Endometriosis is a benign gynecological condition in which endometrial-like tissue grows outside of the uterus, and the mechanisms of its pathogenesis are not fully understood. The anatomical and physiological parallels between pigs and humans have made pigs a good model for investigating other human diseases. Here, we report on the development of a swine model for endometriosis in which the peritoneal cavity was inoculated with autologous endometrial tissue fragments labeled with fluorescein isothiocyanate (FITC) dye-doped silica nanoparticles. After 6 weeks of endometriosis induction, FITC positive endometriotic lesions were observed on the peritoneal surface of the abdominal wall as well as on the serosal surfaces of the uterus and small intestine. Histological analysis of the endometriotic lesions revealed endometrial-like epithelial and stromal cells that were morphologically comparable to human endometriotic lesions. The identification of epithelial and stromal cells in these lesions was confirmed by immunostaining of e-cadherin, an endometrial epithelial marker, and Chicken ovalbumin upstream promoter-transcription factor II, an endometrial stromal marker. Our results illustrate successful induction of endometriosis with fluorescent-labeled endometriotic lesions to identify in situ endometriotic lesions. According to the size and physiological similarity of pigs to humans, this is an important first step toward the development of a non-invasive tool to diagnose endometriosis. Furthermore, the availability of a new large animal model for translational endometriosis research provides a novel preclinical animal model for laparoscopic monitoring and retrieval of experimental endometriotic lesions with ample serum for serial analyses.

Abstract:The eutherian placenta is highly complex, evolving to regulate the inflammatory phase of pregnancy during conceptus attachment and placental tissue development. Tripartite motif family-like (TRIMLs) proteins are implicated in downregulating inflammation. In mammals, TRIML1 and TRIML2 show preferential expression in gonads, preimplantation embryos and placenta. TRIML1 domains differ between eutherians and marsupials, while TRIML2 is absent in marsupials, suggesting it may play a unique role in regulating the inflammatory phase during conceptus attachment, critical for establishing and maintaining pregnancy to term. This study aimed to investigate the expression pattern of TRIML1 and TRIML2 in various tissues, as well as during embryo development, conceptus attachment, and placental formation in pigs. Transcripts for TRIML2 were detected in embryos, conceptuses, extraembryonic membranes, ovary and testis but not in any of the other tissues examined. In contrast, TRIML1 expression was only observed in testis. In situ hybridization of TRIML1 and TRIML2 confirmed these results. The specific expression of TRIML2 in immune privileged sites is consistent with it serving as an anti-inflammatory factor to provide immunological protection of the eutherian placenta. To further investigate the role of TRIML2, CRISPR/Cas9 gene editing was employed to knock out either TRIML1 (control) or TRIML2. TRIML1 -/- and TRIML2 -/- porcine fetal fibroblasts were used for somatic cell nuclear transfer, and the resulting embryos were transferred into surrogate gilts. Early conceptus and placental development were not affected by the loss of conceptus TRIML2. Although a tissue-specific expression pattern was found, TRIML1 or TRIML2 are not required for pregnancy establishment in the pig. Lay summary:This study investigates the expression and possible roles of two specific proteins in pigs. These proteins are implicated in regulating inflammation and are thought to be important for the proper development of the placenta, which is essential for a successful pregnancy. TRIML2 was found in embryos and certain tissues, including ovary, testis and placenta, while TRIML1 appears only in the testis. We further used gene-editing techniques to generate pig embryos lacking these proteins to test whether their absence would affect early pregnancy and placental development. Lack of either TRIML1 or TRIML2 did not disrupt the early stages of pregnancy or placental formation, indicating that these proteins may not be critical for these processes in pigs.

