Genetic diversity, growth and heart function of Auckland Island pigs, a potential source for organ xenotransplantation

One of the prerequisites for successful organ xenotransplantation is a reasonable size match between the porcine organ and the recipient's organ to be replaced. Therefore, the selection of a suitable genetic background of source pigs is important. In this study, we investigated body and organ growth, cardiac function, and genetic diversity of a colony of Auckland Island pigs established at the Center for Innovative Medical Models (CiMM), LMU Munich. Male and female Auckland Island pig kidney cells (selected to be free of porcine endogenous retrovirus C) were imported from New Zealand, and founder animals were established by somatic cell nuclear transfer (SCNT). Morphologically, Auckland Island pigs have smaller body stature compared to many domestic pig breeds, rendering their organ dimensions well-suited for human transplantation. Furthermore, echocardiography assessments of Auckland Island pig hearts indicated normal structure and functioning across various age groups throughout the study. Single nucleotide polymorphism (SNP) analysis revealed higher runs of homozygosity (ROH) in Auckland Island pigs compared to other domestic pig breeds and demonstrated that the entire locus coding the swine leukocyte antigens (SLAs) was homozygous. Based on these findings, Auckland Island pigs represent a promising genetic background for organ xenotransplantation.

Xenografts Show Signs of Concentric Hypertrophy and Dynamic Left Ventricular Outflow Tract Obstruction After Orthotopic Pig-to-baboon Heart Transplantation

BACKGROUND

Orthotopic cardiac xenotransplantation has seen substantial advancement in the last years and the initiation of a clinical pilot study is close. However, donor organ overgrowth has been a major hurdle for preclinical experiments, resulting in loss of function and the decease of the recipient. A better understanding of the pathogenesis of organ overgrowth after xenotransplantation is necessary before clinical application.

METHODS

Hearts from genetically modified ( GGTA1-KO , hCD46/hTBM transgenic) juvenile pigs were orthotopically transplanted into male baboons. Group I (control, n = 3) received immunosuppression based on costimulation blockade, group II (growth inhibition, n = 9) was additionally treated with mechanistic target of rapamycin inhibitor, antihypertensive medication, and fast corticoid tapering. Thyroid hormones and insulin-like growth factor 1 were measured before transplantation and before euthanasia, left ventricular (LV) growth was assessed by echocardiography, and hemodynamic data were recorded via a wireless implant.

RESULTS

Insulin-like growth factor 1 was higher in baboons than in donor piglets but dropped to porcine levels at the end of the experiments in group I. LV mass increase was 10-fold faster in group I than in group II. This increase was caused by nonphysiological LV wall enlargement. Additionally, pressure gradients between LV and the ascending aorta developed, and signs of dynamic left ventricular outflow tract (LVOT) obstruction appeared.

CONCLUSIONS

After orthotopic xenotransplantation in baboon recipients, untreated porcine hearts showed rapidly progressing concentric hypertrophy with dynamic LVOT obstruction, mimicking hypertrophic obstructive cardiomyopathy in humans. Antihypertensive and antiproliferative drugs reduced growth rate and inhibited LVOT obstruction, thereby preventing loss of function.

Phenotypic features of dystrophin gene knockout pigs harboring a human artificial chromosome containing the entire dystrophin gene

Mammalian artificial chromosomes have enabled the introduction of extremely large amounts of genetic information into animal cells in an autonomously replicating, nonintegrating format. However, the evaluation of human artificial chromosomes (HACs) as novel tools for curing intractable hereditary disorders has been hindered by the limited efficacy of the delivery system. We generated dystrophin gene knockout (DMD-KO) pigs harboring the HAC bearing the entire human DMD via a somatic cell cloning procedure (DYS-HAC-cloned pig). Restored human dystrophin expression was confirmed by immunofluorescence staining in the skeletal muscle of the DYS-HAC-cloned pigs. Viability at the first month postpartum of the DYS-HAC-cloned pigs, including motor function in the hind leg and serum creatinine kinase level, was improved significantly when compared with that in the original DMD-KO pigs. However, decrease in systemic retention of the DYS-HAC vector and limited production of the DMD protein might have caused severe respiratory impairment with general prostration by 3 months postpartum. The results demonstrate that the use of transchromosomic cloned pigs permitted a straightforward estimation of the efficacy of the DYS-HAC carried in affected tissues/organs in a large-animal disease model, providing novel insights into the therapeutic application of exogenous mammalian artificial chromosomes.

Immobility-associated thromboprotection is conserved across mammalian species from bear to human

Venous thromboembolism (VTE) comprising deep venous thrombosis and pulmonary embolism is a major cause of morbidity and mortality. Short-term immobility-related conditions are a major risk factor for the development of VTE. Paradoxically, long-term immobilized free-ranging hibernating brown bears and paralyzed spinal cord injury (SCI) patients are protected from VTE. We aimed to identify mechanisms of immobility-associated VTE protection in a cross-species approach. Mass spectrometry-based proteomics revealed an antithrombotic signature in platelets of hibernating brown bears with heat shock protein 47 (HSP47) as the most substantially reduced protein. HSP47 down-regulation or ablation attenuated immune cell activation and neutrophil extracellular trap formation, contributing to thromboprotection in bears, SCI patients, and mice. This cross-species conserved platelet signature may give rise to antithrombotic therapeutics and prognostic markers beyond immobility-associated VTE.

O-027 Small extracellular vesicle (sEV) protein cargo as potential biomarker for endometriosis

Study question

Can an endometriosis-specific protein signature in small extracellular vesicles (sEV) from peritoneal fluid (PF) be utilised as a non-invasive biomarker of the condition?

Summary answer

Yes, potentially. We found differences in the concentrations and protein cargo of PF-derived sEV between controls and endometriosis samples, most notably in CD44 expression.

What is known already

Endometriosis, defined as endometrial-like tissue outside the uterus, causes pain and/or subfertility in 10% of reproductive age women. The cause is unknown, resulting in inadequate diagnostic methods and treatment options. There is no clinically relevant biomarker for endometriosis yet. Small extracellular vesicles (sEV), produced by virtually every cell, have been described in diseases such as cancer, diabetes, and pre-eclampsia, and could similarly be important in endometriosis. We previously identified sEV in PF of women with endometriosis, and here investigated the protein cargo of PF sEV as biomarker of the disease.

Study design, size, duration

PF samples were obtained from participants in the ENDOX study, Endometriosis CaRe Centre, Nuffield Department of Women’s and Reproductive Health, University of Oxford (REC ref. 09/H0604/58) according to WERF EPHect standards. Women between 18-49 years of age (n = 63) who had undergone diagnostic laparoscopy were classified according to cycle phase (proliferative/secretory/menstrual) and severity of endometriosis (ASRM stages I+II or stages III+IV). Exclusion criteria were hormonal treatment, malignancy, pregnancy, breastfeeding, and inability to understand the consent form.

