RESUMEN
Many small molecule kinase inhibitors (SMKIs), used predominantly in cancer therapy, have been implicated in serious clinical cardiac adverse events, which means that traditional preclinical drug development assays were not sufficient for identifying these cardiac liabilities. To improve clinical cardiac safety predictions, the effects of SMKIs targeting many different signaling pathways were studied using human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) in combined assays designed for the detection of both electrophysiological (proarrhythmic) and non-electrophysiological (non-proarrhythmic) drug-induced cardiotoxicity. Several microplate-based assays were used to quantitate cell death, apoptosis, mitochondrial damage, energy depletion, and oxidative stress as mechanism-based non-electrophysiological cardiomyocyte toxicities. Microelectrode arrays (MEA) were used to quantitate in vitro arrhythmic events (iAEs), field potential duration (FPD) prolongation, and spike amplitude suppression (SAS) as electrophysiological effects. To enhance the clinical relevance, SMKI-induced cardiotoxicities were compared by converting drug concentrations into multiples of reported clinical maximum therapeutic plasma concentration, "FoldCmax", for each assay. The results support the conclusion that the combination of the hPSC-CM based electrophysiological and non-electrophysiological assays have significantly more predictive value than either assay alone and significantly more than the current FDA-recommended hERG assay. In addition, the combination of these assays provided mechanistic information relevant to cardiomyocyte toxicities, thus providing valuable information on potential drug-induced cardiotoxicities early in drug development prior to animal and clinical testing. We believe that this early information will be helpful to guide the development of safer and more cost-effective drugs.
Asunto(s)
Miocitos Cardíacos/efectos de los fármacos , Células Madre Pluripotentes/fisiología , Inhibidores de Proteínas Quinasas/farmacología , Diferenciación Celular , Supervivencia Celular/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Inhibidores de Proteínas Quinasas/química , Receptores de Factores de Crecimiento/genética , Receptores de Factores de Crecimiento/metabolismoRESUMEN
The functional heart is comprised of distinct mesoderm-derived lineages including cardiomyocytes, endothelial cells and vascular smooth muscle cells. Studies in the mouse embryo and the mouse embryonic stem cell differentiation model have provided evidence indicating that these three lineages develop from a common Flk-1(+) (kinase insert domain protein receptor, also known as Kdr) cardiovascular progenitor that represents one of the earliest stages in mesoderm specification to the cardiovascular lineages. To determine whether a comparable progenitor is present during human cardiogenesis, we analysed the development of the cardiovascular lineages in human embryonic stem cell differentiation cultures. Here we show that after induction with combinations of activin A, bone morphogenetic protein 4 (BMP4), basic fibroblast growth factor (bFGF, also known as FGF2), vascular endothelial growth factor (VEGF, also known as VEGFA) and dickkopf homolog 1 (DKK1) in serum-free media, human embryonic-stem-cell-derived embryoid bodies generate a KDR(low)/C-KIT(CD117)(neg) population that displays cardiac, endothelial and vascular smooth muscle potential in vitro and, after transplantation, in vivo. When plated in monolayer cultures, these KDR(low)/C-KIT(neg) cells differentiate to generate populations consisting of greater than 50% contracting cardiomyocytes. Populations derived from the KDR(low)/C-KIT(neg) fraction give rise to colonies that contain all three lineages when plated in methylcellulose cultures. Results from limiting dilution studies and cell-mixing experiments support the interpretation that these colonies are clones, indicating that they develop from a cardiovascular colony-forming cell. Together, these findings identify a human cardiovascular progenitor that defines one of the earliest stages of human cardiac development.
Asunto(s)
Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Miocitos Cardíacos/citología , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Activinas/farmacología , Proteína Morfogenética Ósea 4 , Proteínas Morfogenéticas Óseas/farmacología , Diferenciación Celular/efectos de los fármacos , Línea Celular , Linaje de la Célula/efectos de los fármacos , Células Madre Embrionarias/efectos de los fármacos , Células Madre Embrionarias/trasplante , Factor 2 de Crecimiento de Fibroblastos/farmacología , Humanos , Péptidos y Proteínas de Señalización Intercelular/farmacología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Técnicas de Placa-Clamp , Proteínas Proto-Oncogénicas c-kit/genética , Factor A de Crecimiento Endotelial Vascular/farmacología , Receptor 2 de Factores de Crecimiento Endotelial Vascular/deficiencia , Receptor 2 de Factores de Crecimiento Endotelial Vascular/genéticaRESUMEN
In order to define the molecular mechanisms regulating the specification and differentiation of pancreatic ß-islet cells, we investigated the effect of upregulating Pdx1 and Ngn3 during the differentiation of the ß-islet-like cells from murine embryonic stem (ES) cell-derived activin induced-endoderm. Induced overexpression of Pdx1 resulted in a significant upregulation of insulin (Ins1 and Ins2), and other pancreas-related genes. To enhance the developmental progression from the pancreatic bud to the formation of the endocrine lineages, we induced the overexpression express of Ngn3 together with Pdx1. This combination dramatically increased the level and timing of maximal Ins1 mRNA expression to approximately 100% of that found in the ßTC6 insulinoma cell line. Insulin protein and C-peptide expression was confirmed by immunohistochemistry staining. These inductive effects were restricted to c-kit(+) endoderm enriched EB-derived populations suggesting that Pdx1/Ngn3 functions after the specification of pancreatic endoderm. Although insulin secretion was stimulated by various insulin secretagogues, these cells had only limited glucose response. Microarray analysis was used to evaluate the expression of a broad spectrum of pancreatic endocrine cell-related genes as well as genes associated with glucose responses. Taken together, these findings demonstrate the utility of manipulating Pdx1 and Ngn3 expression in a stage-specific manner as an important new strategy for the efficient generation of functionally immature insulin-producing ß-islet cells from ES cells.