Preclinical animal models are essential for the development of effective treatments. For instance, the 5xFAD mouse model successfully represents the pathophysiology of Alzheimer’s disease (AD). Expression of humanized APP (K670N/M671L - Swedish, I716V - Florida, V717I - London) and PSEN1 (M146L and L286V), found in early onset AD patients, induces the production of amyloid-β 42 (Aβ42) and amyloid deposition, gliosis, and progressive neuronal loss. While these mouse models are necessary to identify mechanisms of the disease progression, translating the findings by using large animal models such as pigs allows us to explore treatments under clinical conditions, and therefore, improve the success of clinical trial outcomes. For example, the gray-to-white matter ratio and the complexity of the distribution of crossing fibers in the pig brain is more similar to humans than are rodents. Phenotypes of previous swine models carrying humanized APP and PSEN1 to mimic the 5xFAD mouse model did not align with the mouse model, presumably due to differences in aging rates or variation in the expression level of the genes. To accelerate the impact of the humanized APP and PSEN1 , we first inactivated endogenous porcine APP and PSEN1 genes by using the CRISPR/Cas9 system in fetal fibroblast cells. Subsequently, constructs designed to express human APP and PSEN1 under the control of the neuron specific Thy1 promoter were transfected into the cells. Cells carrying the humanized APP and PSEN1 genes and the cells were used for somatic cell nuclear transfer to produce AD swine model. Thirteen piglets were born from a single pregnant sow and the genotyping of the piglets indicated that the piglets carried inactivated porcine APP and PSEN1 and carry humanized APP/PSEN1 as expected. Immunohistochemistry on the brain of the newborn AD piglets revealed an elevated abundance of Aβ42 compared to the wild type. Production of the novel AD swine model will offer a new pre-clinical animal resource to expand our understanding of Alzheimer’s disease pathogenesis and develop effective treatments against the disease.

Although advances in the porcine embryo culture system have been achieved, the artificial environment continues to be stressful for the embryos, which hinders development. To identify areas of improvement, transcriptional profiling was performed on in vivo-derived, in vivo-matured and in vitro-cultured, and in vitro-matured and cultured porcine blastocyst-stage embryos. Numerous differentially expressed genes were detected between in vitro-cultured vs in vivo-derived (489 downregulated, 701 upregulated), in vitro-matured and cultured vs in vivo-derived (435 downregulated, 1124 upregulated), and in vitro-matured and cultured vs in vitro-cultured (32 downregulated, 168 upregulated). Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed upregulation of the p53 signaling pathway in vitro-matured and cultured embryos compared to in vivo-derived embryos. Therefore, in vitro-matured and cultured embryos were cultured with different p53 inhibitors, pifithrin-alpha, pifithrin-beta, or pifithrin-mu, to determine if the stress response could be suppressed to improve development to the blastocyst stage. Culture with 50 μM pifithrin-alpha improved development to the blastocyst stage (P < 0.05), but total cell number and transcript abundance of p53 target genes remained unaltered. No difference in development was observed after culturing embryos with pifithrin-beta, and embryos cultured with pifithrin-mu demonstrated decreased development. Lastly, two embryo transfers of embryos cultured with pifithrin-alpha demonstrated that the inhibitor did not disrupt developmental competence. Overall, the addition of pifithrin-alpha in the porcine embryo culture medium was shown to have beneficial effects on development and is suitable for generating live pigs with this system.

