Genetically engineered pigs as models for human disease

Animals in Moral Limbo: How Literary Pigs May Help Lab-Generated Ones

When considering that artistic and literary artifacts reflect the cultural views and mores of a particular time period, there is a significant misalignment between stories depicting increased moral status of pigs (e.g., vis-à-vis human-porcine relationships) and ongoing practices of pig consumption, commodification, and medical experimentation. In fact, there has been increased industrial farm meat production and biotechnological experimentation. Xenotransplantation trials, for example, are being heralded "the answer" to organ shortages needed for human transplantation, while significant ethical concerns persist. In this paper, I posit that literary reflections add a valuable dimension to animal ethics deliberations, providing a meta-narrative against which to assess normative practices. Beginning with synopses of three books: E.B. White's Charlotte's Web (1952), Robert Newton Peck's A Day No Pigs Would Die (1972), and Paul Griffin's Saving Marty (2017), I illustrate a shifting moral status view of human-pig relationships. Next, I discuss personhood attributions through biological, philosophical, and legal frameworks; review benefits and risks of xenotransplantation; reflect on the moral status of non-human animals; and offer concluding thoughts.

Longitudinal phenotype development in a minipig model of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a rare, autosomal dominant disease with variable clinical presentations. Large animal models are useful to help dissect molecular mechanisms, determine relevant biomarkers, and develop effective therapeutics. Here, we studied a NF1 minipig model (NF1+/ex42del) for the first 12 months of life to evaluate phenotype development, track disease progression, and provide a comparison to human subjects. Through systematic evaluation, we have shown that compared to littermate controls, the NF1 model develops phenotypic characteristics of human NF1: [1] café-au-lait macules, [2] axillary/inguinal freckling, [3] shortened stature, [4] tibial bone curvature, and [5] neurofibroma. At 4 months, full body computed tomography imaging detected significantly smaller long bones in NF1+/ex42del minipigs compared to controls, indicative of shorter stature. We found quantitative evidence of tibial bowing in a subpopulation of NF1 minipigs. By 8 months, an NF1+/ex42del boar developed a large diffuse shoulder neurofibroma, visualized on magnetic resonance imaging, which subsequently grew in size and depth as the animal aged up to 20 months. The NF1+/ex42del minipig model progressively demonstrates signature attributes that parallel clinical manifestations seen in humans and provides a viable tool for future translational NF1 research.

Resolution of Deep Venous Thrombosis: Proposed Immune Paradigms

Venous thromboembolism (VTE) is a pathology encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE) associated with high morbidity and mortality. Because patients often present after a thrombus has already formed, the mechanisms that drive DVT resolution are being investigated in search of treatment. Herein, we review the current literature, including the molecular mechanisms of fibrinolysis and collagenolysis, as well as the critical cellular roles of macrophages, neutrophils, and endothelial cells. We propose two general models for the operation of the immune system in the context of venous thrombosis. In early thrombus resolution, neutrophil influx stabilizes the tissue through NETosis. Meanwhile, macrophages and intact neutrophils recognize the extracellular DNA by the TLR9 receptor and induce fibrosis, a complimentary stabilization method. At later stages of resolution, pro-inflammatory macrophages police the thrombus for pathogens, a role supported by both T-cells and mast cells. Once they verify sterility, these macrophages transform into their pro-resolving phenotype. Endothelial cells both coat the stabilized thrombus, a necessary early step, and can undergo an endothelial-mesenchymal transition, which impedes DVT resolution. Several of these interactions hold promise for future therapy.

A Cross-Sectional Study of Obesity Effects on the Metabolomic Profile of a Leptin-Resistant Swine Model

Identifying metabolite signatures associated with obesity and related diseases might represent a valuable preventive and therapeutic tool to predict subjects at risk, establish an accurate prognosis, and monitor treatment success. The current cross-sectional study is aimed to evaluate the metabolite profile of diet-induced obesity in a porcine model of leptin resistance. Six Iberian female pigs prone to develop obesity (OB) were ad libitum fed a fat-enriched diet (HFD) for 82 days. Five lean Iberian sows (CON) in a maintenance diet served as controls. At the end of the dietary treatments, all animals were sacrificed, and plasma, liver, and muscle samples were immediately collected for nuclear magnetic resonance analysis. In plasma, signals corresponding to betaine, glycerophosphocholine/phosphocholine, glycine, and glutamate were decreased; and the valine signal was increased in OB sows compared to controls. Similarly, the betaine signal was decreased in the liver. No differences were detected in muscle. The observed metabolite changes suggest alterations in branched chain amino-acid metabolism and the methionine-homocysteine cycle, which have been previously associated with obesity-related diseases and type 2 diabetes in human observational studies. The current study supports the utilization of the leptin resistant Iberian pig for further interventional research in the field.

