Effect of transfection and co-incubation of bovine sperm with exogenous DNA on sperm quality and functional parameters for its use in sperm-mediated gene transfer

Comparison of two methods of sperm- and testis-mediated gene transfer in production of transgenic animals: A systematic review

Transgenic (Tg) animal technology is one of the growing areas in biology. Various Tg technologies, each with its own advantages and disadvantages, are available for generating Tg animals. These include zygote microinjection, electroporation, viral infection, embryonic stem cell or spermatogonial stem cell-mediated production of Tg animals, sperm-mediated gene transfer (SMGT), and testis-mediated gene transfer (TMGT). However, there are currently no comprehensive studies comparing SMGT and TMGT methods, selecting appropriate gene delivery carriers (such as nanoparticles and liposomes), and determining the optimal route for gene delivery (SMGT and TMGT) for producing Tg animal. Here we aim to provide a comprehensive assessment comparing SMGT and TMGT methods, and to introduce the best carriers and gene transfer methods to sperm and testis to generate Tg animals in different species. From 2010 to 2022, 47 studies on SMGT and 25 studies on TMGT have been conducted. Mice and rats were the most commonly used species in SMGT and TMGT. Regarding the SMGT approach, nanoparticles, streptolysin-O, and virus packaging were found to be the best gene transfer methods for generating Tg mice. In the TMGT method, the best gene transfer methods for generating Tg mice and rats were virus packaging, dimethyl sulfoxide, electroporation, and liposome. Our study has shown that the efficiency of producing Tg animals varies depending on the species, gene carrier, and method of gene transfer.

Methyl β-Cyclodextrin-sperm-mediated gene editing (MBCD-SMGE): a simple and efficient method for targeted mutant mouse production

BACKGROUND

Generating targeted mutant mice is a crucial technology in biomedical research. This study focuses on optimizing the CRISPR/Cas9 system uptake into sperm cells using the methyl β-cyclodextrin-sperm-mediated gene transfer (MBCD-SMGT) technique to generate targeted mutant blastocysts and mice efficiently. Additionally, the present study elucidates the roles of cholesterol and reactive oxygen species (ROS) in the exogenous DNA uptake by sperm.

RESULTS

In this study, B6D2F1 mouse sperm were incubated in the c-TYH medium with different concentrations of MBCD (0, 0.75, 1, and 2 mM) in the presence of 20 ng/µl pCAG-eCas9-GFP-U6-gRNA (pgRNA-Cas9) for 30 min. Functional parameters, extracellular ROS, and the copy numbers of internalized plasmid per sperm cell were evaluated. Subsequently, in vitro fertilization (IVF) was performed and fertilization rate, early embryonic development, and transfection rate were assessed. Finally, our study investigated the potential of the MBCD-SMGT technique in combination with the CRISPR-Cas9 system, referred to as MBCD-SMGE (MBCD-sperm-mediated gene editing), for generating targeted mutant blastocysts and mice. Results indicated that cholesterol removal from the sperm membrane using MBCD resulted in a premature acrosomal reaction, an increase in extracellular ROS levels, and a dose-dependent influence on the copy numbers of the internalized plasmids per sperm cell. Moreover, the MBCD-SMGT technique led to a larger population of transfected motile sperm and a higher production rate of GFP-positive blastocysts. Additionally, the current study validated the targeted indel in blastocyst and mouse derived from MBCD-SMGE technique.

CONCLUSION

Overall, this study highlights the significant potential of the MBCD-SMGE technique for generating targeted mutant mice. It holds enormous promise for modeling human diseases and improving desirable traits in animals.

A New Toolbox in Experimental Embryology-Alternative Model Organisms for Studying Preimplantation Development

Preimplantation development is well conserved across mammalian species, but major differences in developmental kinetics, regulation of early lineage differentiation and implantation require studies in different model organisms, especially to better understand human development. Large domestic species, such as cattle and pig, resemble human development in many different aspects, i.e., the timing of zygotic genome activation, mechanisms of early lineage differentiations and the period until blastocyst formation. In this article, we give an overview of different assisted reproductive technologies, which are well established in cattle and pig and make them easily accessible to study early embryonic development. We outline the available technologies to create genetically modified models and to modulate lineage differentiation as well as recent methodological developments in genome sequencing and imaging, which form an immense toolbox for research. Finally, we compare the most recent findings in regulation of the first lineage differentiations across species and show how alternative models enhance our understanding of preimplantation development.