Growth hormone controls animal growth, lactation, and reproduction. The actions of GH are dependent on the GHR. Two promoter complexes control GHR expression. The GHRP1 controls the liver-specific inducible expression of the GHR1A mRNA. The GHRP2 controls the non-tissue specific constitutive expression of GHR1B mRNA. The objective was to test the functional significance [effect on body weight (BW)] of each GHR promoter by using genetically modified pigs. The CRISPR/Cas9 system was used to delete GHRP1 and GHRP2 in fetal fibroblasts that were cloned to create two independent lines for each promoter deletion. Adults that were heterozygous (HET) for the GHRP1 or GHRP2 deletions were mated to create litters of +/+ (wildtype, WT), +/- (HET), and -/- (knockout, KO) pigs for the respective promoters. Offspring were weighed at birth and weaning (d21) and at 50, 80, 110, 140, 170, 200, 230 and 260 d of age. There were 4 litters from HET-HET matings for the GHRP1 deletion. Litters were weighed from birth to weaning (n=1), birth to d110 (n=1) or birth to d260 (n=2). The number of BW observations for d0 and d21 was 7, 11, and 8; for d50 to 110 was 5, 7, and 5; and for d140 to d260 was 3, 5, and 2 (WT, HET and KO, respectively). There was no effect (P >0.10) of GHRP1 genotype on birth weight (1.5±0.1, 1.4±0.1, and 1.4±0.1 kg), weaning weight (5.2±0.6, 5.9±0.5, and 4.7±0.5 kg), or subsequent BW including d260 (135.6±10.8, 143.4±6.2, and 138.1±9.1 kg) (WT, HET, and KO, respectively). There were 5 litters from HET-HET matings for GHRP2 deletion. Litters were weighed from birth to weaning (n=1), birth to d80 (n=2) or birth to d260 (n=2). The number of BW observations for d0 and d21 was 11, 22, and 16; for d50 and d80 was 9, 16, and 13; and for d110 to d260 was 2, 6, and 9 (WT, HET and KO, respectively). The BW for WT and HET were similar (P >0.10) across all days. There was an effect (P< 0.001) of GHRP2 genotype on birth weight (1.6±0.1, 1.4±0.1, and 1.1±0.1 kg), weaning weight (6.6±0.3, 6.2±0.2, and 4.6±0.2 kg), and all subsequent body weights including d260 (123.1±8.2, 123.4±4.8, and 71.4±3.9 kg) (WT, HET, and KO, respectively). The BW for GHRP2 KO relative to WT (expressed as a percentage) differed (P< 0.001) by age (80.4±3.7, 75.0±3.7, 43.0±4.2, 35.8±4.2, 38.7±7.5, 40.4±5.0, 51.3±5.0, 54.1±5.0, 54.6±5.0, and 57.7±5.0% for d1, 21, 50, 80, 110, 140, 170, 200, 230, and 260, respectively). In conclusion, the GHRP1 deletion had no effect on growth. GHRP2 deletion had a profound effect on growth, the magnitude of which differed across different ages perhaps explained by developmental changes in GHR expression. Work supported by USDA NIFA 2019-67015-29484.

Abstract:The central goal of the following studies was to understand how FGF2, LIF, and IGF1, a cocktail called 'FLI', influence bovine embryo development by the degree of transcriptomic variation throughout preimplantation development. All embryos were produced in vitro with or without FLI supplementation at the beginning of culture. For each treatment, embryos were collected at the 4-6 cell, 9-16 cell, morula, or blastocyst stages, and RNA was isolated and sequenced at a depth of 50 million reads per sample. In the FLI group, at the 9-16 cell stage, there were seven upregulated and six downregulated differentially expressed genes (DEGs). At the morula stage, of the 1,856 DEGs, 580 were upregulated in FLI. Gene ontology analysis showed increased MAPK signaling, TGF-beta signaling, and Hippo signaling, which all help regulate cell adhesion, lineage commitment, and growth regulation in the developing embryo. In FLI blastocyst stage embryos, 199 upregulated and 545 downregulated DEGs revealed an increase in processes associated with interferon-gamma production and cell differentiation. Overall, FLI modulates many of the regulatory pathways in the developing embryo to drive increased cell survival, cell integrity, and overall embryo development. Lay summary:This study investigated whether adding three supportive proteins - FGF2, LIF, and IGF1 (together called FLI) - could improve the development of cow embryos grown in vitro. In cattle breeding, embryos are often produced outside the body to enhance fertility and support genetic selection. However, many embryos fail to develop properly under laboratory conditions. To address this, researchers tested whether FLI could create a more favorable environment for early embryo growth. Although embryos grown with and without FLI appeared similar under the microscope, gene expression analysis revealed important differences. Embryos exposed to FLI showed signs of improved cell survival, healthier growth, and reduced stress. These molecular changes suggest that FLI may help embryos become more resilient to key procedures such as freezing and transfer. The findings support the use of FLI as a culture supplement to improve the efficiency and success of in vitro embryo production systems used in livestock reproductive biotechnologies.

