Large Animal Research Articles

An Ovine Model Yields Histology and Gene Expression Changes Consistent with Laryngotracheal Stenosis.

Animal models for laryngotracheal stenosis (LTS) are critical to understand underlying mechanisms and study new therapies. Current animal models for LTS are limited by small airway sizes compared to human. The objective of this study was to develop and validate a novel, large animal ovine model for LTS. Sheep underwent either bleomycin-coated polypropylene brush injury to the subglottis (n = 6) or airway stent placement (n = 2) via suspension microlaryngoscopy. Laryngotracheal complexes were harvested 4 weeks following injury or stent placement. For the airway injury group, biopsies (n = 3 at each site) were collected of tracheal scar and distal normal regions, and analyzed for fibrotic gene expression. Lamina propria (LP) thickness was compared between injured and normal areas of trachea. No mortality occurred in sheep undergoing airway injury or stent placement. There was no migration of tracheal stents. After protocol optimization, LP thickness was significantly increased in injured trachea (Sheep #3: 529.0 vs. 850.8 um; Sheep #4: 933.0 vs. 1693.2 um; Sheep #5: 743.7 vs. 1378.4 um; Sheep #6: 305.7 vs. 2257.6 um). A significant 62-fold, 20-fold, 16-fold, 16-fold, and 9-fold change of COL1, COL3, COL5, FN1, and TGFB1 was observed in injured scar specimen relative to unaffected airway, respectively. An ovine LTS model produces histologic and transcriptional changes consistent with fibrosis seen in human LTS. Airway stent placement in this model is safe and feasible. This large airway model is a reliable and reproducible method to assess the efficacy of novel LTS therapies prior to clinical translation. N/A Laryngoscope, 2024.

Peri-anesthetic environmental and occupational exposure to desflurane waste anesthetic gas in a large animal veterinary hospital.

The goals were to determine the environmental levels of desflurane waste anesthetic gas and the desflurane occupational exposure of operating room staff during the anesthesia of large animal veterinary patients. Active environmental sampling was performed using single-beam infrared spectrophotometry. Passive sampling with dosimeter badges was used to measure the occupational exposure of anesthesia and operating room staff. Higher concentrations of desflurane (n = 16) were measured at all recovery timepoints relative to the concentrations measured at all locations and timepoints at the start of anesthesia and surgery (p < 0.05). Time-weighted average desflurane concentrations from dosimeter badges (n = 310) were higher for anesthesia staff than for other operating room personnel (p < 0.0001). The anesthetic recovery of large animal patients is a period of increased exposure to desflurane waste anesthetic gas for veterinary staff.

On-farm calf assessment and practical fluid therapy

Large animal practitioners are faced with varying levels of dehydration in neonatal cattle. The goal of this talk will be to describe and formulate fluid therapy plans using intravenous catheter placement in varying circumstances in an ambulatory setting. Determining route of fluid administration and intrave­nous catherization techniques will be reviewed. Following this presentation, the practitioner will be able to identify the proper use intravenous catherization and fluid therapy plans in clini­cal cases to be administered on farm.

A partnership for success: Tips for retaining associates and tips on getting the most out of your first year in practice

Large animal practices have historically had a difficult time recruiting new veterinarians into the profession. Recently, the data on retention has shown that veterinarians are leav­ing large animal practice for other sectors of clinical practice. Onboarding new associates is different in ambulatory prac­tice when compared with companion animal practice. Setting up the new associate for success will benefit both the existing practitioners as well as the new veterinarian. Spelling out ex­pectations, communicating these expectations, and flexibility will help retain the new associate. This paper gives some tips on ways to increase the retention of associates as well as tips for the new graduate veterinarian on how to make the first year in practice a success.

Uterine parasites: A clinician’s guide to pregnancy toxemia

Pregnancy toxemia in late gestation small ruminants is a com­mon condition presented to large animal practitioners. The goal of this talk will be to review the current pathophysiology and therapy plans in varying circumstances in an ambula­tory setting. Identifying risk factors and negative prognostic considerations needed to implement valuable therapeutic and preventative plans is critical. Following this presentation, the practitioner will be able to diagnosis and implement supportive therapy for pregnancy toxemia, identify risk factors and nega­tive prognostic indicators, and design preventive plans for a small ruminant herd.

