Transgenic chicken, mice, cattle, and pig embryos by somatic cell nuclear transfer into pig oocytes

In vitro and in vivo development of interspecies Asian elephant embryos reconstructed with pig enucleated oocytes

Interspecies somatic cell nuclear transfer (iSCNT) has an immense potential to rescue endangered animals and extinct species like mammoths. In this study, we successfully established an Asian elephant's fibroblast cell lines from ear tissues, performed iSCNT with porcine oocytes and evaluated the in vitro and in vivo development of reconstructed embryos. A total of 7780 elephant-pig iSCNT embryos were successfully reconstructed and showed in vitro development with cleavage rate, 4-cell, 8-cell and blastocyst rate of 73.01, 30.48, 5.64, and 4.73%, respectively. The total number of elephant-pig blastocyte cells and diameter of hatched blastocyte was 38.67 and 252.75 μm, respectively. Next, we designed species-specific markers targeting EDNRB, AGRP and TYR genes to verify the genome of reconstructed embryos with donor nucleus/species. The results indicated that 53.2, 60.8, and 60.8% of reconstructed embryos (n = 235) contained elephant genome at 1-cell, 2-cell and 4-cell stages, respectively. However, the percentages decreased to 32.3 and 32.7% at 8-cell and blastocyst stages, respectively. Furthermore, we also evaluated the in vivo development of elephant-pig iSCNT cloned embryos and transferred 2260 reconstructed embryos into two surrogate gilts that successfully became pregnant and a total of 11 (1 and 10) fetuses were surgically recovered after 17 and 19 days of gestation, respectively. The crown-rump length and width of elephant-pig cloned fetuses were smaller than the control group. Unfortunately, none of these fetuses contained elephant genomes, which suggested that elephant embryos failed to develop in vivo. In conclusion, we successfully obtained elephant-pig reconstructed embryos for the first time and these embryos are able to develop to blastocyst, but the in vivo developmental failure needs further investigated.

Effect of arginine-induced motility and capacitation on RNA population in goat spermatozoa

INTRODUCTION

In vitro capacitation is essential in assisted reproductive technologies (ART) for embryo production. Recently, arginine has been proven to enhance capacitation in mammalian spermatozoa. However, the detailed mechanism of action of arginine remains elusive.

AIM

This study investigated the effect of arginine-induced capacitation and motility enhancement on the spermatozoal RNA (spRNA) population in goats.

MATERIAL AND METHODS

Goat spermatozoa were treated with arginine for up to six hours and compared with non-treated or PHE (penicillamine, hypotaurine, and epinephrine)-treated spermatozoa at different intervals (0, 1, 2, 4, and 6 hours). Sperm parameters, including viability, individual motility, capacitation, acrosome reaction, and ROS production, were evaluated. The spRNA population was analyzed by short-read RNA sequencing (RNA-seq).

RESULTS

The percentage of capacitated (73.21 ± 4.22%) and acrosome reacted (18.35 ± 0.56%) spermatozoa was highest in arginine treatment, while PHE treatment showed the highest percentage (79.82 ± 4.31%) of motile spermatozoa from 0 to 4 hours of incubation. RNA-seq analysis identified 1,321 differentially expressed genes (DEGs) in arginine-treated spermatozoa compared to the control. The PGK2, RNASE10, ODF1, and ROPN1L genes involved in sperm motility and ACR, DKKL1, KCNJ11, and PRND genes involved in the capacitation process were upregulated in arginine-treated spermatozoa. The DEGs regulate sperm capacitation-related cAMP-PKA, PI3-Akt, calcium, and MAPK signaling pathways.

CONCLUSION

The arginine-induced capacitation and enhanced sperm motility were associated with the upregulation of several genes involved in sperm motility and capacitation pathways. The comparative study also suggests that arginine may be used in lieu of PHE for motility enhancement and in vitro capacitation of goat spermatozoa.

Analyzing the effect of heparin on in vitro capacitation and spermatozoal RNA population in goats