Release of interferon-gamma (IFNG), a pro-inflammatory type II interferon, by the early conceptus is critical for pregnancy establishment in the pig. Yet, the cellular and molecular mechanisms underpinning conceptus-derived IFNG actions in maternal peripheral immune cells and at the embryo-maternal interface remain unclear. Here we show that pregnancy status up-regulates expression of IRF1, an IFNG target-gene, in peripheral blood mononuclear cells on day 15 of pregnancy in the pig. In a second study, loss-of-function IFNG (IFNG-/-) embryos were generated by using CRISPR/Cas9 gene editing and somatic cell nuclear transfer. Single-nuclei RNA sequencing of endometrium from gilts carrying wild-type (Control) or IFNG-/- conceptuses on day 15 of pregnancy revealed cell-type-specific signatures at the embryo-maternal interface in response to conceptus IFNG. Changes in the transcriptome of epithelial and IFNG receptor-expressing immune cells were evident between Control and IFNG-/- samples, along with a downregulation of IFNG target-genes involved in chemotaxis and immune cell differentiation in IFNG-/- recipient endometria. A notable reduction in monocytes and macrophages was observed in IFNG-/- samples, confirmed by immunohistochemistry for AIF1. Differential gene expression (DEG) analysis revealed 391 DEGs in monocytes, implicating IFNG in macrophage polarization, with evidence suggesting a shift toward an M2 phenotype. The study concludes that conceptus IFNG plays an important role in monocyte recruitment and macrophage polarization at the embryo-maternal interface for regulation of inflammation upon conceptus attachment. Insufficient numbers or skewed IFNG-activated macrophages within the endometrium may contribute to pregnancy failure in the IFNG-/- pig model.

Background:There remains a need for animal models with human translatability in lung cancer (LC) research. Findings in pigs have high impact on humans due to similar anatomy and physiology. We present the characterization of a bronchoscopically-induced LC model in Oncopigs carrying inducible KRASG12D and TP53R167H mutations. Methods:Twelve Oncopigs underwent 29 injections via flexible bronchoscopy. Eighteen Adenovirus-Cre recombinase gene (AdCre) inductions were performed endobronchially (n=6) and transbronchially with a needle (n=12). Eleven control injections were performed without AdCre. Oncopigs underwent serial contrast-enhanced chest CT with clinical follow-up for 29 weeks. Following autopsy, lung and organ tissues underwent histopathology, immunohistochemistry, and RNA-sequencing with comparative analysis with The Cancer Genome Atlas (TCGA) human LC data. Results:All 18 sites of AdCre injections had lung consolidations on CT imaging. Transbronchial injections led to histopathologic invasive cancer and/or carcinoma in situ (CIS) in 11/12 (91.7%), and invasive cancer (excluding CIS) in 8/12 (66.6%). Endobronchial inductions led to invasive cancer in 3/6 (50%). A soft tissue metastasis was observed in one Oncopig. Immunohistochemistry confirmed expression of Pan-CK+/epithelial cancer cells, with macrophages and T cells infiltration in the tumor microenvironment. Transcriptome comparison showed 54.3% overlap with human LC (TCGA), in contrast to 29.88% overlap of KRAS-mutant mouse LC with human LC. Conclusions:The transgenic and immunocompetent Oncopig model has a high rate of LC following bronchoscopic transbronchial induction. Overlap of the Oncopig LC transcriptome with human LC transcriptome was noted. This pig model is expected to have high clinical translatability to the human LC patient.

Partial heart transplantation is a new approach to deliver growing heart valve implants. Partial heart transplants differ from heart transplants because only the part of the heart containing the necessary heart valve is transplanted. This allows partial heart transplants to grow, similar to the valves in heart transplants. However, the transplant biology of partial heart transplantation remains unexplored. This is a critical barrier to progress of the field. Without knowledge about the specific transplant biology of partial heart transplantation, children with partial heart transplants are empirically treated like children with heart transplants because the valves in heart transplants are known to grow. In order to progress the field, an animal model for partial heart transplantation is necessary. Here, we contribute our surgical protocol for partial heart transplantation in growing piglets. All aspects of partial heart transplantation, including the donor procedure, the recipient procedure, and recipient perioperative care are described in detail. There are important nuances in the conduct of virtually all aspects of open heart surgery that differs in piglets from humans. Our surgical protocol, which is based on our experience with 34 piglets, will allow other investigators to leverage our experience to seek fundamental knowledge about the nature of partial heart transplants. This is significant because the partial heart transplant model in piglets is complex and very resource intensive.

