Stem cell therapy for ischemic heart disease

Cardiomyocyte Death and Genome-Edited Stem Cell Therapy for Ischemic Heart Disease

Massive death of cardiomyocytes is a major feature of cardiovascular diseases. Since the regenerative capacity of cardiomyocytes is limited, the regulation of their death has been receiving great attention. The cell death of cardiomyocytes is a complex mechanism that has not yet been clarified, and it is known to appear in various forms such as apoptosis, necrosis, etc. In ischemic heart disease, the apoptosis and necrosis of cardiomyocytes appear in two types of programmed forms (intrinsic and extrinsic pathways) and they account for a large portion of cell death. To repair damaged cardiomyocytes, diverse stem cell therapies have been attempted. However, despite the many positive effects, the low engraftment and survival rates have clearly limited the application of stem cells in clinical therapy. To solve these challenges, the introduction of the desired genes in stem cells can be used to enhance their capacity and improve their therapeutic efficiency. Moreover, as genome engineering technologies have advanced significantly, safer and more stable delivery of target genes and more accurate deletion of genes have become possible, which facilitates the genetic modification of stem cells. Accordingly, stem cell therapy for damaged cardiac tissue is expected to further improve. This review describes myocardial cell death, stem cell therapy for cardiac repair, and genome-editing technologies. In addition, we introduce recent stem cell therapies that incorporate genome-editing technologies in the myocardial infarction model. Graphical Abstract.

Harnessing the secretome of adipose-derived stem cells in the treatment of ischemic heart diseases

Adipose-derived stem cells (ASCs) are promising therapeutic cells for ischemic heart diseases, due to the ease and efficiency of acquisition, the potential of myocardial lineage differentiation, and the paracrine effects. Recently, many researchers have claimed that the ASC-based myocardial repair is mainly attributed to its paracrine effects, including the anti-apoptosis, pro-angiogenesis, anti-inflammation effects, and the inhibition of fibrosis, rather than the direct differentiation into cardiovascular lineage cells. However, the usage of ASCs comes with the problems of low cardiac retention and survival after transplantation, like other stem cells, which compromises the effectiveness of the therapy. To overcome these drawbacks, researchers have proposed various strategies for improving survival rate and ensuring sustained paracrine secretion. They also investigated the safety and efficacy of phase I and II clinical trials of ASC-based therapy for cardiovascular diseases. In this review, we will discuss the characterization and paracrine effects of ASCs on myocardial repair, followed by the strategies for stimulating the paracrine secretion of ASCs, and finally their clinical usage.

From embryonic stem cells to induced pluripotent stem cells-Ready for clinical therapy?

Embryonic stem cells and induced pluripotent stem cells have increasingly important roles in many different fields of research and medicine. Major areas of impact include improved in vitro disease models, drug screening, and the development of cell-based clinical therapies. Here, we review the generation and uses of embryonic stem cells compared to induced pluripotent stem cells and discuss their advantages and limitations. We also evaluate the feasibility of clinical therapies and the future prospects for induced pluripotent cell-based treatments.

Simultaneous isolation of mesenchymal stem cells and endothelial progenitor cells derived from murine bone marrow

Mesenchymal stem or stromal cells (MSCs) are identified as sources of pluripotent stem cells with varying degrees of plasticity. Endothelial progenitor cells (EPCs) originate from either bone marrow (BM) or peripheral blood and can mature into cells that line the lumen of blood vessels. MSC and EPC therapies exhibit promising results in a variety of diseases. The current study described the simultaneous isolation of EPCs and MSCs from murine BM using a straightforward approach. The method is based on differences in attachment time and trypsin sensitivity of MSCs and EPCs. The proposed method revealed characteristics of isolated cells. Isolated MSCs were positive for cell surface markers, cluster of differentiation (CD)29, CD44 and stem cell antigen-1 (Sca-1), and negative for hematopoietic surface markers, CD45 and CD11b. Isolated EPCs were positive for Sca-1 and vascular endothelial growth factor receptor 2 and CD133. The results indicate that the proposed method ensured simultaneous isolation of homogenous populations of MSCs and EPCs from murine BM.

