Swine as models in biomedical research and toxicology testing

Dynamic Assessment of Local Abdominal Tissue Concentrations of Cisplatin During a HIPEC Procedure: Insights from a Porcine Model

BACKGROUND

This study aimed to establish a feasible large porcine model for dynamic assessment of cisplatin concentrations in carcinomatosis-relevant abdominal tissues using microdialysis during and after HIPEC combined with cytoreductive surgery.

METHODS

In total, eight pigs underwent open abdominal cytoreductive surgery followed by HIPEC. Microdialysis was employed for dynamic cisplatin concentration sampling in abdominal organs and tissue. Cisplatin dialysate concentrations were analyzed using the UPLC-MS/MS method. STATA (version 18.0) was used to perform a two-compartment model with a zero-order distribution to analyze pharmacokinetic parameters.

RESULTS

Detectable cisplatin concentrations in the evaluated target tissues persisted for at least 6 h post-HIPEC. Higher concentrations were found in superficial tissues; however, the difference was not statistically significant. The cisplatin concentrations were comparable for the stomach, rectum, and liver but higher in the peritoneal lining of the abdominal wall, with the lowest median average peak concentration (Cmax) in the rectum (0.50 µg/mL) and the highest median Cmax in the peritoneum (2.80 µg/mL). No statistically significant differences in cisplatin area under the curve from time zero to the time of the last sample collection (AUC0-last) were found between any of the abdominal compartments except the peritoneal lining of the abdominal wall, which was significantly higher compared with most of the other abdominal tissues {smallest difference; peritoneum 1/liver 2; 1.96 [95% confidence interval (CI) 0.90; 4.26, P = 0.09] and largest difference; peritoneum 3/rectum profound; 4.60 [95% CI 1.94; 10.90, P = 0.001]}.

CONCLUSIONS

Our investigation revealed comparable cisplatin concentrations across abdominal organ surfaces, except higher concentrations in the peritoneal lining of the abdominal wall than in the stomach, rectum, and liver. This model holds promise for future research into HIPEC interventions and anticancer effectiveness.

MSTN gene knockout suppresses the activation of lung fibroblasts through the inhibition of the Smad/AKT signaling pathway, thereby ameliorating pulmonary fibrosis

Pulmonary fibrosis is a chronic interstitial lung disease characterized by irreversible, progressive lung scarring and eventual respiratory failure. Fibroblast activation plays a crucial role in the progression of pulmonary fibrosis. Transforming growth factor-β (TGF-β) signaling contributes to pulmonary fibrosis by regulating lung fibroblast activation. Currently, most studies focus on TGF-β1 regulatory effects on fibroblasts, with limited reports on myostatin (MSTN), another member of the same family. This study used MSTN gene knockout (MSTN-/-) boars as animal models to explore MSTN regulatory effects on pulmonary fibrosis by modulating lung fibroblast activation. Studies have demonstrated that MSTN is significantly upregulated in the lungs during pulmonary fibrosis, promoting the activation of downstream Smad and AKT signaling pathways. MSTN-/- inhibits alveolar collapse and interstitial thickening in pulmonary fibrosis pigs and suppresses downstream Smad and AKT signaling. In vitro experiments showed that MSTN-/- inhibits lung fibroblast activation by blocking Smad/AKT signaling. These findings suggest that the MSTN/Smad/AKT signaling axis suppresses pulmonary fibrosis by inhibiting lung fibroblast activation, indicating that MSTN could be a potential therapeutic target for pulmonary fibrosis.

Intramuscular vasopressin: A feasible intervention for prehospital hemodynamic stabilization in porcine hemorrhagic shock and whole blood transfusion

BACKGROUND

Hemorrhagic shock is the leading cause of preventable prehospital trauma deaths. While arginine vasopressin (AVP) is a well-known hormone with vasopressor effects, its potential for hemodynamic stabilization in prehospital hemorrhagic shock remains underexplored. This study investigated intramuscular (IM) AVP during hemorrhagic shock to evaluate its feasibility and efficacy for prehospital trauma resuscitation.

STUDY DESIGN AND METHODS

In this randomized, controlled, double-blinded trial, 16 swine (mean [standard deviation, SD] weight 56.2 [3.8] kg) underwent a mean (SD) 1205 (124) mL Class III hemorrhage for 45 min and 45 min of hypotension. Animals were randomized to 40 U IM AVP (n = 7) or NaCl (n = 9), followed immediately by 500 mL autologous whole blood transfusion over 30 and 120 min posttransfusion monitoring of hemodynamic, respiratory, and metabolic parameters.

RESULTS

AVP increased systolic arterial pressure 30 min after administration (mean increase: 33.5 mmHg vs. 7.5 mmHg, p < 0.05) and improved cardiac index (CI) 90 min after AVP (mean increase: 19.2% vs. 4.1% decrease, p < 0.05) and stroke volume (mean increase: 37.0% vs. 1.0%, p < 0.05). These effects normalized by 120 min. AVP did not affect respiratory parameters, oxygen delivery, or consumption. Increased serum AVP confirmed systemic uptake (median 68.7 pg/mL vs. 10.0 pg/mL in controls, p < 0.05).

CONCLUSION

IM AVP, combined with whole blood transfusion, transiently stabilized hemodynamics by increasing systemic vascular resistance index, systolic blood pressure, and CI without respiratory compromise. These findings suggest that IM AVP may be a viable intervention for prehospital resuscitation of severe hemorrhagic shock, offering vital short-term stabilization to facilitate transport to definitive care.

Optimizing feasibility and reproducibility of pacing-induced heart failure model in pigs

Heart failure (HF) is a major health problem worldwide, where gene therapy could provide promising new approaches for effective treatments. Pacing-induced tachycardiomyopathy in large animals is a well-established HF model but it suffers from poor tolerability and variable outcomes. In this study, we developed a reproducible, feasible, and tolerable pacing protocol for HF gene therapy studies. Single-chamber pacemakers were implanted in pigs. HF development was monitored with trans-thoracic echocardiography (TTE), invasive left-ventricular (LV) pressure measurements, and a treadmill exercise stress test. Four weeks of rapid right-ventricular pacing at over 200 bpm produced a significant impairment of cardiac function (LV stroke volume index 11.8 ± 1.22 (mL/m2) at day 28 vs 18.1 ± 0.99 (mL/m2) at day 0, p < 0.01, mean ± SEM, paired t-test), and reduced exercise capacity (- 14 ± 3.19% change in 15-min treadmill exercise stress test at day 28 compared to day 0, p = 0.02, mean ± SEM, paired t-test). Further pacing at 150 bpm was a well-tolerated way to prevent functional recovery. Good tolerability and reproducibility of the pacing were achieved by a gradual increase in the pacing rate, no higher than 200 bpm. Global left ventricular adenoviral (Ad) gene transfer via cardiac veins was performed after three weeks of rapid pacing and found well-tolerated and feasible. In this study, the protocols of pacemaker implantation and TTE in pigs were also optimized. In conclusion, the optimized pacing protocol considerably increases the feasibility and reproducibility of the pacing-induced HF for testing of new therapeutic applications.

Effects of Endotracheal Weight-Based Epinephrine on Pharmacokinetics and Survival in Swine With a Cardiac Arrest

BACKGROUND

The aims of this study were to compare concentration maximum (Cmax), time to Cmax, area under the curve, mean concentration over 4 minutes, and frequency and time to return of spontaneous circulation (ROSC) by group.

METHODS

This was a prospective, experimental study using swine. In total, 40 pigs (n = 8 per group) were assigned as follows: 0.1 mg/kg endotracheal (ET) tube, 1 mg intravenous (IV), 2 mg ET, Cardio Pulmonary Resuscitation (CPR) + defibrillation (CPR + defib), and CPR-Only. Pigs were placed in arrest for 2 minutes, CPR was then initiated for 2 minutes, and epinephrine was then administered and repeated every 4 minutes or until ROSC. Blood samples were collected over 4 minutes. Defibrillation was initiated at 3 minutes and continued every 2 minutes for 30 minutes or until ROSC. CPR + defib and CPR-Only Groups served as controls. The CPR + defib Group had defibrillations but did not receive epinephrine. The CPR-Only Group did not receive defibrillations or epinephrine.