Improve the developmental competence of porcine oocytes from small antral follicles by pre-maturation culture method

The oocytes from small antral follicle have low developmental potential to reach blastocyst due to incomplete cytoplasmic maturation during in vitro maturation (IVM). Thus, we developed an in vitro culture system for porcine oocytes derived from small antral follicles with l-ascorbic acid supplement during pre-maturation (pre-IVM) to support their development to blastocyst stage. Besides that, how l-ascorbic acid effect on the developmental competence of porcine oocytes with a special focus on histone modifications will be elucidated. The in vitro culture process consisted of two steps. The first step is 22 h of pre-IVM and the second step is 42 h of IVM. We utilized dibutyryl-cyclicAMP (dbcAMP) with L-ascorbic supplement during pre-IVM. Based on the result of this procedure, we proposed that the best culture condition in which hormone human chorionic gonadotropin (hCG) be added during the last 7 h of pre-IVM and continued culture to complete IVM. We observed that, in this culture system, the meiotic competence of porcine oocytes derived from small follicles was as high as those derived from large follicles after undergoing IVM. In addition, our study suggested that l-ascorbic acid supplementation at 100 μg/mL sharply enhanced the developmental potential of porcine oocytes. Interestingly, oocytes from small antral follicles treated with l-ascorbic acid could obtain the blastocyst quantity and quality as high as that of large antral follicles. The treated groups showed a significantly higher number of blastomeres compared to those in non-treated groups in both small and large follicle groups. Besides that, = The increasing levels of acetylation of histone H3 at lysine 9 (H3K9) and methylation of histone H3 at lysine 4 (H3K4) in blastocyst derived from small and large antral follicle under the present of l-ascrobic acid lead to a significant positive effect on the developmental competence and improvement in quality of porcine embryos.

Swine Disease Models for Optimal Vascular Engineering

Swine disease models are essential for mimicry of human metabolic and vascular pathophysiology, thereby enabling high-fidelity translation to human medicine. The worldwide epidemic of obesity, metabolic disease, and diabetes has prompted the focus on these diseases in this review. We highlight the remarkable similarity between Ossabaw miniature swine and humans with metabolic syndrome and atherosclerosis. Although the evidence is strongest for swine models of coronary artery disease, findings are generally applicable to any vascular bed. We discuss the major strengths and weaknesses of swine models. The development of vascular imaging is an example of optimal vascular engineering in swine. Although challenges regarding infrastructure and training of engineers in the use of swine models exist, opportunities are ripe for gene editing, studies of molecular mechanisms, and use of swine in coronary artery imaging and testing of devices that can move quickly to human clinical studies.

Dietary supplementation of Morus nigra L. leaves decrease fat mass partially through elevating leptin-stimulated lipolysis in pig model

ETHNOPHARMACOLOGICAL RELEVANCE

Mulberry leaves are the dry leaves of Morus nigra L. trees, which are widely cultivated in central and southern China. Mulberry has a long history of medicinal use, such as anti-stress, lowering blood glucose and anti-obesity.

AIM OF THE STUDY

Explore the effects of mulberry leaves on fat deposition as well as the underlying mechanisms.

MATERIALS AND METHODS

Total of 48 fattening pigs weighing about 70 kg were randomly allotted to normal diet or die supplemented with 5% (w/w) mulberry leave powder. Changes of fat mass, indicated by backfat thickness was measured with Piggyback tester, blood triglyceride and cholesterol were tested using commercial biochemical kits, serum hormones were estimated by ELISA, and leptin-related signaling activity were assessed using western-blot.

RESULTS

Supplementation with Mulberry leaf feed (MF) significantly reduced serum triglyceride and free cholesterol concentrations and increased the ratio of high-density lipoprotein cholesterol (HDL-c) to low-density lipoprotein cholesterol (LDL-c), while serum glucose and free fatty acids remained unchanged. Dietary MF resulted in a significant reduction in the size of adipocytes and backfat thickness (P < 0.05). Accordingly, hormone-sensitive lipase (HSL) in backfat was significantly up-regulated and fatty acid synthase (FAS) was down-regulated by MF supplementation (both P < 0.05). Furthermore, MF supplementation significantly elevated circulating leptin and adiponectin without influencing serum insulin and glucocorticoid. Moreover, significantly higher leptin receptor (Leptin-R) and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) were detected in MF-supplemented pigs, suggesting an enhanced leptin signaling induced by MF in the subcutaneous fat.

CONCLUSIONS

Mulberry leaves have obvious anti-obesity effects, providing a theoretical basis for the development of mulberry leaves as a drug against obesity.

Using multidimensional scaling in model choice for congenital oesophageal atresia: similarity analysis of human autopsy organ weights with those from a comparative assessment of Aachen Minipig and Pietrain piglets

