An induced pluripotent stem cell model of hypoplastic left heart syndrome (HLHS) reveals multiple expression and functional differences in HLHS-derived cardiac myocytes

hiPSC-derived iMSCs: NextGen MSCs as an advanced therapeutically active cell resource for regenerative medicine

Mesenchymal stem cells (MSCs) are being assessed for ameliorating the severity of graft‐versus‐host disease, autoimmune conditions, musculoskeletal injuries and cardiovascular diseases. While most of these clinical therapeutic applications require substantial cell quantities, the number of MSCs that can be obtained initially from a single donor remains limited. The utility of MSCs derived from human‐induced pluripotent stem cells (hiPSCs) has been shown in recent pre‐clinical studies. Since adult MSCs have limited capability regarding proliferation, the quantum of bioactive factor secretion and immunomodulation ability may be constrained. Hence, the alternate source of MSCs is being considered to replace the commonly used adult tissue‐derived MSCs. The MSCs have been obtained from various adult and foetal tissues. The hiPSC‐derived MSCs (iMSCs) are transpiring as an attractive source of MSCs because during reprogramming process, cells undergo rejuvination, exhibiting better cellular vitality such as survival, proliferation and differentiations potentials. The autologous iMSCs could be considered as an inexhaustible source of MSCs that could be used to meet the unmet clinical needs. Human‐induced PSC‐derived MSCs are reported to be superior when compared to the adult MSCs regarding cell proliferation, immunomodulation, cytokines profiles, microenvironment modulating exosomes and bioactive paracrine factors secretion. Strategies such as derivation and propagation of iMSCs in chemically defined culture conditions and use of footprint‐free safer reprogramming strategies have contributed towards the development of clinically relevant cell types. In this review, the role of iPSC‐derived mesenchymal stromal cells (iMSCs) as an alternate source of therapeutically active MSCs has been described. Additionally, we also describe the role of iMSCs in regenerative medical applications, the necessary strategies, and the regulatory policies that have to be enforced to render iMSC's effectiveness in translational medicine.

Induced pluripotent stem cells: at the heart of cardiovascular precision medicine

The advent of human induced pluripotent stem cell (hiPSC) technology has revitalized the efforts in the past decade to realize more fully the potential of human embryonic stem cells for scientific research. Adding to the possibility of generating an unlimited amount of any cell type of interest, hiPSC technology now enables the derivation of cells with patient-specific phenotypes. Given the introduction and implementation of the large-scale Precision Medicine Initiative, hiPSC technology will undoubtedly have a vital role in the advancement of cardiovascular research and medicine. In this Review, we summarize the progress that has been made in the field of hiPSC technology, with particular emphasis on cardiovascular disease modelling and drug development. The growing roles of hiPSC technology in the practice of precision medicine will also be discussed.

Young at Heart: Pioneering Approaches to Model Nonischaemic Cardiomyopathy with Induced Pluripotent Stem Cells

A mere 9 years have passed since the revolutionary report describing the derivation of induced pluripotent stem cells from human fibroblasts and the first in-patient translational use of cells obtained from these stem cells has already been achieved. From the perspectives of clinicians and researchers alike, the promise of induced pluripotent stem cells is alluring if somewhat beguiling. It is now evident that this technology is nascent and many areas for refinement have been identified and need to be considered before induced pluripotent stem cells can be routinely used to stratify, treat and cure patients, and to faithfully model diseases for drug screening purposes. This review specifically addresses the pioneering approaches to improve induced pluripotent stem cell based models of nonischaemic cardiomyopathy.

Concise Review: Cardiac Disease Modeling Using Induced Pluripotent Stem Cells

Genetic cardiac diseases are major causes of morbidity and mortality. Although animal models have been created to provide some useful insights into the pathogenesis of genetic cardiac diseases, the significant species differences and the lack of genetic information for complex genetic diseases markedly attenuate the application values of such data. Generation of induced pluripotent stem cells (iPSCs) from patient-specific specimens and subsequent derivation of cardiomyocytes offer novel avenues to study the mechanisms underlying cardiac diseases, to identify new causative genes, and to provide insights into the disease aetiology. In recent years, the list of human iPSC-based models for genetic cardiac diseases has been expanding rapidly, although there are still remaining concerns on the level of functionality of iPSC-derived cardiomyocytes and their ability to be used for modeling complex cardiac diseases in adults. This review focuses on the development of cardiomyocyte induction from pluripotent stem cells, the recent progress in heart disease modeling using iPSC-derived cardiomyocytes, and the challenges associated with understanding complex genetic diseases. To address these issues, we examine the similarity between iPSC-derived cardiomyocytes and their ex vivo counterparts and how this relates to the method used to differentiate the pluripotent stem cells into a cardiomyocyte phenotype. We progress to examine categories of congenital cardiac abnormalities that are suitable for iPSC-based disease modeling.

Bioengineering and Stem Cell Technology in the Treatment of Congenital Heart Disease

Congenital heart disease places a significant burden on the individual, family and community despite significant advances in our understanding of aetiology and treatment. Early research in ischaemic heart disease has paved the way for stem cell technology and bioengineering, which promises to improve both structural and functional aspects of disease. Stem cell therapy has demonstrated significant improvements in cardiac function in adults with ischaemic heart disease. This finding, together with promising case studies in the paediatric setting, demonstrates the potential for this treatment in congenital heart disease. Furthermore, induced pluripotent stems cell technology, provides a unique opportunity to address aetiological, as well as therapeutic, aspects of disease.