Participants/materials, setting, methods

The participant groups were control proliferative, n = 7; control secretory, n = 9; control menstrual, n = 3; StI+II proliferative, n = 8; StI+II secretory, n = 10; St1+II menstrual, n = 7; StIII+IV proliferative, n = 5; StIII+IV secretory, n = 11; StIII+IV menstrual, n = 3. 1 mL PF was centrifuged to remove cells, debris, and microvesicles. sEV were isolated using size exclusion chromatography (SEC) and analysed by nanoparticle tracking analysis (NTA), immunoblotting, and mass spectrometry (LC-MS/MS).

Main results and the role of chance

We confirmed the presence of exosomes in PF from women at different stages of endometriosis and from disease-free patients at different menstrual cycle phases by NTA, immunoblotting and mass spectrometry. Enriched sEV were positive for ALIX, CD9, and syntenin. The mode size of PF particles from women with endometriosis was 115 ± 15.5 nm, whereas in non-endometriotic women it was 95 ± 17.3 nm (n.s.). sEV concentrations were higher in endometriosis compared to controls, and highest in stage III-IV endometriosis, followed by stage I-II endometriosis and controls, irrespective of menstrual cycle phase (P = 0.0210). sEV concentration in stage III-IV endometriosis decreased consistent with a transition from proliferative to secretory phase. Likewise, PF-derived sEV numbers within stage I-II endometriosis samples increased, as these samples transitioned from proliferative to secretory cycle phases. Proteomic analysis showed distinct distribution patterns of proteins within endometriosis PF-derived sEVs compared to controls. Consistent with earlier studies, we found CD44 as an sEV protein uniquely within the endometriosis population and contributing significantly to the separation of endometriosis and control samples by the highest variable importance projection (VIP) score in our data set.

Limitations, reasons for caution

The main limitation of this study is the small number of samples across the different groups, and the limited amount of PF per sample.

Wider implications of the findings

PF-derived sEV differ between endometriosis and control patients. Concentrations vary regardless of cycle phase and disease stage, and this difference appears to be reflected in the proteomics analysis. The presence of CD44 within sEV could help diagnose endometriosis.

Trial registration number

not applicable

Early disruption of photoreceptor cell architecture and loss of vision in a humanized pig model of usher syndromes

Usher syndrome (USH) is the most common form of monogenic deaf-blindness. Loss of vision is untreatable and there are no suitable animal models for testing therapeutic strategies of the ocular constituent of USH, so far. By introducing a human mutation into the harmonin-encoding USH1C gene in pigs, we generated the first translational animal model for USH type 1 with characteristic hearing defect, vestibular dysfunction, and visual impairment. Changes in photoreceptor architecture, quantitative motion analysis, and electroretinography were characteristics of the reduced retinal virtue in USH1C pigs. Fibroblasts from USH1C pigs or USH1C patients showed significantly elongated primary cilia, confirming USH as a true and general ciliopathy. Primary cells also proved their capacity for assessing the therapeutic potential of CRISPR/Cas-mediated gene repair or gene therapy in vitro. AAV-based delivery of harmonin into the eye of USH1C pigs indicated therapeutic efficacy in vivo.

Transgenic pigs expressing near infrared fluorescent protein-A novel tool for noninvasive imaging of islet xenotransplants

BACKGROUND

Islet xenotransplantation is a promising concept for beta-cell replacement therapy. Reporter genes for noninvasive monitoring of islet engraftment, graft mass changes, long-term survival, and graft failure support the optimization of transplantation strategies. Near-infrared fluorescent protein (iRFP) is ideal for fluorescence imaging (FI) in tissue, but also for multispectral optoacoustic tomography (MSOT) with an even higher imaging depth. Therefore, we generated reporter pigs ubiquitously expressing iRFP.

METHODS

CAG-iRPF720 transgenic reporter pigs were generated by somatic cell nuclear transfer from FACS-selected stable transfected donor cells. Neonatal pig islets (NPIs) were transplanted into streptozotocin-diabetic immunodeficient NOD-scid IL2Rg^null (NSG) mice. FI and MSOT were performed to visualize different numbers of NPIs and to evaluate associations between signal intensity and glycemia. MSOT was also tested in a large animal model.

RESULTS

CAG-iRFP transgenic NPIs were functionally equivalent with wild-type NPIs. Four weeks after transplantation under the kidney capsule, FI revealed a twofold higher signal for 4000-NPI compared to 1000-NPI grafts. Ten weeks after transplantation, the fluorescence intensity of the 4000-NPI graft was inversely correlated with glycemia. After intramuscular transplantation into diabetic NSG mice, MSOT revealed clear dose-dependent signals for grafts of 750, 1500, and 3000 NPIs. Dose-dependent MSOT signals were also revealed in a pig model, with stronger signals after subcutaneous (depth ∼6 mm) than after submuscular (depth ∼15 mm) placement of the NPIs.

CONCLUSIONS

Islets from CAG-iRFP transgenic pigs are fully functional and accessible to long-term monitoring by state-of-the-art imaging modalities. The novel reporter pigs will support the development and preclinical testing of novel matrices and engraftment strategies for porcine xeno-islets.

A scalable, clinically severe pig model for Duchenne muscular dystrophy

Large animal models for Duchenne muscular dystrophy (DMD) are crucial for evaluation of diagnostic procedures and treatment strategies. Pigs cloned from male cells lacking DMD exon 52 (DMDΔ52) resemble molecular, clinical and pathological hallmarks of DMD, but die before sexual maturity and cannot be propagated by breeding. Therefore, we generated female DMD+/- carriers. A single founder animal had 11 litters with 29 DMDY/-, 34 DMD+/- as well as 36 male and 29 female wild-type offspring. Breeding with F1 and F2 DMD+/- carriers resulted in additional 114 DMDY/- piglets. With intensive neonatal management, the majority survived for 3-4 months, providing statistically relevant cohorts for experimental studies. Pathological investigations and proteome studies of skeletal muscles and myocardium confirmed the resemblance of human disease mechanisms. Importantly, DMDY/- pigs reveal progressive myocardial fibrosis and increased expression of connexin-43, associated with significantly reduced left ventricular ejection fraction already at age 3 months. Furthermore, behavioral tests provided evidence for impaired cognitive ability. Our breeding cohort of DMDΔ52 pigs and standardized tissue repositories provide important resources for studying DMD disease mechanisms and for testing novel treatment strategies.