Transfection of exogenous DNA complexed to cationic dendrimer induces alterations of bovine sperm microRNAome

MicroRNAs have been hypothesized to be involved in the regulation of male fertility potential. The primary aim of our study was to demonstrate the effects of transfection with dendrimer nanostructure on the parameters of bovine sperm quality and to investigate whether the microRNA profile could be disturbed after cationic dendrimer-mediated exogenous DNA transfection of bovine spermatozoa. The binding of exogenous DNA was significantly increased when dendrimer-based transfection was implemented. However, cationic dendrimer transfection induced detrimental changes in the kinetics and sperm quality parameters, such as membrane integrity, acrosome reaction, and mitochondrial membrane potential, when compared to the control group. Sperm microRNA sequencing revealed 218 known and 106 novel microRNAs in the sperm samples, among which nine were dysregulated after transfection (one was upregulated and eight were downregulated), in comparison to the non-transfected sperm. All the dysregulated microRNAs were related to sperm quality and embryonic development. These results suggest that the transfection process using the dendrimer nanostructure has an impact on the quality and microRNA profile of bovine sperm.

Tauroursodeoxycholic acid (TUDCA) enhanced intracytoplasmic sperm injection (ICSI) embryo developmental competence by ameliorating endoplasmic reticulum (ER) stress and inhibiting apoptosis

PURPOSE

The objective of this study was to examine the effect of tauroursodeoxycholic acid (TUDCA) on intracytoplasmic sperm injection (ICSI) embryos by evaluating endoplasmic reticulum (ER) stress, apoptosis, and embryo developmental competence in vitro and in vivo.

METHODS

ER stress-associated genes and apoptosis-associated genes were measured and apoptosis index was analyzed. Embryo developmental competence was assessed in vitro and in vivo via the inner cell mass (ICM)/trophectoderm (TE) index, pregnancy and implantation rates, and birth rate.

RESULTS

The relative mRNA and protein expression of binding immunoglobulin protein (BIP) was significantly higher in the ICSI embryo group without TUDCA treatment (ICSI-C) than in the in vitro fertilization (IVF) group and in the ICSI embryo group with TUDCA treatment (200 μM) (ICSI-T), while TUDCA ameliorated ER stress in ICSI embryos. Embryos in the ICSI-C group showed a higher apoptosis index than those in the IVF group and ICSI-T group, and there was no significant difference between the IVF group and ICSI-T group. TUDCA can significantly improve ICSI embryo developmental competence in vitro and in vivo based on the ICM/TE index, pregnancy and implantation rates, and birth rate.

CONCLUSION

ICSI embryos manifested high ER stress and high apoptosis, while TUDCA ameliorated ER stress and reduced apoptosis in ICSI embryos. TUDCA can significantly improve the developmental competence of ICSI embryos in vitro and in vivo. This study provides a new idea for improving the efficiency of ICSI, and it will also have a positive effect on the development of assisted reproduction technologies for humans and other animals.

Improved expression of green fluorescent protein in cattle embryos produced by ICSI-mediated gene transfer with spermatozoa treated with streptolysin-O

The ICSI-sperm mediated gene transfer (ICSI-SMGT) has been used to produce transgenic mice with high efficiency; however, the efficiency of this technique in farm animals is still less than desirable. Pretreatment of sperm with membrane destabilizing agents can improve the efficiency of ICSI in cattle. The objective of the present study was to evaluate streptolysin-O (SLO) as a novel treatment to permeabilize the bovine sperm membrane and assess its effect on efficiency of generating transgenic embryos by ICSI-SMGT. First, there was evaluation of the plasma membrane integrity (SYBR/PI), acrosome membrane integrity (PNA/FITC), DNA damage (TUNEL) and binding capacity of exogenous DNA (Nick Translation) in bull sperm treated with SLO. Subsequently, there was assessment of embryonic development and the efficiency in generating transgenic embryos with enhanced expression of the gene for green fluorescent protein (EGFP). Results indicate that SLO efficiently permeabilizes the plasma and acrosome membranes of bull spermatozoa and increases binding of exogenous DNA mostly to the post-acrosomal region and tail without greatly affecting the integrity of the DNA. Furthermore, treatment of bull spermatozoa with SLO prior to the injection of oocytes by ICSI-SMGT significantly increased the rate of embryo expression of the EGFP gene. Future experiments are still needed to determine the effect of this treatment on the development and transgene expression in fetuses and animals produced by ICSI-SMGT.

