Simple derivation of skeletal muscle from human pluripotent stem cells using temperature-sensitive Sendai virus vector.

Human pluripotent stem cells have the potential to differentiate into various cell types including skeletal muscles (SkM), and they are applied to regenerative medicine or in vitro modelling for intractable diseases. A simple differentiation method is required for SkM cells to accelerate neuromuscular disease studies. Here, we established a simple method to convert human pluripotent stem cells into SkM cells by using temperature-sensitive Sendai virus (SeV) vector encoding myoblast determination protein 1 (SeV-Myod1), a myogenic master transcription factor. SeV-Myod1 treatment converted human embryonic stem cells (ESCs) into SkM cells, which expressed SkM markers including myosin heavy chain (MHC). We then removed the SeV vector by temporal treatment at a high temperature of 38℃, which also accelerated mesodermal differentiation, and found that SkM cells exhibited fibre-like morphology. Finally, after removal of the residual human ESCs by pluripotent stem cell-targeting delivery of cytotoxic compound, we generated SkM cells with 80% MHC positivity and responsiveness to electrical stimulation. This simple method for myogenic differentiation was applicable to human-induced pluripotent stem cells and will be beneficial for investigations of disease mechanisms and drug discovery in the future.

Induced pluripotent stem cells derived from an autosomal dominant lateral temporal epilepsy (ADLTE) patient carrying S473L mutation in leucine-rich glioma inactivated 1 (LGI1).

Autosomal dominant lateral temporal epilepsy (ADLTE) is an inherited epileptic syndrome, and it is associated with mutations of leucine-rich glioma inactivated 1 (LGI1) gene. The underlying mechanisms of ADLTE are still unknown, as human neurons are difficult to obtain as a research tool. Human induced pluripotent stem cells (iPSCs) allow the generation of patient-derived neuronal cells in a dish, and can be a promising tool to model ADLTE. Here, we report the establishment of human iPSCs from an ADLTE patient carrying LGI1 mutation (c.1418C>T, p.Ser473Leu).

Engineering the AAVS1 locus for consistent and scalable transgene expression in human iPSCs and their differentiated derivatives.

The potential use of induced pluripotent stem cells (iPSCs) in personalized regenerative medicine applications may be augmented by transgenics, including the expression of constitutive cell labels, differentiation reporters, or modulators of disease phenotypes. Thus, there is precedence for reproducible transgene expression amongst iPSC sub-clones with isogenic or diverse genetic backgrounds. Using virus or transposon vectors, transgene integration sites and copy numbers are difficult to control, and nearly impossible to reproduce across multiple cell lines. Moreover, randomly integrated transgenes are often subject to pleiotropic position effects as a consequence of epigenetic changes inherent in differentiation, undermining applications in iPSCs. To address this, we have adapted popular TALEN and CRISPR/Cas9 nuclease technologies in order to introduce transgenes into pre-defined loci and overcome random position effects. AAVS1 is an exemplary locus within the PPP1R12C gene that permits robust expression of CAG promoter-driven transgenes. Gene targeting controls transgene copy number such that reporter expression patterns are reproducible and scalable by ∼2-fold. Furthermore, gene expression is maintained during long-term human iPSC culture and in vitro differentiation along multiple lineages. Here, we outline our AAVS1 targeting protocol using standardized donor vectors and construction methods, as well as provide practical considerations for iPSC culture, drug selection, and genotyping.