Murine transgenic iPS cell line for monitoring and selection of cardiomyocytes

In vitro effect of hydroxychloroquine on pluripotent stem cells and their cardiomyocytes derivatives

Introduction: Hydroxychloroquine (HDQ) is an antimalarial drug that has also shown its effectiveness in autoimmune diseases. Despite having side effects such as retinopathy, neuromyopathy and controversial cardiac toxicity, HDQ has been presented and now intensively studied for the treatment and prevention of coronavirus disease 2019 (COVID-19). Recent works revealed both beneficial and toxic effects during HDQ treatment. The cardiotoxic profile of HDQ remains unclear and identifying risk factors is challenging. Methods: Here, we used well-established cell-cultured to study the cytotoxic effect of HDQ, mouse induced pluripotent stem cells (miPSC) and their cardiomyocytes (CMs) derivatives were exposed to different concentrations of HDQ. Cell colony morphology was assessed by microscopy whereas cell viability was measured by flow cytometry and impedance-based methods. The effect of HDQ on beating activity of mouse and human induced pluripotent stem cell-derived CMs (miPSC-CMs and hiPSC-CMs, respectively) and mouse embryonic stem cell-derived CMs (mESC-CMs) were captured by the xCELLigence RTCA and microelectrode array (MEA) systems. Results and discussion: Our results revealed that 20 µM of HDQ promotes proliferation of stem cells used suggesting that if appropriately monitored, HDQ may have a cardioprotective effect and may also represent a possible candidate for tissue repair. In addition, the field potential signals revealed that higher doses of this medication caused bradycardia that could be reversed with a higher concentration of ß-adrenergic agonist, Isoproterenol (Iso). On the contrary, HDQ caused an increase in the beating rate of hiPSC-CMs, which was further helped upon application of Isoproterenol (Iso) suggesting that HDQ and Iso may also work synergistically. These results indicate that HDQ is potentially toxic at high concentrations and can modulate the beating activity of cardiomyocytes. Moreover, HDQ could have a synergistic inotropic effect with isoproterenol on cardiac cells.

Effect of Ethanolic Extract of Vernonia amygdalina on the Proliferation, Viability and Function of Mouse Induced Pluripotent Stem Cells and Cardiomyocytes

Vernonia amygdalina (V. amygdalina) leaves are commonly used in traditional medicine around the world for the treatment of a plethora disorders, including heart disease. The aim of this study was to examine and evaluate the cardiac effect of V. amygdalina leaf extracts using mouse induced pluripotent stem cells (miPSCs) and their cardiomyocytes' (CMs) derivatives. We used a well-established stem cell culture to assess the effect of V. amygdalina extract on miPSC proliferation, EB formation and the beating activity of miPS cell-derived CMs. To study the cytotoxic effect of our extract, undifferentiating miPSCs were exposed to different concentrations of V. amygdalina. Cell colony formation and EB morphology were assessed using microscopy, whereas the cell viability was accessed with an impedance-based method and immunocytochemistry following treatment with different concentrations of V. amygdalina. Ethanolic extract of V. amygdalina induced toxicity in miPSCs, as revealed by a decrease in cell proliferation and colony formation, and an increase in cell death at a concentration of ≥20 mg/mL. At a concentration of 10 mg/mL, the rate of beating EBs was observed with no significant difference regarding the yield of cardiac cells. In addition, V. amygdalina did not affect the sarcomeric organization, but induced positive or negative effects on miPS cell-derived CMs' differentiation in a concentration-dependent manner. Taken together, our findings demonstrate that the ethanolic extract of V. amygdalina affected cell proliferation, colony forming and cardiac beating capacities in a concentration-dependent manner.

QuinoMit Q10-Fluid attenuates hydrogen peroxide-induced irregular beating in mouse pluripotent stem cell-derived cardiomyocytes

BACKGROUND

Coenzyme Q10 (CoQ10) is a crucial component of the mitochondrial structure which is involved in producing more than 90% of cellular ATP. This study aimed to investigate the protective effects and underlying mechanisms of QuinoMit Q10-Fluid against hydrogen peroxide (H₂O₂)-induced arrhythmias on cardiomyocytes (CMs).

METHODS

Undifferentiated stem cell-derived CMs were cultured in the presence of different concentrations of QuinoMit Q10-Fluid. To investigate if CoQ10 has anti-apoptotic activity, CMs were exposed to H₂O₂ for up to 100 h with or without CoQ10. The expression levels of cardiac reference genes were determined by RT-PCR. The structural and functional properties of CMs were examined by immunofluorescence and the xCELLigence system. Caspase 3/7 assay was also performed for cell apoptosis study.

RESULTS

The study showed that QuinoMit Q10-Fluid inhibits the proliferation of pluripotent stem cells at high concentrations and had less effect on cardiomyogenesis. However, the beating rate of clusters containing CMs generated under QuinoMit Q10-Fluid (1:100) was significantly increased. This increase was accompanied by the up-regulated expression level of some important cardiac markers during differentiation. Treatment of CMs with H₂O₂ notably induced irregular beating and decreased the amplitude of the beating signal of CMs, concomitantly with increased caspase-3/7 activity. However, CMs pretreated with QuinoMit exhibited a protective effect against H₂O₂-induced arrhythmia.