Living Organisms Author Their Read-Write Genomes in Evolution

Evolutionary variations generating phenotypic adaptations and novel taxa resulted from complex cellular activities altering genome content and expression: (i) Symbiogenetic cell mergers producing the mitochondrion-bearing ancestor of eukaryotes and chloroplast-bearing ancestors of photosynthetic eukaryotes; (ii) interspecific hybridizations and genome doublings generating new species and adaptive radiations of higher plants and animals; and, (iii) interspecific horizontal DNA transfer encoding virtually all of the cellular functions between organisms and their viruses in all domains of life. Consequently, assuming that evolutionary processes occur in isolated genomes of individual species has become an unrealistic abstraction. Adaptive variations also involved natural genetic engineering of mobile DNA elements to rewire regulatory networks. In the most highly evolved organisms, biological complexity scales with "non-coding" DNA content more closely than with protein-coding capacity. Coincidentally, we have learned how so-called "non-coding" RNAs that are rich in repetitive mobile DNA sequences are key regulators of complex phenotypes. Both biotic and abiotic ecological challenges serve as triggers for episodes of elevated genome change. The intersections of cell activities, biosphere interactions, horizontal DNA transfers, and non-random Read-Write genome modifications by natural genetic engineering provide a rich molecular and biological foundation for understanding how ecological disruptions can stimulate productive, often abrupt, evolutionary transformations.

Intracytoplasmic sperm injection in domestic and wild mammals

Intracytoplasmic sperm injection (ICSI) has become a useful technique for clinical applications in the horse-breeding industry. However, both ICSI blastocyst and offspring production continues to be limited for most farm and wild species. This article reviews technical differences of ICSI performance among species, possible biological and methodological reasons for the variable efficiency and potential strategies to improve the outcomes. One of the major applications of ICSI in animal production is the reproduction of high-value specimens. Unfortunately, some domestic species like the bovine show low rates of pronuclei formation after sperm injection, which led to the development of various artificial activation protocols and sperm pre-treatments that are discussed in this article. The impact of ICSI technique on equine breeding programs is considered in detail, since in contrast to other species, its use for elite horse reproduction has increased in recent years. ICSI has also been used to produce genetically modified animals; however, despite numerous attempts in several domestic species, only transgenic pigs have been consistently produced. Finally, the ICSI is a promising tool for genetic rescue of endangered and wild species. In conclusion, while ICSI has become a consistent ART for some species, it needs further development for others. The low results obtained for some domestic species, the high training needed and the equipment required have limited this technique to the production of elite specimens or for research purposes.

Flow cytometric sex sorting affects CD4 membrane distribution and binding of exogenous DNA on bovine sperm cells

Bovine sex-sorted sperm have been commercialized and successfully used for the production of transgenic embryos of the desired sex through the sperm-mediated gene transfer (SMGT) technique. However, sex-sorted sperm show a reduced ability to internalize exogenous DNA. The interaction between sperm cells and the exogenous DNA has been reported in other species to be a CD4-like molecule-dependent process. The flow cytometry-based sex-sorting process subjects the spermatozoa to different stresses causing changes in the cell membrane. The aim of this study was to elucidate the relationship between the redistribution of CD4-like molecules and binding of exogenous DNA to sex-sorted bovine sperm. In the first set of experiments, the membrane phospholipid disorder and the redistribution of the CD4 were evaluated. The second set of experiments was conducted to investigate the effect of CD4 redistribution on the mechanism of binding of exogenous DNA to sperm cells and the efficiency of lipofection in sex-sorted bovine sperm. Sex-sorting procedure increased the membrane phospholipid disorder and induced the redistribution of CD4-like molecules. Both X-sorted and Y-sorted sperm had decreased DNA bound to membrane in comparison with the unsorted sperm; however, the binding of the exogenous DNA was significantly increased with the addition of liposomes. Moreover, we demonstrated that the number of sperm-bound exogenous DNA was decreased when these cells were preincubated with anti-bovine CD4 monoclonal antibody, supporting our hypothesis that CD4-like molecules indeed play a crucial role in the process of exogenous DNA/bovine sperm cells interaction.