Swine models had been popular in paediatric oesophageal surgery in the past. Although being largely replaced by rodent models, swine experienced a revival with the establishment of minipig models. However, none of them has ever been investigated for similarity to humans. We conducted a pilot study to determine whether three-week old Pietrain piglets and three-month old Aachen Minipigs are suitable for experimental paediatric oesophageal atresia surgery. We tested the operation's feasibility, performed a necropsy, weighed organs, measured organ length and calculated relative weights and lengths, and measured laboratory parameters. We used multidimensional scaling to assess the similarity of the swine breeds with previously published human data. Pietrain piglets had a higher a priori bodyweight than Aachen Minipigs (Δ = 1.31 kg, 95% confidence interval (CI): 0.37-2.23, p = 0.015), while snout-to-tail length was similar. Pietrain piglets had higher absolute and relative oesophageal lengths (Δ = 5.43 cm, 95% CI: 2.2-8.6; p = 0.0062, q1* = 0.0083 and Δ = 11.4%, 95% CI: 5.1-17.6; p = 0.0025, q3* = 0.0053). Likewise, absolute and relative small intestinal lengths were higher in Pietrains, but all other parameters did not differ, with the exception of minor differences in laboratory parameters. Multidimensional scaling revealed three-week old Pietrain piglets to be similar to two-month old humans based on their thoracoabdominal organ weights. This result indicates three-week old Pietrain piglets are a suitable model of paediatric oesophageal atresia surgery, because clinically many procedures are performed at around eight weeks age. Three-month old Aachen Minipigs were more dissimilar to eight-week old humans than three-week old Pietrain piglets.

Functional Annotation of the Transcriptome of the Pig, Sus scrofa, Based Upon Network Analysis of an RNAseq Transcriptional Atlas

The domestic pig (Sus scrofa) is both an economically important livestock species and a model for biomedical research. Two highly contiguous pig reference genomes have recently been released. To support functional annotation of the pig genomes and comparative analysis with large human transcriptomic data sets, we aimed to create a pig gene expression atlas. To achieve this objective, we extended a previous approach developed for the chicken. We downloaded RNAseq data sets from public repositories, down-sampled to a common depth, and quantified expression against a reference transcriptome using the mRNA quantitation tool, Kallisto. We then used the network analysis tool Graphia to identify clusters of transcripts that were coexpressed across the merged data set. Consistent with the principle of guilt-by-association, we identified coexpression clusters that were highly tissue or cell-type restricted and contained transcription factors that have previously been implicated in lineage determination. Other clusters were enriched for transcripts associated with biological processes, such as the cell cycle and oxidative phosphorylation. The same approach was used to identify coexpression clusters within RNAseq data from multiple individual liver and brain samples, highlighting cell type, process, and region-specific gene expression. Evidence of conserved expression can add confidence to assignment of orthology between pig and human genes. Many transcripts currently identified as novel genes with ENSSSCG or LOC IDs were found to be coexpressed with annotated neighbouring transcripts in the same orientation, indicating they may be products of the same transcriptional unit. The meta-analytic approach to utilising public RNAseq data is extendable to include new data sets and new species and provides a framework to support the Functional Annotation of Animals Genomes (FAANG) initiative.

Skeletal muscle in health and disease

Skeletal muscle fibres are multinucleated cells that contain postmitotic nuclei (i.e. they are no longer able to divide) and perform muscle contraction. They are formed by fusion of muscle precursor cells, and grow into elongating myofibres by the addition of further precursor cells, called satellite cells, which are also responsible for regeneration following injury. Skeletal muscle regeneration occurs in most muscular dystrophies in response to necrosis of muscle fibres. However, the complex environment within dystrophic skeletal muscle, which includes inflammatory cells, fibroblasts and fibro-adipogenic cells, together with the genetic background of the in vivo model and the muscle being studied, complicates the interpretation of laboratory studies on muscular dystrophies. Many genes are expressed in satellite cells and in other tissues, which makes it difficult to determine the molecular cause of various types of muscular dystrophies. Here, and in the accompanying poster, we discuss our current knowledge of the cellular mechanisms that govern the growth and regeneration of skeletal muscle, and highlight the defects in satellite cell function that give rise to muscular dystrophies.

Summary: The mechanisms of skeletal muscle development, growth and regeneration are described. We discuss whether these processes are dysregulated in inherited muscle diseases and identify pathways that may represent therapeutic targets.

Genetically Engineered Pigs to Study Cancer

Recent decades have seen groundbreaking advances in cancer research. Genetically engineered animal models, mainly in mice, have contributed to a better understanding of the underlying mechanisms involved in cancer. However, mice are not ideal for translating basic research into studies closer to the clinic. There is a need for complementary information provided by non-rodent species. Pigs are well suited for translational biomedical research as they share many similarities with humans such as body and organ size, aspects of anatomy, physiology and pathophysiology and can provide valuable means of developing and testing novel diagnostic and therapeutic procedures. Porcine oncology is a new field, but it is clear that replication of key oncogenic mutation in pigs can usefully mimic several human cancers. This review briefly outlines the technology used to generate genetically modified pigs, provides an overview of existing cancer models, their applications and how the field may develop in the near future.

