Shahin Eghbalsaied

Extracellular vesicles (EVs) have been investigated due to their natural biocompatibility and targeting capabilities. The specific approach of combining EVs with liposomes to create hybrid nanoparticles (ELNPs) for the delivery of the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas9) system for deletion of the HGF gene in stem cells, but their effectiveness in encapsulating large nucleic acids is limited due to their small size. This study aimed to knock out the HGF gene by the CRISPR/Cas9 system by ELNPs, and it was expected that the efficiency of the CRISPR/Cas9 system transfer would increase compared to the usual methods of using lipofectamine in stem cells from apical papilla (SCAPs). In this study, gRNA suitable for the HGF gene is designed first, and after insertion into the CRISPR/Cas9 vector, it enters Lipofectamine 2000. In the next step, ELNPs are prepared after collecting EVs and hybridizing them with liposomes containing CRISPR/Cas9 vector. Then, these integrated nanoparticles were presented to SCAPs, and the removal of HGF gene expression was evaluated at the level of RNA and protein. This study showed that the CRISPR/Cas9 system can be efficiently transferred to SCAP cells using ELNPs. Genomic DNA sequencing analyses of SCAP cells showed a unique pattern of mutation, highly likely mediated through EVs. Quantitative PCR and protein staining further showed a decrease in HGF gene expression in the knockout cells. Moreover, cell proliferation analysis showed a decrease in cell proliferation in KO-HGF adipose cells compared to the nonedited counterpart. In summary, this study highlights the supportive role of EVs in facilitating cell transfection and promoting a dominant DNA repair pattern, likely through an RNA-mediated mechanism, rather than the random insertions and deletions typically induced during CRISPR editing of the HGF gene in SCAPs.

CRISPR/Cas9 technology represents a powerful tool for advancing livestock breeding by enabling precise, on-target gene edits without the genomic mixing associated with traditional introgression methods. In this study, we employed a dual gRNA-based CRISPR/Cas9 strategy to induce targeted deletions and indel mutations in both reproductive and growth-related genes. These included the metacentric genes bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9), which are associated with increased ovulation rate and litter size, as well as the telomeric genes myostatin (MSTN) and callipyge (CLPG), which are linked to muscle development and enhanced meat production. We employed an optimized electrotransfection protocol consisting of 10–20 µg of each plasmid DNA, 250 µL OptiMEM-GlutaMAX, and one million goat fibroblast cells. The electroporation was performed using a Bio-Rad system in a 4-mm cuvette, with two 10-millisecond pulses at 270 volts, separated by a 10-second interval. This protocol enabled efficient genome editing of goat embryonic fibroblast cells, which were subsequently used to generate cloned embryos via handmade somatic cell nuclear transfer (SCNT), involving manual enucleation and cell–oocyte fusion steps. Sequencing revealed high mutation rates (78–97%) and a predominance of biallelic edits in BMP15, GDF9, and MSTN. Notably, MSTN gRNAs with a 7-bp overlapping sequence at their 3′ ends showed a high editing efficiency. In contrast, the imprinted CLPG gene exhibited a significantly lower mutation rate (~ 30%), likely due to epigenetic constraints. While overall mutation rates did not differ significantly between metacentric and telomeric genes, on-target deletions were more frequent in metacentric genes (43%) than in telomeric ones (20%). Embryo development rates from gene-edited cells were comparable to those from non-edited controls. These findings underscore the utility of combining electrotransfection with SCNT for efficient editing of non-imprinted genes and highlight the need for improved strategies to overcome barriers in editing imprinted loci.

The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) system is revolutionizing genome engineering and is expected to bring significant advancements in livestock traits, including the treatment of genetic diseases. This study focuses on CRISPR/Cas9-mediated modifications of the CYP19 gene, which encodes aromatase, an enzyme crucial for converting testosterone to estrogen and essential for steroid metabolism. Guide RNAs (gRNAs) were designed to target the CYP19 gene and cloned into the pX459 vector. The recombinant plasmid was then electrotransfected into fibroblast cells from a Lori-Bakhtiari buck, and these transfected cells were used for embryo production via somatic cell nuclear transfer (SCNT). The cloned embryos were evaluated for their progression through embryonic stages, showing no significant difference in blastocyst development between knock-out and unedited groups. The knockout efficiency was 78.4% in cells and 68.9% in goat blastocysts, demonstrating the successful depletion of CYP19. We successfully achieved a high rate of CYP19 gene-edited embryos through the combined application of cell electrotransfection and SCNT technologies, while maintaining the normal developmental rate of the embryos. These embryos can be used for transfer to generate knock-out goats, providing a foundation for further studies on CYP19's role in male fertility and production traits.

