Pluripotency pertains to the cells of early embryos that can generate all of the tissues in the organism. Embryonic stem cells are embryo-derived cell lines that retain pluripotency and represent invaluable tools for research into the mechanisms of tissue formation. Recently, murine fibroblasts have been reprogrammed directly to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4 and Myc) to yield induced pluripotent stem (iPS) cells. Using these same factors, we have derived iPS cells from fetal, neonatal and adult human primary cells, including dermal fibroblasts isolated from a skin biopsy of a healthy research subject. Human iPS cells resemble embryonic stem cells in morphology and gene expression and in the capacity to form teratomas in immune-deficient mice. These data demonstrate that defined factors can reprogramme human cells to pluripotency, and establish a method whereby patient-specific cells might be established in culture.

/pdf/reprogramming-of-human-somatic-cells-to-pluripotency-with-4lycgkg8te.pdf

Reprogramming of human somatic cells to pluripotency with defined factors

Cardiomyocytes derived from human embryonic stem (hES) cells potentially offer large numbers of cells to facilitate repair of the infarcted heart. However, this approach has been limited by inefficient differentiation of hES cells into cardiomyocytes, insufficient purity of cardiomyocyte preparations and poor survival of hES cell-derived myocytes after transplantation. Seeking to overcome these challenges, we generated highly purified human cardiomyocytes using a readily scalable system for directed differentiation that relies on activin A and BMP4. We then identified a cocktail of pro-survival factors that limits cardiomyocyte death after transplantation. These techniques enabled consistent formation of myocardial grafts in the infarcted rat heart. The engrafted human myocardium attenuated ventricular dilation and preserved regional and global contractile function after myocardial infarction compared with controls receiving noncardiac hES cell derivatives or vehicle. The ability of hES cell-derived cardiomyocytes to partially remuscularize myocardial infarcts and attenuate heart failure encourages their study under conditions that closely match human disease.

https://courses.washington.edu/conj504/readings/murry_reading2.pdf

Cardiomyocytes derived from human embryonic stem cells in pro-survival factors enhance function of infarcted rat hearts

Differentiation of embryonic stem cells to clinically relevant populations: lessons from embryonic development.

Human induced pluripotent stem (iPS) cells hold great promise for cardiovascular research and therapeutic applications, but the ability of human iPS cells to differentiate into functional cardiomyocytes has not yet been demonstrated. The aim of this study was to characterize the cardiac differentiation potential of human iPS cells generated using OCT4, SOX2, NANOG, and LIN28 transgenes compared to human embryonic stem (ES) cells. The iPS and ES cells were differentiated using the embryoid body (EB) method. The time course of developing contracting EBs was comparable for the iPS and ES cell lines, although the absolute percentages of contracting EBs differed. RT-PCR analyses of iPS and ES cell-derived cardiomyocytes demonstrated similar cardiac gene expression patterns. The pluripotency genes OCT4 and NANOG were downregulated with cardiac differentiation, but the downregulation was blunted in the iPS cell lines due to residual transgene expression. Proliferation of iPS and ES cell derived-cardiomyocytes based on BrdU labeling was similar, and immunocytochemistry of isolated cardiomyocytes revealed indistinguishable sarcomeric organizations. Electrophysiology studies indicated that iPS cells have a capacity like ES cells for differentiation into nodal-, atrial-, and ventricular-like phenotypes based on action potential characteristics. Both iPS and ES cell-derived cardiomyocytes exhibited responsiveness to β-adrenergic stimulation manifest by an increase in spontaneous rate and a decrease in action potential duration. We conclude that human iPS cells can differentiate into functional cardiomyocytes, and thus iPS cells are a viable option as an autologous cell source for cardiac repair and a powerful tool for cardiovascular research.

Functional Cardiomyocytes Derived From Human Induced Pluripotent Stem Cells

A method for inducing cardiomyocyte differentiation of a hES cell, the method comprising co-culturing the hES cell with a cell excreting at least one cardiomyocyte differentiation inducing factor or with an extracellular medium therefrom, under conditions that induce differentiation, cells and cell populations so produced, and uses of the cells.

Differentiation of human embryonic stem cells to cardiomyocytes

Cell replacement therapy is a promising approach for the treatment of cardiac diseases, but is challenged by a limited supply of appropriate cells. We have investigated whether functional cardiomyocytes can be efficiently generated from human embryonic stem (hES) cells. Cardiomyocyte differentiation was evaluated using 3 parent (H1, H7, and H9) hES cell lines and 2 clonal (H9.1 and H9.2) hES cell lines. All cell lines examined differentiated into cardiomyocytes, even after long-term culture (50 passages or approximately 260 population doublings). Upon differentiation, beating cells were observed after one week in differentiation conditions, increased in numbers with time, and could retain contractility for over 70 days. The beating cells expressed markers characteristic of cardiomyocytes, such as cardiac alpha-myosin heavy chain, cardiac troponin I and T, atrial natriuretic factor, and cardiac transcription factors GATA-4, Nkx2.5, and MEF-2. In addition, cardiomyocyte differentiation could be enhanced by treatment of cells with 5-aza-2'-deoxycytidine but not DMSO or retinoic acid. Furthermore, the differentiated cultures could be dissociated and enriched by Percoll density centrifugation to give a population containing 70% cardiomyocytes. The enriched population was proliferative and showed appropriate expression of cardiomyocyte markers. The extended replicative capacity of hES cells and the ability to differentiate and enrich for functional human cardiomyocytes warrant further development of these cells for clinical application in heart diseases.

Characterization and Enrichment of Cardiomyocytes Derived From Human Embryonic Stem Cells

This disclosure provides a newly developed strategy and particular options for differentiating pluripotent stem cells into cells of the hepatocyte lineage. Many of the protocols are based on a strategy in which the cells are first differentiated into early germ layer cells, then into hepatocyte precursors, and then into mature cells. The cells obtained have morphological features and phenotypic markers characteristic of human adult hepatocytes. They also show evidence of cytochrome p450 enzyme activity, validating their utility for commercial applications such as drug screening, or use in the manufacture of medicaments and medical devices for clinical therapy.

Protocols for making hepatocytes from embryonic stem cells

A presente invention concerne une nouvelle strategie developpee et des options particulieres permettant de differencier des cellules souches pluripotentes en cellules de lignee hepatocyte. De nombreux protocoles sont fondees sur une strategie dans laquelle les cellules sont d'abord differenciees en cellules de feuillet d'embryons precoces, puis en precurseur d'hepatocyte, puis en cellules matures. Les cellules obtenues presentent des caracteristiques morphologiques et des marqueurs phenotypiques caracteristiques des hepatocytes adultes humaines. Elles demontrent aussi une activite d'enzyme p450 cytochrome, validant leur utilite pour des applications commerciales telles que la recherche de medicaments ou pour une utilisation dans la fabrication de medicaments et de dispositifs medicaux destines a une therapie clinique.

Namitha Rao

Papers

Characterization and Enrichment of Cardiomyocytes Derived From Human Embryonic Stem Cells

Protocols for making hepatocytes from embryonic stem cells

Nouveau protocole de preparation d'hepatocytes a partir de cellules souches embryonnaires