BACKGROUND:Xenotransplantation has made significant advances recently using pigs genetically engineered to remove carbohydrate antigens, either alone or with addition of various human complement, coagulation, and anti-inflammatory ''transgenes''. Here we evaluated results associated with gene-edited (GE) pig hearts transplanted in baboons using an established costimulation-based immunosuppressive regimen and a cold-perfused graft preservation technique. METHODS:Eight baboons received heterotopic abdominal heart transplants from 3-GE (GalKO.β4GalNT2KO.hCD55, n = 3), 9-GE (GalKO.β4GalNT2KO.GHRKO.hCD46.hCD55. TBM.EPCR.hCD47. HO-1, n = 3) or 10-G (9-GE+CMAHKO, n = 2) pigs using Steen's cold continuous perfusion for ischemia minimization. Immunosuppression (IS) included induction with anti-thymocyte globulin and αCD20, ongoing αCD154, MMF, and tapered corticosteroid. RESULTS:All three 3-GE grafts functioned well initially, but failed within 5 days. One 9-GE graft was lost intraoperatively due to a technical issue and another was lost at POD 13 due to antibody mediated rejection (AMR) in a baboon with a strongly positive pre-operative cross-match. One 10-GE heart failed at POD113 with combined cellular and antibody mediated rejection. One 9-GE and one 10-GE hearts had preserved graft function with normal myocardium on protocol biopsies, but exhibited slowly progressive graft hypertrophy until elective necropsy at POD393 and 243 respectively. Elevated levels of IL-6, MCP-1, C-reactive protein, and human thrombomodulin were variably associated with conditioning, the transplant procedure, and clinically significant postoperative events. CONCLUSION:Relative to reference genetics without thrombo-regulatory and anti-inflammatory gene expression, 9- or 10-GE pig hearts exhibit promising performance in the context of a clinically applicable regimen including ischemia minimization and αCD154-based IS, justifying further evaluation in an orthotopic model.

Abstract Editing the genome of livestock provides solutions to otherwise intractable problems and can provide a tool to better understand the role of specific proteins during development. The potential benefit for production agriculture is so great that the USDA Agricultural Research Service has invested in 4 positions now located in a research unit at the University of Missouri with a focus currently on swine and poultry. Genome editing can result in introducing alleles from divergent populations or novel alleles to produce animals that have new proteins, modified proteins or animals that no longer produce a protein. Applications of genome editing include improving disease resistance (viral and bacterial), improving digestion, disseminating valuable genetics, improved thermoregulation, changing the body/milk composition, and creating hypoallergenic meat. Changes in these animals will improve animal welfare, animal productivity and the sustainability of animal agriculture. In addition to improving animal agriculture, gene editing has enabled a new understanding of maternal recognition of pregnancy in the pig and a better understanding of molecules involved in growth and development of pigs. With new developments in editing of just somatic cells [somatic cell gene editing (SCGE), rather than germline editing], it will be possible to edit some cells in existing animals and thus change their phenotype. SCGE technologies such as this are being developed via the biomedical community as models to lead to human clinical applications. One such application is to correct cells in the lungs that produce the CFTR protein. Correction of just 10% of the cells in the lungs is estimated to correct the lung symptoms associated with cystic fibrosis. Similar applications in production agriculture might produce animals that have novel phenotypes of an altered carcass composition or better use of nutrients. Application of genetic engineering technologies such as genome editing is limited by biology and the imagination of the investigator.