The Missing Link: Cre Pigs for Cancer Research

The Cre/loxP system is a powerful tool for the generation of animal models with precise spatial and temporal gene expression. It has proven indispensable in the generation of cancer models with tissue specific expression of oncogenes or the inactivation of tumor suppressor genes. Consequently, Cre-transgenic mice have become an essential prerequisite in basic cancer research. While it is unlikely that pigs will ever replace mice in basic research they are already providing powerful complementary resources for translational studies. But, although conditionally targeted onco-pigs have been generated, no Cre-driver lines exist for any of the major human cancers. To model human pancreatic cancer in pigs, Cre-driver lines were generated by CRISPR/Cas9-mediated insertion of codon-improved Cre (iCre) into the porcine PTF1A gene, thus guaranteeing tissue and cell type specific function which was proven using dual fluorescent reporter pigs. The method used can easily be adapted for the generation of other porcine Cre-driver lines, providing a missing tool for modeling human cancers in large animals.

Sequential in vivo labeling of insulin secretory granule pools in INS-SNAP transgenic pigs

β cells produce, store, and secrete insulin upon elevated blood glucose levels. Insulin secretion is a highly regulated process. The probability for insulin secretory granules to undergo fusion with the plasma membrane or being degraded is correlated with their age. However, the molecular features and stimuli connected to this behavior have not yet been fully understood. Furthermore, our understanding of β cell function is mostly derived from studies of ex vivo isolated islets in rodent models. To overcome this translational gap and study insulin secretory granule turnover in vivo, we have generated a transgenic pig model with the SNAP-tag fused to insulin. We demonstrate the correct targeting and processing of the tagged insulin and normal glycemic control of the pig model. Furthermore, we show specific single- and dual-color granular labeling of in vivo-labeled pig pancreas. This model may provide unprecedented insights into the in vivo insulin secretory granule behavior in an animal close to humans.

Gene Regulatory and Expression Differences between Mouse and Pig Limb Buds Provide Insights into the Evolutionary Emergence of Artiodactyl Traits

Digit loss/reductions are evolutionary adaptations in cursorial mammals such as pigs. To gain mechanistic insight into these processes, we performed a comparative molecular analysis of limb development in mouse and pig embryos, which revealed a loss of anterior-posterior polarity during distal progression of pig limb bud development. These alterations in pig limb buds are paralleled by changes in the mesenchymal response to Sonic hedgehog (SHH) signaling, which is altered upstream of the reduction and loss of Fgf8 expression in the ectoderm that overlaps the reduced and vestigial digit rudiments of the pig handplate, respectively. Furthermore, genome-wide open chromatin profiling using equivalent developmental stages of mouse and pig limb buds reveals the functional divergence of about one-third of the regulatory genome. This study uncovers widespread alterations in the regulatory landscapes of genes essential for limb development that likely contributed to the morphological diversion of artiodactyl limbs from the pentadactyl archetype of tetrapods.

Cas9-expressing chickens and pigs as resources for genome editing in livestock

Genetically modified animals continue to provide important insights into the molecular basis of health and disease. Research has focused mostly on genetically modified mice, although other species like pigs resemble the human physiology more closely. In addition, cross-species comparisons with phylogenetically distant species such as chickens provide powerful insights into fundamental biological and biomedical processes. One of the most versatile genetic methods applicable across species is CRISPR-Cas9. Here, we report the generation of transgenic chickens and pigs that constitutively express Cas9 in all organs. These animals are healthy and fertile. Functionality of Cas9 was confirmed in both species for a number of different target genes, for a variety of cell types and in vivo by targeted gene disruption in lymphocytes and the developing brain, and by precise excision of a 12.7-kb DNA fragment in the heart. The Cas9 transgenic animals will provide a powerful resource for in vivo genome editing for both agricultural and translational biomedical research, and will facilitate reverse genetics as well as cross-species comparisons.

Cold non-ischemic heart preservation with continuous perfusion prevents early graft failure in orthotopic pig-to-baboon xenotransplantation

BACKGROUND

Successful preclinical transplantations of porcine hearts into baboon recipients are required before commencing clinical trials. Despite years of research, over half of the orthotopic cardiac xenografts were lost during the first 48 hours after transplantation, primarily caused by perioperative cardiac xenograft dysfunction (PCXD). To decrease the rate of PCXD, we adopted a preservation technique of cold non-ischemic perfusion for our ongoing pig-to-baboon cardiac xenotransplantation project.

METHODS

Fourteen orthotopic cardiac xenotransplantation experiments were carried out with genetically modified juvenile pigs (GGTA1- KO/hCD46/hTBM) as donors and captive-bred baboons as recipients. Organ preservation was compared according to the two techniques applied: cold static ischemic cardioplegia (IC; n = 5) and cold non-ischemic continuous perfusion (CP; n = 9) with an oxygenated albumin-containing hyperoncotic cardioplegic solution containing nutrients, erythrocytes and hormones. Prior to surgery, we measured serum levels of preformed anti-non-Gal-antibodies. During surgery, hemodynamic parameters were monitored with transpulmonary thermodilution. Central venous blood gas analyses were taken at regular intervals to estimate oxygen extraction, as well as lactate production. After surgery, we measured troponine T and serum parameters of the recipient's kidney, liver and coagulation functions.

RESULTS

In porcine grafts preserved with IC, we found significantly depressed systolic cardiac function after transplantation which did not recover despite increasing inotropic support. Postoperative oxygen extraction and lactate production were significantly increased. Troponin T, creatinine, aspartate aminotransferase levels were pathologically high, whereas prothrombin ratios were abnormally low. In three of five IC experiments, PCXD developed within 24 hours. By contrast, all nine hearts preserved with CP retained fully preserved systolic function, none showed any signs of PCXD. Oxygen extraction was within normal ranges; serum lactate as well as parameters of organ functions were only mildly elevated. Preformed anti-non-Gal-antibodies were similar in recipients receiving grafts from either IC or CP preservation.

CONCLUSIONS

While standard ischemic cardioplegia solutions have been used with great success in human allotransplantation over many years, our data indicate that they are insufficient for preservation of porcine hearts transplanted into baboons: Ischemic storage caused severe impairment of cardiac function and decreased tissue oxygen supply, leading to multi-organ failure in more than half of the xenotransplantation experiments. In contrast, cold non-ischemic heart preservation with continuous perfusion reliably prevented early graft failure. Consistent survival in the perioperative phase is a prerequisite for preclinical long-term results after cardiac xenotransplantation.

