Development of an improved porcine embryo culture medium for cloning, transgenesis and embryonic stem cell isolation

Work in our laboratory for more than two decades has focussed on the production of genetically modified pigs for xeno transplantion research. More recent work has focussed on the isolation of porcine embryonic stem cells to facilitate this as well as and other research applications. Central to this research has been the production of in vitro Produced (IVP) embryos. These embryos are produced using a twostep culture system based on NCSU23. This culture system which was developed by modifying energy substrate availability and concentrations and by adding non-essential and essential amino acids in a sequential manner. As a result of this work we have developed a culture system that better suits the changing metabolic needs of the pig embryo and produces embryos with relatively high developmental competence compared to the original formulation. These embryos can be used for a range of research applications including the isolation of embryonic stem cells.Luke FS Beebe, Stephen M McIlfatrick, Ivan M Vassiliev and Mark B Nottl

Multipotent cell types in primary fibroblast cell lines used to clone pigs using somatic cell nuclear transfer

We have previously demonstrated that the use of porcine mesenchymal stem cells (MSCs) isolated from the bone marrow can increase the proportion of somatic cell nuclear transfer (SCNT) embryos that develop to the blastocyst stage compared with adult fibroblasts obtained from the same animal. The aim of the present study was to determine if MSCs are also present in primary cultures of adult fibroblasts which are commonly used for cloning live animals. To do this we chose a primary culture of adult fibroblasts that we had previously used to clone pigs. Single cell clones were isolated using low-density plating. After seven days of culture 63% of colonies displayed typical fibroblast morphology, while the remainder appeared cobblestone-like in appearance. Two of the 57 clones that displayed fibroblast morphology differentiated into adipocytes but not chondrocytes or osteocytes (uni-potent clones). Three of the 33 cobblestone-like clones differentiated into chondrocytes only, while 3 differentiated into adipocytes and chondrocytes but not osteocytes (bi-potent clones). One of the bi-potent cobblestone-like clones was then used for SCNT and in vitro development compared with a fibroblast-like clone which did not differentiate. Both cell types produced blastocysts at similar rates. In conclusion we have identified uni-potent and bi-potent cell types in primary cultures of adult fibroblasts used previously to clone live piglets.Sharon J. Harrison, Luke F.S. Beebe, Ivan Vassiliev, Stephen M. McIlfatrick and Mark B. Nottl

Low guanine content and biased nucleotide distribution in vertebrate mtDNA can cause overestimation of non-CpG methylation

Mitochondrial DNA (mtDNA) methylation in vertebrates has been hotly debated for over 40 years. Most contrasting results have been reported following bisulfite sequencing (BS-seq) analyses. We addressed whether BS-seq experimental and analysis conditions influenced the estimation of the levels of methylation in specific mtDNA sequences. We found false positive non-CpG methylation in the CHH context (fpCHH) using unmethylated Sus scrofa mtDNA BS-seq data. fpCHH methylation was detected on the top/plus strand of mtDNA within low guanine content regions. These top/plus strand sequences of fpCHH regions would become extremely AT-rich sequences after BS-conversion, whilst bottom/minus strand sequences remained almost unchanged. These unique sequences caused BS-seq aligners to falsely assign the origin of each strand in fpCHH regions, resulting in false methylation calls. fpCHH methylation detection was enhanced by short sequence reads, short library inserts, skewed top/bottom read ratios and non-directional read mapping modes. We confirmed no detectable CHH methylation in fpCHH regions by BS-amplicon sequencing. The fpCHH peaks were located in the D-loop, ATP6, ND2, ND4L, ND5 and ND6 regions and identified in our S. scrofa ovary and oocyte data and human BS-seq data sets. We conclude that non-CpG methylation could potentially be overestimated in specific sequence regions by BSseq analysis.Takashi Okada, Xin Sun, Stephen McIlfatrick, and Justin C. St. Joh

Targeted insertion of an anti-CD2 monoclonal antibody transgene into the GGTA1 locus in pigs using FokI-dCas9

Xenotransplantation from pigs has been advocated as a solution to the perennial shortage of donated human organs and tissues. CRISPR/Cas9 has facilitated the silencing of genes in donor pigs that contribute to xenograft rejection. However, the generation of modified pigs using second-generation nucleases with much lower off-target mutation rates than Cas9, such as FokI-dCas9, has not been reported. Furthermore, there have been no reports on the use of CRISPR to knock protective transgenes into detrimental porcine genes. In this study, we used FokI-dCas9 with two guide RNAs to integrate a 7.1 kilobase pair transgene into exon 9 of the GGTA1 gene in porcine fetal fibroblasts. The modified cells lacked expression of the αGal xenoantigen, and secreted an anti-CD2 monoclonal antibody encoded by the transgene. PCR and sequencing revealed precise integration of the transgene into one allele of GGTA1, and a small deletion in the second allele. The cells were used for somatic cell nuclear transfer to generate healthy male knock-in piglets, which did not express αGal and which contained anti-CD2 in their serum. We have therefore developed a versatile high-fidelity system for knocking transgenes into the pig genome for xenotransplantation purposes.Mark B. Nottle, Evelyn J. Salvaris, Nella Fisicaro, Stephen McIlfatrick, Ivan Vassiliev, Wayne J. Hawthorne, Philip J. O’Connell, Jamie L. Brady, Andrew M. Lew and Peter J. Cowa