A toolbox for transitioning from student to veterinarian: Setting yourself up for success and reframing failure in your first year of practice

The transition from veterinary student to private practice vet­erinarian is difficult. As a practitioner, one must put into action what was learned in veterinary school. Being a mixed large ani­mal veterinarian poses additional challenges due to the ambu­latory nature of the job. Clinical skills are important to master, and they will develop over time; but it is important to also con­sider intangible skills, such as cultivating fingertip facts, un­derstanding appropriate applications of chemical and physical restraint, honing one’s planning abilities, communicating with clients, maintaining relationships with mentors, and refram­ing failure. This presentation will highlight the experience of Dr. Dayna Locitzer as a recent graduate in mixed large animal practice and illustrate how she used these intangible skills to help with the transition from student to practitioner.

Physical and mental preparedness for large animal practice

Veterinary medicine, specifically large animal practice, is a highly physical job with inherent physical danger. Being in good physical shape and cultivating good fitness habits can de­crease our risk of injury. Physical fitness will affect our perfor­mance. For example, measurements of grip strength have been shown to be indicative of accuracy in transrectal bovine palpa­tion pregnancy diagnosis at the student level. This session also covers acute and chronic stress and tools we can use to com­plete stress cycles.

Diversity and host interaction of the gut microbiota in specific pathogen-free pigs

Pigs are widely used as animal models in various studies related to humans. The interaction between the gut microbiota and the host has significant effects on the host’s health and disease status. However, although there have been many studies investigating the pig gut microbiota, the findings have been inconsistent due to variations in rearing conditions. Interactions between the gut microbiota and host have not been fully explored in pigs. Specific pathogen-free (SPF) pigs are ideal non-primate large animals to study the interactions between the gut microbiota and the host. In this study, we performed high-throughput sequencing analysis of the gut microbiota and the gut tissue transcriptome of six SPF pigs to provide a systematic understanding of the composition, function, and spatial distribution of gut microbiota in SPF pigs. We identified significant differences in microbial diversity and functionality among different gastrointestinal tract sites. Metagenomics data analysis revealed significant differences in alpha diversity and beta diversity of microbiota in different gastrointestinal sites of SPF pigs. Additionally, transcriptomic data indicated significant differences in gene expression as well as KEGG and GO functional enrichment between the small intestine and large intestine. Furthermore, by combining microbial metagenomics and host transcriptomics analyses, specific correlations were found between gut microbiota and host genes. These included a negative correlation between the TCN1 gene and Prevotella dentalis, possibly related to bacterial metabolic pathways involving vitamin B12, and a positive correlation between the BDH1 gene and Roseburia hominis, possibly because both are involved in fatty acid metabolism. These findings lay the groundwork for further exploration of the co-evolution between the microbiota and the host, specifically in relation to nutrition, metabolism, and immunity. In conclusion, we have elucidated the diversity of the gut microbiota in SPF pigs and conducted a detailed investigation into the interactions between the gut microbiota and host gene expression. These results contribute to our understanding of the intricate dynamics between the gut microbiota and the host, offering important references for advancements in life science research, bioproduct production, and sustainable development in animal husbandry.

Porcine Model of Cerebral Ischemic Stroke Utilizing Intracortical Recordings for the Continuous Monitoring of the Ischemic Area

Purpose: Our aim was to use intracortical recording to enable the tracking of ischemic infarct development over the first few critical hours of ischemia with a high time resolution in pigs. We employed electrophysiological measurements to obtain quick feedback on neural function, which might be useful for screening, e.g., for the optimal dosage and timing of agents prior to further pre-clinical evaluation. Methods: Micro-electrode arrays containing 16 (animal 1) or 32 electrodes (animal 2–7) were implanted in the primary somatosensory cortex of seven female pigs, and continuous electrical stimulation was applied at 0.2 Hz to a cuff electrode implanted on the ulnar nerve. Ischemic stroke was induced after 30 min of baseline recording by injection of endothelin-1 onto the cortex adjacent to the micro-electrode array. Evoked responses were extracted over a moving window of 180 s and averaged across channels as a measure of cortical excitability. Results: Across the animals, the cortical excitability was significantly reduced in all seven 30 min segments following endothelin-1 injection, as compared to the 30 min preceding this intervention. This difference was not explained by changes in the anesthesia, ventilation, end-tidal CO2, mean blood pressure, heart rate, blood oxygenation, or core temperature, which all remained stable throughout the experiment. Conclusions: The animal model may assist in maturing neuroprotective approaches by testing them in an accessible model of resemblance to human neural and cardiovascular physiology and body size. This would constitute an intermediate step for translating positive results from rodent studies into human application, by more efficiently enabling effective optimization prior to chronic pre-clinical studies in large animals.