Heparin is a glycosaminoglycan polymer that is commonly used as an anticoagulant. Heparin also induces in vitro capacitation in spermatozoa, although its molecular mechanism is elusive. This study investigated the effect of heparin on in vitro capacitation and spermatozoal RNA (spRNA) population in goats. Goat spermatozoa were treated with 20 μM heparin for 0-6 h and evaluated for motility, capacitation, acrosome reaction, and spRNA population by RNA sequencing (RNA-seq). It was observed that heparin enhanced sperm motility up to 6 h of incubation (p < 0.05). Heparin also induced capacitation and acrosome reaction within 4 h. RNA-seq identified 1254 differentially expressed genes (DEGs) between heparin-treated and control spermatozoa. Most DEGs (1251 nos.) were upregulated and included 1090 protein-coding genes. A few genes (PRND, ITPR1, LLCFC1, and CHRM2) showed >5-fold increased expression in heparin-treated spermatozoa compared to the control. The upregulated genes were found to be involved in cAMP-PKA, PI3-Akt, calcium, MAPK signaling, and oxidative stress pathways. DCFDA staining confirmed the increased oxidative stress in heparin-treated spermatozoa compared to the control (p < 0.05). In conclusion, the results of the present study suggest that heparin enhances sperm motility and induces capacitation by upregulation of the spRNA population and oxidative stress pathway.

The role of passage numbers of donor cells in the development of Arabian Oryx – Cow interspecific somatic cell nuclear transfer embryos

The cloning between different animals known as interspecific somatic cell nuclear transfer (iSCNT) was carried out for endangered species. The iSCNT has been characterized by a poor success rate due to several factors that influence the formation of the SCNT in various cytoplasms. The cell cycle of the transferred somatic cell, the passage number of the cultured somatic cell, the mitochondria oocytes, and their capabilities are among these factors. This study investigates the role of the passage number of the Arabian Oryx somatic cell culture when transplanted to an enucleated domestic cow oocyte and embryo development in vitro. The fibroblast somatic cell of the Arabian Oryx was cultured for several passage lanes (3–13). The optimal passage cell number was found to be 10–13 Oryx cell lines that progressed to various cell stages up to the blastula stage. There was some variation between the different passage numbers of the oryx cell line. The 3–9 cell line did not show a good developmental stage. These could be attributed to several factors that control the iSCNT as stated by several investigators. More investigation is needed to clarify the role of factors that affect the success rate for the iSCNT.

Comparison of spermatozoal RNA extraction methods in goats

RNA sequencing (RNAseq) has divulged newer role of spermatozoal RNA in male fertility. This study aimed to evaluate different sperm purification and RNA extraction methods for long-read RNA sequencing of poly(A) transcriptome in goat spermatozoa. Sperm samples were purified by swim-up separation using different purification medium. Spermatozoal RNA was extracted by seven different methods with additional supplementation of reducing agents in lysis buffer. poly(A) selected RNA was used for cDNA library preparation and long-read RNAseq in Nanopore sequencer. Sperm purification by 1 h swim-up resulted in higher recovery (89.20 ± 1.15%), motility (82.33 ± 1.53%), viability (88.10 ± 5.03%) and plasma membrane integrity (71.33 ± 4.51%) in sperm TALP (sp-TL) medium. A monophasic solution of GITC with phenol and DTT resulted in the highest yield of large sized RNAs (3.89 ± 0.46 ng/million cells) suitable for long-read RNAseq of poly(A) transcripts. RNAseq resulted in reads of length, ranging from 500bp to 2 Kb. A total of 123 transcripts were identified in goat spermatozoa by de novo assembly and included sperm-specific transcripts such as CATSPERG, PRM2, CYLC2, SPATA6, PLCZ1 etc. This study is the first report of long-read RNAseq of poly(A) transcriptome in goat spermatozoa.

Overcoming bioethical, legal, and hereditary barriers to mitochondrial replacement therapy in the USA

The purpose of the paper is to explore novel means to overcome the controversial ban in the USA against mitochondrial replacement therapy, a form of IVF, with the added step of replacing a woman’s diseased mutated mitochondria with a donor’s healthy mitochondria to prevent debilitating and often fatal mitochondrial diseases. Long proven effective in non-human species, MRT recently performed in Mexico resulted in the birth of a healthy baby boy. We explore the ethics of the ban, the concerns over hereditability of mitochondrial disease and its mathematical basis, the overlooked role of Mitochondrial Eve, the financial burden of mitochondrial diseases for taxpayers, and a woman’s reproductive rights. We examine applicable court cases, particularly protection of autonomy within the reproductive rights assured by Roe v Wade. We examine the consequences of misinterpreting MRT as genetic engineering in the congressional funding prohibitions causing the MRT ban by the FDA. Allowing MRT to take place in the USA would ensure a high standard of reproductive medicine and safety for afflicted women wishing to have genetically related children, concurrently alleviating the significant financial burden of mitochondrial diseases on its taxpayers. Since MRT does not modify any genome, it falls outside the “heritable genetic modification” terminology of concern to Congress and the FDA. Correcting this terminology, the IOM’s conclusion that MRT is ethical, the continuing normalcy of the first MRT recipient, and increasing public awareness of the promising benefits might be all that is required to modify the FDA’s position on MRT.