RESULTS AND CONCLUSIONS

The Cmax and area under the curve were significantly higher in the IV Group compared to the 0.1 mg/kg ET Group (P < .05). The time to Cmax was significantly longer in the 0.1 mg/kg Group than the 1 mg IV Group (P = .03). The mean concentration of the 1 mg IV Group was higher than the 0.1 mg/kg ET Group until 180 and 240 seconds. There was no significant difference between the groups relative to time to ROSC (P > .05). Return of spontaneous circulation frequencies were: 0.1 mg/kg ET Group (7 of 8); 1 mg IV Group (5 of 8); and 2 mg ET Group (1 of 8), and both CPR + defib and CPR-Only (0 out of 8). This study challenges the current guidelines relative to ET epinephrine administration. Based on our ROSC data, the 0.1 mg/kg dose of epinephrine by ET should be used as a first-line intervention.

Biofabrication of small-diameter vascular graft with acellular human amniotic membrane: a proof-of-concept study in pig

Expanded polytetrafluoroethylene (ePTFE) grafts are Food and Drug Administration approved and effective for large vessel surgeries but face challenges in smaller vessels (Inner Diameter, ID ⩽ 6 mm) due to reduced blood flow and higher risks of thrombosis, stenosis, and infection. This study developed a vascular graft with an ID of 6 mm from decellularized human amniotic membrane (DAM graft) and compared its performance to ePTFE grafts in a porcine carotid artery model for one month. DAM grafts retained key extracellular matrix structures and mechanical properties post-decellularization, with customizable layers and stiffness to meet specific clinical needs. DAM grafts demonstrated successful carotid artery replacement, showing good surgical feasibility, patency, and post-operative recovery in all animals. In contrast to ePTFE grafts, which exhibited significant neointimal hyperplasia (NIH), poor endothelialization, and inflammation, DAM grafts displayed organized endothelial coverage, smooth muscle alignment, and reduced inflammation, minimizing NIH, thrombosis, and graft failure. These findings position DAM grafts as a promising alternative to synthetic grafts, especially for small-diameter applications. Future research should focus on improving endothelialization, exploring molecular mechanisms, and assessing long-term outcomes to further optimize DAM grafts for clinical use.

Evaluation of a translational swine model of respiratory hypersensitivity induced by exposure to Phleum pratense pollen allergens

Introduction

Asthma is a disease characterized by chronic inflammation of the airway mucosa that causes tissue remodeling and a reversible decrease in airflow. The causative agent of asthma is still unknown; however, several studies have shown that environmental factors such as allergens present in pollens are involved. This project's objective was to develop and evaluate a model of respiratory hypersensitivity in Vietnamese minipigs, which is closer in many aspects to humans than rodents, using Phleum pratense allergenic pollen extract.

Methods

In this hypersensitivity model, human-like signs were observed during a challenge with the allergens. Intradermal and passive anaphylaxis tests confirmed that specific IgE mediated the response.

Results

Significant changes in lung tissue remodeling, high levels of serum allergen-specific IgA, IgG, and to a lesser extent IgE were found in the sensitized pigs, which could favor tolerance and pathogenesis. However, since chronic pathology did not develop, elevated levels of cytokines were not proven.

Discussion

This work demonstrated that the immunization protocol in this experimental model can induce a type I respiratory hypersensitivity-like response mediated by antigen-specific IgE, with pathophysiological similarities to those of humans and prospective for translational basic and applied research.

First-time cefuroxime target tissue concentrations in long-lasting spine surgery: Continuous evaluation after repeated weight-dosed administrations

AIMS

Antimicrobial prophylaxis is central in preventing postoperative spine infections, yet knowledge on clinical target spine tissue concentrations remain limited. Current dosing regimens often involve fixed doses based on empirical knowledge, surrogate measures, non-clinical evidence and methodology of variying quality. The objective was to continuously evaluate peri- and postoperative cefuroxime target tissue concentrations in long-lasting spine surgery.

METHODS

Twenty patients scheduled for spine deformity surgery with hypotensive anaesthesia completed the study. Weight-dosed cefuroxime was administered intravenously (20 mg/kg) to all patients preoperativey and after 4 h. Microdialysis probes were placed in vertebral bone (intraoperative sampling), paravertebral muscle, subcutaneous tissue and profoundly/superficially in the wound. Microdialysates and plasma samples were obtained for up to 12 h. The primary endpoint was the time with cefuroxime concentrations above the minimal inhibitory concentration for Staphylococcus aureus of 4 μg/mL as a percentage (%fT>MIC4).

RESULTS

The median cefuroxime %fT>MIC4 (range) of patients' individual surgery time was 100% (100-100) in all investigated tissues and plasma. Median cefuroxime %fT>MIC4 (range) in the first dosing interval was 93% (93-93) in vertebral bone, paravertebral muscle and subcutaneous tissue, and 100% (99-100) in plasma. Median cefuroxime %fT>MIC4 (range) in the second dosing interval was 85% (52-100) in paravertebral muscle, 94% (52-100) in subcutaneous tissue, 99% (71-100) in the profound wound, 100% (72-100) in the superficial wound, and 70% (42-100) in plasma.

CONCLUSIONS

Repeated weight-dosed intravenous cefuroxime administrations (20 mg/kg) provided homogenous and sufficient intraoperative target tissue exposure of cefuroxime (100% fT>MIC4) in long-lasting spine surgery with hypotensive anaesthesia and postoperative exposure (>4 μg/mL) for 5.5-7.5 h.

Biocompatibility of Water-Dispersible Pristine Graphene and Graphene Oxide Using a Close-to-Human Animal Model: A Pilot Study on Swine

Graphene-based materials (GBMs) are of considerable interest for biomedical applications, and the pilot study on the toxicological and immunological impact of pristine graphene (GR) and graphene oxide (GO) using swine as a close-to-human provides valuable insights. First, ex vivo experiments are conducted on swine blood cells, then GBMs are injected intraperitoneally (i.p.) into swine. Hematological and biochemical analyses at various intervals indicate that neither GO nor GR cause systemic inflammation, pro-coagulant responses, or renal or hepatic dysfunction. Importantly, no systemic toxicity is observed. Analysis of a panel of 84 immune-related genes shows minimal impact of GO and GR. The animals are sacrificed 21 days post-injection, and transient absorption imaging and Raman mapping show the presence of GO and GR in the mesentery only. Histological evaluation reveals no signs of alterations in other organs. Thus, clusters of both materials are detected in the mesentery, and GO aggregates are surrounded only by macrophages with the formation of granulomas. In contrast, modest local reactions are observed around the GR clusters. Overall, these results reveal that i.p. injection of GBMs resulted in a modest local tissue reaction without systemic toxicity. This study, performed in swine, provides essential guidance for future biomedical applications of graphene.

Gap-induced inhibition of the post-auricular muscle response in miniature pigs

BACKGROUND

Tinnitus, a persistent condition that significantly impairs the quality of life for patients, poses a substantial burden on society. Owing to its complex and poorly understood pathogenesis, the development of effective animal models for tinnitus is imperative to enhance our comprehension of this condition.

OBJECTIVES

The present study aims to establish a large animal model to delineate the mechanisms underlying the onset of tinnitus.

MATERIALS AND METHODS

For the first time, we conducted a comparative analysis of the Post-Auricular Muscle Response (PAMR) and the Eye Blink Response (EBR) in miniature pigs, demonstrating their utility in manifesting Gap Prepulse Inhibition of the Acoustic Startle (GPIAS). Subsequently, we employed the gap-induced inhibition of PAMR to ascertain evidence of tinnitus following noise exposure.