Electrical Stimulation Enhances Cardiac Differentiation of Human Induced Pluripotent Stem Cells for Myocardial Infarction Therapy

AIMS

Electrical stimulation (EleS) can promote cardiac differentiation, but the underlying mechanism is not well known. This study investigated the effect of EleS on cardiomyocyte (CM) differentiation of human induced pluripotent stem cells (hiPSCs) and evaluated the therapeutic effects for the treatment of myocardial infarction (MI).

RESULTS

Cardiac differentiation of hiPSCs was induced with EleS after embryoid body formation. Spontaneously beating hiPSCs were observed as early at 2 days when treated with EleS compared with control treatment. The cardiac differentiation efficiency of hiPSCs was significantly enhanced by EleS. In addition, the functional maturation of hiPSC-CMs under EleS was confirmed by calcium indicators, intracellular Ca²⁺ levels, and expression of structural genes. Mechanistically, EleS mediated cardiac differentiation of hiPSCs through activation of Ca²⁺/PKC/ERK pathways, as revealed by RNA sequencing, quantitative polymerase chain reaction, and Western blotting. After transplantation in immunodeficient MI mice, EleS-preconditioned hiPSC-derived cells significantly improved cardiac function and attenuated expansion of infarct size. The preconditioned hiPSC-derived CMs were functionally integrated with the host heart.

INNOVATION

We show EleS as an efficacious time-saving approach for CM generation. The global RNA profiling shows that EleS can accelerate cardiac differentiation of hiPSCs through activation of multiple pathways. The cardiac-mimetic electrical signals will provide a novel approach to generate functional CMs and facilitate cardiac tissue engineering for successful heart regeneration.

CONCLUSION

EleS can enhance efficiency of cardiac differentiation in hiPSCs and promote CM maturation. The EleS-preconditioned CMs emerge as a promising approach for clinical application in MI treatment. Antioxid. Redox Signal. 28, 371-384.

Local and sustained miRNA delivery from an injectable hydrogel promotes cardiomyocyte proliferation and functional regeneration after ischemic injury

MicroRNA-based therapies that target cardiomyocyte proliferation have great potential for the treatment of myocardial infarction (MI). In previous work, we showed that the miR-302/367 cluster regulates cardiomyocyte proliferation in the prenatal and postnatal heart. Here, we describe the development and application of an injectable hyaluronic acid (HA) hydrogel for the local and sustained delivery of miR-302 mimics to the heart. We show that the miR-302 mimics released in vitro promoted cardiomyocyte proliferation over one week, and that a single injection of the hydrogel in the mouse heart led to local and sustained cardiomyocyte proliferation for two weeks. After MI, gel/miR-302 injection caused local clonal proliferation and increased cardiomyocyte numbers in the border zone of a Confetti mouse model. Gel/miR-302 further decreased cardiac end-diastolic (39%) and end-systolic (50%) volumes, and improved ejection fraction (32%) and fractional shortening (64%) four weeks after MI and injection, compared to controls. Our findings suggest that biomaterial-based miRNA delivery systems can lead to improved outcomes in cardiac regeneration.

Bone marrow-derived mesenchymal stem cells rescue injured H9c2 cells via transferring intact mitochondria through tunneling nanotubes in an in vitro simulated ischemia/reperfusion model

The transplantation of mesenchymal stem cells (MSCs) is considered to be a promising treatment for ischemic heart disease; however, the therapeutic effects and underlying mechanisms of action require further evaluation. Mitochondrial dysfunction is a key event in simulated ischemia/reperfusion (SI/R) injury. The purpose of the present study was to investigate the mechanism of mitochondrial transfer, which may be involved the antiapoptotic action of co-culture with MSCs. An in vitro model of simulated ischemia/reperfusion (SI/R) was used in the present study. The apoptotic indexes were significantly increased when H9c2 cardiomyocytes were induced in the SI/R group. Following co-culture with bone marrow-derived (BM)-MSCs, H9c2 cells exhibited marked resistance against the SI/R-induced apoptotic process. Besides, mitochondrial transfer via a tunneling nanotube (TNT) like structure was detected by confocal fluorescent microscopy. In addition, following pretreated with latrunculin-A (LatA), an inhibitor of TNT formation, the BM-MSCs were not able to rescue injured H9c2 cells from apoptosis, as previously observed. In conclusion, the anti-apoptotic ability of BM-MSCs may be partially attributed to the recovery of mitochondrial dysfunction in SI/R, and the formation of TNTs appears to be involved in this action of mitochondrial transfer between adjacent cells.

