Homologous recombination-mediated targeted integration in monkey embryos using TALE nucleases

An expedition in the jungle of pluripotent stem cells of non-human primates

For nearly three decades, more than 80 embryonic stem cell lines and more than 100 induced pluripotent stem cell lines have been derived from New World monkeys, Old World monkeys, and great apes. In this comprehensive review, we examine these cell lines originating from marmoset, cynomolgus macaque, rhesus macaque, pig-tailed macaque, Japanese macaque, African green monkey, baboon, chimpanzee, bonobo, gorilla, and orangutan. We outline the methodologies implemented for their establishment, the culture protocols for their long-term maintenance, and their basic molecular characterization. Further, we spotlight any cell lines that express fluorescent reporters. Additionally, we compare these cell lines with human pluripotent stem cell lines, and we discuss cell lines reprogrammed into a pluripotent naive state, detailing the processes used to attain this. Last, we present the findings from the application of these cell lines in two emerging fields: intra- and interspecies embryonic chimeras and blastoids.

The history, use, and challenges of therapeutic somatic cell and germline gene editing

The advent of directed gene-editing technologies now over 10 years ago ushered in a new era of precision medicine wherein specific disease-causing mutations can be corrected. In parallel with developing new gene-editing platforms, optimizing their efficiency and delivery has been remarkable. With their development, there has been interest in using gene-editing systems for correcting disease mutations in differentiated somatic cells ex vivo or in vivo or for germline gene editing in gametes or 1-cell embryos to potentially limit genetic diseases in the offspring and in future generations. This review details the development and history of the current gene-editing systems and the advantages and challenges in their use for somatic cell and germline gene editing.

Modeling genetic diseases in nonhuman primates through embryonic and germline modification: Considerations and challenges

Genetic modification of the embryo or germ line of nonhuman primates is envisioned as a method to develop improved models of human disease, yet the promise of such animal models remains unfulfilled. Here, we discuss current methods and their limitations for producing nonhuman primate genetic models that faithfully genocopy and phenocopy human disease. We reflect on how to ethically maximize the translational relevance of such models in the search for new therapeutic strategies to treat human disease.

Development of transgenic Daphnia magna for visualizing homology-directed repair of DNA

In the crustacean Daphnia magna, studying homology-directed repair (HDR) is important to understand genome maintenance during parthenogenesis, effects of environmental toxicants on the genome, and improvement of HDR-mediated genome editing. Here we developed a transgenic D. magna that expresses green fluorescence protein (GFP) upon HDR occurrence. We utilized the previously established reporter plasmid named DR-GFP that has a mutated eGFP gene (SceGFP) and the tandemly located donor GFP gene fragment (iGFP). Upon double-strand break (DSB) introduction on SceGFP, the iGFP gene fragment acts as the HDR template and restores functional eGFP expression. We customized this reporter plasmid to allow bicistronic expression of the mCherry gene under the control of the D. magna EF1α-1 promoter/enhancer. By CRISPR/Cas-mediated knock-in of this plasmid via non-homologous joining, we generated the transgenic D. magna that expresses mCherry ubiquitously, suggesting that the DR-GFP reporter gene is expressed in most cells. Introducing DSB on the SceGFP resulted in eGFP expression and this HDR event could be detected by fluorescence, genomic PCR, and quantitative reverse-transcription PCR, suggesting this line could be used for evaluating HDR. The established reporter line might expand our understanding of the HDR mechanism and also improve the HDR-based gene-editing system in this species.

Developing Non-Human Primate Models of Inherited Retinal Diseases

Inherited retinal diseases (IRDs) represent a genetically and clinically heterogenous group of diseases that can eventually lead to blindness. Advances in sequencing technologies have resulted in better molecular characterization and genotype–phenotype correlation of IRDs. This has fueled research into therapeutic development over the recent years. Animal models are required for pre-clinical efficacy assessment. Non-human primates (NHP) are ideal due to the anatomical and genetic similarities shared with humans. However, developing NHP disease to recapitulate the disease phenotype for specific IRDs may be challenging from both technical and cost perspectives. This review discusses the currently available NHP IRD models and the methods used for development, with a particular focus on gene-editing technologies.

Non-human primates as a model for human development

Human development has been studied for over a century, but the molecular mechanisms underlying human embryogenesis remain largely unknown due to technical difficulties and ethical issues. Accordingly, mice have been used as a model for mammalian development and studied extensively to infer human biology based on the conservation of fundamental processes between the two species. As research has progressed, however, species-specific differences in characteristics between rodents and primates have become apparent. Non-human primates (NHPs) have also been used for biomedical research, and are now attracting attention as a model for human development. Here, we summarize primate species from the evolutionary and genomic points of view. Then we review the current issues and progress in gene modification technology for NHPs. Finally, we discuss recent studies on the early embryogenesis of primates and future perspectives.

Primate Organoids and Gene-Editing Technologies toward Next-Generation Biomedical Research

The improved ability to organize pluripotent stem cells (PSCs) into 3D structures in vitro has shed light on organoid technology to recapitulate organs and tumors in vivo. Advances in gene-editing technologies, particularly CRISPR-mediated techniques, offer tremendous potential in facilitating organoid research, including the study of development, disease modeling, and personalized medicine. This review discusses how the combination of two novel technologies - organoids and gene editing - not only contributes to revealing molecular events taking place during development and tumorigenesis but also has implications for biobanking, precision medicine, and other diverse biomedical applications.