RESULTS AND CONCLUSION

Through comparing the efficacy of PAMR and EBR in GPIAS detection, we have substantiated that PAMR provides a stable and objective reflection of GPIAS. Consequently, PAMR emerges as a reliable method for measuring GPIAS in miniature pigs. Furthermore, the behavioral paradigm of gap-induced inhibition of PAMR successfully identified behavioral evidence of tinnitus subsequent to noise exposure.

Distribution and Neurochemical Characterization of Dorsal Root Ganglia (DRG) Neurons Containing Phoenixin (PNX) and Supplying the Porcine Urinary Bladder

The present study was designed to establish the distribution pattern and immunohistochemical characteristics of phoenixin-immunoreactive (PNX-IR) urinary bladder afferent neurons (UB-ANs) of dorsal root ganglia (DRG) in female pigs. The sensory neurons investigated were visualized with a retrograde tracing method using Fast Blue (FB), while their chemical profile(s) were identified using double-labelling immunohistochemistry with antibodies against PNX, calcitonin gene-related peptide (CGRP), calretinin (CRT), galanin (GAL), neuronal nitric oxide synthase (nNOS), pituitary adenylate cyclase-activating polypeptide (PACAP), somatostatin (SOM) and substance P (SP). Nearly half of UB-ANs contained PNX (45%), and the majority of such encoded sensory neurons were small in size (66%). The most numerous subpopulation of FB/PNX-positive neurons were those containing SP (71%). CGRP, GAL or PACAP were observed in a smaller number of PNX-containing UB-ANs (50%, 30% or 25%, respectively), while PNX-positive sensory neurons simultaneously immunostained with nNOS, CRT or SOM constituted a small fraction of all retrogradely-traced DRG neurons (DRGs; 15%, 6.5% or 1.6%, respectively). Furthermore, the numerical analysis of neurons expressing individual antigens, performed on 10 μm-thick consecutive sections, allows us to state that studied sensory neurons can be classified as neurons "coded" either by the simultaneous presence of SP/CGRP/PACAP/GAL, SP/CGRP/PACAP/NOS, SP/CGRP/PACAP/NOS/CRT and/or SP/CGRP/GAL/PACAP, or, as a separate population, those capable of SOM synthesis (SP/CGRP/SOM/PACAP/GAL-positive neurons). The present study reveals the extensive expression of PNX in the DRGs supplying to the urinary bladder, indicating an important regulatory role of this neuropeptide in the control of physiological function(s) of this organ.

Effect of repeated bolus and continuous doxorubicin administration on bone and soft tissue concentrations- a randomized study evaluated in a tumour-free porcine model

PURPOSE

The aim of this study was to evaluate plasma and bone- and soft-tissue concentrations of doxorubicin following two administrations of either bolus or continuous infusion administered at a three-week interval. The achievement of adequate concentration at target sites is believed to be positively correlated to effect, and it has been suggested that concentrations are affected by the number of administrations.

METHODS

Eighteen female pigs were included in the study and randomized into two groups of nine receiving either a bolus or continuous infusion. The animals received a dosage of 2 mg/kg on day 1 and on day 22. From day 1 to 10, doxorubicin concentrations, as well as kidney and liver function, were monitored with plasma samples (total concentrations). On day 22, doxorubicin was measured in plasma samples (total concentration) and microdialysates (unbound concentrations) from subcutaneous tissue, muscle, synovial fluid of the knee joint, cancellous bone, and intravenously.

RESULTS

On day 22, the pharmacokinetic profiles were comparable between the two groups except for plasma AUC0 - 12 h, which was higher after continuous infusion, and intravenous Cmax, which was higher after bolus infusion. Bone- and soft tissue concentrations were below 0.10 µg/mL. Except for mean plasma (total) concentration at the 6 h timepoint on day 1 and 22 in the continuous group, which was higher after the first administration (p = 0.037), no differences in plasma concentrations were found between the two administrations.

CONCLUSION

Low mean tissue doxorubicin concentrations and similar pharmacokinetic profiles were found between the bolus and continuous infusion groups. Thus, similar anti-neoplastic efficacy is to be expected with both administration types.

Multi-tool copy number detection highlights common body size-associated variants in miniature pig breeds from different geographical regions

BACKGROUND

Copy number variations (CNVs) represent a common and highly specific type of variation in the genome, potentially influencing genetic diversity and mammalian phenotypic development. Structural variants, such as deletions, duplications, and insertions, have frequently been highlighted as key factors influencing traits in high-production pigs. However, comprehensive CNV analyses in miniature pig breeds are limited despite their value in biomedical research.

RESULTS

This study performed whole-genome sequencing in 36 miniature pigs from nine breeds from America, Asia and Oceania, and Europe. By employing a multi-tool approach (CNVpytor, Delly, GATK gCNV, Smoove), the accuracy of CNV identification was improved. In total, 34 homozygous CNVs overlapped with exonic regions in all samples, suggesting a role in expressing specific phenotypes such as uniform growth patterns, fertility, or metabolic function. In addition, 386 copy number variation regions (CNVRs) shared by all breeds were detected, covering 33.6 Mb (1.48% of the autosomal genome). Further, 132 exclusive CNVRs were identified for American breeds, 47 for Asian and Oceanian breeds, and 114 for European breeds. Functional enrichment analysis revealed genes within the common CNVRs involved in body height determination and other growth-related parameters. Exclusive CNVRs were located in the region of genes enriched for lipid metabolism in American minipigs, reproductive traits in Asian and Oceanian breeds, and cardiovascular features and body height in European breeds. In the selected groups, quantitative trait loci associated with body size, meat quality, reproduction, and disease susceptibility were highlighted.

CONCLUSION

This investigation of the CNV landscape of minipigs underlines the impact of selective breeding on structural variants and its role in the development of specific breed phenotypes across geographical areas. The multi-tool approach provides a valuable resource for future studies on the effects of artificial selection on livestock genomes.

Expression of recombinant swine ferritin heavy chain with enhanced solubility in Escherichia coli and simplified purification of ferritin nanoparticles

Ferritin is a versatile biomolecule used in various medical applications such as drug delivery, vaccines, biological imaging, and diagnostics. The purity and concentration of the ferritin nanoparticles are crucial for achieving excellent outcomes. In this study, we expressed and purified the recombinant swine ferritin heavy chain (rsFTH) as a new candidate for recombinant ferritin nanoparticles. We generated two types of plasmids that can express rsFTH in mammalian and prokaryotic systems. The myc-tagged rsFTH expressed in the mammalian system was purified and ferritin nanoparticles were validated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). A prokaryotic expression system was used to produce rsFTH on a large scale. Protein expression was optimized in Escherichia coli BL21 under varying temperatures and IPTG conditions, and solubility was enhanced by incubation at 25 °C for 18-22 h in auto-induction media, resulting in approximately >50 % protein content in the soluble fraction compared with the pellet. Protein purification was achieved using His-tag affinity chromatography and dialysis with Tris-HCl buffer, yielding adequately pure rsFTH without any apparent protein aggregates. SDS-PAGE and Western blot analysis confirmed the expected molecular weight of rsFTH, and Native-PAGE demonstrated polymerization into higher molecular weight forms. Particle size analysis of purified rsFTH revealed a mean diameter of 15.5 nm, with transmission electron microscopy (TEM) imaging confirming spherical ferritin particles with an iron core. These results suggest that rsFTH can be efficiently expressed and purified in both mammalian and bacterial systems, and has potential applications in nanotechnology and biotechnology.