Cardiac differentiation potential of human induced pluripotent stem cells in a 3D self-assembling peptide scaffold

In the past decade, various strategies for cardiac reparative medicine involving stem cells from multiple sources have been investigated. However, the intra-cardiac implantation of cells with contractile ability may seriously disrupt the cardiac syncytium and de-synchronize cardiac rhythm. For this reason, bioactive cardiac implants, consisting of stem cells embedded in biomaterials that act like band aids, have been exploited to repair the cardiac wall after myocardial infarction. For such bioactive implants to function properly after transplantation, the choice of biomaterial is equally important as the selection of the stem cell source. While adult stem cells have shown promising results, they have various disadvantages including low proliferative potential in vitro, which make their successful usage in human transplants difficult. As a first step towards the development of a bioactive cardiac patch, we investigate here the cardiac differentiation properties of human induced pluripotent stem cells (hiPSCs) when cultured with and without ascorbic acid (AA) and when embedded in RAD16-I, a biomaterial commonly used to develop cardiac implants. In adherent cultures and in the absence of RAD16-I, AA promotes the cardiac differentiation of hiPSCs by enhancing the expression of specific cardiac genes and proteins and by increasing the number of contracting clusters. In turn, embedding in peptide hydrogel based on RAD16-I interferes with the normal cardiac differentiation progression. Embedded hiPSCs up-regulate genes associated with early cardiogenesis by up to 105 times independently of the presence of AA. However, neither connexin 43 nor troponin I proteins, which are related with mature cardiomyocytes, were detected and no contraction was noted in the constructs. Future experiments will need to focus on characterizing the mature cardiac phenotype of these cells when implanted into infarcted myocardia and assess their regenerative potential in vivo.

Heart-on-a-chip based on stem cell biology

Heart diseases are one of the main causes of death around the world. The great challenge for scientists is to develop new therapeutic methods for these types of ailments. Stem cells (SCs) therapy could be one of a promising technique used for renewal of cardiac cells and treatment of heart diseases. Conventional in vitro techniques utilized for investigation of heart regeneration do not mimic natural cardiac physiology. Lab-on-a-chip systems may be the solution which could allow the creation of a heart muscle model, enabling the growth of cardiac cells in conditions similar to in vivo conditions. Microsystems can be also used for differentiation of stem cells into heart cells, successfully. It will help better understand of proliferation and regeneration ability of these cells. In this review, we present Heart-on-a-chip systems based on cardiac cell culture and stem cell biology. This review begins with the description of the physiological environment and the functions of the heart. Next, we shortly described conventional techniques of stem cells differentiation into the cardiac cells. This review is mostly focused on describing Lab-on-a-chip systems for cardiac tissue engineering. Therefore, in the next part of this article, the microsystems for both cardiac cell culture and SCs differentiation into cardiac cells are described. The section about SCs differentiation into the heart cells is divided in sections describing biochemical, physical and mechanical stimulations. Finally, we outline present challenges and future research concerning Heart-on-a-chip based on stem cell biology.

Conjoint propagation and differentiation of human embryonic stem cells to cardiomyocytes in a defined microcarrier spinner culture

Introduction

Myocardial infarction is accompanied by a significant loss of cardiomyocytes (CMs). Functional CMs, differentiated from human embryonic stem cells (hESCs), offer a potentially unlimited cell source for cardiac disease therapies and regenerative cardiovascular medicine. However, conventional production methods on monolayer culture surfaces cannot adequately supply the large numbers of cells required for such treatments. To this end, an integrated microcarrier (MC) bioprocessing system for hESC propagation and subsequent CM differentiation was developed.

Methods

Production of hESC-derived CMs was initially established in monolayer cultures. This control condition was compared against hESC expansion on laminin-coated MC with cationic surface charge, in a stirred serum-free defined culture. Following expansion, the hESC/MC aggregates were placed in a CM differentiation medium, using Wnt signalling modulators in four different culture conditions. This process eliminated the need for manual colony cutting. The final optimized protocol was tested in stirred spinner flasks, combining expansion and differentiation on the same MC, with only media changes during the culture process.

