In-vivo gene transfer induces transgene expression in cells and secretions of the mouse cauda epididymis

Nucleic acids delivery methods for genome editing in zygotes and embryos: the old, the new, and the old-new

In the recent years, sequence-specific nucleases such as ZFNs, TALENs, and CRISPR/Cas9 have revolutionzed the fields of animal genome editing and transgenesis. However, these new techniques require microinjection to deliver nucleic acids into embryos to generate gene-modified animals. Microinjection is a delicate procedure that requires sophisticated equipment and highly trained and experienced technicians. Though over a dozen alternate approaches for nucleic acid delivery into embryos were attempted during the pre-CRISPR era, none of them became routinely used as microinjection. The addition of CRISPR/Cas9 to the genome editing toolbox has propelled the search for novel delivery approaches that can obviate the need for microinjection. Indeed, some groups have recently developed electroporation-based methods that have the potential to radically change animal transgenesis. This review provides an overview of the old and new delivery methods, and discusses various strategies that were attempted during the last three decades. In addition, several of the methods are re-evaluated with respect to their suitability to deliver genome editing components, particularly CRISPR/Cas9, to embryos.

Gene transfer to the mammalian reproductive tract

This review summarizes the results of research on gene transfer to the mammalian genital tract. Gene transfer experiments have been developed during the last 2 decades and have been applied using in vitro, ex vivo and in vivo procedures. (i) In vitro methods have been applied to the uterine epithelial cells with the principal purpose of analysing some pathological change occurring in the uterus. In the male tract, epididymal cell lines have been used to evaluate the expression of particular genes and the function of specific proteins. (ii) Ex vivo methods have been applied to both the uterus and the vas deferens in humans, and good transgene expression has been recorded. (iii) In vivo gene transfer in the female tract has been employed in the uterus and oviduct using gene injections or electroporation methods. The glandular epithelium of both organs can be transfected efficiently, and transfection efficiency depends on the hormonal stage of the animal. The best expression occurred during pseudopregnancy and meta-estrus periods, when high progesterone and low estradiol concentrations occur. In the male tract, in vivo methods have been applied to mouse vas deferens and epididymis. In both organs, patches of epithelial regions appeared to express the transgenes. Furthermore, the secretions of both organs were also modified using gene constructions that led to the expression of some secretory proteins. In summary, gene modifications in the epithelium of the mammalian reproductive tract have been successful employing different technologies. Further improvements in transfection efficiency would help provide new insights into the physiology of these reproductive organs. Furthermore, the use of these methods could also be used to modify the fertility of mammals.