Single-cell transcriptomics predict novel potential regulators of acute epithelial restitution in the ischemia-injured intestine

Intestinal ischemic injury damages the epithelial barrier and predisposes patients to life-threatening sepsis unless that barrier is rapidly restored. There is an age dependency in intestinal recovery in that neonates are the most susceptible to succumb to disease of the intestinal barrier compared with older patients. We have developed a pig model that demonstrates age-dependent failure of intestinal barrier restitution in neonatal pigs, which can be rescued by the direct application of juvenile pig mucosal tissue, but the mechanisms of rescue remain undefined. We hypothesized that by identifying a subpopulation of restituting enterocytes by their expression of cell migration transcriptional pathways, we can then predict novel upstream regulators of age-dependent restitution response programs. Superficial mucosal epithelial cells from recovering ischemic jejunum of juvenile pigs underwent single-cell transcriptomics and the predicted upstream regulator, colony stimulating factor-1 (CSF-1), was interrogated in our model. A subcluster of absorptive enterocytes expressed several cell migration pathways key to restitution. Differentially expressed genes in this subcluster predicted their upstream regulation by colony stimulating factor-1 (CSF-1). We validated age-dependent induction of CSF-1 by ischemia and documented that CSF-1 and colony-stimulating factor-1 receptor (CSF1R) co-localized in ischemic juvenile, but not neonatal, wound-adjacent epithelial cells and in the restituted epithelium of juveniles and rescued neonates. Furthermore, the CSF-1 blockade reduced restitution in vitro, and CSF-1 improved barrier function in injured neonatal pigs in preliminary ex vivo experiments. These studies validate an approach to inform potential novel therapeutic targets, such as CSF-1, to improve outcomes in neonates with intestinal injury in a unique pig model.NEW & NOTEWORTHY These studies validate an approach to identify and predict upstream regulation of restituting epithelium in a unique pig intestinal ischemic injury model. Identification of potential molecular mediators of restitution, such as CSF-1, will inform the development of targeted therapeutic interventions for the medical management of patients with ischemia-mediated intestinal injury.

Intradermally injected abobotulinumtoxinA administered preemptively before surgery alleviates post-surgical pain and normalizes behavior in a translational animal model

Previously, abobotulinumtoxinA (aboBoNT-A) injected intraoperatively resulted in effective, but delayed post-surgical analgesia in pigs. Here, we explore the efficacy of preemptively administered aboBoNT-A in intact animals on pain and associated behaviors following a full-skin-muscle incision and retraction surgery on the lower back. AboBoNT-A (200 U/animal) or saline, distributed across ten points, were injected around anticipated incision 15, 5, or 1 day before surgery via ID route (part A) or 15 days before surgery via ID, intramuscular (IM) or subcutaneous (SC) routes (part B). We assessed mechanical sensitivity (withdrawal force; WF), distress behavior score (DBS), and latency to approach the investigator before and after surgery for 7 days.AboBoNT-A, injected ID 15 days before surgery, didn't alter any baseline behaviors, but resulted in 5-fold increases in WF, 75% reduction in DBS and 70% reduction in approach latencies (all p < 0.01). Injections 5 days before surgery led to similar effects, albeit with a fewer animals reaching thresholds, while those made 1 day before surgery were less effective. SC and IM injections were ineffective. Thus, aboBoNT-A administered ID 15 days before surgery represents the most optimal condition for postoperative analgesia. These findings warrant for clinical investigation of preemptively administered aboBoNT-A in postsurgical pain.

Inhibiting mechanotransduction prevents scarring and yields regeneration in a large animal model

Modulating mechanotransduction by inhibiting yes-associated protein (YAP) in mice yields wound regeneration without scarring. However, rodents are loose-skinned and fail to recapitulate key aspects of human wound repair. We sought to elucidate the effects of YAP inhibition in red Duroc pig wounds, the most human-like model of scarring. We show that one-time treatment with verteporfin, a YAP inhibitor, immediately after wounding is sufficient to prevent scarring and to drive wound regeneration in pigs. By performing single-cell RNA sequencing (scRNA-seq) on porcine wounds in conjunction with spatial proteomic analysis, we found perturbations in fibroblast dynamics with verteporfin treatment and the presence of putative pro-regenerative/profibrotic fibroblasts enriched in regenerating/scarring pig wounds, respectively. We also identified differences in enriched myeloid cell subpopulations after treatment and linked this observation to increased elaboration of interleukin-33 (IL-33) in regenerating wounds. Finally, we validated our findings in a xenograft wound model containing human neonatal foreskin engrafted onto nude mice and used scRNA-seq of human wound cells to draw parallels with fibroblast subpopulation dynamics in porcine wounds. Collectively, our findings provide support for the clinical translation of local mechanotransduction inhibitors to prevent human skin scarring, and they clarify a YAP/IL-33 signaling axis in large animal wound regeneration.

Untargeted lipidomics reveals unique lipid signatures of extracellular vesicles from porcine colostrum and milk

Extracellular vesicles (EV) are membranous vesicles considered as significant players in cell-to-cell communication. Milk provides adequate nutrition, transfers immunity, and promotes neonatal development, and milk EV are suggested to play a crucial role in these processes. Milk samples were obtained on days 0, 7, and 14 after parturition from sows receiving either a standard diet (ω-6:ω-3 = 13:1) or a test diet enriched in ω-3 (ω-6:ω-3 = 4:1). EV were isolated using ultracentrifugation coupled with size exclusion chromatography, and characterized by nanoparticle tracking analysis, transmission electron microscopy, and assessment of EV markers via Western blotting. The lipidome was determined following a liquid chromatography-quadrupole time-of-flight mass spectrometry approach. Here, we show that different stages of lactation (colostrum vs mature milk) have a distinct extracellular vesicle lipidomic profile. The distinct lipid content can be further explored to understand and regulate milk EV functionalities and primordial for enabling their diagnostic and therapeutic potential.

A Positive-Reinforcement Training Regimen for Refined Sample Collection in Laboratory Pigs

Positive-reinforcement training of laboratory pigs can reduce the reliance on forced manual restraint and anaesthesia for sample collection, reducing stress and physiological disruption. Training regimens for laboratory pigs typically rely on specialised equipment for restraint, such as Panepinto slings, with a time investment that may not be justified for short-term studies. These training regimens also commonly rely on pigs being lifted into sling restraints, which is not practical for studies involving large pigs. We developed and assessed a rapid, three-phase, positive-reinforcement training regimen for both individually housed and group-housed laboratory pigs to facilitate the collection of minimally invasive samples consciously and voluntarily. The time to complete each phase of training in both individually housed and group-housed pigs was recorded. The behaviour of the individually housed pigs was assessed via an ethogram of behaviours exhibited during a human approach test, and stress response was assessed by analysing salivary corticosterone. The rapid, positive-reinforcement training regimen successfully facilitated oral swabbing, rectal swabbing and rectal thermometer insertion from individually housed (within 18 days) and group-housed (within 6 days) pigs. The trained pigs displayed increasing positive behaviours, no or very few negative behaviours and corticosterone levels within normal limits throughout the study. This training regimen provides a practical and welfare-positive tool for the collection of minimally invasive samples from both small and large laboratory pigs, with a low time investment of 2-5 min/pig/day without the need for specialised restraint equipment.

Does a carboxamide moiety alter the toxicokinetics of synthetic cannabinoids? A study after pulmonary and intravenous administration of cumyl-5F-P7AICA to pigs

Synthetic cannabinoids (SCs) are consumed as an alternative to cannabis. Novel compounds are developed by minor modifications in their chemical structure, e.g. insertion of a carboxamide moiety as a linker, which can potentially lead to altered toxicokinetics (TK). Knowledge on the TK data of SCs, especially structural modified substances, is scarce. Hence, interpretation of toxicological results is challenging. Therefore, the aim of the present study was to evaluate the TK of cumyl-5F-P7AICA in a pig model, which was shown to be suitable for TK studies of SCs. A 200 µg/kg body weight dose of cumyl-5F-P7AICA was administered intravenously (n = 6) or inhalatively (n = 10) via an ultrasonic nebulizer to pigs. Blood specimens were repeatedly drawn over 6 h and the concentrations of cumyl-5F-P7AICA as well as its N-pentanoic acid (NPA) metabolite were determined using a fully validated LC-MS/MS method. Based on the concentration-time profiles, a population TK analysis yielded a three-compartment model for the TK of cumyl-5F-P7AICA, whilst a two-compartment model described the NPA best. The incorporation of transit compartments accounts for the time delay between the appearance of cumyl-5F-P7AICA and NPA in serum. Finally, the model was upscaled to humans using allometric scaling. In comparison to older SCs, a higher volume of distribution was determined for cumyl-5F-P7AICA. No further relevant differences of the TK properties were observed. Insertion of a carboxamide moiety into the chemical structure of SCs does not appear to have only minor influence on the TK.