Maternal Yes-Associated Protein Participates in Porcine Blastocyst Development via Modulation of Trophectoderm Epithelium Barrier Function

The establishment of a functional trophectoderm (TE) epithelium is an essential prerequisite for blastocyst formation and placentation. Transcription coactivator yes-associated protein (YAP), a downstream effector of the hippo signaling pathway, is required for specification of both the TE and epiblast lineages in mice. However, the biological role of YAP in porcine blastocyst development is not known. Here, we report that maternally derived YAP protein is localized to both the cytoplasm and nuclei prior to the morula stage and is then predominantly localized to the TE nuclei in blastocysts. Functionally, maternal YAP knockdown severely impeded blastocyst formation and perturbed the allocation of the first two lineages. The treatment of embryos with verteporfin, a pharmacological inhibitor of YAP, faithfully recapitulated the phenotype observed in YAP deleted embryos. Mechanistically, we found that maternal YAP regulates multiple genes which are important for lineage commitment, tight junction assembly, and fluid accumulation. Consistent with the effects on tight junction gene expression, a permeability assay revealed that paracellular sealing was defective in the trophectoderm epithelium. Lastly, YAP knockdown in a single blastomere at the 2-cell stage revealed that the cellular progeny of the YAP⁺ blastomere were sufficient to sustain blastocyst formation via direct complementation of the defective trophectoderm epithelium. In summary, these findings demonstrate that maternal YAP facilitates porcine blastocyst development through transcriptional regulation of key genes that are essential for lineage commitment, tight junction assembly, and fluid accumulation.

MiR-370 enhances cell cycle and represses lipid accumulation in porcine adipocytes

MicroRNAs (miRNAs) are emerging as an important regulator during adipose development. Previous studies have revealed that miR-370 is related to lipid metabolic homeostasis, however, its roles in lipid accumulation remain to be established. In this study, we demonstrated that ssc-miR-370 was highly conserved across domestic animals, and relatively enriched in adipose tissues and skeletal muscles. Overexpression of ssc-miR-370 significantly promoted the proliferation of porcine preadipocytes through facilitating G₁/S phase transition. Meanwhile, ssc-miR-370 mimics dramatically suppressed adipogenic differentiation, indicated by reduced triglyceride deposition as well as downregulated PPARγ and aP2 expressions. Furthermore, ssc-miR-370 was demonstrated to repress FoxO1 expression via directly targeting FoxO1 3'-UTR using dual luciferase activity assay. Our data evaluates miR-370 as a novel adipogenic modulator, which may be a potential target to reduce backfat thickness in pigs and fight obesity in humans.

Agricultural Animals as Biomedical Models: Occupational Health and Safety Considerations

The use of agricultural animals in biomedical research is increasing. Their overall size and metabolic rate, organ size, longer gestation period, and other physiological similarities make them good candidates for animal models of human disease. There are a number of special considerations for use of traditional farm animals for biomedical research. Differences in physical plant infrastructure, handling equipment, training of personnel, and potential zoonoses are some of the important considerations when traditional farm animals are used in biomedical research. This article provides an overview of some of the special considerations for using traditional agricultural animals in biomedical research. With the growing need for improved translational research, it is reasonable to predict significant growth in these animal models.

Oocytes, embryos and pluripotent stem cells from a biomedical perspective

The veterinary and animal science professions are rapidly developing and their inherent and historical connection to agriculture is challenged by more biomedical and medical directions of research. While some consider this development as a risk of losing identity, it may also be seen as an opportunity for developing further and more sophisticated competences that may ultimately feed back to veterinary and animal science in a synergistic way. The present review describes how agriculture-related studies on bovine in vitro embryo production through studies of putative bovine and porcine embryonic stem cells led the way to more sophisticated studies of human induced pluripotent stem cells (iPSCs) using e.g. gene editing for modeling of neurodegeneration in man. However, instead of being a blind diversion from veterinary and animal science into medicine, these advanced studies of human iPSC-derived neurons build a set of competences that allowed us, in a more competent way, to focus on novel aspects of more veterinary and agricultural relevance in the form of porcine and canine iPSCs. These types of animal stem cells are of biomedical importance for modeling of iPSC-based therapy in man, but in particular the canine iPSCs are also important for understanding and modeling canine diseases, as e.g. canine cognitive dysfunction, for the benefit and therapy of dogs.

CRISPR/Cas9-mediated genome editing in nonhuman primates

Owing to their high similarity to humans, non-human primates (NHPs) provide an exceedingly suitable model for the study of human disease. In this Review, we summarize the history of transgenic NHP models and the progress of CRISPR/Cas9-mediated genome editing in NHPs, from the first proof-of-principle green fluorescent protein-expressing monkeys to sophisticated NHP models of human neurodegenerative disease that accurately phenocopy several complex disease features. We discuss not only the breakthroughs and advantages, but also the potential shortcomings of the application of the CRISPR/Cas9 system to NHPs that have emerged from the expanded understanding of this technology in recent years. Although off-target and mosaic mutations are the main concerns in CRISPR/Cas9-mediated NHP modeling, recent progress in genome editing techniques make it likely that these technical limitations will be overcome soon, bringing excellent prospects to human disease studies.