CONCLUSION

Our results reveal that QuinoMit Q10-Fluid attenuates H₂O₂-induced irregular beating in mouse pluripotent stem cell-derived CMs, at least partly by reducing the generation of ROS, suggesting a protective effect against CM dysfunctions.

Salicylic diamines selectively eliminate residual undifferentiated cells from pluripotent stem cell-derived cardiomyocyte preparations

Clinical translation of pluripotent stem cell (PSC) derivatives is hindered by the tumorigenic risk from residual undifferentiated cells. Here, we identified salicylic diamines as potent agents exhibiting toxicity to murine and human PSCs but not to cardiomyocytes (CMs) derived from them. Half maximal inhibitory concentrations (IC₅₀) of small molecules SM2 and SM6 were, respectively, 9- and 18-fold higher for human than murine PSCs, while the IC₅₀ of SM8 was comparable for both PSC groups. Treatment of murine embryoid bodies in suspension differentiation cultures with the most effective small molecule SM6 significantly reduced PSC and non-PSC contamination and enriched CM populations that would otherwise be eliminated in genetic selection approaches. All tested salicylic diamines exerted their toxicity by inhibiting the oxygen consumption rate (OCR) in PSCs. No or only minimal and reversible effects on OCR, sarcomeric integrity, DNA stability, apoptosis rate, ROS levels or beating frequency were observed in PSC-CMs, although effects on human PSC-CMs seemed to be more deleterious at higher SM-concentrations. Teratoma formation from SM6-treated murine PSC-CMs was abolished or delayed compared to untreated cells. We conclude that salicylic diamines represent promising compounds for PSC removal and enrichment of CMs without the need for other selection strategies.

Persistence of intramyocardially transplanted murine induced pluripotent stem cell-derived cardiomyocytes from different developmental stages

Background

Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) are regarded as promising cell type for cardiac cell replacement therapy, but it is not known whether the developmental stage influences their persistence and functional integration in the host tissue, which are crucial for a long-term therapeutic benefit. To investigate this, we first tested the cell adhesion capability of murine iPSC-CM in vitro at three different time points during the differentiation process and then examined cell persistence and quality of electrical integration in the infarcted myocardium in vivo.

Methods

To test cell adhesion capabilities in vitro, iPSC-CM were seeded on fibronectin-coated cell culture dishes and decellularized ventricular extracellular matrix (ECM) scaffolds. After fixed periods of time, stably attached cells were quantified. For in vivo experiments, murine iPSC-CM expressing enhanced green fluorescent protein was injected into infarcted hearts of adult mice. After 6–7 days, viable ventricular tissue slices were prepared to enable action potential (AP) recordings in transplanted iPSC-CM and surrounding host cardiomyocytes. Afterwards, slices were lysed, and genomic DNA was prepared, which was then used for quantitative real-time PCR to evaluate grafted iPSC-CM count.

Results

The in vitro results indicated differences in cell adhesion capabilities between day 14, day 16, and day 18 iPSC-CM with day 14 iPSC-CM showing the largest number of attached cells on ECM scaffolds. After intramyocardial injection, day 14 iPSC-CM showed a significant higher cell count compared to day 16 iPSC-CM. AP measurements revealed no significant difference in the quality of electrical integration and only minor differences in AP properties between d14 and d16 iPSC-CM.

Conclusion

The results of the present study demonstrate that the developmental stage at the time of transplantation is crucial for the persistence of transplanted iPSC-CM. iPSC-CM at day 14 of differentiation showed the highest persistence after transplantation in vivo, which may be explained by a higher capability to adhere to the extracellular matrix.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02089-5.

Negative chronotropic and inotropic effects of lubiprostone on iPS cell-derived cardiomyocytes via activation of CFTR

Background

Lubiprostone (LBP) is a novel chloride channel opener that has been reported to activate chloride channel protein 2 (ClC-2) and cystic fibrosis transmembrane conductance regulator (CFTR). LBP facilitates fluid secretion by activating CFTR in the intestine and is used as a drug for treating chronic constipation. While ClC-2 and CFTR expression has been confirmed in cardiomyocytes (CMs), the effect of LBP on CMs has not yet been investigated. Thus, the present study aimed to investigate the effect of LBP on CMs using mouse-induced pluripotent stem (iPS) cell-derived CMs (iPS-CMs).

Methods

We induced mouse iPS cells into CMs through embryoid body (EB) formation. We compared the differentiated cells to CMs isolated from adult and fetal mice using gene expression, spontaneous beating rate, and contraction ratio analyses.

Results

Gene expression analysis revealed that, in the iPS-CMs, the mRNA expression of the undifferentiated cell markers Rex1 and Nanog decreased, whereas the expression of the unique cardiomyocyte markers cardiac troponin I (cTnI) and cardiac troponin T (cTNT), increased. Immunostaining showed that the localization of cTnI and connexin-43 in the iPS-CMs was similar to that in the primary fetal CMs (FCMs) and adult CMs (ACMs). LBP decreased the spontaneous beating rate of the iPS-CMs and FCMs, and decreased the contraction ratio of the iPS-CMs and ACMs. The reduction in the beating rate and contraction ratio caused by LBP was inhibited by glycine hydrazide (GlyH), which is a CFTR inhibitor.

Conclusion

These results suggest that LBP stimulates CFTR in CMs and that LBP has negative chronotropic and inotropic effects on CMs. LBP may be useful for treating cardiac diseases such as heart failure, ischemia, and arrhythmia.