Genetic Engineering Publications - GEG Tech top picks

The analysis of stem cell hierarchies in human cancers has been hampered by the impossibility of identifying or tracking tumor cell populations in an intact environment. To overcome this limitation, the scientists devised a strategy based on editing the genomes of patient‐derived tumor organoids using CRISPR/Cas9 technology to integrate reporter cassettes at desired marker genes. As proof of concept, they engineered human colorectal cancer (CRC) organoids that carry EGFP and lineage‐tracing cassettes knocked in the LGR5 locus.

The strategy described herein may have broad applications to study cell heterogeneity in human tumors.

In this study, the scientists deployed Cpf1 to correct DMD mutations in patient-derived induced pluripotent stem cells (iPSCs) and mdx mice, an animal model of DMD. Cpf1-mediated genomic editing of human iPSCs, either by skipping of an out-of-frame DMD exon or by correcting a nonsense mutation, restored dystrophin expression after differentiation to cardiomyocytes and enhanced contractile function. Similarly, pathophysiological hallmarks of muscular dystrophy were corrected in mdx mice following Cpf1-mediated germline editing. These findings are the first to show the efficiency of Cpf1-mediated correction of genetic mutations in human cells and an animal disease model and represent a significant step toward therapeutic translation of gene editing for correction of DMD.

Genome editing of human ES/iPS cells has been limited by technical difficulties that result in a low efficiency of homologous recombination (HR) in human ES/iPS cells.

In this work, the authors demonstrated that RAD51 overexpression and valproic acid treatment enhanced biallelic-targeting efficiency in human ES/iPS cells regardless of the transcriptional activity of the targeted locus. Their findings would facilitate genome editing study using human ES/iPS cells.

An antibody-based conditioning agent may open the way to wider application of gene therapy with hematopoietic stem cells.

In this review, the authors will discuss the specific applications of gene-editing technologies in human HSPC, as informed by prior experience with gene addition strategies. HSPC are desirable but challenging targets; the specific mechanisms these cells evolved to protect themselves from DNA damage render them potentially more susceptible to oncogenesis, especially given their ability to self-renew and their long-term proliferative potential. They further review scientists’ experience with gene-editing technologies to date, focusing on strategies to move these techniques towards implementation in safe and effective clinical trials.

For many of these applications, the ability to genetically modify pluripotent stem cells (PSCs) is indispensable, but efficient site-specific and safe technologies for genetic engineering of PSCs is a very important issue. Customized engineered nucleases could provide excellent tools for targeted genome editing and opening new perspectives for biomedical research and cellular therapies.

Gene editing using CRISPR-Cas9 offers the potential of targeted treatment for a variety of genetic diseases. These include inherited abnormalities of β hemoglobin, which can be indirectly targeted by increasing the amount of healthy fetal hemoglobin even without fully correcting the disease-causing mutation. Humbert et al.  published paper in Science Translational Medicine, titled “Therapeutically relevant engraftment of a CRISPR-Cas9–edited HSC-enriched population with HbF reactivation in nonhuman primates.”

Here the authors report a method for differentiating human pluripotent stem cells to inner ear organoids that harbor functional hair cells. Using a three-dimensional culture system, the authors modulate TGF, BMP, FGF, and WNT signaling to generate multiple otic-vesicle-like structures from a single stem-cell aggregate. Over 2 months, the vesicles develop into inner ear organoids with sensory epithelia that are innervated by sensory neurons. Their culture system should facilitate the study of human inner ear development and research on therapies for diseases of the inner ear.

Here the authors review the history of genome editing in stem cells (including via zinc finger nucleases, transcription activator-like effector nucleases and CRISPR–Cas9), discuss recent developments leading to the implementation of stem cell gene therapies in clinical trials and consider the prospects for future advances in this rapidly evolving field.

In this work, the scientists assess the capacity of intra-arterial delivered autologous engineered canine CD133+ cells of restoring dystrophin expression in golden Retriever dystrophic dogs (GRMD) . This is the first demonstration of five-year follow up study, showing initial clinical amelioration followed by stabilization in mild and severe affected GRMD dogs. The occurrence of T-cell response in three GRMD dogs, consistent with a memory response boosted by the exon skipped-dystrophin protein, suggests an adaptive immune response against dystrophin.

The use of the Cas9/CRISPR system for efficient generation of precisely modified human pluripotent stem cells without secondary deleterious mutations in the untargeted allele
can be challenging. In this article, Howden and colleagues describe a variant of Cas9 that has been fused to a peptide derived from human Geminin to facilitate its degradation
during G1 phase of the cell cycle when DNA repair by NHEJ predominates. Using this variant (SpCas9-Gem) they demonstrate reliable and efficient derivation of both knockin
reporter iPSCs and genetically repaired patient-specific iPSC lines free of NHEJ-mediated indels at the target locus.