Construction of versatile fibroin/nanozyme hybrid microneedles with controllable phototherapeutic sterilization property against periodontitis

Periodontitis is a highly prevalent disease that affects up to 90% of the worldwide population. The highly dynamic oral environment, tissue-teeth “pocket” structure, and antimicrobial resistance pose challenges to periodontitis local treatments, which urgently need to be upgraded with advanced biomaterials and novel therapeutics. Herein, a new treatment strategy for periodontitis is proposed by synergistic nanozyme catalyzed phototherapeutic/chemodynamic sterilization and microneedles (MNs) in situ delivery platform. A biodegradable versatile photothermal microneedles (MN-SF/CuS) patch was constructed by the in situ growth of monodispersed ultrasmall CuS nanozyme on silk-fibroin (SF) biomolecule and then hybridization in methacrylated hyaluronic acid (HAMA). The synthetic SF/CuS nanozyme endows microneedles with amplifies phototherapeutic/chemodynamic sterilization, excellent mechanical properties, and promotes periodontal tissue regeneration. The constructed MN-SF/CuS can be conveniently and minimally invasively inserted deeply into periodontal tissue without being affected by saliva, where it delivers thermal action, reactive oxygen species, and copper to the specified depth, achieving rapid sterilization and inhibition of bacterial growth. Meanwhile, MN-SF/CuS achieves on-demand phototherapy effect without damaging surrounding normal tissues. A preclinical large animal model confirmed that the MN-SF/CuS provided excellent irreversible antibacterial activity and promoted tissue regeneration, substantially improving the tolerance and compliance of periodontal treatment.

Alginate-Encapsulated Mesenchymal Stromal Cells Improve Hind Limb Ischemia in a Translational Swine Model.

Cellular therapies have been investigated to improve blood flow and prevent amputation in peripheral artery disease with limited efficacy in clinical trials. Alginate-encapsulated mesenchymal stromal cells (eMSCs) demonstrated improved retention and survival and promoted vascular generation in murine hind limb ischemia through their secretome, but large animal evaluation is necessary for human applicability. We sought to determine the efficacy of eMSCs for peripheral artery disease-induced limb ischemia through assessment in our durable swine hind limb ischemia model. Autologous bone marrow eMSCs or empty alginate capsules were intramuscularly injected 2 weeks post-hind limb ischemia establishment (N=4/group). Improvements were quantified for 4 weeks through walkway gait analysis, contrast angiography, blood pressures, fluorescent microsphere perfusion, and muscle morphology and histology. Capsules remained intact with mesenchymal stromal cells retained for 4 weeks. Adenosine-induced perfusion deficits and muscle atrophy in ischemic limbs were significantly improved by eMSCs versus empty capsules (mean±SD, 1.07±0.19 versus 0.41±0.16, P=0.002 for perfusion ratios and 2.79±0.12 versus 1.90±0.62 g/kg, P=0.029 for ischemic muscle mass). Force- and temporal-associated walkway parameters normalized (ratio, 0.63±0.35 at week 3 versus 1.02±0.19 preligation; P=0.17), and compensatory footfall patterning was diminished in eMSC-administered swine (12.58±8.46% versus 34.85±15.26%; P=0.043). Delivery of eMSCs was associated with trending benefits in collateralization, local neovascularization, and muscle fibrosis. Hypoxia-cultured porcine mesenchymal stromal cells secreted vascular endothelial growth factor and tissue inhibitor of metalloproteinase 2. This study demonstrates the promise of the mesenchymal stromal cell secretome at improving peripheral artery disease outcomes and the potential for this novel swine model to serve as a component of the preclinical pipeline for advanced therapies.