High-frequency electrical stimulation increases cortical excitability and mechanical sensitivity in a chronic large animal model

ABSTRACT

Translational models of the sensitized pain system are needed to progress the understanding of involved mechanisms. In this study, long-term potentiation was used to develop a mechanism-based large-animal pain model. Event-related potentials to electrical stimulation of the ulnar nerve were recorded by intracranial recordings in pigs, 3 weeks before, immediately before and after, and 3 weeks after peripheral high-frequency stimulation (HFS) applied to the ulnar nerve in the right forelimb (7 pigs) or in control animals (5 pigs). Event-related potential recordings and peripheral HFS were done during anesthesia. Two weeks before and after the HFS, behavioral responses reflecting mechanical and thermal sensitivity were collected using brush, noxious limb-mounted pressure algometer, and noxious laser stimuli. The HFS intervention limb was progressively sensitized to noxious mechanical stimulation in week 1 and 2 compared with baseline ( P = 0.045) and the control group ( P < 0.034) but not significantly to laser or brush stimulation. The first negative (N1) peak of the event-related potential was increased 30 minutes after HFS compared with before ( P < 0.05). The N1 peak was also larger compared with control pigs 20 to 40 minutes after HFS ( P < 0.031) but not significantly increased 3 weeks after. The relative increase in N1 30 minutes after HFS and the degree of mechanical hyperalgesia 2 weeks post-HFS was correlated ( P < 0.033). These results show for the first time that the pig HFS model resembles the human HFS model closely where the profile of sensitization is comparable. Interestingly, the degree of sensitization was associated with the cortical signs of hyperexcitability at HFS induction.

Welfare Implications of Low-Dose Atipamezole Reversal of Tiletamine/Zolazepam/Xylazine Anaesthesia in Pigs

Anaesthesia is sometimes required for the effective restraint of laboratory pigs for sample collection. Yet, anaesthesia can initiate a range of physiological disruptions that can increase variability in study data and lead to poorer animal welfare. Judicious use of anaesthesia can mitigate experimental, human safety, and animal welfare concerns, but it does not eliminate the potential for adverse effects. The use of reversal agents can shorten recovery time and reduce the physiological impacts of anaesthesia but can also cause additional side effects. We, therefore, trialled the use of low-dose atipamezole (0.12 mg/kg) for the antagonism of xylazine in laboratory pigs anaesthetised using a combination of xylazine and zolazepam/tiletamine. We measured time to recovery, selected clinical variables, recovery characteristics, and behaviours to investigate if a low dose of antagonist decreased recovery time and reduced the physiological impacts of anaesthesia whilst avoiding adverse negative side effects. We categorised side effects and behaviours as having either a low or high negative welfare impact based on the potential risk of injury and whether behaviours were displayed before or after return to consciousness. Collectively, our results indicated that while the use of low-dose atipamezole decreased recovery time and improved thermoregulation in most pigs, it introduced and exacerbated adverse side effects and behaviours that can lead to poorer welfare outcomes for laboratory pigs.

Incorporating a poly-ε-caprolactone scaffold in a stapled small intestinal anastomosis with induced ischemia significantly increased anastomotic tensile strength. An experimental study in pigs

OBJECTIVE

Anastomotic leakage is a severe complication with multifactorial aetiology, including impaired tissue oxygenation, infection, inflammation, and anastomotic tension. Reinforcement with poly-ε-caprolactone (PCL) scaffold incorporated in a stapled intestinal anastomosis has demonstrated a significant increase in the anastomotic tensile strength. This study aimed to investigate whether incorporation of the scaffold would influence tensile strength with induced ischemia compared to normal blood perfusion.

METHODS

Eighteen pigs were randomly allocated into an intervention group with a induced relative reduction in blood perfusion to 30% at the anastomotic area and a control group with normal perfusion controlled by quantitative fluorescence angiography. Each pig recieved two stapled small intestinal anastomoses, one with a PCL scaffold incorporated and one without. On postoperative day five, the anastomoses were subjected to a maximal tensile strength test (MATS) and a histopathological analysis. Tensile strength was measured at three events: when a serosal tear became visible (MATS-1), at transmural rupture (MATS-2), and at maximum load before the load-strain curve dropped (MATS-3).

RESULTS

In the intervention group, MATS-1 was significantly higher in scaffold-reinforced anastomoses compared to controls (7.9 ± 4.2N and 4.4 ± 2.5N, p < 0.02). The same tendency was found for MATS-2 and MATS-3, with statistically significant differences after adjusting for adhesion grade (p < 0.05). Histological analysis revealed no significant differences in wound healing between groups.

CONCLUSION

Incorporating a PCL scaffold in a stapled small intestinal anastomosis with induced ischemia improved anastomotic tensile strength.

Transplantation of Autologous Dermo-Epidermal Skin Substitutes in a Pig Model

Due to its similarity of skin anatomy and physiology, the pig appears to be a well-suited animal model for pre-clinical studies of skin analogue transplantations. The choice of the location of the skin defect and appropriate post-operative measures are essential for the protection of the transplanted graft. This protocol describes in detail a porcine skin transplantation model including peri- and postoperative measures taken to improve and refine the studies outcome.

The Wound Reporting in Animal and Human Preclinical Studies (WRAHPS) Guidelines

Preclinical studies for wound healing disorders are an essential step in translating discoveries into therapies. Also, they are an integral component of initial safety screening and gaining mechanistic insights using an in vivo approach. Given the complexity of the wound healing process, existing guidelines for animal testing do not capture key information due to the inevitable variability in experimental design. Variations in study interpretation are increased by complexities associated with wound aetiology, wounding procedure, multiple treatment conditions, wound assessment, and analysis, as well as lack of acknowledgement of limitation of the model used. Yet, no standards exist to guide reporting crucial experimental information required to interpret results in translational studies of wound healing. Consistency in reporting allows transparency, comparative, and meta-analysis studies and avoids repetition and redundancy. Therefore, there is a critical and unmet need to standardise reporting for preclinical wound studies. To aid in reporting experimental conditions, The Wound Reporting in Animal and Human Preclinical Studies (WRAHPS) Guidelines have now been created by the authors working with the Wound Care Collaborative Community (WCCC) GAPS group to provide a checklist and reporting template for the most frequently used preclinical models in support of development for human clinical trials for wound healing disorders. It is anticipated that the WRAHPS Guidelines will standardise comprehensive methods for reporting in scientific manuscripts and the wound healing field overall. This article is not intended to address regulatory requirements but is intended to provide general guidelines on important scientific considerations for such studies.

Animal models for transplant immunology: bridging bench to bedside

The progress of transplantation has been propelled forward by animal experiments. Animal models have not only provided opportunities to understand complex immune mechanisms in transplantation but also served as a platform to assess therapeutic interventions. While small animals have been instrumental in uncovering new therapeutic concepts related to immunosuppression and immune tolerance, the progression to human trials has largely been driven by studies in large animals. Recent research has begun to explore the potential of porcine organs to address the shortage of available organs. The consistent progress in transplant immunology research can be attributed to a thorough understanding of animal models. This review provides a comprehensive overview of the available animal models, detailing their modifications, strengths, and weaknesses, as well as their historical applications, to aid researchers in selecting the most suitable model for their specific research needs.

A Novel Porcine Model of Bilateral Hindlimb Bypass Graft Surgery Integrating Transit Time Flowmetry

BACKGROUND

Bypass graft surgery is a key surgical intervention for ischemic heart disease (coronary bypass graft surgery) and critical limb ischemia (peripheral bypass graft surgery). Graft occlusion remains a significant clinical problem for both types. Further research into the pathobiological mechanisms of graft occlusion are needed in order to design targeted therapeutic strategies.