Suberoylanilide hydroxamic acid during in vitro culture improves development of dog-pig interspecies cloned embryos but not dog cloned embryos

This study was conducted to investigate whether the treatment of dog to pig interspecies somatic cell nuclear transfer (iSCNT) embryos with a histone deacetylase inhibitor, to improve nuclear reprogramming, can be applied to dog SCNT embryos. The dog to pig iSCNT embryos were cultured in fresh porcine zygote medium-5 (PZM-5) with 0, 1, or 10 µM suberoylanilide hydroxamic acid (SAHA) for 6 h, then transferred to PZM-5 without SAHA. Although there were no significant differences in cleavage rates, the rates of 5-8-cell stage embryo development were significantly higher in the 10 µM group (19.5 ± 0.8%) compared to the 0 µM groups (13.4 ± 0.8%). Acetylation of H3K9 was also significantly higher in embryos beyond the 4-cell stage in the 10 µM group compared to the 0 or 1 µM groups. Treatment with 10 µM SAHA for 6 h was chosen for application to dog SCNT. Dog cloned embryos with 0 or 10 µM SAHA were transferred to recipients. However, there were no significant differences in pregnancy and delivery rates between the two groups. Therefore, it can be concluded that although porcine oocytes support nuclear reprogramming of dog fibroblasts, treatment with a histone deacetylase inhibitor that supports nuclear reprogramming in dog to pig iSCNT embryos was not sufficient for reprogramming in dog SCNT embryos.

Scriptaid improves the reprogramming of donor cells and enhances canine-porcine interspecies embryo development

Histone methylation, histone acetylation, and DNA methylation are the important factors for somatic cell nuclear transfer (SCNT). Histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors (DNMTi) have been used to improve cloning efficiency. In particular, scriptaid, an HDACi, has been shown to improve SCNT efficiency. However, no studies have been performed on canines. Here, we evaluated the effects of scriptaid on histone modification in canine ear fibroblasts (cEFs) and cloned canine embryos derived from cEFs. The early development of cloned canine-porcine interspecies SCNT (iSCNT) embryos was also examined. cEFs were treated with scriptaid (0, 100, 250, 500, 750, and 1000nM) in a medium for 24h. Scriptaid treatment (all concentrations) did not significantly affect cell apoptosis. Treatment with 500nM scriptaid caused a significant increase in the acetylation of H3K9, H3K14, and H4K5. cEFs treated with 500nM scriptaid showed significantly decreased Gcn5, Hat1, Hdac6, and Bcl2 and increased Oct4 and Sox2 expression levels. After SCNT with canine oocytes, H3K14 acetylation was significantly increased in the one- and two-cell cloned embryos from scriptaid-treated cEFs. In iSCNT, the percentage of embryos in the 16-cell stage was significantly higher in the scriptaid-treated group (21.6±2.44%) than in the control (7.5±2.09%). The expression levels of Oct4, Sox2, and Bcl2 were significantly increased in 16-cell iSCNT embryos, whereas that of Hdac6 was decreased. These results demonstrated that scriptaid affected the reprogramming of canine donor and cloned embryos, as well as early embryo development in canine-porcine iSCNT, by regulating reprogramming and apoptotic genes.

Choosing a culture medium for SCNT and iSCNT reconstructed embryos: from domestic to wildlife species

Over the past decades, in vitro culture media have been developed to successfully support IVF embryo growth in a variety of species. Advanced reproductive technologies, such as somatic cell nuclear transfer (SCNT), challenge us with a new type of embryo, with special nutritional requirements and altered physiology under in vitro conditions. Numerous studies have successfully reconstructed cloned embryos of domestic animals for biomedical research and livestock production. However, studies evaluating suitable culture conditions for SCNT embryos in wildlife species are scarce (for both intra- and interspecies SCNT). Most of the existing studies derive from previous IVF work done in conventional domestic species. Extrapolation to non-domestic species presents significant challenges since we lack information on reproductive processes and embryo development in most wildlife species. Given the challenges in adapting culture media and conditions from IVF to SCNT embryos, developmental competence of SCNT embryos remains low. This review summarizes research efforts to tailor culture media to SCNT embryos and explore the different outcomes in diverse species. It will also consider how these culture media protocols have been extrapolated to wildlife species, most particularly using SCNT as a cutting-edge technical resource to assist in the preservation of endangered species.