Somatic gene editing ameliorates skeletal and cardiac muscle failure in pig and human models of Duchenne muscular dystrophy

Frameshift mutations in the DMD gene, encoding dystrophin, cause Duchenne muscular dystrophy (DMD), leading to terminal muscle and heart failure in patients. Somatic gene editing by sequence-specific nucleases offers new options for restoring the DMD reading frame, resulting in expression of a shortened but largely functional dystrophin protein. Here, we validated this approach in a pig model of DMD lacking exon 52 of DMD (DMDΔ52), as well as in a corresponding patient-derived induced pluripotent stem cell model. In DMDΔ52 pigs1, intramuscular injection of adeno-associated viral vectors of serotype 9 carrying an intein-split Cas9 (ref. 2) and a pair of guide RNAs targeting sequences flanking exon 51 (AAV9-Cas9-gE51) induced expression of a shortened dystrophin (DMDΔ51-52) and improved skeletal muscle function. Moreover, systemic application of AAV9-Cas9-gE51 led to widespread dystrophin expression in muscle, including diaphragm and heart, prolonging survival and reducing arrhythmogenic vulnerability. Similarly, in induced pluripotent stem cell-derived myoblasts and cardiomyocytes of a patient lacking DMDΔ52, AAV6-Cas9-g51-mediated excision of exon 51 restored dystrophin expression and amelioreate skeletal myotube formation as well as abnormal cardiomyocyte Ca2+ handling and arrhythmogenic susceptibility. The ability of Cas9-mediated exon excision to improve DMD pathology in these translational models paves the way for new treatment approaches in patients with this devastating disease.

Viable pigs after simultaneous inactivation of porcine MHC class I and three xenoreactive antigen genes GGTA1, CMAH and B4GALNT2

BACKGROUND

Cell surface carbohydrate antigens play a major role in the rejection of porcine xenografts. The most important for human recipients are α-1,3 Gal (Galactose-alpha-1,3-galactose) causing hyperacute rejection, also Neu5Gc (N-glycolylneuraminic acid) and Sd(a) blood group antigens both of which are likely to elicit acute vascular rejection given the known human immune status. Porcine cells with knockouts of the three genes responsible, GGTA1, CMAH and B4GALNT2, revealed minimal xenoreactive antibody binding after incubation with human serum. However, human leucocyte antigen (HLA) antibodies cross-reacted with swine leucocyte antigen class I (SLA-I). We previously demonstrated efficient generation of pigs with multiple xeno-transgenes placed at a single genomic locus. Here we wished to assess whether key xenoreactive antigen genes can be simultaneously inactivated and if combination with the multi-transgenic background further reduces antibody deposition and complement activation.

METHODS

Multiplex CRISPR/Cas9 gene editing and somatic cell nuclear transfer were used to generate pigs carrying functional knockouts of GGTA1, CMAH, B4GALNT2 and SLA class I. Fibroblasts derived from one- to four-fold knockout animals, and from multi-transgenic cells (human CD46, CD55, CD59, HO1 and A20) with the four-fold knockout were used to examine the effects on human IgG and IgM binding or complement activation in vitro.

RESULTS

Pigs were generated carrying four-fold knockouts of important xenoreactive genes. In vitro assays revealed that combination of all four gene knockouts reduced human IgG and IgM binding to porcine kidney cells more effectively than single or double knockouts. The multi-transgenic background combined with GGTA1 knockout alone reduced C3b/c and C4b/c complement activation to such an extent that further knockouts had no significant additional effect.

CONCLUSION

We showed that pigs carrying several xenoprotective transgenes and knockouts of xenoreactive antigens can be readily generated and these modifications will have significant effects on xenograft survival.

Mild maternal hyperglycemia in INS C93S transgenic pigs causes impaired glucose tolerance and metabolic alterations in neonatal offspring

Alongside the obesity epidemic, the prevalence of maternal diabetes is rising worldwide, and adverse effects on fetal development and metabolic disturbances in the offspring's later life have been described. To clarify whether metabolic programming effects are due to mild maternal hyperglycemia without confounding obesity, we investigated wild-type offspring of INS^C93S transgenic pigs, which are a novel genetically modified large-animal model expressing mutant insulin (INS) C93S in pancreatic β-cells. This mutation results in impaired glucose tolerance, mild fasting hyperglycemia and insulin resistance during late pregnancy. Compared with offspring from wild-type sows, piglets from hyperglycemic mothers showed impaired glucose tolerance and insulin resistance (homeostatic model assessment of insulin resistance: +3-fold in males; +4.4-fold in females) prior to colostrum uptake. Targeted metabolomics in the fasting and insulin-stimulated state revealed distinct alterations in the plasma metabolic profile of piglets from hyperglycemic mothers. They showed increased levels of acylcarnitines, gluconeogenic precursors such as alanine, phospholipids (in particular lyso-phosphatidylcholines) and α-aminoadipic acid, a potential biomarker for type 2 diabetes. These observations indicate that mild gestational hyperglycemia can cause impaired glucose tolerance, insulin resistance and associated metabolic alterations in neonatal offspring of a large-animal model born at a developmental maturation status comparable to human babies.

Editor's choice: Mild maternal hyperglycemia causes impaired glucose tolerance and metabolic alterations in wild-type neonatal offspring of INS^C93S transgenic pigs, a novel large animal model for mutant INS gene-induced diabetes of youth (MIDY).

Transmission of Porcine Circovirus 3 (PCV3) by Xenotransplantation of Pig Hearts into Baboons

Porcine circovirus 3 (PCV3) is a newly described member of the virus family Circoviridae. PCV3 is highly distributed among pigs and wild boars worldwide. A sudden introduction of PCV3 was recently observed in a herd of triple genetically modified pigs generated for xenotransplantation. These animals were used as donor pigs for orthotopic heart transplantation into baboons. In four cases, PCV3-positive hearts were transplanted, and transmission of PCV3 to the recipient was observed. PCV3 was found in all organs of the recipient baboons and a higher virus load was found in animals with a longer survival time of the transplant, indicating replication of the virus. This is the first report showing trans-species transmission of PCV3 to baboons by transplantation of a heart from a PCV3-positive donor pig. Sequence analysis showed that PCV3a and PCV3b were present in the infected pigs and were transmitted. Experiments to infect human 293 cells with PCV3 failed.

Early weaning completely eliminates porcine cytomegalovirus from a newly established pig donor facility for xenotransplantation

For clinical xenotransplantation, transplants must be free of porcine cytomegalovirus (PCMV). Piglets become infected primarily in the perinatal period by the mother sow. While individual donor animals can be protected from infection by isolation husbandry, success is not guaranteed and this strategy poses the risk of undetected infections and raises animal welfare questions. Here, we present the establishment of a completely PCMV-negative pig herd for breeding donor animals for xenotransplantation. Eleven pregnant DanAvl Basic hybrid sows were purchased from a designated pathogen-free (DPF), PCMV-positive colony and transferred to a new pig facility at the Centre for Innovative Medical Models (CiMM) 4 weeks prior to farrowing. At the age of 24 hours, piglets were early-weaned and transferred to a commercially available Rescue Deck system dedicated to motherless rearing of piglets. Sows were removed from the facility. The PCMV status of F1-generation animals was determined at regular intervals over a period of 14 months by a sensitive real-time PCR-based detection method testing blood, nasal swabs and cultured peripheral blood mononuclear cells (PBMCs). F1 sows were used as recipients of genetically modified embryos to generate a xenotransplant donor herd. Offspring were tested for PCMV accordingly. All offspring have remained PCMV negative over the whole observation period of 14 months. A completely PCMV-negative pig herd for xenotransplantation has thus been successfully established.