Cumulus cell-derived and maternal SIRT6 differentially regulates porcine oocyte meiotic maturation

SIRT6, a member of the sirtuin family, is a NAD + dependent protein deacetylase and has been implicated in transcriptional regulation of somatic cells and post-transcriptional regulation of oocyte meiosis. However, the function of cumulus cell-derived and maternal SIRT6 in meiotic maturation of porcine oocytes is not yet known. Here, we report that SIRT6 mRNA and protein exists in the oocyte and its surrounding cumulus cells during meiotic maturation. Functional studies using a specific inhibitor in cumulus-enclosed oocytes revealed important roles for SIRT6 in germinal vesicle breakdown (GVBD) and cumulus expansion. Moreover, inhibitor treatment led to a significant reduction in the rate of first polar body (PB1) extrusion and early development of parthenogenetically activated embryos. In contrast, SIRT6 inhibition in cumulus-free oocytes only resulted in a significant reduction in the rate of PB1 extrusion. Furthermore, SIRT6 dysfunction regardless of the origin in both cumulus cells and oocytes severely impaired spindle organization and chromosome alignment at the metaphase stage. Molecularly, SIRT6 inhibition in cumulus cells significantly reduced expression of genes associated with cumulus expansion and gap junctional communication and even expression levels of active phosphorylated CDK1 in oocytes. Importantly, adenylate cyclase inhibition could partially rescue GVBD and PB1 extrusion in SIRT6-inhibited cumulus-enclosed oocytes. Taken together, these results demonstrate that cumulus cell-expressed and maternal SIRT6 differentially regulates porcine oocyte meiotic maturation.

Three-to-5-day weaning-to-estrus intervals do not affect neither efficiency of collection nor in vitro developmental ability of in vivo-derived pig zygotes

An efficient system to collect large numbers of vital zygotes is a pre-requisite for application of zygote genome-editing technology, including development of efficient models for xenotransplantation using pigs. Owing to the sub-optimal in vitro production of zygotes in pigs, efficient collection of in vivo developed zygotes is required. Timing of ovulation is a key factor to sustain efficiency since the interval between pronuclear formation and the first division is very short in pigs. The weaning-to-estrus interval can, due to its inverse relation with length of estrus and time of ovulation, interfere with ovulation and make it asynchronous, which reduces the probability of obtaining zygotes. This retrospective study compared the effects of three weaning-to-estrus intervals of 3, 4 or 5 days on zygote collection efficiency in a total of 17 trials over a 3-year period including 223 sows. Donor sows in groups of 10-15 animals were super-ovulated with eCG 24 h after weaning and those in estrus at 48-72 h post-eCG were immediately treated with hCG, followed by insemination 6 and 24 h thereafter. Collected structures during laparotomy on Day 2 (Day 0: onset of estrus) were morphologically evaluated and only those with a single cell and two visible polar bodies were considered as zygotes. Zygotes were injected with CRISPR-Cas9 editor mixture and cultured for 6 days to evaluate their developmental ability against non-injected control zygotes. Of all recovered structures (N = 5,468), 67.4%, 30.8% and 1.8% were zygotes, 2-cell embryos and oocytes-degenerated embryos, respectively. The different weaning-to-estrus intervals did not affect either the percentages of collected zygotes (range: 64.1%-70.0%) or the percentages of sows with zygotes at collection time (range: 69.0%-73.3%). The weaning-to-estrus intervals did not affect the in vitro developmental ability of zygotes. After 24 h of culture, 78.1 ± 2.0% and 95.1 ± 0.6 (P < 0.05) of injected (N = 2,345) and non-injected (N = 335) zygotes, respectively, developed to 2-to-4-cell embryo stage. The total efficiency of the system was 64.1 ± 2.2% and 85.8 ± 1.5% (P < 0.05) for injected and non-injected zygotes, respectively. In conclusion, the results indicate that neither the efficiency of collecting in vivo derived porcine zygotes from superovulated sows nor the zygote ability to develop to blastocyst after cytoplasmic genome-editing injection were affected by a weaning-to-estrus interval between 3-to-5 days.

Trehalose supplementation during porcine oocytes in vitro maturation improves the developmental capacity of parthenotes

Autophagy is a critical process in early mammalian embryogenesis. Mammalian target of rapamycin (mTOR) inhibitors are major regulators of autophagy. However, mTOR plays a vital role in major signaling pathways controlling cell growth and metabolism; thus, more secure autophagy activation methods should be considered. The present study investigated the effects of supplementary trehalose, a novel mTOR-independent autophagy enhancer, on oocyte maturation and embryonic development after parthenogenetic activation (PA). Trehalose treatment during in vitro maturation (IVM) did not affect the nuclear maturation rates of oocytes. Oocytes treated with 25 mM trehalose during IVM had a significantly higher (P < 0.05) blastocyst formation rate (64.2%) after PA compared to that in control oocytes (52.0%). Blastocyst quality was also improved in the trehalose-treated group. The total cell numbers for blastocyst formation and expanded blastocyst formation were significantly increased in the trehalose-treated group (52.2% and 27.7%, respectively) compared to those in the control group (36.9% and 11.0%, respectively). Trehalose treatment led to the increased expression of LC3, an autophagy marker, in metaphase II oocytes and 4-cell stage embryos. Gene expression analysis revealed that the expression of several autophagy related genes (LAMP2, pATG5, and LC3) increased, while the Bax/Bcl2 ratio and pro-apoptotic Bak transcript levels were decreased in the trehalose-treated group. In conclusion, these results indicate that treatment with trehalose during IVM improved the developmental potential of porcine embryos by down-regulation of pro-apoptotic genes and up-regulation of autophagy-related genes and marker. Trehalose may be useful for the large-scale production of high-quality porcine blastocysts in vitro.