In vitro development and cytological quality of inter-species (porcine→bovine) cloned embryos are affected by trichostatin A-dependent epigenomic modulation of adult mesenchymal stem cells

Artificial epigenomic modulation of in vitro cultured mesenchymal stem cells (MSCs) by applying a non-selective HDAC inhibitor, termed TSA, can facilitate more epigenetic reprogramming of transcriptional activity of the somatic cell-descended nuclear genome in NT pig embryos. The results of the present investigation showed that TSA-dependent epigenomic modulation of nuclear donor MSCs highly affects both the in vitro developmental capability and the cytological quality of inter-species (porcine→bovine) cloned embryos. The developmental competences to reach the blastocyst stage among hybrid (porcine→bovine) nuclear-transferred embryos that had been reconstructed with bovine ooplasts and epigenetically modulated porcine MSCs were maintained at a relatively high level. These competences were higher than those noted in studies by other authors, but they were still decreased compared to those of intra-species (porcine) cloned embryos that had been reconstituted with porcine ooplasts and either the cell nuclei of epigenetically transformed MSCs or the cell nuclei of epigenetically non-transformed MSCs. In conclusion, MSCs undergoing TSA-dependent epigenetic transformation were used for the first time as a source of nuclear donor cells not only for inter-species somatic cell cloning in pigs but also for inter-species somatic cell cloning in other livestock species. Moreover, as a result of the current research, efficient sequential physicochemical activation of inter-species nuclear-transferred clonal cybrids derived from bovine ooplasm and porcine MSC nuclei was developed.

Embryo aggregation does not improve the development of interspecies somatic cell nuclear transfer embryos in the horse

The low efficiency of interspecies somatic cell nuclear transfer (iSCNT) makes it necessary to investigate new strategies to improve embryonic developmental competence. Embryo aggregation has been successfully applied to improve cloning efficiency in mammals, but it remains unclear whether it could also be beneficial for iSCNT. In this study, we first compared the effect of embryo aggregation over in vitro development and blastocyst quality of porcine, bovine, and feline zona-free (ZF) parthenogenetic (PA) embryos to test the effects of embryo aggregation on species that were later used as enucleated oocytes donors in our iSCNT study. We then assessed whether embryo aggregation could improve the in vitro development of ZF equine iSCNT embryos after reconstruction with porcine, bovine, and feline ooplasm. Bovine- and porcine-aggregated PA blastocysts had significantly larger diameters compared with nonaggregated embryos. On the other hand, feline- and bovine-aggregated PA embryos had higher blastocyst cell number. Embryo aggregation of equine-equine SCNT was found to be beneficial for embryo development as we have previously reported, but the aggregation of three ZF reconstructed embryos did not improve embryo developmental rates on iSCNT. In vitro embryo development of nonaggregated iSCNT was predominantly arrested around the stage when transcriptional activation of the embryonic genome is reported to start on the embryo of the donor species. Nevertheless, independent of embryo aggregation, equine blastocyst-like structures could be obtained in our study using domestic feline-enucleated oocytes. Taken together, these results reported that embryo aggregation enhance in vitro PA embryo development and embryo quality but effects vary depending on the species. Embryo aggregation also improves, as expected, the in vitro embryo development of equine-equine SCNT embryos; however, we did not observe positive effects on equine iSCNT embryo development. Among oocytes from domestic animals tested in our study, the feline ooplasm might be the most appropriate recipient to partially allow preimplantation embryo development of iSCNT equine embryos.

Ooplast transfer of triploid pronucleus zygote improve reconstructed human-goat embryonic development

Poor development of the interspecies somatic cell nuclear transfer (iSCNT) embryos was due to nuclear-mitochondrial incompatibility. In humans, it has been known that ooplast transfer (OT) could support normal fertilization, the development of embryos and prevents the transmission of mtDNA disease. To investigate whether OT could support development of the iSCNT embryos, the ooplast of Triploid Pronucleus (3PN) zygote which would be discarded in IVF lab was transferred into the enucleated goat oocytes to construct humanized iSCNT embryos in our study. The results showed the 3PN-OT could significantly improve the early development of humanized iSCNT embryos. The percentage of blastocyst development of OT group was also higher than that of the control group. Interestingly, the morphology of some OT-iSCNT blastocysts was similar to normal human blastocysts in vitro fertilization, while the morphology of iSCNT blastocysts from control group was similar to goat blastocysts. Importantly, the pluripotent marker Oct4 of the OT-iSCNT blastocyst was expressed stronger than that of the control group. These results suggested that 3PN-OT could improve the developmental potency of human iSCNT embryos and would facilitate establishing ESCs from iSCNT blastocysts.