Kinetin enhances in vitro development of parthenogenetic and nuclear transfer porcine embryos

Evaluation of guide-free Cas9-induced genomic damage and transcriptome changes in pig embryos

Cas9 protein without sgRNAs can induce genomic damage at the cellular level in vitro. However, whether the detrimental effects occur in embryos after Cas9 treatment remains unknown. Here, using pig embryos as subjects, we observed that Cas9 protein transcribed from injected Cas9 mRNA can persist until at least the blastocyst stage. Cas9 protein alone can induce genome damage in preimplantation embryos, represented by the increased number of phosphorylated histone H2AX foci on the chromatin fiber, which led to apoptosis and decreased cell number of blastocysts. In addition, single-blastocyst RNA sequencing confirmed that Cas9 protein without sgRNAs can cause changes in the blastocyst transcriptome, depressing embryo development signal pathways, such as cell cycle, metabolism, and cellular communication-related signal pathways, while activating apoptosis and necroptosis signal pathways, which together resulted in impaired preimplantation embryonic development. These results indicated that attention should be given to the detrimental effects caused by the Cas9 protein when using CRISPR-Cas9 for germline genome editing, especially for the targeted correction of human pathological mutations using germline gene therapy.

Overview on the Antioxidants, Egg Yolk Alternatives, and Mesenchymal Stem Cells and Derivatives Used in Canine Sperm Cryopreservation

Sperm cryopreservation is a widely used assisted reproductive technology for canine species. The long-term storage of dog sperm is effective for the breeding of dogs living far apart, scheduling the time of artificial insemination that suits the female, and preventing diseases of the reproductive tract. However, spermatozoa functions are impaired during the freeze-thaw processes, which may decrease reproductive performance. Numerous attempts have been made to restore such impairments, including the use of cryoprotectants to prevent the damage caused by ice crystal formation, and supplementation of antioxidants to reduce reactive oxygen species generation due to osmotic stress during the procedure. Egg yolk derivatives, antioxidants, and, more recently, mesenchymal stem cells (MSCs) and their derivatives have been proposed in this research field. This review article will summarize the current literature available on the topic.

Effects of kinetin supplementation on the post-thaw motility, viability, and structural integrity of dog sperm

Oxidative stress is one of the major issues associated with cryopreservation because it causes a marked reduction in the post-thaw quality of semen. This study investigated the ability of kinetin to preserve the structural and functional integrity of dog sperm during cryopreservation. Pooled ejaculates were divided into 5 equal aliquots, diluted with buffer 2 supplemented with different concentrations of kinetin (0, 25, 50, 100, and 200 μM), and finally cryopreserved. The optimal concentration of kinetin was 50 μM based on the significantly improved (P < 0.05) motion characteristics and viability of post-thaw sperm samples. Moreover, kinetin-supplemented samples exhibited significantly higher (P < 0.05) sperm counts with the intact plasma membrane, normal acrosomes, mitochondria, and chromatin than control. The beneficial effects of kinetin were also reflected by the significant increase in the expression levels of anti-apoptotic (B-cell lymphoma, BCL2) and protamine-related genes (protamine 2, PRM2; protamine 3, PRM3), and decrease in the expression of pro-apoptotic (BCL2-associated X, BAX) and mitochondrial reactive oxygen species-modulating genes (ROS modulator 1, ROMO1) in kinetin-supplemented sperm samples than in control. The results demonstrated that supplementation of buffer 2 with 50 μM kinetin is ideal for reducing the magnitude of oxidative damage during semen cryoprocessing and improving the post-thaw quality of dog semen.