Low rate of prenatal diagnosis among neonates with critical aortic stenosis: insight into the natural history in utero

OBJECTIVES

To better understand the natural history and spectrum of fetal aortic stenosis (AS), we aimed to (1) determine the prenatal diagnosis rate of neonates with critical AS and a biventricular (BV) outcome, and (2) describe the findings at fetal echocardiography in patients diagnosed prenatally.

METHODS

A multicenter, retrospective study was performed on neonates who presented with critical AS and who were discharged with a BV outcome from 2000 to 2013. The prenatal diagnosis rate was compared with that reported for hypoplastic left heart syndrome (HLHS). We reviewed fetal echocardiographic findings in patients who were diagnosed prenatally.

RESULTS

In only 10 (8.5%) of 117 neonates with critical AS and a BV outcome was the diagnosis made prenatally, a rate significantly lower than that for HLHS in the contemporary era (82%; P < 0.0001). Of the 10 patients diagnosed prenatally, all had developed left ventricular dysfunction by a median gestational age of 33 (range, 28-35) weeks. When present, Doppler abnormalities such as retrograde flow in the aortic arch (n = 2), monophasic mitral inflow (n = 3) and left-to-right flow across the foramen ovale (n = 8) developed late in gestation (median 33 weeks).

CONCLUSION

The prenatal diagnosis rate of critical AS and a BV outcome among neonates is very low, probably owing to a relatively normal four-chamber view in mid-gestation with development of significant obstruction in the third trimester. The natural history contrasts with that of severe mid-gestation AS with evolving HLHS and suggests that the gestational timing of development of significant AS has an important impact on subsequent left-heart growth in utero.

How to mend a broken heart: adult and induced pluripotent stem cell therapy for heart repair and regeneration

The recently developed ability to differentiate primary adult stem cells and induced pluripotent stem cells (iPSCs) into cardiomyocytes is providing unprecedented opportunities to produce an unlimited supply of cardiomyocytes for use in patients with heart disease. Here, we examine the evidence for the preclinical use of such cells for successful heart regeneration. We also describe advances in the identification of new cardiac molecular and cellular targets to induce proliferation of cardiomyocytes for heart regeneration. Such new advances are paving the way for a new innovative drug development process for the treatment of heart disease.

Human stem cells for modeling heart disease and for drug discovery

A major research focus in the field of cardiovascular medicine is the prospect of using stem cells and progenitor cells for cardiac regeneration. With the advent of induced pluripotent stem cell (iPSC) technology, major efforts are also underway to use iPSCs to model heart disease, to screen for new drugs, and to test candidate drugs for cardiotoxicity. Here, we discuss recent advances in the exciting fields of stem cells and cardiovascular disease.

Stem and progenitor cell dysfunction in human trisomies

Trisomy 21, the commonest constitutional aneuploidy in humans, causes profound perturbation of stem and progenitor cell growth, which is both cell context dependent and developmental stage specific and mediated by complex genetic mechanisms beyond increased Hsa21 gene dosage. While proliferation of fetal hematopoietic and testicular stem/progenitors is increased and may underlie increased susceptibility to childhood leukemia and testicular cancer, fetal stem/progenitor proliferation in other tissues is markedly impaired leading to the characteristic craniofacial, neurocognitive and cardiac features in individuals with Down syndrome. After birth, trisomy 21-mediated premature aging of stem/progenitor cells may contribute to the progressive multi-system deterioration, including development of Alzheimer's disease.

Directed differentiation of patient-specific induced pluripotent stem cells identifies the transcriptional repression and epigenetic modification of NKX2-5, HAND1, and NOTCH1 in hypoplastic left heart syndrome

The genetic basis of hypoplastic left heart syndrome (HLHS) remains unknown, and the lack of animal models to reconstitute the cardiac maldevelopment has hampered the study of this disease. This study investigated the altered control of transcriptional and epigenetic programs that may affect the development of HLHS by using disease-specific induced pluripotent stem (iPS) cells. Cardiac progenitor cells (CPCs) were isolated from patients with congenital heart diseases to generate patient-specific iPS cells. Comparative gene expression analysis of HLHS- and biventricle (BV) heart-derived iPS cells was performed to dissect the complex genetic circuits that may promote the disease phenotype. Both HLHS- and BV heart-derived CPCs were reprogrammed to generate disease-specific iPS cells, which showed characteristic human embryonic stem cell signatures, expressed pluripotency markers, and could give rise to cardiomyocytes. However, HLHS-iPS cells exhibited lower cardiomyogenic differentiation potential than BV-iPS cells. Quantitative gene expression analysis demonstrated that HLHS-derived iPS cells showed transcriptional repression of NKX2-5, reduced levels of TBX2 and NOTCH/HEY signaling, and inhibited HAND1/2 transcripts compared with control cells. Although both HLHS-derived CPCs and iPS cells showed reduced SRE and TNNT2 transcriptional activation compared with BV-derived cells, co-transfection of NKX2-5, HAND1, and NOTCH1 into HLHS-derived cells resulted in synergistic restoration of these promoters activation. Notably, gain- and loss-of-function studies revealed that NKX2-5 had a predominant impact on NPPA transcriptional activation. Moreover, differentiated HLHS-derived iPS cells showed reduced H3K4 dimethylation as well as histone H3 acetylation but increased H3K27 trimethylation to inhibit transcriptional activation on the NKX2-5 promoter. These findings suggest that patient-specific iPS cells may provide molecular insights into complex transcriptional and epigenetic mechanisms, at least in part, through combinatorial expression of NKX2-5, HAND1, and NOTCH1 that coordinately contribute to cardiac malformations in HLHS.