Metabolite Exchange between Mammalian Organs Quantified in Pigs

Mammalian organs continually exchange metabolites via circulation, but systems-level analysis of this shuttling process is lacking. Here, we compared, in fasted pigs, metabolite concentrations in arterial blood versus draining venous blood from 11 organs. Greater than 90% of metabolites showed arterial-venous differences across at least one organ. Surprisingly, the liver and kidneys released not only glucose but also amino acids, both of which were consumed primarily by the intestine and pancreas. The liver and kidneys exhibited additional unexpected activities: liver preferentially burned unsaturated over more atherogenic saturated fatty acids, whereas the kidneys were unique in burning circulating citrate and net oxidizing lactate to pyruvate, thereby contributing to circulating redox homeostasis. Furthermore, we observed more than 700 other cases of tissue-specific metabolite production or consumption, such as release of nucleotides by the spleen and TCA intermediates by pancreas. These data constitute a high-value resource, providing a quantitative atlas of inter-organ metabolite exchange.

The use of non-rodent model species in microbiota studies

In recent years, tremendous advances have been made in our ability to characterize complex microbial communities such as the gut microbiota, and numerous surveys of the human gut microbiota have identified countless associations between different compositional attributes of the gut microbiota and adverse health conditions. However, most of these findings in humans are purely correlative and animal models are required for prospective evaluation of such changes as causative factors in disease initiation or progression. As in most fields of biomedical research, microbiota-focused studies are predominantly performed in mouse or rat models. Depending on the field of research and experimental question or objective, non-rodent models may be preferable due to better translatability or an inability to use rodents for various reasons. The following review describes the utility and limitations of several non-rodent model species for research on the microbiota and its influence on host physiology and disease. In an effort to balance the breadth of potential model species with the amount of detail provided, four model species are discussed: zebrafish, dogs, pigs, and rabbits.

Binding affinities of human IgG1 and chimerized pig and rabbit derivatives to human, pig and rabbit Fc gamma receptor IIIA

While pigs and rabbits are used as models for human immune diseases, FcγR binding is poorly characterized in both test species. To evaluate antibody binding to FcγRIIIA, a receptor involved in antibody-dependent cellular cytotoxicity, chimerized antibodies were generated by grafting the variable regions of a human IgG1 onto scaffolds from both species. The affinities of the parent and chimeric antibodies to the FcγRIIIA proteins from all three species were determined. While the human IgG1 and rabbit IgG had similar affinities for each FcγRIIIA with notable differences across species, pig IgG1 only bound pig FcγRIIIA with appreciable affinity. Also, the functional pig and rabbit proteins described here can be used in future experiments, such as pharmacology and mechanism of action studies.

Isolation and Characterization of Small Extracellular Vesicles from Porcine Blood Plasma, Cerebrospinal Fluid, and Seminal Plasma

Extracellular vesicles (EVs) are a highly attractive subject of biomedical research as possible carriers of nucleic acid and protein biomarkers. EVs released to body fluids enable indirect access to inner organs by so-called "liquid biopsies". Obtaining a high-quality EV sample with minimum contaminants is crucial for proteomic analyses using LC-MS/MS or other techniques. However, the EV content in various body fluids largely differs, which may hamper subsequent analyses. Here, we present a comparison of extracellular vesicle yields from blood plasma, cerebrospinal fluid, and seminal plasma using an experimental pig model. Pigs are widely used in biomedical research as large animal models with anatomy and physiology close to those of humans and enable studies (e.g., of the nervous system) that are unfeasible in humans. EVs were isolated from body fluids by differential centrifugation followed by ultracentrifugation. EVs were characterized according to protein yields and to the quality of the isolated vesicles (e.g., size distribution, morphology, positivity for exosome markers). In our experimental setting, substantial differences in EV amounts were identified among body fluids, with the seminal plasma being the richest EV source. The yields of pellet proteins from ultracentrifugation of 1 mL of porcine body fluids may help to estimate body fluid input volumes to obtain sufficient samples for subsequent proteomic analyses.

Improved Delivery of CRISPR/Cas9 System Using Magnetic Nanoparticles into Porcine Fibroblast

Genetically modified pigs play an important role in agriculture and biomedical research; hence, new efficient methods are needed to obtain genetically engineered cells and animals. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas (CRISPR-associated) system represents an effective genome editing tool. It consists of two key molecules: single guide RNA (sgRNA) and the Cas9 endonuclease that can be introduced into the cells as one plasmid. Typical delivery methods for CRISPR/Cas9 components are limited by low transfection efficiency or toxic effects on cells. Here, we describe the use of magnetic nanoparticles and gradient magnetic field to improve delivery of CRISPR/Cas9 constructs into porcine fetal fibroblasts. Polyethylenimine-coated nanoparticles with magnetic iron oxide core were used to form magnetic plasmid DNA lipoplexes. CRISPR/Cas9 construct was prepared to induce site-specific cutting at the porcine H11 locus. Quantitative assessment of genomic cleavage by sequence trace decomposition demonstrated that the magnetofection efficiency was more than 3.5 times higher compared to the classic lipofection method. The Tracking of Indels by Decomposition web tool precisely determined the spectrum of indels that occurred. Simultaneously, no additional cytotoxicity associated with the utilization of magnetic nanoparticles was observed. Our results indicate that magnetofection enables effective delivery of the CRISPR/Cas9 construct into porcine fetal fibroblasts with low cell toxicity.

