Effective derivation of ventricular cardiomyocytes from hPSCs using ascorbic acid-containing maturation medium.

Cardiomyocytes derived from human pluripotent stem cells (hPSCs) can be used in various applications including disease modeling, drug safety screening, and novel cell-based cardiac therapies. Here, we report an optimized selection and maturation method to induce maturation of cardiomyocytes into a specific subtype after differentiation driven by the regulation of Wnt signaling. The medium used to optimize selection and maturation was in a glucose starvation conditions, supplemented with either a nutrition complex or ascorbic acid. Following optimized selection and maturation, more cardiac Troponin T (cTnT)-positive cardiomyocytes were detected using albumin and ascorbic acid than B27. In addition, ascorbic acid enriched maturation of ventricular cardiomyocytes. We compared cardiomyocyte-specific gene expression patterns under different selection and maturation conditions by next-generation sequencing (NGS) analysis. Our optimized conditions will enable simple and efficient maturation and specification of the desired cardiomyocyte subtype, facilitating both biomedical research and clinical applications.

Evaluation of nefazodone-induced cardiotoxicity in human induced pluripotent stem cell-derived cardiomyocytes.

The recent establishment of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), which express the major cardiac ion channels and recapitulate spontaneous mechanical and electrical activities, may provide a possible solution for the lack of in vitro human-based cardiotoxicity testing models. Cardiotoxicity induced by the antidepressant nefazodone was previously revealed to cause an acquired QT prolongation by hERG channel blockade. To elucidate the cellular mechanisms underlying the cardiotoxicity of nefazodone beyond hERG, its effects on cardiac action potentials (APs) and ion channels were investigated using hiPSC-CMs with whole-cell patch clamp techniques. In a proof of principle study, we examined the effects of cardioactive channel blockers on the electrophysiological profile of hiPSC-CMs in advance of the evaluation of nefazodone. Nefazodone dose-dependently prolonged the AP duration at 90% (APD90) and 50% (APD50) repolarization, reduced the maximum upstroke velocity (dV/dtmax) and induced early after depolarizations. Voltage-clamp studies of hiPSC-CMs revealed that nefazodone inhibited various voltage-gated ion channel currents including IKr, IKs, INa, and ICa. Among them, IKr and INa showed relatively higher sensitivity to nefazodone, consistent with the changes in the AP parameters. In summary, hiPSC-CMs enabled an integrated approach to evaluate the complex interactions of nefazodone with cardiac ion channels. These results suggest that hiPSC-CMs can be an effective model for detecting drug-induced arrhythmogenicity beyond the current standard assay of heterologously expressed hERG K(+) channels.

Platycodon grandiflorus alleviates DNCB-induced atopy-like dermatitis in NC/Nga mice.

OBJECTIVE: To investigate the therapeutic effect of crude extract from Platycodon grandiflorum (PG) roots on atopic dermatitis (AD)-like skin lesions in NC/Nga mice. MATERIALS AND METHODS: To develop atopic dermatitis-like lesions, 200 µl of 0.3% 1-chloro-2, 4-dinitro benzene (DNCB) in acetone/olive oil (3:1) was applied 3 times a week for 2 weeks on the shaved skin of their backs. PG extract was dissolved in saline and orally administrated at concentrations of 300 and 500 mg/kg every day for 2 weeks. The therapeutic effect of PG on AD-like skin lesions was assessed by measuring skin severity scores and epithermal thickness, serum total immunoglobulin (Ig) E, histopathological findings for inflammatory cells including mast cells, macrophage and T cells, and mRNA expression of various cytokines related to the inflammatory and allergic response. The significance of inter-group differences was analyzed using the ANOVA test. Data were considered to be significant when P < 0.05 or P < 0.01. RESULTS: Oral treatment of PG suppressed AD-like skin lesions according to the assessment of skin severity and epithermal thickness in the DNCB-treated NC/Nga mice. This alleviation was further correlated with a reduction of elevated serum total IgE or cytokine mRNA in the PG-treated group compared with vehicle-treated positive group. In addition, infiltrated inflammatory cells decreased on the skin lesions compared with vehicle-treated group. CONCLUSION: These results suggest that PG may have a potential therapeutic effect for AD via the inhibition of both inflammatory and allergic reaction.