Cyclin D1 acts as a barrier to pluripotent reprogramming by promoting neural progenitor fate commitment

AbstractA short G1 phase is a characteristic feature of the cell cycle structure of pluripotent cells, and is reestablished during Yamanaka factor-mediated pluripotent reprogramming. How cell cycle control is adjusted to meet the requirements of pluripotent cell fate commitment during reprogramming is less well understood. Elevated levels of cyclin D1 were initially found to impair pluripotency maintenance. The current work further identified Cyclin D1 to be capable of transcriptionally upregulating Pax6, which promoted reprogramming cells to commit to a neural progenitor fate rather than a pluripotent cell fate. These findings explain the importance of reestablishment of G1-phase restriction in pluripotent reprogramming

The roles of non-coding RNAs in cardiac regenerative medicine

The emergence of non-coding RNAs (ncRNAs) has challenged the central dogma of molecular biology that dictates that the decryption of genetic information starts from transcription of DNA to RNA, with subsequent translation into a protein. Large numbers of ncRNAs with biological significance have now been identified, suggesting that ncRNAs are important in their own right and their roles extend far beyond what was originally envisaged. ncRNAs do not only regulate gene expression, but are also involved in chromatin architecture and structural conformation. Several studies have pointed out that ncRNAs participate in heart disease; however, the functions of ncRNAs still remain unclear. ncRNAs are involved in cellular fate, differentiation, proliferation and tissue regeneration, hinting at their potential therapeutic applications. Here, we review the current understanding of both the biological functions and molecular mechanisms of ncRNAs in heart disease and describe some of the ncRNAs that have potential heart regeneration effects. Keywords: Non-coding RNAs, Cardiac regeneration, Cardiac fate, Proliferation, Differentiation, Reprogramin

Custom design of the cardiac microenvironment with biomaterials

© 2005 American Heart Association, Inc. All rights reserved. The electronic version of this article is the complete one and can be found online at: http://circres.ahajournals.org/content/97/1/8DOI: 10.1161/01.RES.0000184694.03262.6dMany strategies for repairing injured myocardium are under active investigation, with some early encouraging results. These strategies include cell therapies, despite little evidence of long-term survival of exogenous cells, and gene or protein therapies, often with incomplete control of locally-delivered dose of the factor. We propose that, ultimately, successful repair and regeneration strategies will require quantitative control of the myocardial microenvironment. This precision control can be engineered through designed biomaterials that provide quantitative adhesion, growth, or migration signals. Quantitative timed release of factors can be regulated by chemical design to direct cellular differentiation pathways such as angiogenesis and vascular maturation. Smart biomaterials respond to the local environment, such as protease activity or mechanical forces, with controlled release or activation. Most of these new biomaterials provide much greater flexibility for regenerating tissues ex vivo, but emerging technologies like self-assembling nanofibers can now establish intramyocardial cellular microenvironments by injection. This may allow percutaneous cardiac regeneration and repair approaches, or injectable-tissue engineering. Finally, materials can be made to multifunction by providing sequential signals with custom design of differential release kinetics for individual factors. Thus, new rationally-designed biomaterials no longer simply coexist with tissues, but can provide precision bioactive control of the microenvironment that may be required for cardiac regeneration and repair

Controlled delivery of PDGF-BB for myocardial protection using injectable self-assembling peptide nanofibers