Conceptus estrogens and prostaglandins have long been considered the primary signals for maternal recognition of pregnancy (MRP) in the pig. However, loss-of-function studies targeting conceptus aromatase genes (CYP19A1 and CYP19A2) and prostaglandin-endoperoxide synthase 2 (PTGS2) indicated that conceptuses can not only signal MRP without estrogens or prostaglandins but can maintain early pregnancy. However, complete loss of estrogen production leads to abortion after day 25 of gestation. Although neither conceptus estrogens nor prostaglandins had a significant effect on early maintenance of corpora lutea (CL) function alone, the two conceptus factors have a biological relationship. To investigate the role that both conceptus estrogens and prostaglandins have on MRP and maintenance of pregnancy, a triple loss-of function model (TKO) was generated for conceptus CYP19A1, CYP19A2, and PTGS2. In addition, a conceptus CYP19A2-/- model (A2KO) was established to determine the role of placental estrogen during later pregnancy. Estrogen and prostaglandin synthesis were greatly reduced in TKO concept uses which resulted in a failure to inhibit luteolysis after day 15 of pregnancy despite the presence of conceptuses in the uterine lumen. However, A2KO placentae not only maintained functional CL but were able to maintain pregnancy to day 32 of gestation. Despite the loss of placental CYP19A2 expression, the allantois fluid content of estrogen was not affected as the placenta compensated by expressing CYP19A1 and CYP19A3, which are normally absent in controls. Results suggest conceptuses can signal MRP through production of conceptus PGE or stimulating PGE synthesis from the endometrium through conceptus estrogen. Failure of conceptuses to produce both factors results in failure of MRP and loss of pregnancy.

Genetic modification of genes such as recombination activating gene 2 (RAG2) or interleukin-2 receptor-γ (IL2RG) results in pigs exhibiting severe combined immunodeficiency (SCID). Pigs presenting a SCID phenotype are important animal models that can be used to establish xenografts and to study immune system development and various immune-related pathologies. However, due to their immunocompromised nature, SCID pigs have shortened lifespans and are notoriously difficult to maintain. The failure-to-thrive phenotype makes the establishment of a breeding population of RAG2/IL2RG double-knockout pigs virtually impossible. Here, to overcome this limitation, we investigated whether reconstituting the immune system of SCID piglets with a fetal bone allograft would extend their lifespan. Following intramuscular transplantation, allografts gave rise to lymphocytes expressing T cell (CD3, CD4 and CD8), B cell (CD79α) and natural killer cell (CD335) lineage markers, which were detected in circulation as well in the spleen, liver, bone marrow and thymic tissues. The presence of lymphocytes indicates broad engraftment of donor cells in the recipient SCID pigs. Unlike unreconstituted SCID pigs, the engrafted animals thrived and reached puberty under standard housing conditions. This study demonstrates a novel method to extend the survival of SCID pigs, which may improve the availability and use of SCID pigs as a biomedical animal model.

There is a critical need for improving animal resilience, welfare, and productivity to meet the nutritional needs of the growing global population. While selective breeding has brought about tremendous improvement in livestock genetics and improving traits, it is a relatively lengthy process to integrate beneficial alleles into the herd and it is not possible to introduce variants identified in other species. Therefore, gene editing provides researchers with a tool to rapidly overcome many of these challenges. This review highlights the advances in gene editing technology, the methods used to generate gene edited livestock, and approaches that can be used to accelerate the discovery of novel alleles linked to specific traits in vitro. Additionally, the application of organoid technology is discussed, and how that linked with gene editing technology can mimic the in vivo physiology and biological functions in vitro, providing answers to important biological questions and decreasing the number of large animals needed for research. Together, these tools will enable production agriculture to be more productive and thus better able to meet the growing worldwide demand for food.