Effects of manganese on maturation of porcine oocytes in vitro and their subsequent embryo development after parthenogenetic activation and somatic cell nuclear transfer

This study was carried out to examine the effects of manganese (Mn) on the developmental competence of porcine oocytes during in vitro maturation (IVM) after parthenogenetic activation (PA) and somatic cell nuclear transfer (SCNT). Upon treatment of porcine oocytes with different concentrations (0, 3, 6, and 12 ng/ml) of Mn during IVM, PA was performed to determine the optimum concentration. Following PA, the rate of blastocyst formation was higher significantly in treated porcine oocytes at 6 ng/ml of Mn than in other groups (P < 0.05). However, there was no substantial difference in the cleavage rate and total blastocyst cell numbers among all groups. SCNT was performed using the optimal concentration of Mn from PA, which showed an improved blastocyst formation rate in treated oocytes compared to that in control group (P < 0.05). However, the cleavage rate and total cell numbers per blastocyst were not different between the control and the Mn treated groups after SCNT. Additionally, oocyte nuclear maturation, intracellular glutathione (GSH), and reactive oxygen species (ROS) levels were assessed. There was no significant difference observed in nuclear maturation among all the groups. However, enhanced intracellular GSH levels while lower levels of ROS were seen in the Mn treated group compared to the control group (P < 0.05). Thus, these results indicate that Mn supplementation can improve the developmental competence of porcine PA and SCNT embryos by increasing GSH and decreasing ROS levels.

From gene to treatment: supporting rare disease translational research through model systems

Individual rare diseases may affect only a few people, making them difficult to recognize, diagnose or treat by studying humans alone. Instead, model organisms help to validate genetic associations, understand functional pathways and develop therapeutic interventions for rare diseases. In this Editorial, we point to the key parameters in face, construct, predictive and target validity for accurate disease modelling, with special emphasis on rare disease models. Raising the experimental standards for disease models will enhance successful clinical translation and benefit rare disease research.

Summary: This Editorial discusses the importance of model systems with accurate face, construct, target and predictive validity for rare disease research.

Potential use of transgenic domestic pigs expressing recombinant human erythropoietin in diabetes translation research

Recently, diabetes mellitus (DM) has shown rapid global increases with about five million deaths annually. Animal models are imperative to understand disease mechanisms and develop diagnostic, preventive, and therapeutic interventions in translational research. Rodent and mini-pig models have been established and widely used for DM research. However, domestic pig models are limited in spite of advantages such as pharmacokinetic and physiopathological availability. This study examines the potential use of domestic pigs expressing recombinant human erythropoietin (rhEPO) as disease and therapeutic response models for DM. We previously generated transgenic pigs (n = 16, EPO Tg) in which rhEPO was expressed and circulated in all organs. Thirty-two pigs, including 16 controls, were fed high fat (HF) diets for 42 weeks. Subsequently, blood samples for chemical and metabolic analysis were collected after fasting for 24 h and glucose loading for oral glucose tolerance tests (OGTTs). We found increased activation of the PI3 K/Akt signaling pathway under hypoxic conditions after rhEPO treatment, and HF diet-inducible-obesity in the EPO Tg and control pigs. OGTTs showed lower fasting glucose levels in the EPO Tg pigs than in controls before and after the HF diet, suggesting that rhEPO may affect glucose concentrations. Insulin and C-peptide concentrations responded slowly to glucose administration and returned to initial levels after 2 h. The blood test results suggest that EPO might affect metabolic and chemical components such as glucose, high-density lipoprotein, glucagon, triglyceride, and free fatty acid. Our findings support the use of rhEPO transgenic domestic pigs as model animals for translational DM research.

Applications of Gene Editing in Chickens: A New Era Is on the Horizon

The chicken represents a valuable model for research in the area of immunology, infectious diseases as well as developmental biology. Although it was the first livestock species to have its genome sequenced, there was no reverse genetic technology available to help understanding specific gene functions. Recently, homologous recombination was used to knockout the chicken immunoglobulin genes. Subsequent studies using immunoglobulin knockout birds helped to understand different aspects related to B cell development and antibody production. Furthermore, the latest advances in the field of genome editing including the CRISPR/Cas9 system allowed the introduction of site specific gene modifications in various animal species. Thus, it may provide a powerful tool for the generation of genetically modified chickens carrying resistance for certain pathogens. This was previously demonstrated by targeting the Trp38 region which was shown to be effective in the control of avian leukosis virus in chicken DF-1 cells. Herein we review the current and future prospects of gene editing and how it possibly contributes to the development of resistant chickens against infectious diseases.