Consistent success in life-supporting porcine cardiac xenotransplantation

Heart transplantation is the only cure for patients with terminal cardiac failure, but the supply of allogeneic donor organs falls far short of the clinical need^1-3. Xenotransplantation of genetically modified pig hearts has been discussed as a potential alternative⁴. Genetically multi-modified pig hearts that lack galactose-α1,3-galactose epitopes (α1,3-galactosyltransferase knockout) and express a human membrane cofactor protein (CD46) and human thrombomodulin have survived for up to 945 days after heterotopic abdominal transplantation in baboons⁵. This model demonstrated long-term acceptance of discordant xenografts with safe immunosuppression but did not predict their life-supporting function. Despite 25 years of extensive research, the maximum survival of a baboon after heart replacement with a porcine xenograft was only 57 days and this was achieved, to our knowledge, only once⁶. Here we show that α1,3-galactosyltransferase-knockout pig hearts that express human CD46 and thrombomodulin require non-ischaemic preservation with continuous perfusion and control of post-transplantation growth to ensure long-term orthotopic function of the xenograft in baboons, the most stringent preclinical xenotransplantation model. Consistent life-supporting function of xenografted hearts for up to 195 days is a milestone on the way to clinical cardiac xenotransplantation⁷.

Targeting αGal epitopes for multi-species embryo immunosurgery

Immunosurgical isolation of the inner cell mass (ICM) from blastocysts is based on complement-mediated lysis of antibody-coated trophectoderm (TE) cells. Conventionally, anti-species antisera, containing antibodies against multiple undefined TE-cell epitopes, have been used as the antibody source. We previously generated α-1,3-galactosyltransferase deficient (GTKO) pigs to prevent hyperacute rejection of pig-to-primate xenotransplants. Since GTKO pigs lack galactosyl-α-1,3-galactose (αGal) but are exposed to this antigen (e.g. αGal on gut bacteria), they produce anti-αGal antibodies. In this study, we examined whether serum from GTKO pigs could be used as a novel antibody source for multi-species embryo immunosurgery. Mouse, rabbit, pig and cattle blastocysts were used for the experiment. Expression of αGal epitopes on the surface of TE cells was detected in blastocysts of all species tested. GTKO pig serum contained sufficient anti-αGal antibodies to induce complement-mediated lysis of TE cells in blastocysts from all species investigated. Intact ICMs could be successfully recovered and the majority showed the desired level of purity. Our study demonstrates that GTKO pig serum is a reliable and effective source of antibodies targeting the αGal epitopes of TE cells for multi-species embryo immunosurgery.

Growth hormone receptor-deficient pigs resemble the pathophysiology of human Laron syndrome and reveal altered activation of signaling cascades in the liver

OBJECTIVE

Laron syndrome (LS) is a rare, autosomal recessive disorder in humans caused by loss-of-function mutations of the growth hormone receptor (GHR) gene. To establish a large animal model for LS, pigs with GHR knockout (KO) mutations were generated and characterized.

METHODS

CRISPR/Cas9 technology was applied to mutate exon 3 of the GHR gene in porcine zygotes. Two heterozygous founder sows with a 1-bp or 7-bp insertion in GHR exon 3 were obtained, and their heterozygous F1 offspring were intercrossed to produce GHR-KO, heterozygous GHR mutant, and wild-type pigs. Since the latter two groups were not significantly different in any parameter investigated, they were pooled as the GHR expressing control group. The characterization program included body and organ growth, body composition, endocrine and clinical-chemical parameters, as well as signaling studies in liver tissue.

RESULTS

GHR-KO pigs lacked GHR and had markedly reduced serum insulin-like growth factor 1 (IGF1) levels and reduced IGF-binding protein 3 (IGFBP3) activity but increased IGFBP2 levels. Serum GH concentrations were significantly elevated compared with control pigs. GHR-KO pigs had a normal birth weight. Growth retardation became significant at the age of five weeks. At the age of six months, the body weight of GHR-KO pigs was reduced by 60% compared with controls. Most organ weights of GHR-KO pigs were reduced proportionally to body weight. However, the weights of liver, kidneys, and heart were disproportionately reduced, while the relative brain weight was almost doubled. GHR-KO pigs had a markedly increased percentage of total body fat relative to body weight and displayed transient juvenile hypoglycemia along with decreased serum triglyceride and cholesterol levels. Analysis of insulin receptor related signaling in the liver of adult fasted pigs revealed increased phosphorylation of IRS1 and PI3K. In agreement with the loss of GHR, phosphorylation of STAT5 was significantly reduced. In contrast, phosphorylation of JAK2 was significantly increased, possibly due to the increased serum leptin levels and increased hepatic leptin receptor expression and activation in GHR-KO pigs. In addition, increased mTOR phosphorylation was observed in GHR-KO liver samples, and phosphorylation studies of downstream substrates suggested the activation of mainly mTOR complex 2.

CONCLUSION

GHR-KO pigs resemble the pathophysiology of LS and are an interesting model for mechanistic studies and treatment trials.

Strong xenoprotective function by single-copy transgenes placed sequentially at a permissive locus

BACKGROUND

Multiple xenoprotective transgenes are best grouped at a single locus to avoid segregation during breeding and simplify production of donor animals.

METHODS

We used transgene stacking to place a human CD55 transgene adjacent to a human heme oxygenase 1 construct at the porcine ROSA26 locus. A transgenic pig was analyzed by PCR, RT-PCR, droplet digital PCR, immunohistochemistry, immunofluorescence, and flow cytometry. Resistance to complement-mediated cell lysis and caspase 3/7 activation were determined in vitro.

RESULTS

The ROSA26 locus was retargeted efficiently, and animals were generated by nuclear transfer. RNA and protein analyses revealed abundant expression in all organs analyzed, including pancreatic beta cells. Transgenic porcine kidney fibroblasts were almost completely protected against complement-mediated lysis and showed reduced caspase 3/7 activation.

CONCLUSION

Step-by-step placement enables highly expressed single-copy xenoprotective transgenes to be grouped at porcine ROSA26.

