Efficient Feeder-Free Episomal Reprogramming with Small Molecules

Genetic reprogramming of human somatic cells to induced pluripotent stem cells (iPSCs) could offer replenishable cell sources for transplantation therapies. To fulfill their promises, human iPSCs will ideally be free of exogenous DNA (footprint-free), and be derived and cultured in chemically defined media free of feeder cells. Currently, methods are available to enable efficient derivation of footprint-free human iPSCs. However, each of these methods has its limitations. We have previously derived footprint-free human iPSCs by employing episomal vectors for transgene delivery, but the process was inefficient and required feeder cells. Here, we have greatly improved the episomal reprogramming efficiency using a cocktail containing MEK inhibitor PD0325901, GSK3β inhibitor CHIR99021, TGF-β/Activin/Nodal receptor inhibitor A-83-01, ROCK inhibitor HA-100 and human leukemia inhibitory factor. Moreover, we have successfully established a feeder-free reprogramming condition using chemically defined medium with bFGF and N2B27 supplements and chemically defined human ESC medium mTeSR1 for the derivation of footprint-free human iPSCs. These improvements enabled the routine derivation of footprint-free human iPSCs from skin fibroblasts, adipose tissue-derived cells and cord blood cells. This technology will likely be valuable for the production of clinical-grade human iPSCs

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP. Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies

Establishment and characterization of an iPSC line (UCLi023-A) derived from a Late-Onset Retinal Degeneration patient carrying a founder mutation in C1QTNF5

Late-Onset Retinal Degeneration (L-ORD) is a rare autosomal dominant macular disease, with most cases being caused by a founder mutation in C1QTNF5. Initial symptoms, which generally occur during or after the sixth decade, include abnormal dark adaptation and changes in peripheral vision. Over time, the build-up of sub-retinal pigment epithelium (RPE) deposits leads to macular atrophy and bilateral central vision loss1. Here, we describe the generation of a human induced pluripotent stem cell (iPSC) line from dermal fibroblasts of a 61-year-old L-ORD Caucasian male patient carrying the founder mutation (c.489C>G, p.Ser163Arg), using episomal reprogramming

A Simple Nonviral Method to Generate Human Induced Pluripotent Stem Cells Using SMAR DNA Vectors

Induced pluripotent stem cells (iPSCs) are a powerful tool for biomedical research, but their production presents challenges and safety concerns. Yamanaka and Takahashi revolutionised the field by demonstrating that somatic cells could be reprogrammed into pluripotent cells by overexpressing four key factors for a sufficient time. iPSCs are typically generated using viruses or virus-based methods, which have drawbacks such as vector persistence, risk of insertional mutagenesis, and oncogenesis. The application of less harmful nonviral vectors is limited as conventional plasmids cannot deliver the levels or duration of the factors necessary from a single transfection. Hence, plasmids that are most often used for reprogramming employ the potentially oncogenic Epstein–Barr nuclear antigen 1 (EBNA-1) system to ensure adequate levels and persistence of expression. In this study, we explored the use of nonviral SMAR DNA vectors to reprogram human fibroblasts into iPSCs. We show for the first time that iPSCs can be generated using nonviral plasmids without the use of EBNA-1 and that these DNA vectors can provide sufficient expression to induce pluripotency. We describe an optimised reprogramming protocol using these vectors that can produce high-quality iPSCs with comparable pluripotency and cellular function to those generated with viruses or EBNA-1 vectors.</p

Derivation of induced pluripotent stem cells from a familial Alzheimer's disease patient carrying the L282F mutation in presenilin 1

AbstractMutations in presenilin 1 (PSEN1) lead to the most aggressive form of familial Alzheimer's disease (AD). Human induced pluripotent stem cells (hiPSCs) derived from AD patients can be differentiated and used for disease modeling. Here, we derived hiPSC from skin fibroblasts obtained from an AD patient carrying a L282F mutation in PSEN1. We transfected skin fibroblasts with episomal iPSC reprogramming vectors targeting human OCT4, SOX2, L-MYC, KLF4, NANOG, LIN28, and short hairpin RNA against TP53. Our hiPSC line, L282F-hiPSC, displayed typical stem cell characteristics with consistent expression of pluripotency genes and the ability to differentiation into the three germ layers

Ultrastructural visualization of the Mesenchymal-to-Epithelial Transition during reprogramming of human fibroblasts to induced pluripotent stem cells

The Mesenchymal-to-Epithelial Transition (MET) has been recognized as a crucial step for successful reprogramming of fibroblasts to induced pluripotent stem cells (iPSCs). Thus, it has been demonstrated, that the efficiency of reprogramming can be enhanced by promoting an epithelial expression program in cells, with a concomitant repression of key mesenchymal genes. However, a detailed characterization of the epithelial transition associated with the acquisition of a pluripotent phenotype is still lacking to this date. Here, we integrate a panel of morphological approaches with gene expression analyses to visualize the dynamics of episomal reprogramming of human fibroblasts to iPSCs. We provide the first ultrastructural analysis of human fibroblasts at various stages of episomal iPSC reprogramming, as well as the first real-time live cell visualization of a MET occurring during reprogramming. The results indicate that the MET manifests itself approximately 6–12 days after electroporation, in synchrony with the upregulation of early pluripotency markers, and resembles a reversal of the Epithelial-to-Mesenchymal Transition (EMT) which takes place during mammalian gastrulation

Generation and characterization of three human induced pluripotent stem cell lines (EURACi007-A, EURACi008-A, EURACi009-A) from three different individuals of the same family with arrhythmogenic cardiomyopathy (ACM) carrying the plakophillin2 p.N346Lfs*12 mutation.

Abstract Arrhythmogenic Cardiomyopathy (ACM) is a genetically based cardiomyopathy associated with ventricular arrhythmias and fibro-fatty substitution of cardiac tissue. It is characterized by incomplete penetrance. We generated human iPSCs by episomal reprogramming of blood cells from three members of the same family: the proband, affected by ACM and carrying the heterozygous plakophillin2 p.N346Lfs*12 mutation, one asymptomatic carrier of the same mutation and one apparently healthy control. hiPSCs were characterized according to standard protocols including karyotyping, pluripotency marker expression and differentiation towards the three germ layers. These hiPSC lines can be used to study the mechanisms of ACM incomplete penetrance in vitro