human body, secreted growth factors and cytokines instruct, among others, proliferation, differentiation, and migration. In the hematopoietic stem cell (HSC) niche, stromal cells provide instructive cues to stem cells via paracrine signaling and one of these cell types, known to secrete a broad panel of growth factors and cytokines, is mesenchymal stromal cells (MSCs). The factors secreted by MSCs have trophic, immunomodulatory, antiapoptotic, and proangiogenic properties, and their paracrine profile varies according to their initial activation by various stimuli. MSCs are currently studied as treatment for inflammatory diseases such as graft-versus-host disease and Crohn's disease, but also as treatment for myocardial infarct and solid organ transplantation. In addition, MSCs are investigated for their use in tissue engineering applications, in which their differentiation plays an important role, but as we have recently demonstrated, their trophic factors may also be involved. Furthermore, a functional improvement of MSCs might be obtained after preconditioning or tailoring the cells themselves. Also, the way the cells are clinically administered may be specialized for specific therapeutic scenarios. In this review we will first discuss the HSC niche, in which MSCs were recently identified and are thought to play an instructive and supportive role. We will then evaluate therapeutic applications that currently try to utilize the trophic and/or immunomodulatory properties of MSCs, and we will also discuss new options to enhance their therapeutic effects.

Efficacy of Atorvastatin combined with adipose-derived mesenchymal stem cell transplantation on cardiac function in rats with acute myocardial infarction

Mesenchymal stem cells (MSCs) have been extensively applied for the restoration of cardiomyocytes loss after acute myocardial infarction (AMI). However, the optimal therapeutic efficacy of MSCs in ischemic heart diseases has been hampered by their poor survival and low differentiated rates. Therefore, the improvement of MSC survival and differentiated rates is warranted and critical for the efficacy of MSCs in AMI. In this paper, MSCs isolated from rat inguinal fat tissues were termed as adipose-derived mesenchymal stem cells (ASCs), and the fourth passage of ASCs was pre-specified by co-culturing with cardiomyocytes in a transwell system termed as co-ASCs. Fourteen days later, GATA-4 (a transcription factor) and cardiac troponin-I were detected by cellular immunofluorescence. Atorvastatin (Ator group) or vehicle (control group) was administrated for the first 24 h after AMI production in rats. Fourteen days later, inflammatory parameters and cardiac function were evaluated. The other surviving rats were injected with a total of 1 × 10(6) co-ASCs/100 μl phosphate-buffered saline (PBS), 1×10(6) ASCs/100 μl PBS, or 100 μl PBS. Twenty-eight days after cell injection, survival and differentiated rates of transplanted cells and cardiac function were evaluated. The percentage of GATA-4 expression in co-ASCs was 28.5% ± 5.6% and of cardiac troponin-I was 22.8% ± 3.2%. Compared with the control group, the number of infiltrating inflammatory cells, myeloperoxidase activity, inflammatory cytokines (VCAM-1, TNF-α, Hs-CRP) mRNA expression, and Bax protein expression were significantly reduced in the three Ator groups, accompanied by a significant improvement of Bcl-2 protein expression and cardiac function (P< 0.05). Compared with the Ator2 + ASCs group and Con + co-ASCs group, the number of 4-6-diamidino-2-phenylindole-stained cells and cardiac troponin-I-positive transplanted cells, concomitant with cardiac function, were improved most prominently in the Ator3 + co-ASCs group (P< 0.05). Pre-amelioration of the cardiac milieu, in conjunction with pre-specification of ASCs, was beneficial for enhancing ASCs' therapeutic efficacy on cardiac function after AMI.

14S,21R-dihydroxy-docosahexaenoic acid treatment enhances mesenchymal stem cell amelioration of renal ischemia/reperfusion injury

Bone marrow mesenchymal stem cells (MSCs) have shown potential to improve treatment of renal failure. The prohealing functions of MSCs have been found to be enhanced by treatment with the lipid mediator, 14S,21R-dihydroxy-docosa4Z,7Z,10Z,12E,16Z,19Z-hexaenoic acid (14S,21R-diHDHA). In this article, using a murine model of renal ischemia/reperfusion (I/R) injury, we found that treatment with 14S,21R-diHDHA enhanced MSC amelioration of renal I/R injury. Treated MSCs more efficiently inhibited I/R-induced elevation of serum creatinine levels, reduced renal tubular cell death, and inhibited infiltration of neutrophils, macrophages, and dendritic cells in kidneys. Conditioned medium from treated MSCs reduced the generation of tumor necrosis factor-α and reactive oxygen species by macrophages under I/R conditions. Infusion of treated MSCs more efficiently reduced I/R-damage to renal histological structures compared with untreated MSCs (injury score: 7.9±0.4 vs. 10.5±0.5). Treated MSCs were resistant to apoptosis in vivo when transplanted under capsules of I/R-injured kidneys (active caspase-3+ MSCs: 4.2%±2.8% vs. 11.7%±2.4% of control) and in vitro when cultured under I/R conditions. Treatment with 14S,21R-diHDHA promoted viability of MSCs through a mechanism involving activation of the phosphoinositide 3-kinase -Akt signaling pathway. Additionally, treatment of MSCs with 14S,21R-diHDHA promoted secretion of renotrophic hepatocyte growth factor and insulin growth factor-1. Similar results were obtained when 14S,21RdiHDHA was used to inhibit apoptosis of human MSCs (hMSCs) and to increase the generation of renotrophic cytokines from hMSCs. These findings provide a lead for new strategies in the treatment of acute kidney injury with MSCs.

Mesenchymal stromal cells for cardiovascular disease

The fields of regenerative medicine and cellular therapy have been the subject of tremendous hype and hope. In particular, the perceived usage of somatic cells like mesenchymal stromal cells (MSCs) has captured the imagination of many. MSCs are a rare population of cells found in multiple regions within the body that can be readily expanded ex vivo and utilized clinically. Originally, it was hypothesized that transplantation of MSCs to sites of injury would lead to de novo tissue-specific differentiation and thereby replace damaged tissue. Now, it is generally agreed that MSC home to sites of injury and direct positive remodeling via the secretion of paracrine factors. Consequently, their clinical utilization has largely revolved around their abilities to promote neovascularization for ischemic disorders and modulate overly exuberant inflammatory responses for autoimmune and alloimmune conditions. One of the major issues surrounding the development of somatic cell therapies like MSCs is that despite evoking a positive response, long-term engraftment and persistence of these cells is rare. Consequently, very large cell doses need be administered for raising production, delivery, and efficacy issues. In this review, we will outline the field of MSC in the context of ischemia and discuss causes for their lack of persistence. In addition, some of the methodologies be used to enhance their therapeutic potential will be highlighted.