3D-MuPPET: 3D Multi-Pigeon Pose Estimation and Tracking

AbstractMarkerless methods for animal posture tracking have been rapidly developing recently, but frameworks and benchmarks for tracking large animal groups in 3D are still lacking. To overcome this gap in the literature, we present 3D-MuPPET, a framework to estimate and track 3D poses of up to 10 pigeons at interactive speed using multiple camera views. We train a pose estimator to infer 2D keypoints and bounding boxes of multiple pigeons, then triangulate the keypoints to 3D. For identity matching of individuals in all views, we first dynamically match 2D detections to global identities in the first frame, then use a 2D tracker to maintain IDs across views in subsequent frames. We achieve comparable accuracy to a state of the art 3D pose estimator in terms of median error and Percentage of Correct Keypoints. Additionally, we benchmark the inference speed of 3D-MuPPET, with up to 9.45 fps in 2D and 1.89 fps in 3D, and perform quantitative tracking evaluation, which yields encouraging results. Finally, we showcase two novel applications for 3D-MuPPET. First, we train a model with data of single pigeons and achieve comparable results in 2D and 3D posture estimation for up to 5 pigeons. Second, we show that 3D-MuPPET also works in outdoors without additional annotations from natural environments. Both use cases simplify the domain shift to new species and environments, largely reducing annotation effort needed for 3D posture tracking. To the best of our knowledge we are the first to present a framework for 2D/3D animal posture and trajectory tracking that works in both indoor and outdoor environments for up to 10 individuals. We hope that the framework can open up new opportunities in studying animal collective behaviour and encourages further developments in 3D multi-animal posture tracking.

Generation of allogenic and xenogeneic functional muscle stem cells for intramuscular transplantation.

Satellite cells, the stem cells of skeletal muscle tissue, hold a remarkable regeneration capacity and therapeutic potential in regenerative medicine. However, low satellite cell yield from autologous or donor-derived muscles hinders the adoption of satellite cell transplantation for the treatment of muscle diseases, including Duchenne muscular dystrophy (DMD). To address this limitation, here we investigated whether satellite cells can be derived in allogeneic or xenogeneic animal hosts. First, injection of CRISPR/Cas9-corrected mouse DMD-induced pluripotent stem cells (iPSCs) into mouse blastocysts carrying an ablation system of host satellite cells gave rise to intraspecies chimeras exclusively carrying iPSC-derived satellite cells. Furthermore, injection of genetically corrected DMD-iPSCs into rat blastocysts resulted in the formation of interspecies rat-mouse chimeras harboring mouse satellite cells. Remarkably, iPSC-derived satellite cells or derivative myoblasts produced in intraspecies or interspecies chimeras restored dystrophin expression in DMD mice following intramuscular transplantation, and contributed to the satellite cell pool. Collectively, this study demonstrates the feasibility of producing therapeutically competent stem cells across divergent animal species, raising the possibility of generating human muscle stem cells in large animals for regenerative medicine purposes.

Genome editing: An insight into disease resistance, production efficiency, and biomedical applications in livestock.

One of the primary concerns for the survival of the human species is the growing demand for food brought on by an increasing global population. New developments in genome-editing technology present promising opportunities for the growth of wholesome and prolific farm animals. Genome editing in large animals is used for a variety of purposes, including biotechnology to improve food production, animal health, and pest management, as well as the development of animal models for fundamental research and biomedicine. Genome editing entails modifying genetic material by removing, adding, or manipulating particular DNA sequences from a particular locus in a way that does not happen naturally. The three primary genome editors are CRISPR/Cas 9, TALENs, and ZFNs. Each of these enzymes is capable of precisely severing nuclear DNA at a predetermined location. One of the most effective inventions is base editing, which enables single base conversions without the requirement for a DNA double-strand break (DSB). As reliable methods for precise genome editing in studies involving animals, cytosine and adenine base editing are now well-established. Effective zygote editing with both cytosine and adenine base editors (ABE) has resulted in the production of animal models. Both base editors produced comparable outcomes for the precise editing of point mutations in somatic cells, advancing the field of gene therapy. This review focused on the principles, methods, recent developments, outstanding applications, the advantages and disadvantages of ZFNs, TALENs, and CRISPR/Cas9 base editors, and prime editing in diverse lab and farm animals. Additionally, we address the methodologies that can be used for gene regulation, base editing, and epigenetic alterations, as well as the significance of genome editing in animal models to better reflect real disease. We also look at methods designed to increase the effectiveness and precision of gene editing tools. Genome editing in large animals is used for a variety of purposes, including biotechnology to improve food production, animal health, and pest management, as well as the development of animal models for fundamental research and biomedicine. This review is an overview of the existing knowledge of the principles, methods, recent developments, outstanding applications, the advantages and disadvantages of zinc finger nucleases (ZFNs), transcription-activator-like endonucleases (TALENs), and clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR/Cas 9), base editors and prime editing in diverse lab and farm animals, which will offer better and healthier products for the entire human race.

Long-term continuous monitoring of arrhythmias in pigs with insertable cardiac monitors.