METHODS

Three Large White female pigs (mean weight 52.3 +/- 4.4 kg) received general anaesthesia prior to surgery. The external jugular vein was harvested bilaterally, and a bilateral femoral peripheral arterial bypass was performed, with the superficial femoral artery permanently ligated. The grafts were interrogated immediately post operatively on-table using Medistim MiraQ transit time flowmetry system (Medistim, Oslo, Norway) to assess graft performance. On postoperative day three, the pigs were returned to the operating room, and the grafts were interrogated once again using transit time flowmetry.

RESULTS

Six out of six (100%) successful bilateral EJV to femoral artery bypass grafts were performed. All pigs were successfully recovered, and returned to the operating room at postoperative day 3. The wounds were re-opened and the grafts were inspected. Postoperative graft assessment was performed with transit time flowmetry using the Medistim MiraQTM system (Medistim, Oslo, Norway), demonstrating all grafts were patent (100%).

CONCLUSION

This model may serve as a platform to gain further mechanistic insight into graft failure pathobiology. By combining a bilateral graft model with gold-standard transit time flowmetry, longitudinal experimentation of targeted therapeutic interventions to combat graft failure may be further studied with improved objectivity.

In Vivo Evaluation of Two Hemorrhagic Shock Resuscitation Controllers with Non-Invasive, Intermittent Sensors

Hemorrhage is a leading cause of preventable death in military and civilian trauma medicine. Fluid resuscitation is the primary treatment option, which can be difficult to manage when multiple patients are involved. Traditional vital signs needed to drive resuscitation therapy being unavailable without invasive catheter placement is a challenge. To overcome these obstacles, we propose using closed-loop fluid resuscitation controllers managed by non-invasive, intermittent signal sensor inputs to simplify their use in far-forward environments. Using non-invasive, intermittent sensor controllers will allow quicker medical intervention due to negating the need for an arterial catheter to be placed for pressure-guided fluid resuscitation. Two controller designs were evaluated in a swine hemorrhagic shock injury model, with each controller only receiving non-invasive blood pressure (NIBP) measurements simulated from invasive input signals every 60 s. We found that both physiological closed-loop controllers were able to effectively resuscitate subjects out of life-threatening hemorrhagic shock using only intermittent data inputs with a resuscitation effectiveness of at least 95% for each respective controller. We also compared this intermittent signal input to a NIBP cuff and to a deep learning model that predicts blood pressure from a photoplethysmography waveform. Each approach showed evidence of tracking blood pressure, but more effort is needed to refine these non-invasive input approaches. We conclude that resuscitation controllers hold promise to one day be capable of non-invasive sensor input while retaining their effectiveness, expanding their utility for managing patients during mass casualty or battlefield conditions.

Investigation of Minipigs as the Optimal Non-rodent Pre-clinical Species: Exploring Plasma Protein Binding of Marketed Cardiovascular Drugs Across Species

Pre-clinical studies in animals are an essential part of drug development for new chemical entities. Before clinical trials in humans, submission of safety data from one rodent and one non-rodent species is compulsory as per regulatory guidelines. Even though minipigs and monkeys are physiologically closer to humans, dogs are usually employed as the non-rodent pre-clinical species. In this study, the in vitro plasma protein binding of eleven marketed cardiovascular drugs was studied in dog, minipig, monkey and human to determine the preferred species. To conduct plasma protein binding studies, the most reliable equilibrium dialysis method was adopted. Ten out of eleven tested cardiovascular drugs showed statistically similar plasma protein binding in minipig and human plasma which was different from dog and monkey plasma. The results from the studies showed greater similarity between minipigs and humans suggesting that the minipig species maybe a better pre-clinical non-rodent model during drug development of cardiovascular drugs instead of the conventional dog species. Additionally, use of the more accessible minipig species may help in saving time, and resources during pre-clinical studies and may also be more predictive during the safety studies in humans during later stage clinical trials.

Use of Transcriptomics to Identify Candidate Genes for Hematopoietic Differences Between Wujin and Duroc Pigs

Hematopoiesis is a complex physiological process that ensures renewal of blood cells to maintain normal blood circulation and immune function. Wujin pigs exhibit distinct characteristics such as tender meat, high fat storage, strong resistance to roughage, robust disease resistance, and oxidation resistance. Therefore, using Wujin pigs as models may offer valuable insights for hematopoietic-related studies. In this study, twelve healthy 35-day-old piglets, including six Wujin and six Duroc piglets of similar weight, were selected from each of the Wujin and Duroc pig groups and housed in single cages. After 30 days of feeding, blood and bone marrow samples were collected. Routine blood indices and hematopoietic-related serum biochemical indexes of Wujin and Duroc pigs were determined, and bone marrow gene expression levels were analyzed using transcriptomics. (1) Hemoglobin (Hb) and Mean Corpuscular Hemoglobin Concentration (MCHC) levels in Wujin pigs were significantly higher than in Duroc pigs (p < 0.05), and platelet counts and serum Hb levels in Wujin pigs were significantly lower than in Duroc pigs (p < 0.05). (2) A total of 312 significantly differentially expressed genes were identified between the pigs. Their functions were mainly related to blood systems, inflammation, and oxidation. Six differentially expressed genes may be related to hematopoietic function. (3) By combining the differential genes screened through sequencing with Weighted Gene Co-expression Network Analysis results, 16 hematopoietic function differential genes were obtained, mainly focusing on immunity, inflammation, and induction of apoptosis functions. Differences were present in the immune and inflammatory responses between Wujin pigs and Duroc pigs, suggesting that differences in hematopoietic function between the two breeds were related to antioxidant capacity and disease resistance.

Opportunities and challenges for use of minipigs in nonclinical pharmaceutical development: Results of a follow-up IQ DruSafe survey

Minipigs are valid nonrodent species infrequently utilized for pharmaceutical research and development (R&D) compared with dogs or nonhuman primates (NHPs). A 2022 IQ DruSafe survey revealed a modest increase in minipig use by pharmaceutical companies compared with a prior 2014 survey, primarily in the development of oral small molecules and parenteral protein molecules. Some companies considered using minipigs more often due to NHP shortages and regional ethical concerns with using NHPs and dogs. However, for most pharmaceutical companies, minipigs still represent ≤5% of their nonrodent animal use. Key challenges noted by companies to wider adoption of minipigs were high test article requirement, limited historical control data, and lack of relevant reagents or assays. Additionally, some companies expressed uncertainties about contract research organization (CRO) capabilities and experience, a perception not shared by respondent CROs. These latest survey results indicate persistence of many concerns previously identified in 2014. Several case studies are included to illustrate areas of expanded minipig use as well as the challenges that hinder broader adoption. Ongoing, focused, and industry-wide initiatives to address the identified or perceived challenges may lead to more frequent or routine consideration of minipigs as a test species in pharmaceutical R&D.