Kinetin improves motility, viability and antioxidative parameters of ram semen during storage at refrigerator temperature

The present experiment was conducted to evaluate the effect of kinetin on ram semen quality during cold storage. Ejaculates were collected using an artificial vagina from five Qezel rams. Ejaculates which met the criteria (volume of 0.75-2 ml; minimum spermatozoa concentration of 2.5 × 109 spermatozoa/ml and forward progressive motility of 80%), were pooled, diluted with extender without kinetin (control) or enriched with 25 (K 25), 50 (K 50), 100 (K 100) and 200 (K 200) μM kinetin at a final concentration of 500 × 106 spermatozoa per mL. Spermatozoa motion characteristics were evaluated by computer-assisted sperm analysis. In addition, percent of viability (spermatozoa showing no color was considered to be alive) and spermatozoa with intact plasma membrane (spermatozoa with curled/swollen tail was considered healthy) were determined. Moreover, amounts of malondialdehyde (MDA), total antioxidant activity (AOA), nitric oxide (NO) and superoxide dismutase (SOD) activity were determined in the seminal plasma and spermatozoa at 0, 24, 48 and 72 h of storage. Higher percent of total and forward progressive motility was observed in K 25, K 50 and K 100 groups compared to control group at 72 h of storage (P < 0.001). Moreover, K 25 (78.61 ± 1.11%), K 50 (82.46 ± 1.08%) and K 100 (82.96 ± 1.49%) groups showed higher percentage of viability compared to control (72.38 ± 1.49%) at 72 h of storage (P < 0.05). Semen enrichment with kinetin resulted in the higher percent of intact plasma membrane of spermatozoa at 48 and 72 h (P < 0.001). Amounts of MDA were lower and amounts of AOA were higher in K 50 and K 100 groups compared to control at 48 and 72 h (P < 0.05). There were no significant differences in NO levels and SOD activities of seminal plasma and spermatozoa among groups during the experiment. The present experiment revealed that kinetin at proper concentration could enhances spermatozoa kinematics, viability, spermatozoa plasma membrane functionality and amounts of AOA and reduces the level of lipid peroxidation during chilled storage of ram semen.

A simplified one-step nuclear transfer procedure alters the gene expression patterns and developmental potential of cloned porcine embryos

Various somatic cell nuclear transfer (SCNT) techniques for mammalian species have been developed to adjust species-specific procedures to oocyte-associated differences among species. Species-specific SCNT protocols may result in different expression levels of developmentally important genes that may affect embryonic development and pregnancy. In the present study, porcine oocytes were treated with demecolcine that facilitated enucleation with protruding genetic material. Enucleation and donor cell injection were performed either simultaneously with a single pipette (simplified one-step SCNT; SONT) or separately with different pipettes (conventional two-step SCNT; CTNT) as the control procedure. After blastocysts from both groups were cultured in vitro, the expression levels of developmentally important genes (OCT4, NANOG, EOMES, CDX2, GLUT-1, PolyA, and HSP70) were analyzed by real-time quantitative polymerase chain reaction. Both the developmental rate according to blastocyst stage as well as the expression levels CDX2, EOMES, and HSP70 were elevated with SONT compared to CTNT. The genes with elevated expression are known to influence trophectoderm formation and heat stress-induced arrest. These results showed that our SONT technique improved the development of SCNT porcine embryos, and increased the expression of genes that are important for placental formation and stress-induced arrest.

Porcine nuclear transfer using somatic donor cells altered to express male germ cell function

Recent studies reported that the direct transformation of one differentiated somatic cell type into another is possible. In the present study, we were able to modulate the cell fate of somatic cells to take on male germ cell function by introducing cell extracts derived from porcine testis tissue. Fibroblasts were treated with streptolysin O, which reversibly permeabilises the plasma membrane, and incubated with testis extracts. Our results showed that the testis extracts (TE) could activate expression of male germ cell-specific genes, implying that TE can provide regulatory components required for altering the cell fate of fibroblasts. Male germ cell function was sustained for more than 10 days after the introduction of TE. In addition, a single TE-treated cell was injected directly into the cytoplasm of in vitro-matured porcine oocytes. The rate of blastocyst formation was significantly higher in the TE-treated nuclear donor cell group than in the control cell group. The expression level of Nanog, Sox9 and Eomes was drastically increased when altered cells were used as donor nuclei. Our results suggest that TE can be used to alter the cell fate of fibroblasts to express male germ cell function and improve the developmental efficiency of the nuclear transfer porcine embryos.