202 Targeting Galactosyl-α-1,3-Galactose (αGal) Epitopes for Multi-Species Embryo Immunosurgery

Immunosurgical isolation of the inner cell mass (ICM) from blastocysts is based on complement-mediated lysis of antibody-coated trophectoderm (TE) cells. Conventionally, anti-species antisera, containing antibodies against multiple undefined TE cell epitopes, have been used as antibody source. We previously generated α-1,3-galactosyltransferase deficient (GTKO) pigs to prevent hyper-acute rejection of pig-to-primate xenotransplants. Because GTKO pigs lack galactosyl-α-1,3-galactose (αGal) but are exposed to this antigen (e.g. αGal on gut bacteria), they are expected to produce anti-αGal antibodies. In this study, we examined whether serum from GTKO pigs can be used as a novel antibody source for embryo immunosurgery. First, the presence of αGal epitopes in mouse (E3.5), rabbit (Day 4), pig (Day 6–7), and bovine (Day 7–8) blastocysts was examined by staining with fluorescein isothiocyanate (FITC)-conjugated BSI-B4 lectin (Sigma, St. Louis, MO, USA) that binds αGal. Expression of αGal epitopes on the surface of TE cells was detected in blastocysts of all examined species. Next, pig blastocysts were incubated with a medium containing GTKO pig serum. Swollen TE cells were observed in some of the blastocysts already after 2 min and, after 10 min, almost all TE cells of these blastocysts were completely destroyed. No lysis was recorded when the same experiment was done with wild-type pig serum, suggesting the presence of sufficient quantities of anti-αGal antibodies in GTKO serum to coat the TE cells and induce their complement-mediated lysis. Finally, GTKO serum was systematically tested for immunosurgery. Zona-free blastocysts of the species mentioned above were incubated with heat-inactivated GTKO pig serum for 1 h at 38°C. After washing, the blastocysts were labelled with Hoechst 33342 and TE was stained with FITC-conjugated concanavalin A (ConA) to distinguish the ICM from TE cells. Eventually, the blastocysts were individually incubated in complement solution for 30 to 40 min. Complement-mediated lysis of TE cells was efficiently induced in mouse, rabbit, pig, and bovine blastocysts (10/10, 7/7, 10/10, and 5/6, respectively), and intact ICM were successfully recovered from all species (100, 100, 60, and 80%, respectively). Double fluorescent staining with Hoechst 33342 and ConA clearly showed that the majority of isolated ICM was not contaminated with TE cells. Our study demonstrates that GTKO pig serum is a reliable source of antibodies targeting the αGal epitope of TE cells. Major advantages of using GTKO serum for embryo immunosurgery are (1) that it can be produced easily in large batches, thus reducing experimental variation; and (2) that it reacts with a large number of different species, except for humans, apes, and old world monkeys that lack αGal epitopes. Interesting applications include the preparation of TE and ICM for transcriptome profiling or chimeric embryo complementation experiments. This work is supported by the German Research Council (TR-CRC 127).

Debridement and implant retention in the management of hip periprosthetic joint infection: outcomes following guided and rapid treatment at a single centre

AIMS

To analyse the effectiveness of debridement and implant retention (DAIR) in patients with hip periprosthetic joint infection (PJI) and the relationship to patient characteristics. The outcome was evaluated in hips with confirmed PJI and a follow-up of not less than two years.

PATIENTS AND METHODS

Patients in whom DAIR was performed were identified from our hip arthroplasty register (between 2004 and 2013). Adherence to criteria for DAIR was assessed according to a previously published algorithm.

RESULTS

DAIR was performed as part of a curative procedure in 46 hips in 42 patients. The mean age was 73.2 years (44.6 to 87.7), including 20 women and 22 men. In 34 hips in 32 patients (73.9%), PJI was confirmed. In 12 hips, the criteria for PJI were not fulfilled and antibiotics stopped. In 41 (89.1%) of all hips and in 32 (94.1%) of the confirmed PJIs, all criteria for DAIR were fulfilled. In patients with exogenous PJI, DAIR was performed not more than three days after referral. In haematogenous infections, the duration of symptoms did not exceed 21 days. In 28 hips, a single debridement and in six hips two surgical debridements were required. In 28 (87.5%) of 32 patients, the total treatment duration was three months. Failure was noted in three hips (9%). Long-term follow-up results (mean 4.0 years, 1.4 to 10) were available in 30 of 34 (88.2%) confirmed PJIs. The overall successful outcome rate was 91% in 34 hips, and 90% in 30 hips with long-term follow-up results.

CONCLUSION

Prompt surgical treatment with DAIR, following strict diagnostic and therapeutic criteria, in patients with suspected periprosthetic joint infection, can lead to high rates of success in eradicating the infection. Cite this article: Bone Joint J 2017;99-B:330-6.

Direct introduction of gene constructs into the pronucleus-like structure of cloned embryos: a new strategy for the generation of genetically modified pigs

Due to a rising demand of porcine models with complex genetic modifications for biomedical research, the approaches for their generation need to be adapted. In this study we describe the direct introduction of a gene construct into the pronucleus (PN)-like structure of cloned embryos as a novel strategy for the generation of genetically modified pigs, termed "nuclear injection". To evaluate the reliability of this new strategy, the developmental ability of embryos in vitro and in vivo as well as the integration and expression efficiency of a transgene carrying green fluorescence protein (GFP) were examined. Eighty percent of the cloned pig embryos (633/787) exhibited a PN-like structure, which met the prerequisite to technically perform the new method. GFP fluorescence was observed in about half of the total blastocysts (21/40, 52.5%), which was comparable to classical zygote PN injection (28/41, 68.3%). In total, 478 cloned embryos injected with the GFP construct were transferred into 4 recipients and from one recipient 4 fetuses (day 68) were collected. In one of the fetuses which showed normal development, the integration of the transgene was confirmed by PCR in different tissues and organs from all three primary germ layers and placenta. The integration pattern of the transgene was mosaic (48 out of 84 single-cell colonies established from a kidney were positive for GFP DNA by PCR). Direct GFP fluorescence was observed macro- and microscopically in the fetus. Our novel strategy could be useful particularly for the generation of pigs with complex genetic modifications.

19 DIRECT INTRODUCTION OF GENE CONSTRUCTS INTO THE PRONUCLEUS-LIKE STRUCTURE OF CLONED EMBRYOS: A NEW STRATEGY FOR THE GENERATION OF GENETICALLY MODIFIED PIGS