Effects of 5G radiofrequency electromagnetic radiation on indicators of vitality and DNA integrity of in vitro exposed boar semen

The effects of radiofrequency electromagnetic radiation (RF-EMR) on semen quality have been in the spotlight in recent years, though research results to date have been contradictory. The effects of RF-EMR amongst others depend upon frequency, and there is currently no literature concerning the influence of 5G frequencies on both DNA integrity and spermatozoa vitality in males. The aim of this study was to investigate the effect of 5G RF-EMR on sperm membrane integrity, mitochondrial potential, and DNA integrity of in vitro exposed semen of breeding boars. The study included semen samples of eight breeding boars of the Pietren breed and four breeding boars of the German Landrace breed, from 1.5 to 3.5 years in age. Freshly diluted semen of each boar was divided into a control (n = 12) and experimental group (n = 12). The samples of the experimental group were exposed for 2 hours to continuous RF-EMR at a single frequency (700 MHz, 2500 MHz and 3500 MHz) and an electromagnetic field strength of 10 V/m using a transverse gigahertz electromagnetic cell. Sperm DNA fragmentation was assessed using a Halomax® kit and sperm membrane integrity and mitochondrial potential was assessed using a PI⁄SYBR-14 LIVE⁄DEAD viability kit with JC-1. A significantly higher proportion of spermatozoa with DNA fragmentation was found in exposed semen samples for all frequencies compared to the control group. The highest DNA damage was recorded in semen samples exposed to 5G RF-EMR at 2500 MHz (p < 0.01) and 3500 MHz (p < 0.05) vs. control semen samples. A significantly higher proportion of spermatozoa with damaged cell membrane and good mitochondrial potential was recorded in semen samples exposed with 3500 MHz. In vitro exposure of breading boar semen to 5G RF-EMR significantly increases the proportion of DNA fragmentation. The harmful effect of 5G RF-EMR on the proportion of spermatozoa with damaged DNA was frequency dependent. The 3500 MHz frequency displayed the most harmful effects due to significant impacts on DNA integrity and spermatozoa vitality indicators.

Dynamic distribution of systemically administered antibiotics in orthopeadically relevant target tissues and settings

This review aimed to summarize the current literature on antibiotic distribution in orthopedically relevant tissues and settings where dynamic sampling methods have been used. PubMed and Embase databases were systematically searched. English-published studies between 2004 and 2024 involving systemic antibiotic administration in orthopedically relevant tissues and settings based on dynamic measurements were included. In total, 5385 titles were identified. After title and abstract screening, 97 eligible studies (43 different antibiotic drugs) were included. The studies covered both preclinical (42%) and clinical studies including healthy and infected tissues (21%) and prophylactic and steady-state situations (35%). Microdialysis emerged as the predominant sampling method in 98% of the studies. Most of the presented antibiotics (80%) were only assessed once or twice. Among the most extensively studied antibiotics were cefuroxime (18 studies), linezolid (9 studies) and vancomycin (9 studies). This review presents valuable insights into the microenvironmental distribution of antibiotics in orthopedically relevant target tissues and settings and seeks to provide a basis for improving dosing recommendations and treatment outcomes. However, it is important to acknowledge that our findings are limited to the specific drug, dosing regimens, administration method and target tissue, and are crucially linked to the selected PK/PD target.

Application of a minimally invasive full-thickness autologous microcolumn skin harvesting device for donor site tissue collection and augmenting wound healing in a porcine wound model

Using a 6-week porcine full-thickness excisional wound grafting model, we evaluated the Autologous Regeneration of Tissue (ART®) System, a novel skin harvesting device designed to collect autologous full-thickness autologous microcolumns (FTAM) at 0.5 mm in diameter. The donor skin sites were harvested using the ART® System and compared to split-thickness skin grafts (STSGs). Recipient sites were divided into three treatment groups: FTAM, STSG and Untreated control. Comparing the FTAM donor sites to the STSG donor sites, we observed significantly faster re-epithelization by Day 4 (p < 0.05), earlier adnexal structures and rete ridge formation by Week 3, and increased collagen and elastin content by Week 6. We also observed an increased rate of healing at the FTAM donor site whilst limiting donor site morbidity compared to traditional STSG donor sites. Time to recipient site closure was 2.4 weeks for STSG treated, 3.3 weeks for FTAM treated and 4.1 weeks for the Untreated control (p < 0.05). The STSG and FTAM recipient sites reached complete re-epithelialization by Weeks 4 and 5, respectively which was significantly faster compared to the Untreated control. However, the FTAM recipient site received only 10% of the donor site tissue relative to the recipient site area and the amount of donor site tissue grafted on the STSG recipient sites was 5× more than the FTAM recipient sites. Additionally, the FTAMs harvested by the ART® System augmented recipient wound site healing as a result of 'epithelial island' expansion in contrast to Untreated control sites that closed primarily by contracture.

Hypoxic-ischemic brain injury in pig after cardiac arrest - A new histopathological scoring system for non-specialists

Introduction

After cardiac arrest and successful resuscitation patients often present with hypoxic-ischemic brain injury, which is a major cause of death due to poor neurological outcome. The development of a robust histopathological scoring system for the reliable and easy identification and quantification of hypoxic-ischemic brain injury could lead to a standardization in the evaluation of brain damage. We wanted to establish an easy-to-use neuropathological scoring system to identify and quantify hypoxic-ischemic brain injury.

Methods

The criteria for regular neurons, hypoxic-ischemic brain injury neurons and neurons with ischemic neuronal change (ischemic change neurons) were established in collaboration with specialized neuropathologists. Nine non-specialist examiners performed cell counting using the mentioned criteria in brain tissue samples from a porcine cardiac arrest model. The statistical analyses were performed using the interclass correlation coefficient for counting data and reliability testing.

Results

The inter-rater reliability for regular neurons (ICC 0.68 (0.42 - 0.84; p < 0.001) and hypoxic-ischemic brain injury neurons (ICC 0.87 (0.81 - 0.92; p < 0.001) showed moderate to excellent correlation while ischemic change neurons showed poor reliability. Excellent results were seen for intra-rater reliability for regular neurons (ICC 0.9 (0.68 - 0.97; p < 0.001) and hypoxic-ischemic brain injury neurons (ICC 0.99 (0.83 - 1; p < 0.001).

Conclusion

The scoring system provides a reliable method for the discrimination between regular neurons and neurons affected by hypoxic/ischemic injury. This scoring system allows an easy and reliable identification and quantification of hypoxic-ischemic brain injury for non-specialists and offers a standardization to evaluate hypoxic-ischemic brain injury after cardiac arrest.

Expression of key immune genes in polarized porcine monocyte-derived macrophage subsets

Swine are considered one of the most relevant large animal biomedical models since they share many immunological similarities with humans. Despite that, macrophage polarization has not comprehensively investigated in pigs. In this study, porcine monocyte-derived macrophages (moMΦ) were untreated or stimulated with IFN-γ + LPS (classical activation), or by different M2 polarizing stimuli: IL-4, IL-10, TGF-β, or dexamethasone. Expression of key cytokine genes (IL1B2, IL33, IL19, IL22, IL26, CCL17, CCL24, IFNA, IFNB) in macrophage subsets were investigated over time. Expression of the genes encoding the two main enzymes of the arginine pathway (ARG1, NOS2), and molecules related to alternative macrophage polarization in human and mice (MMP9, MRC1, FIZZ1, VEGFA) were also assessed. Stimulation with IFN-γ + LPS triggered up-regulation of IL1B2, IFNB, NOS2, whereas IL-4 triggered upregulation of CCL17, CCL24, CXCR2, and ARG1 expression. IL19 and IL22 expression was enhanced by stimulation with IFN-γ + LPS or TGF-β, but not IL-4, IL-10, or dexamethasone. Our data highlighted some peculiarities in swine, such as induced expression of IL33 after stimulation with IFN-γ + LPS, and no up-regulation of FIZZ1, VEGFA or MMP9 after exposure to any of the M2 polarizing stimuli. A better understanding of porcine macrophage polarization could benefit translational studies using this large animal model.

Development and evaluation of an autism pig model

Developing cost-effective and disease-relevant animal models is essential for advancing biomedical research into human disorders. Here we investigate the feasibility of a pig model for autism spectrum disorder (ASD) using embryonic exposure to valproic acid (VPA), an antiepileptic drug known to increase ASD risk. We established experimental paradigms to assess the behavioral characteristics of these pig models. Administration of VPA to Bama miniature pigs (Sus scrofa domestica) during critical embryonic stages resulted in abnormal gait, increased anxiety levels, reduced learning capabilities and altered social patterns, while largely preserving social preference of treated piglets. Notably, we detected significant neuroanatomical changes in cortical regions associated with ASD in the VPA-treated pigs, including cortical malformation, increased neuronal soma size, decreased dendritic complexity and reduced dendritic spine maturation. Transcriptome analysis of the prefrontal cortex of VPA-treated pigs further revealed substantial alterations in the expression of genes linked to ASD, especially genes of the dopamine signaling pathway, highlighting the model's relevance and potential for shedding light on ASD's underlying neuropathological and molecular mechanisms. These findings suggest that pig models could serve as a promising alternative to traditional rodent models and provide a more ethical substitute for the use of primates in translational research on neurodevelopmental disorders.