Results

In the propagation phase, a 15-fold expansion of viable pluripotent HES-3 was achieved, with homogeneous sized aggregates of 316 ± 11 μm. Of the four differentiation conditions, stirred spinner flask cultures (MC-Sp) provided the best controlled aggregate sizes and yielded 1.9 × 10⁶ CM/ml, as compared to 0.5 × 10⁶ CM/ml using the monolayer cultures method: a four-fold increase in CM/ml. Similar results (1.3 × 10⁶ CM/ml) were obtained with an alternative hESC H7 line. The hESC/MC-derived CM expressed cardiac-specific transcription factors, structural, ion channel genes, and exhibited cross-striations of sarcomeric proteins, thus confirming their cardiac ontogeny. Moreover, E-4031 (0.3 μM) prolonged the QT-interval duration by 40% and verapamil (3 μM) reduced it by 45%, illustrating the suitability of these CM for pharmacological assays.

Conclusions

We have demonstrated a robust and scalable microcarrier system for generating hESC-derived CM. This platform is enabled by defined microcarrier matrices and it integrates cell propagation and differentiation within a continuous process, in serum-free culture media. It can generate significant numbers of CM, which are potentially suitable for future clinical therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/scrt498) contains supplementary material, which is available to authorized users.

Cyclosporine A-nanoparticles enhance the therapeutic benefit of adipose tissue-derived stem cell transplantation in a swine myocardial infarction model

Treatment of myocardial infarction (MI) with adipose-derived stem cells (ASCs) has produced promising results. Cyclosporine A (CsA) inhibits apoptosis by preventing the opening of mitochondrial permeability transition pores. A CsA nanoparticle emulsion (CsA-NP) has lower toxicity and higher efficiency as compared to CsA. In this study, we hypothesized that a combination of ASCs and CsA-NP would enhance the therapeutic efficiency in a swine MI model. MI was induced in pig hearts by occlusion of the left anterior descending artery. The animals that survived MI were divided into four groups and 1 week later received intracoronary ASCs (ASCs, n=6), intracoronary culture media in combination with CsA-NP (CsA-NP, n=6), intracoronary ASCs in combination with CsA-NP (ASCs + CsA-NP, n=6), or remained untreated (control, n=4). Animals were sacrificed 8 weeks later and were evaluated for cardiac function by delayed-enhanced magnetic resonance imaging and immunohistopathology. We observed that the left ventricular ejection fraction (LVEF) was significantly increased in the ASCs + CsA-NP group, compared to the CsA-NP group (53.6%±2.4% versus 48.6%±1.5%, P<0.05), and the ASCs group (53.6%±2.4% versus 48.3%±1.8%, P<0.05). More importantly, the infarct size was significantly smaller in the ASCs + CsA-NP group as compared to the CsA-NP group (6.2±1.7 cm³ versus 9.1±3.4 cm³, P<0.05) and the ASCs group (6.2±1.7 cm³ versus 7.5±0.6 cm³, P<0.05). These findings were further confirmed by analysis of the expression of cardiomyocyte markers, myosin heavy chain (α-actinin) and troponin T. In addition, the CsA-NP + ASCs treatment promoted neovascularization (P<0.05) and inhibited cardiomyocyte apoptosis (P<0.01) compared to the control group. This study demonstrates that CsA-NP enhanced the therapeutic benefits of ASCs transplantation for MI.

Total saponins of Panax notoginseng enhance VEGF and relative receptors signals and promote angiogenesis derived from rat bone marrow mesenchymal stem cells

ETHNOPHARMACOLOGICAL RELEVANCE

Total saponins of Panax notoginseng (tPNS), main constituents extracted from Panax Notoginseng, a highly valued traditional Chinese medicine, has been shown to increase protein expression and the secretion of vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells.

AIMS OF THE STUDY

The effects of tPNS on angiogenesis were studied in rat bone marrow mesenchymal stem cells (rBMSCs).

MATERIALS AND METHODS

rBMSCs were stimulated by tPNS of 48 h. The mRNA expression levels of VEGF-A, Flt-1 and Kdr in rBMSCs were determined by quantitative real time PCR (qRT-PCR). rBMSCs were induced to differentiate into endothelial-like cells and the effects of tPNS on the angiogenesis ability of rBMSCs and rBMSCs after endothelial differentiation were assayed by a Matrigel model in vivo and in vitro.