Genome Editing of Pigs for Agriculture and Biomedicine

Pigs serve as an important agricultural resource and animal model in biomedical studies. Efficient and precise modification of pig genome by using recently developed gene editing tools has significantly broadened the application of pig models in various research areas. The three types of site-specific nucleases, namely, zinc-finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein, are the main gene editing tools that can efficiently introduce predetermined modifications, including knockouts and knockins, into the pig genome. These modifications can confer desired phenotypes to pigs to improve production traits, such as optimal meat production, enhanced feed digestibility, and disease resistance. Besides, given their genetic, anatomic, and physiologic similarities to humans, pigs can also be modified to model human diseases or to serve as an organ source for xenotransplantation to save human lives. To date, many genetically modified pig models with agricultural or biomedical values have been established by using gene editing tools. These pig models are expected to accelerate research progress in related fields and benefit humans.

Elevated expression of p53 in early colon polyps in a pig model of human familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is a hereditary predisposition to formation of colon polyps that can progress to colorectal cancer (CRC). The severity of polyposis varies substantially within families bearing the same germline mutation in the adenomatous polyposis coli (APC) tumour suppressor gene. The progressive step-wise accumulation of genetic events in tumour suppressor genes and oncogenes leads to oncogenic transformation, with driver alterations in the tumour protein p53 (TP53) gene playing a key role in advanced stage CRC. We analysed groups of pigs carrying a truncating mutation in APC (APC^1311/+; orthologous to human APC^1309/+) to study the influence of TP53 polymorphisms and expression on the frequency of polyp formation and polyp progression in early-stage FAP. Five generations of APC^1311/+ pigs were examined by colonoscopy for polyposis severity and development. A total of 19 polymorphisms were found in 5'-flanking, coding, and 3' untranslated regions of TP53. The distribution of TP53 genotypes did not differ between APC^1311/+ pigs with low (LP) and high (HP) number of colon polyps. p53 mRNA expression was analysed in distally located normal mucosa samples of wild-type pigs, APC^1311/+ LP and HP pigs, and also in distally located polyp samples histologically classified as low-grade (LG-IEN) and high-grade intraepithelial dysplastic (HG-IEN) from APC^1311/+ pigs. p53 mRNA expression was found to be significantly elevated in HG-IEN compared to LG-IEN samples (p = 0.012), suggesting a role for p53 in the early precancerous stages of polyp development.

A beginner's guide to understanding and implementing the genetic modification of zebrafish

Zebrafish are a relevant and useful vertebrate model species to study normal- and patho-physiology, including that of the heart, due to conservation of protein-coding genes, organ system organisation and function, and efficient breeding and housing. Their amenability to genetic modification, particularly compared to other vertebrate species, is another great advantage, and is the focus of this review. A vast number of genetically engineered zebrafish lines and methods for their creation exist, but their incorporation into research programs is hindered by the overwhelming amount of technical details. The purpose of this paper is to provide a simplified guide to the fundamental information required by the uninitiated researcher for the thorough understanding, critical evaluation, and effective implementation of genetic approaches in the zebrafish. First, an overview of existing zebrafish lines generated through large scale chemical mutagenesis, retroviral insertional mutagenesis, and gene and enhancer trap screens is presented. Second, descriptions of commonly-used genetic modification methods are provided including Tol2 transposon, TALENs (transcription activator-like effector nucleases), and CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9). Lastly, design features of genetic modification strategies such as promoters, fluorescent reporters, and conditional transgenesis, are summarised. As a comprehensive resource containing both background information and technical notes of how to obtain or generate zebrafish, this review compliments existing resources to facilitate the use of genetically-modified zebrafish by researchers who are new to the field.

Anti-Inflammatory Activity of Boswellia serrata Extracts: An In Vitro Study on Porcine Aortic Endothelial Cells

This study is aimed at investigating the cytotoxicity, anti-inflammatory, and angiogenic activities of two Boswellia serrata extracts on primary culture of porcine aortic endothelial cells (pAECs). Chemical characterization of a dry extract (extract A) and a hydroenzymatic extract (extract G) of B. serrata was performed by HPLC using pure boswellic acids (BAs) as standard. In cultured pAECs, extract G improved cell viability, following LPS challenge, in a dose-dependent manner and did not show any toxic effect. On the other hand, extract A was toxic at higher doses and restored pAEC viability after LPS challenge only at lower doses. Pure BAs, used at the same concentrations as those determined in the phytoextracts, did not contrast LPS-induced cytotoxicity. Extract A showed proangiogenic properties at the lowest dose, and the same result was observed using pure AKBA at the corresponding concentration, whereas extract G did not show any effect on the migration capacity of endothelial cells. In conclusion, an anti-inflammatory activity of B. serrata extracts on endothelial cells was reported, though cytotoxicity or proliferative stimulation can occur instead of a protective effect, depending on the dose and the formulation.