Because of a rising demand for complex porcine disease models for biomedical research, the approaches for their generation need to be adapted. In this study we describe the direct introduction of a gene construct into the pronucleus (PN)-like structure of cloned embryos as a new strategy for the generation of genetically modified pigs, termed “nuclear injection.” This new strategy could allow adding large constructs into cloned embryos with a genetically modified background. Moreover, the generation of multiple transgenic pigs based on already existing transgenic cells could be facilitated due to a reduction of recloning steps. To evaluate the reliability of this approach, developmental ability of the embryos in vitro or in vivo and integration or expression efficiency of the transgene were examined. Somatic cell NT using in vitro matured oocytes was performed. Wild-type cells were used as nuclear donors. Centrifugation was done 10 h after activation for visualisation of a PN-like structure. Subsequently, linearized pmaxGFP (10 ng μL–1; Amaxa Biosystems) was directly injected into the PN-like structure of the cloned embryos. Expression efficiency in blastocysts generated by nuclear injection was compared to blastocysts generated by the classical PN injection using in vitro-produced zygotes. Injected embryos were transferred to recipient pigs without green fluorescent protein (GFP) selection, and fetuses collected at Day 68 were characterised for their integration and expression pattern of the transgene. Eighty percent of the reconstructed embryos (633/787) exhibited a PN-like structure, which made them available for the method. Green fluorescent protein fluorescence was observed in about half of total blastocysts (52.5%, 21/40), which was comparable to classical PN injection (68.4%, 28/41). Green fluorescent protein fluorescence of blastocysts ranged from mosaic to uniform patterns. In total, 478 pmaxGFP-injected embryos were transferred into 4 recipients, 4 fetuses were collected from one of them. In one of the fetuses that developed normally, the integration of the transgene was confirmed by PCR in different major organs from all 3 primary germ layers and placenta. The integration pattern of the transgene was mosaic (43 out of 84 single-cell colonies established from kidney were positive for GFP DNA by PCR). However, the proportion of GFP-expressing cells was very low (5 out of 84 colonies expressed GFP), which might indicate silencing of transgene expression. Our pilot study demonstrated that the direct introduction of gene constructs into cloned embryos could be a new strategy for the generation of genetically modified pigs. This approach could also be applied to rescue embryos with lethal knockouts by transfer of corresponding human genes, to generate pigs as bioreactors, e.g. for antibodies. This work was supported by the German Research Council – Transregio Collaborative Research Center 127 “Xenotransplantation.”

Viable pigs with a conditionally-activated oncogenic KRAS mutation

Oncogenic mutations of KRAS play a major role in human carcinogenesis. Here we describe viable gene-targeted pigs carrying a latent KRAS (G12D) mutant allele that can be activated by Cre recombination. These have been produced as part of a program to model human cancers in pigs by replicating genetic lesions known to initiate and drive human disease. Cre-activated KRAS (G12D) animals add to a growing set of gene-targeted pigs that includes a Cre-activated oncogenic mutant TP53, a Cre-responsive dual fluorescent reporter and two truncating mutations of APC (adenomatous polyposis coli). These alleles can be combined and activated in various tissues to produce new models for cancer research.

Effects of the glucagon-like peptide-1 receptor agonist liraglutide in juvenile transgenic pigs modeling a pre-diabetic condition

Background

The glucagon-like peptide-1 receptor (GLP1R) agonist liraglutide improves glycemic control and reduces body weight of adult type 2 diabetic patients. However, efficacy and safety of liraglutide in adolescents has not been systematically investigated. Furthermore, possible pro-proliferative effects of GLP1R agonists on the endocrine and exocrine pancreas need to be further evaluated. We studied effects of liraglutide in adolescent pigs expressing a dominant-negative glucose-dependent insulinotropic polypeptide receptor (GIPR^dn) in the beta-cells, leading to a pre-diabetic condition including disturbed glucose tolerance, reduced insulin secretion and progressive reduction of functional beta-cell mass.

Methods

Two-month-old GIPR^dn transgenic pigs were treated daily with liraglutide (0.6-1.2 mg per day) or placebo for 90 days. Glucose homeostasis was evaluated prior to and at the end of the treatment period by performing mixed meal and intravenous glucose tolerance tests (MMGTT and IVGTT). Finally animals were subjected to necropsy and quantitative-stereological analyses were performed for evaluation of alpha- and beta-cell mass, beta-cell proliferation as well as acinus-cell proliferation.

Results

MMGTT at the end of the study revealed 23% smaller area under the curve (AUC) for glucose, a 36% smaller AUC insulin, and improved insulin sensitivity, while IVGTT showed a 15% smaller AUC glucose but unchanged AUC insulin in liraglutide- vs. placebo-treated animals. Liraglutide led to marked reductions in body weight gain (-31%) and food intake (-30%) compared to placebo treatment, associated with reduced phosphorylation of insulin receptor beta (INSRB)/insulin-like growth factor-1 receptor beta (IGF1RB) and protein kinase B (AKT) in skeletal muscle. Absolute alpha- and beta-cell mass was reduced in liraglutide-treated animals, but alpha- and beta-cell mass-to-body weight ratios were unchanged. Liraglutide neither stimulated beta-cell proliferation in the endocrine pancreas nor acinus-cell proliferation in the exocrine pancreas, excluding both beneficial and detrimental effects on the pig pancreas.

Conclusions

Although plasma liraglutide levels of adolescent transgenic pigs treated in our study were higher compared to human trials, pro-proliferative effects on the endocrine or exocrine pancreas or other liraglutide-related side-effects were not observed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0431-2) contains supplementary material, which is available to authorized users.

Nuclear transfer and transgenesis in the pig

Somatic cell nuclear transfer (SCNT) using genetically modified donor cells facilitates the generation of tailored pig models for biomedical research and for xenotransplantation. Up to now, SCNT is the main way to generate gene-targeted pigs, since germ line-competent pluripotent stem cells are not available for this species. In this chapter, we introduce our routine workflow for the production of genetically engineered pigs, especially focused on the genetic modification of somatic donor cells, SCNT using in vitro matured oocytes, and laparoscopic embryo transfer.

361 GROWTH HORMONE RECEPTOR MUTANT PIGS PRODUCED BY USING THE CLUSTERED REGULARLY INTERSPACED SHORT PALINDROMIC REPEATS (CRISPR) AND CRISPR-ASSOCIATED SYSTEMS IN IN VITRO-PRODUCED ZYGOTES