Base editors are a type of double-stranded break (DSB)-free gene editing technology that has opened up new possibilities for precise manipulation of mitochondrial DNA (mtDNA). This includes cytosine and adenosine base editors and more recently guanosine base editors. Because of having low off-target and indel rates, there is a growing interest in developing and evolving this research field. Here, we provide a detailed update on DNA base editors. While base editing has widely been used for nuclear genome engineering, the growing interest in applying this technology to mitochondrial DNA has been faced with several challenges. While Cas9 protein has been shown to enter mitochondria, use of smaller Cas proteins, such as Cas12a, has higher import efficiency. However, sgRNA transfer into mitochondria is the most challenging step. sgRNA structure and ratio of Cas protein to sgRNA are both important factors for efficient sgRNA entry into mitochondria. In conclusion, while there are still several challenges to be addressed, ongoing research in this field holds the potential for new treatments and therapies for mitochondrial disorders.

Estradiol is a steroid hormone excreted from the female gonads, mainly during the pre-estrus. However, the potential effects of estradiol are yet to be explored on sperm parameters through cryopreservation. In this study, we supplemented estradiol, 3 and 5 μM, in the goat semen extender and assessed the sperm parameters after a freeze-thawing process. Sperm motility was assessed using the computer-assisted sperm analysis system. Sperm viability and membrane integrity improved using both 3 and 5 μM concentrations of estradiol. The highest rate of progressive motility was observed in the 3 μM estradiol group. However, a higher concentration of estradiol (5 μM) reduced the progressive motility. Then, we were interested to see if the supportive effect of estradiol on sperm motility is mediated through the intracellular concentration of calcium ionophore. We supplemented the semen extender with 1 and 10 mM ethylenediaminetetraacetic acid (EDTA) and showed that 1 mM has no adverse effect on progressive sperm motility. Then, estradiol (3 μM) was supplemented with or without EDTA (1 mM) into the semen extender. Individual EDTA treatment improved the progressive sperm motility compared to the control group. However, in the presence of estradiol, EDTA treatment reduced the progressive motility compared to the individual estradiol group. This indicated a considerable interaction between estradiol and EDTA for progressive sperm motility. Indeed, EDTA reduced the supportive effects of estradiol on sperm cryopreservation parameters. These results indicated that induction of higher progressive sperm motility in response to estradiol is a calcium-dependent process, as the EDTA did completely abrogate the estradiol-mediated effect.

Genetic engineering of farm animals is commonly carried out via cell-mediated transfection followed by somatic cell nuclear transfer. However, efficient transfer of exogenous DNA into ovine embryonic fibroblast (EF) cells without compromising cell viability has remained a challenging issue. Here, we aimed to develop a protocol for electrotransfection of sheep EF cells. First, we optimized the pulsing condition using an OptiMEM-GlutaMAX medium as the electroporation buffer and found 2 pulses of 270 V, each for 10 ms and 10 s interval, is the most efficient condition to have a high rate of transfection and cell survival. Moreover, supplementing 3% dimethyl sulfoxide (DMSO) into the electroporation medium considerably improved the cell viability after the electroporation process. The electroporation procedure resulted in >98% transfection efficiency and >97% cell survival rate using reporter plasmids. Finally, using CRISPR/Cas9-encoding vectors, we targeted BMP15 and GDF9 genes in sheep EF cells. The electroporated cells are associated with a 52% indels rate using single gRNAs as well as a highly efficient target deletion using 2 gRNAs. In conclusion, we have developed an electrotransfection protocol using the OptiMEM-GlutaMAX medium supplemented with 3% DMSO for sheep EF cells. The electroporation method can be used for cell-mediated gene-editing in sheep.

Biopreservation and Biobanking