Effect of cytochalasin types on the production of heterozygous parthenogenetic porcine embryos and the isolation of putative parthenogenetic embryonic stem cells

Parthenogenetic embryos have been suggested as an alternative source of embryonic stem cells (ESCs). The present study was undertaken to determine the efficiency with which porcine heterozygous parthenotes could be produced using cytochalasin B (CB) or cytochalasin D (CD) and whether parthenogenetic ESCs (pESCs) could be isolated from these. Cleavage rate was lower and fewer embryos developed to the blastocyst stage in the CB group compared with the CD group. The number of primary outgrowths obtained was also lower in the CB compared with the CD group. No primary lines were isolated from embryonal outgrowths in the CB group. In contrast, primary cell lines were derived from these in the CD group. These lines survived vitrification and warming, resulting in established cell lines, which maintained a characteristic ESC morphology and expressed the pluripotent markers Oct4 and Nanog following repeated passaging. Putative pESC lines could also be directly differentiated to cell types representative of all three germ layers.Ivan Vassiliev, Anders Tsui, Wan Xian Kang, Stephen McIlfatrick and Mark B. Nottl

Patient and professional factors that impact the perceived likelihood and confidence of healthcare professionals to discuss Implantable Cardioverter Defibrillator deactivation in advanced heart failure: Results from an international factorial survey

Background: Rate of implantable cardioverter defibrillator (ICD) implantations is increasing in patients with advanced heart failure. Despite clear guideline recommendations, discussions addressing deactivation occur infrequently. Aim: The aim of this article is to explore patient and professional factors that impact perceived likelihood and confidence of healthcare professionals to discuss ICD deactivation. Methods and Results: Between 2015 and 2016, an international sample of 262 healthcare professionals (65% nursing, 24% medical) completed an online factorial survey, encompassing a demographic questionnaire and clinical vignettes. Each vignette had 9 randomly manipulated and embedded patient-related factors, considered as independent variables, providing 1572 unique vignettes for analysis. These factors were determined through synthesis of a systematic literature review, a retrospective case note review, and a qualitative exploratory study. Results showed that most healthcare professionals agreed that deactivation discussions should be initiated by a cardiologist (95%, n = 255) or a specialist nurse (81%, n = 215). In terms of experience, 84% of cardiologists (n = 53) but only 30% of nurses (n = 50) had previously been involved in a deactivation decision. Healthcare professionals valued patient involvement in deactivation decisions; however, only 50% (n = 130) actively involved family members. Five of 9 clinical factors were associated with an increased likelihood to discuss deactivation including advanced age, severe heart failure, presence of malignancy, receipt of multiple ICD shocks, and more than 3 hospital admissions during the previous year. Furthermore, nationality and discipline significantly influenced likelihood and confidence in decision making. Conclusions: Guidelines recommend that healthcare professionals discuss ICD deactivation; however, practice is suboptimal with multifactorial factors impacting on decision making. The role and responsibility of nurses in discussing deactivation require clarity and improvement.Funding Agencies|HFA Nurse Fellowship training grant; Public Health Agency NI (Research &amp; Development Division)</p

Does supplementation of oocytes with additional mtDNA influence developmental outcome?

Introducing extra mitochondrial DNA (mtDNA) into oocytes at fertilization can rescue poor quality oocytes. However, supplementation alters DNA methylation and gene expression profiles of preimplantation embryos. To determine if these alterations impacted offspring, we introduced mtDNA from failed-tomature sister (autologous) or third party (heterologous) oocytes into mature oocytes and transferred zygotes into surrogates. Founders exhibited significantly greater daily weight gain (heterologous) and growth rates (heterologous and autologous) to controls. In weaners, cholesterol, bilirubin (heterologous and autologous), anion gap, and lymphocyte count (autologous) were elevated. In mature pigs, potassium (heterologous) and bicarbonate (autologous) were altered. mtDNA and imprinted gene analyses did not reveal aberrant profiles. Neither group exhibited gross anatomical, morphological, or histopathological differences that would lead to clinically significant lesions. Female founders were fertile and their offspring exhibited modified weight and height gain, biochemical, and hematological profiles. mtDNA supplementation induced minor differences that did not affect health and well-being.Stephen McIlfatrick, Sean O, Leary, Takashi Okada, Alexander Penn, Vy Hoang Thao Nguyen, Lisa McKenny, Shang-Yu Huang, Eryk Andreas, John Finnie, Roy Kirkwood, and Justin C. St. Joh