Arrhythmia detection is essential when assessing the safety of novel drugs and therapies in preclinical studies. Many short-term arrhythmia monitoring methods exist, including non-invasive ECG and Holter. However, there are no reliable, long-term, non-invasive, or minimally invasive methods for cardiac arrhythmia follow-up in large animals that allows free movement with littermates. A long follow-up time is needed when estimating the impact of long-lasting drugs or therapies, such as gene therapy. We evaluated the feasibility and performance of insertable cardiac monitors (ICMs) in pigs for minimally invasive, long-term monitoring of cardiac arrhythmias that allows free movement and species-specific behavior. Multiple implantation sites were tested to assess signal quality. ICMs recognized reliably many different arrhythmias but failed to detect single extrasystoles. They also over-diagnosed T-waves, resulting in oversensing. Muscle activity and natural startles of the animals caused noise, leading to a heterogeneous signal requiring post-recording evaluation. In spite of these shortcomings, the ICMs showed to be very useful for minimally invasive long-term monitoring of cardiac rhythm in pigs.

231 Anomaly detection for breed purity analysis

Abstract Recent advancements in genotyping technologies have revolutionized our ability to estimate breed composition in pigs. The classic compositional regression used for this purpose requires a multibreed panel to detect crossbreeding and its application is limited to breed in the panel. In this study, we presented a protocol based on classic anomaly detection algorithms that use single breed panels to detect crossbreeding. By utilizing these methods, we aim to identify and assess breed outliers within large pig genotype panels. The dataset consisted of 44,616 SNP genotypes recorded in purebred Large White, Landrace, Duroc, Pietrain (n = 2,000 from each breed) and 1,010 crossbred pigs (50% Pietrain, 25% Large White, 25% Landrace). Large White pigs (n = 1,500) were randomly selected as reference set. The remaining 500 Large White pigs, other purebred pigs, crossbred pigs, and simulated crossbred animals of known proportion of Large White segments were test sets. We applied two anomaly detection methods: 1) Principal Component Analysis (PCA) and 2) deep learning autoencoders (AE). For PCA the top 600 eigen vectors capturing 85% cumulative proportion of variance in the reference set were selected. Test set genotypes were projected onto the principal components and then they were reconstructed to the full genotype set. For AE, we used a previously published sparse convolutional denoising autoencoder (SCDA) that consisted of two main components: an encoder and a decoder. The encoder compressed the genotypes to 128 components and the decoder reconstructed the set to the original 44,616 SNP. We utilized the model trained in the reference set to reconstruct test set genotypes of the same breed, of alternative breed and of crossbred. Accuracy of reconstruction of genotypes was computed using correlation and mean square error. The proportion of rejected genotypes was used to assess the ability of anomaly detection algorithms to detect crossbreeding. For each criterion, the threshold to reject genotypes was selected as the value at which 5% of Large White animals were rejected (specificity = 0.95). Results are summarized in (Table 1). PCA provided better properties to detect genomic outliers compared with AE. PCA anomaly detection was able to detect purebred individuals with probability 1.0. It also detected over 90% of crossbred individuals that were 75% Large Whites. Crossbred with a lower proportion of Large White genomic segments were detected with P &amp;lt; 0.5. Anomaly detection algorithms can be used to detect genomic outliers but with relatively low sensitivity. More work is needed to optimize these algorithms for breeding applications.