Abstract Growth hormone (GH; somatotropin) has a central role in animal growth, reproduction, and lactation. The biological actions of GH are dependent on the GH receptor (GHR) that is found in important target tissues such as liver, muscle, adipose tissue, and bone. It is widely accepted that GH is the primary hormone controlling animal growth and that its actions are mediated by the GHR. In humans, laboratory species, and farm animals there are two promoter complexes that control GHR expression. The first promoter complex (P1) controls the liver-specific inducible expression of the GHR1A mRNA. The second promoter complex (P2) controls the non-tissue specific constitutive expression of GHR1B mRNA. Despite the central role that GH and the GHR have in animal growth, the independent function of each promoter complex has not yet been tested in any species. The objective was to perform a germ-line deletion of each GHR promoter complex to test their function in a porcine model. The CRISPR/Cas9 system was used to delete the P1 and P2 promoter complexes in porcine fetal fibroblasts and cloned to create two independent lines for each promoter deletion. Adult animals that were heterozygous (het) for the GHRP1 and GHRP2 deletions were mated to create litters of +/+ (wildtype, WT), +/- (het), and -/- (knockout, KO) pigs for the respective promoters. An RTPCR of liver and muscle confirmed that deletion of GHRP1 and GHRP2 effectively knocked out GHR1A and GHR1B mRNA. Piglets were weighed at birth and approximately monthly until 2 (GHRP1) or 5 (GHRP2) mo of age. Piglets from the GHRP1 line were +/+ (n = 3), +/- (n = 10), and -/- (n = 2) across two litters. Birthweights (1.5 ± 0.1, 1.4 ± 0.1, and 1.5 ± 0.2 kg, respectively) and body weight (BW) at 2 mo of age (32.7 ± 2.9, 27.0 ± 1.6, and 27.0 ± 3.5 kg, respectively) were similar (P > 0.10) for GHRP1 piglets. Piglets from the GHRP2 line were +/+ (n = 2), +/- (n = 6), and -/- (n = 9) across two litters. Birthweights were similar (1.4 ± 0.3, 1.3 ± 0.1, and 1.0 ± 0.1 kg, respectively) but GHRP2-/- pigs weighed less (P < 0.01) at weaning compared with GHRP2+/+ or GHRP2+/- piglets (6.4 ± 0.8, 6.5 ± 0.4, and 4.5 ± 0.4 kg, respectively). Monthly BW for the GHRP2-/- piglets were less (P < 0.001) when compared with GHRP2+/+ or GHRP2+/- piglets. At 5 mo of age, the GHRP2-/- piglets were approximately 50% of the BW of GHRP2+/+ or GHRP2+/- (89.6 ± 6.7, 89.6 ± 3.9, and 43.1 ± 3.2 kg, respectively). In conclusion, the deletion of GHRP2 (and GHR1B mRNA) had a profound effect on pig growth. The GHRP1 deletion (GHR1A mRNA) did not affect growth with the caveat that the GHRP1 litters had not reached maturity. This work was supported by USDA NIFA 2019-67015-29484.

Pigs are playing an increasingly vital role as translational biomedical models for studying human pathophysiology. The annotation of the pig genome was a huge step forward in translatability of pigs as a biomedical model for various human diseases. Similarities between humans and pigs in terms of anatomy, physiology, genetics, and immunology have allowed pigs to become a comprehensive preclinical model for human diseases. With a diverse range, from craniofacial and ophthalmology to reproduction, wound healing, musculoskeletal, and cancer, pigs have provided a seminal understanding of human pathophysiology. This review focuses on the current research using pigs as preclinical models for cancer research and highlights the strengths and opportunities for studying various human cancers.

Maternal recognition of pregnancy (MRP) is a term utilized in mammals to describe pathways in which the conceptus alters the endometrial environment to prevent regression of corpora lutea to ensure continued production of progesterone (P4) required for establishment and maintenance of pregnancy. For nearly 40 years after publication of the endocrine/exocrine theory, conceptus estrogen (E2) was considered the primary maternal recognition signal in the pig. Conceptus production of prostaglandin E2 (PGE2) was also considered to be a major factor in preventing luteolysis. An addition to E2 and PGE2, pig conceptuses produce interleukin 1B2 (IL1B2) and interferons (IFN) delta (IFND) and gamma (IFNG). The present review provides brief history of the discovery of E2, PGs and IFNS which led to research investigating the role of these conceptus secreted factors in establishing and maintaining pregnancy in the pig. The recent utilization of gene editing technology allowed a more direct approach to investigate the in vivo roles of IL1B2, E2, PGE2, AND IFNG for establishment of pregnancy. These studies revealed unknown functions for IFNG and ILB2 in addition to PGE2 and E2. Thus, pregnancy recognition signal is via a servomechanism in requiring sequential effects of P4, E2, IL1B2, PGE2 and IFNG. Results indicate that the original established dogma for the role of conceptus E2 and PGs in MRP is a far too simplified model that involves the interplay of numerous mechanisms for inhibiting luteolysis, inducing critical elongation of the conceptuses and resolution of inflammation in pigs.