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) technology is considered as an efficient strategy for generating gene edited large animals, such as pigs. Compared to somatic cell nuclear transfer, this new technology offers a relatively simple way to generate mutant pigs by direct injection of RNA into the cytoplasm of zygotes. Moreover, the use of in vitro produced zygotes would provide a highly effective and practical method for the production of porcine disease models for biomedical research. Here we examined the production efficiency of growth hormone receptor (GHR) mutant pigs by the combination of the CRISPR/Cas system and in vitro produced zygotes. In vitro maturation (IVM) of oocytes was performed as described previously (Kurome et al., Meth. Mol. Biol., in press). In all experiments, the same batch of frozen sperm was used. After IVM, around 20 oocytes with expanded cumulus cells were incubated with 5 × 104 spermatozoa in a 100-μL drop of porcine fertilization medium for 7 h. In vitro-produced embryos were assessed by the ratio of normal fertilization (eggs with 2 pronuclei) and blastocyst formation at Day 7. The Cas9 mRNA and a single guide RNA, recognising a short sequence of 20 base pairs in exon 3 of the GHR gene, were injected directly into the cytoplasm of the embryos 8.5 to 9.5 h after IVF. Injected embryos were transferred laparoscopically to recipient pigs, and 86.4% (57/66) of sperm-penetrated oocytes (66/96) exhibited normal fertilization. Incidence of polyspermy was relatively low (9/66, 13.6%). Developmental ability of in vitro-produced embryos to the blastocyst stage was 17.4% (24/138). In total, 426 RNA-injected embryos were transferred into 2 recipients, one of which became pregnant and gave birth to 8 piglets. All piglets were clinically healthy and developed normally. In 3 out of 8 piglets (37.5%), mutations were introduced. Next-generation sequencing revealed that all of them were mosaics: one with a single mutation (22% wild-type/78% mutant) and 2 piglets with 2 different mutations (80% wild-type/2% mutant_1/18% mutant_2 and 94% wild-type/4% mutant_1/2% mutant_2). Four out of 5 mutations caused a frameshift in the GHR gene. Our study reports for the first time generation of GHR mutant pigs by the use of the CRISPR/Cas system in in vitro-produced zygotes. Because all GHR mutant offspring were mosaic, Cas9 activation probably occurred after the 1-cell stage under our experimental conditions. The founder animal with the highest proportion of mutant GHR alleles will be used for breeding to establish a large animal model for Laron syndrome.This work is supported by the German Research Council (TR-CRC 127).

Cofactor Strap regulates oxidative phosphorylation and mitochondrial p53 activity through ATP synthase

Metabolic reprogramming is a hallmark of cancer cells. Strap (stress-responsive activator of p300) is a novel TPR motif OB-fold protein that contributes to p53 transcriptional activation. We show here that, in addition to its established transcriptional role, Strap is localised at mitochondria where one of its key interaction partners is ATP synthase. Significantly, the interaction between Strap and ATP synthase downregulates mitochondrial ATP production. Under glucose-limiting conditions, cancer cells are sensitised by mitochondrial Strap to apoptosis, which is rescued by supplementing cells with an extracellular source of ATP. Furthermore, Strap augments the apoptotic effects of mitochondrial p53. These findings define Strap as a dual regulator of cellular reprogramming: first as a nuclear transcription cofactor and second in the direct regulation of mitochondrial respiration.

The treatment and outcome of peri-prosthetic infection of the ankle: a single cohort-centre experience of 34 cases

The treatment of peri-prosthetic joint infection (PJI) of the ankle is not standardised. It is not clear whether an algorithm developed for hip and knee PJI can be used in the management of PJI of the ankle. We evaluated the outcome, at two or more years post-operatively, in 34 patients with PJI of the ankle, identified from a cohort of 511 patients who had undergone total ankle replacement. Their median age was 62.1 years (53.3 to 68.2), and 20 patients were women. Infection was exogenous in 28 (82.4%) and haematogenous in six (17.6%); 19 (55.9%) were acute infections and 15 (44.1%) chronic. Staphylococci were the cause of 24 infections (70.6%). Surgery with retention of one or both components was undertaken in 21 patients (61.8%), both components were replaced in ten (29.4%), and arthrodesis was undertaken in three (8.8%). An infection-free outcome with satisfactory function of the ankle was obtained in 23 patients (67.6%). The best rate of cure followed the exchange of both components (9/10, 90%). In the 21 patients in whom one or both components were retained, four had a relapse of the same infecting organism and three had an infection with another organism. Hence the rate of cure was 66.7% (14 of 21). In these 21 patients, we compared the treatment given to an algorithm developed for the treatment of PJI of the knee and hip. In 17 (80.9%) patients, treatment was not according to the algorithm. Most (11 of 17) had only one criterion against retention of one or both components. In all, ten of 11 patients with severe soft-tissue compromise as a single criterion had a relapse-free survival. We propose that the treatment concept for PJI of the ankle requires adaptation of the grading of quality of the soft tissues.

Transcriptome changes in the porcine endometrium during the preattachment phase

The porcine conceptus undergoes rapid differentiation and expansion of its trophoblastic membranes between Days 11 and 12 of gestation. Concomitant with trophoblast elongation, production of conceptus estrogen, the porcine embryonic pregnancy recognition signal, increases. Conceptus attachment to the uterine surface epithelium starts after Day 13, initiating epitheliochorial placentation. To analyze the transcriptome changes in the endometrium in the course of maternal recognition of pregnancy, deep sequencing of endometrial RNA samples of Day 12 pregnant animals (n = 4) and corresponding nonpregnant controls (n = 4) was performed using RNA sequencing (RNA-Seq). Between 30 000 000 and 35 000 000 sequence reads per sample were produced and mapped to the porcine genome (Sscrofa10.2). Analysis of read counts revealed 2593 differentially expressed genes (DEGs). Expression of selected genes was validated by the use of quantitative real-time RT-PCR. Bioinformatics analysis identified several functional terms specifically overrepresented for up-regulated or down-regulated genes. Comparison of the RNA-Seq data from Days 12 and 14 of pregnancy was performed at the level of all expressed genes, the level of the DEG, and the level of functional categories. This revealed specific gene expression patterns reflecting the different functions of the endometrium during these stages (i.e., recognition of pregnancy and preparation for conceptus attachment). Genes related to mitosis, immune response, epithelial cell differentiation and development, proteolysis, and prostaglandin signaling and metabolism are discussed in detail. This study identified comprehensive transcriptome changes in porcine endometrium associated with establishment of pregnancy and could be a resource for targeted studies of genes and pathways potentially involved in regulation of this process.

Dystrophin-deficient pigs provide new insights into the hierarchy of physiological derangements of dystrophic muscle

Duchenne muscular dystrophy (DMD) is caused by mutations in the X-linked dystrophin (DMD) gene. The absence of dystrophin protein leads to progressive muscle weakness and wasting, disability and death. To establish a tailored large animal model of DMD, we deleted DMD exon 52 in male pig cells by gene targeting and generated offspring by nuclear transfer. DMD pigs exhibit absence of dystrophin in skeletal muscles, increased serum creatine kinase levels, progressive dystrophic changes of skeletal muscles, impaired mobility, muscle weakness and a maximum life span of 3 months due to respiratory impairment. Unlike human DMD patients, some DMD pigs die shortly after birth. To address the accelerated development of muscular dystrophy in DMD pigs when compared with human patients, we performed a genome-wide transcriptome study of biceps femoris muscle specimens from 2-day-old and 3-month-old DMD and age-matched wild-type pigs. The transcriptome changes in 3-month-old DMD pigs were in good concordance with gene expression profiles in human DMD, reflecting the processes of degeneration, regeneration, inflammation, fibrosis and impaired metabolic activity. In contrast, the transcriptome profile of 2-day-old DMD pigs showed similarities with transcriptome changes induced by acute exercise muscle injury. Our studies provide new insights into early changes associated with dystrophin deficiency in a clinically severe animal model of DMD.