226 Oral and rumen microbiome characterization to predict host phenotypes

Abstract Studies have utilized rumen microbiome composition and function to predict animal phenotypes. Yet, sample collection for rumen microbial community analysis can be difficult and invasive and hinders the possibility of sampling large animal populations. In this study, we investigated the development of the bovine rumen microbiome over time, to identify the potential of the oral microbiome as a proxy for the rumen microbiome, and to test the applicability of using the oral microbiome for predicting phenotypes in beef cattle. We employed 16S rRNA amplicon sequencing to characterize the rumen and oral bacterial community structure over time and collected both birth and weaning weights in a population of 220 animals. Our findings show that both the oral and rumen microbiomes are established early, and a significant portion of the taxa persists even after weaning. We identified a group of core successional species shared between the oral and rumen bacterial communities, which are established early and persist over time. The oral bacterial community was dominated by phyla Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteria, while the rumen bacterial community was dominated by phyla Bacteroidota, Firmicutes, Verrucomicrobia, Fibrobacteria, and Spirochaetota. Furthermore, we observed that 38% of Amplicon Sequence Variants (ASVs) were shared between the oral and rumen microbiomes at 50 to 120 d of age. At 170 to 240 d of age, 37% of ASVs were shared, and at 295 to 365 d, 33% of ASVs were shared. Finally, at 400 to 468 d, 21% of ASVs were shared. Based on weighted Unifrac analysis, notable differences and distinct clustering was observed between oral and rumen microbiome communities at different sampling ages (P = 0.001; R2 = 0.50969, 50 to 120; P = 0.001; R2 = 0.66247, 170 to 240; P = 0.001; R2 = 0.62036, 295 to 365; and P = 0.001, R2 = 0.66559, 400 to 468). Microbiability estimates varied across different stages and microbial environments. For the oral bacterial community at 50 to 120, the estimates were 0.029%, 0.032%, 0.029%, and 0.028% for birth weight, weaning weight, intramuscular fat (IMF), and ribeye area (REA), respectively. In contrast, the rumen microbiome exhibited microbiability values of 0.034%, 0.058, 0.059, and 0.069% for birth weight, weaning weight, IMF, and REA respectively during the same period. As the animal aged the microbiability increased. At 170 to 240, oral microbiomes showed microbiability estimates of 0.051%, 0.060%, 0.069%, and 0.21% for birth weight, weaning weight, IMF, and REA respectively. In comparison, the rumen microbiome displayed greater microbiability estimates of 0.12%, 0.124%, 0.20%, and 0.26% for birth weight, weaning weight, IMF, and REA respectively. In conclusion, the oral microbiome is not a good proxy for the rumen microbiome composition; however, there is potential to use the oral microbiome for phenotype prediction.

Advances in preclinical surgical therapy of cardiovascular diseases.

Cardiovascular disease is the most common cause of death worldwide, resulting in millions of deaths annually. Currently, there are still some deficiencies in the treatment of cardiovascular diseases. Innovative surgical treatments are currently being developed and tested in response to this situation. Large animal models, which are similar to humans in terms of anatomy, physiology, and genetics, play a crucial role in connecting basic research and clinical applications. This article reviews recent preclinical studies and the latest clinical advancements in cardiovascular disease based on large animal models, with a focus on targeted delivery, neural regulation, cardiac remodeling, and hemodynamic regulation. It provides new perspectives and ideas for clinical translation and offers new methods for clinical treatment.

A rabbit osteochondral defect (OCD) model for evaluation of tissue engineered implants on their biosafety and efficacy in osteochondral repair

Osteochondral defect (OCD) is a common but challenging condition in orthopaedics that imposes huge socioeconomic burdens in our aging society. It is imperative to accelerate the R&amp;amp;D of regenerative scaffolds using osteochondral tissue engineering concepts. Yet, all innovative implant-based treatments require animal testing models to verify their feasibility, biosafety, and efficacy before proceeding to human trials. Rabbit models offer a more clinically relevant platform for studying OCD repair than smaller rodents, while being more cost-effective than large animal models. The core-decompression drilling technique to produce full-thickness distal medial femoral condyle defects in rabbits can mimic one of the trauma-relevant OCD models. This model is commonly used to evaluate the implant’s biosafety and efficacy of osteochondral dual-lineage regeneration. In this article, we initially indicate the methodology and describe a minimally-invasive surgical protocol in a step-wise manner to generate a standard and reproducible rabbit OCD for scaffold implantation. Besides, we provide a detailed procedure for sample collection, processing, and evaluation by a series of subsequent standardized biochemical, radiological, biomechanical, and histological assessments. In conclusion, the well-established, easy-handling, reproducible, and reliable rabbit OCD model will play a pivotal role in translational research of osteochondral tissue engineering.

Development of a large animal orthotopic intestinal transplantation model with long-term survival for study of immunologic outcomes

IntroductionIntestinal transplantation (ITx) is the last remaining therapy for patients with intestinal failure once parenteral nutrition is no longer an option, however its use is limited by immunological complications, including high rates of rejection and morbidity associated with immunosuppression, such as infection and malignancy. We aimed to develop a large animal model of ITx with which to study the immune response to ITx and to design and test tolerance induction regimens.MethodsLearning from prior complications, we developed and progressively improved both surgical methods for the donor and recipient as well as postoperative management strategies. Methods of stoma generation, bowel positioning, vessel preparation, and fluid management were optimized. The immunosuppression strategy mirrored our clinical regimen.ResultsAs a result of our modifications, results improved from survival less than 1 month to consistent long-term survival with good graft function. We review several techniques that were developed to avoid pitfalls that were encountered, which can be used to optimize outcomes in this model.DiscussionAchieving long-term survival after swine orthotopic ITx permits immunological analysis and pre-clinical trials in a large animal model of ITx.