Endothelial cells can protect cardiomyocytes from injury, but the mechanism of this protection is incompletely described. Here we demonstrate that protection of cardiomyocytes by endothelial cells occurs through PDGF-BB signaling. PDGF-BB induced cardiomyocyte Akt phosphorylation in a time- and dose-dependent manner and prevented apoptosis via PI3K/Akt signaling. Using injectable self-assembling peptide nanofibers, which bound PDGF-BB in vitro, sustained delivery of PDGF-BB to the myocardium at the injected sites for 14 days was achieved. A blinded and randomized study in 96 rats showed that injecting nanofibers with PDGF-BB, but not nanofibers or PDGF-BB alone, decreased cardiomyocyte death and preserved systolic function after myocardial infarction. A separate blinded and randomized study in 52 rats showed that PDGF-BB delivered with nanofibers decreased infarct size after ischemia/reperfusion. PDGF-BB with nanofibers induced PDGFR-β and Akt phosphorylation in cardiomyocytes in vivo. These data demonstrate that endothelial cells protect cardiomyocytes via PDGF-BB signaling and that this in vitro finding can be translated into an effective in vivo method of protecting myocardium after infarction. Furthermore, this study shows that injectable nanofibers allow precise and sustained delivery of proteins to the myocardium with potential therapeutic benefits

Primary cardiac manifestation of autosomal dominant polycystic kidney disease revealed by patient induced pluripotent stem cell-derived cardiomyocytesResearch in context

Background: Mutations in PKD1 or PKD2 gene lead to autosomal dominant polycystic kidney disease (ADPKD). The mechanism of ADPKD progression and its link to increased cardiovascular mortality is still elusive. Methods: We differentiated ADPKD patient induced pluripotent stem cells (iPSCs) to cardiomyocytes (CMs). The electrophysiological properties at the cellular level were analyzed by calcium imaging and whole cell patch clamping. Findings: The ADPKD patient iPSC-CMs had decreased sarcoplasmic reticulum calcium content compared with Control-CMs. Spontaneous action potential of the PKD2 mutation line-derived CMs demonstrated slower beating rate and longer action potential duration. The PKD1 mutation line-derived CMs showed a comparable dose-dependent shortening of phase II repolarization with the Control-CMs, but a significant increase in beating frequency in response to L-type calcium channel blocker. The PKD1-mutant iPSC-CMs also showed a relatively unstable baseline as a greater percentage of cells exhibited delayed afterdepolarizations (DADs). Both the ADPKD patient iPSC-CMs showed more β-adrenergic agonist-elicited DADs compared with Control-CMs. Interpretation: Characterization of ADPKD patient iPSC-CMs provides new insights into the increased clinical risk of arrhythmias, and the results enable disease modeling and drug screening for cardiac manifestations of ADPKD. Fund: Ministry of Science and Technology, National Health Research Institutes, Academia Sinica Program for Technology Supporting Platform Axis Scheme, Thematic Research Program and Summit Research Program, and Kaohsiung Medical University Hospital, Taiwan. Keywords: Human iPS cell, Autosomal dominant polycystic kidney disease, Cardiomyocyte, Arrhythmi

Generation of 2 induced pluripotent stem cell lines derived from patients with Parkinson's disease carrying LRRK2 G2385R variant

Leucine rich repeat kinase (LRRK2) is the most prevalent genetic cause for Parkinson's disease. LRRK2 p.G2385R is an Asian specific genetic risk factor for sporadic Parkinson's disease. We generated two induced pluripotent stem cells (iPSCs), IBMS-iPSC-018-09 and IBMS-iPSC-020-01, from the peripheral blood mononuclear cells of two patients carrying LRRK2 p.G2385R variant by using the Sendai-virus delivery system. These iPSCs had a normal karyotype and exhibited pluripotency, such as an embryonic stem cell-like morphology, expression of pluripotent markers, and capacity to differentiate into three germ layers. This cellular model will provide a platform for pathophysiological studies of neurodegeneration in Parkinson's disease

Generation of induced pluripotent stem cells from a patient with Parkinson's disease carrying LRRK2 p.I2012T mutation

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by interactions between genetic and environmental factors. Leucine rich repeat kinase (LRRK2) is the most prevalent mutation in autosomal-dominant inheritance of PD. Here, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with p.I2012T mutation in LRRK2 gene by using the Sendai-virus delivery system. The resulting iPSCs had a normal karyotype. The iPSCs also showed pluripotency confirmed by immunofluorescent staining and differentiated into the 3 germ layers in vivo. This cellular model will provide a useful platform for further pathophysiological studies of PD