RESULTS

tPNS (100 μg/ml) significantly enhanced the mRNA expression level of VEGF-A and Kdr compared to the control group, while they had no obvious effect on the expression of Flt-1. tPNS (1 μg/ml and 100 μg/ml) significantly increased capillary network forming of rBMSCs after endothelial differentiation in Matrigel in vitro. tPNS (50 μg/kg, 100 μg/kg and 150 μg/kg) also significantly increased angiogenesis induced by the combination with implantation of rBMSCs and Matrigel in vivo.

CONCLUSION

tPNS up-regulate VEGF-A and Kdr expression, and promote angiogenesis in rat bone marrow mesenchymal stem cells.

Safe genetic modification of cardiac stem cells using a site-specific integration technique

BACKGROUND

Human cardiac progenitor cells (hCPCs) are a promising cell source for regenerative repair after myocardial infarction. Exploitation of their full therapeutic potential may require stable genetic modification of the cells ex vivo. Safe genetic engineering of stem cells, using facile methods for site-specific integration of transgenes into known genomic contexts, would significantly enhance the overall safety and efficacy of cellular therapy in a variety of clinical contexts.

METHODS AND RESULTS

We used the phiC31 site-specific recombinase to achieve targeted integration of a triple fusion reporter gene into a known chromosomal context in hCPCs and human endothelial cells. Stable expression of the reporter gene from its unique chromosomal integration site resulted in no discernible genomic instability or adverse changes in cell phenotype. Namely, phiC31-modified hCPCs were unchanged in their differentiation propensity, cellular proliferative rate, and global gene expression profile when compared with unaltered control hCPCs. Expression of the triple fusion reporter gene enabled multimodal assessment of cell fate in vitro and in vivo using fluorescence microscopy, bioluminescence imaging, and positron emission tomography. Intramyocardial transplantation of genetically modified hCPCs resulted in significant improvement in myocardial function 2 weeks after cell delivery, as assessed by echocardiography (P=0.002) and MRI (P=0.001). We also demonstrated the feasibility and therapeutic efficacy of genetically modifying differentiated human endothelial cells, which enhanced hind limb perfusion (P<0.05 at day 7 and 14 after transplantation) on laser Doppler imaging.

CONCLUSIONS

The phiC31 integrase genomic modification system is a safe, efficient tool to enable site-specific integration of reporter transgenes in progenitor and differentiated cell types.

Apelin-13 increases myocardial progenitor cells and improves repair postmyocardial infarction

Apelin is an endogenous ligand for the angiotensin-like 1 receptor (APJ) and has beneficial effects against myocardial ischemia-reperfusion injury. Little is known about the role of apelin in the homing of vascular progenitor cells (PCs) and cardiac functional recovery postmyocardial infarction (post-MI). The present study investigated whether apelin affects PC homing to the infarcted myocardium, thereby mediating repair and functional recovery post-MI. Mice were infarcted by coronary artery ligation, and apelin-13 (1 mg·kg(-1)·day(-1)) was injected for 3 days before MI and for 14 days post-MI. Homing of vascular PCs [CD133(+)/c-Kit(+)/Sca1(+), CD133(+)/stromal cell-derived factor (SDF)-1α(+), and CD133(+)/CXC chemokine receptor (CXCR)-4(+)] into the ischemic area was examined. Myocardial Akt, endothelial nitric oxide synthase (eNOS), VEGF, jagged1, notch3, SDF-1α, and CXCR-4 expression were assessed at 24 h and 14 days post-MI. Functional analyses were performed on day 14 post-MI. Mice that received apelin-13 treatment demonstrated upregulation of SDF-1α/CXCR-4 expression and dramatically increased the number of CD133(+)/c-Kit(+)/Sca1(+), CD133(+)/SDF-1α(+), and c-Kit(+)/CXCR-4(+) cells in infarcted hearts. Apelin-13 also significantly increased Akt and eNOS phosphorylation and upregulated VEGF, jagged1, and notch3 expression in ischemic hearts. This was accompanied by a significant reduction of myocardial apoptosis. Furthermore, treatment with apelin-13 promoted myocardial angiogenesis and attenuated cardiac fibrosis and hypertrophy together with a significant improvement of cardiac function at 14 days post-MI. Apelin-13 increases angiogenesis and improves cardiac repair post-MI by a mechanism involving the upregulation of SDF-1α/CXCR-4 and homing of vascular PCs.