Toxicokinetic modelling of the synthetic cannabinoid 5F-MDMB-P7AICA and its main metabolite in pigs following pulmonary administration

AIMS

Since their emergence on the drug market, synthetic cannabinoids (SC) are still gaining increasing importance in forensic toxicology. The representatives of the so-called new psychoactive substances have in common that they have not undergone preclinical safety studies. Hence, knowledge on toxicokinetic (TK) data is sparse. As an alternative to human studies not being allowed for ethical reasons, a sophisticated pig model was applied in the present study to assess the TK of the SC 5F-MDMB-P7AICA.

METHODS

Pigs pulmonarily received 5F-MDMB-P7AICA via an ultrasonic nebulizer. The parent compound and its main metabolite 5F-MDMB-P7AICA dimethyl butanoic acid were determined in serum and whole blood using liquid chromatography-tandem mass spectrometry. Obtained data was analysed by population (pop) TK modelling. The final pop TK model parameters for pigs were upscaled via allometric scaling techniques for the prediction of human exposure.

RESULTS

The serum concentration-time profiles of the parent and the pop TK analysis revealed that a 4-compartment model best describes the TK data. The administration of the aerosol into the lung compartment follows zero-order kinetics. A transit compartment was further included to accurately describe the time delay between detection of the parent and the metabolite. Despite the different structure, TK parameters were found to be comparable to other examined SC.

CONCLUSION

The predictions of human SC exposure suggest that multiple administration of 5F-MDMB-P7AICA substantially enhances the window of detection. The simulations pose extrapolation of the data used for model development with respect to dose linearity and allometric scaling to humans.

Association between cytokines, nitric oxide, hemodynamic and microcirculation in a porcine model of sepsis

Systemic inflammation and hemodynamic or microvascular alterations are a hallmark of sepsis and play a role in organs hypoperfusion and dysfunction. Pimobendan, an inodilator agent, could be an interesting option for inotropic support and microcirculation preservation during shock. The objectives of this study were to evaluate effect of pimobendan on cytokine and nitric oxide (NO) release and investigate whether changes of macro and microcirculation parameters are associated with the release of cytokines and NO in pigs sepsis model. After circulatory failure, induced by intravenous inoculation of live Pseudomonas aeruginosa, eight animals were treated with pimobendan and eight with placebo. Pimobendan did not affect cytokines secretion (TNF-α, IL-6 and IL-10), but decreased time-dependently NO release. Data of macro and microcirculation parameters, NO and TNF- α recorded at the time of circulatory failure (Thypotension) and the time maximum of production cytokines was used for analyses. A positive correlation was observed between TNF-α and cardiac index (r = 0.55, p = 0.03) and a negative with systemic vascular resistance (r = -0.52, p = 0.04). Positive correlations were seen both between IL-10, 30 min after resuscitation (T30min), and systolic arterial pressure (r = 0.57, p = 0.03) and cardiac index (r = 0.67, p = 0.01), and also between IL-6, taken 2 h after resuscitation and systolic arterial pressure (r = 0.53, p = 0.04). Negative correlations were found between IL-10 and lactate, measured resuscitation time (r = -0.58, p = 0.03). Regarding microcirculation parameters, we observed a positive correlation between IL-6 and IL-10 with the microvascular flow index (r = 0.52, p = 0.05; r = 0.84, p = 0.0003) and a negative correlation with the heterogeneity index with TNF-α and IL-10 (r = -0.51, p = 0.05; r = -0.74, p = 0.003) respectively. NO derivatives showed a positive correlation with temperature gradient (r = 0.54, p = 0.04). Pimobendan did not show anti-inflammatory effects in cytokines release. Our results also, suggest changes of macro- and microcirculation are associated mainly with low levels of IL-10 in sepsis.

White matter and latency of visual evoked potentials during maturation: A miniature pig model of adolescent development

BACKGROUND

Continuous myelination of cerebral white matter (WM) during adolescence overlaps with the formation of higher cognitive skills and the onset of many neuropsychiatric disorders. We developed a miniature-pig model of adolescent brain development for neuroimaging and neurophysiological assessment during this critical period. Minipigs have gyroencephalic brains with a large cerebral WM compartment and a well-defined adolescence period.

METHODS

Eight Sinclair™ minipigs (Sus scrofa domestica) were evaluated four times during weeks 14-28 (40, 28 and 28 days apart) of adolescence using monocular visual stimulation (1 Hz)-evoked potentials and diffusion MRI (dMRI) of WM. The latency for the pre-positive 30 ms (PP30), positive 30 ms (P30) and negative 50 ms (N50) components of the flash visual evoked potentials (fVEPs) and their interhemispheric latency (IL) were recorded in the frontal, central and occipital areas during ten 60-second stimulations for each eye. The dMRI imaging protocol consisted of fifteen b-shells (b = 0-3500 s/mm2) with 32 directions/shell, providing measurements that included fractional anisotropy (FA), radial kurtosis, kurtosis anisotropy (KA), axonal water fraction (AWF), and the permeability-diffusivity index (PDI).

RESULTS

Significant reductions (p < 0.05) in the latency and IL of fVEP measurements paralleled significant rises in FA, KA, AWF and PDI over the same period. The longitudinal latency changes in fVEPs were primarily associated with whole-brain changes in diffusion parameters, while fVEP IL changes were related to maturation of the corpus callosum.

CONCLUSIONS

Good agreement between reduction in the latency of fVEPs and maturation of cerebral WM was interpreted as evidence for ongoing myelination and confirmation of the minipig as a viable research platform. Adolescent development in minipigs can be studied using human neuroimaging and neurophysiological protocols and followed up with more invasive assays to investigate key neurodevelopmental hypotheses in psychiatry.

Comparative pharmacokinetics of porcine and human anti-influenza hemagglutinin monoclonal antibodies in outbred pigs and minipigs

Assessing the pharmacokinetics of monoclonal antibodies (mAbs) in relevant animal models is essential for designing improved formulations and developing mAb delivery platforms. We have established the pig, a large natural host animal for influenza with many similarities to humans, as a robust model for testing the therapeutic efficacy of anti-influenza mAbs and evaluating mAb delivery platforms. Here, we compared the pharmacokinetic characteristics of two anti-influenza hemagglutinin mAbs, human 2-12C and porcine pb27, in Göttingen minipigs and Landrace × Large White outbred pigs. Minipigs offer the advantage of a more stable weight, whereas outbred pigs are more readily available but exhibit rapid growth. Outbred pigs and minipigs showed similar pharmacokinetics and a similar porcine pb27 half-life (half-life of 15.7 days for outbred pigs and 16.6 days for minipigs). In contrast, the half-life of human 2-12C was more rapid in two of the minipigs but not in the outbred pigs, correlating with the development of antidrug antibodies in the two minipigs. Our results demonstrate that both outbred pigs and minipigs are appropriate models for pharmacokinetic studies and the evaluation of mAb delivery platforms, potentially bridging the gap between small animals and human trials.

Characterization of pediatric porcine pulmonary valves as a model for tissue engineered heart valves

Heart valve tissue engineering holds the potential to transform the surgical management of congenital heart defects affecting the pediatric pulmonary valve (PV) by offering a viable valve replacement. While aiming to recapitulate the native valve, the minimum requirement for tissue engineered heart valves (TEHVs) has historically been adequate mechanical function at implantation. However, long-term in situ functionality of TEHVs remains elusive, suggesting that a closer approximation of the native valve is required. The realization of biomimetic engineered pediatric PV is impeded by insufficient characterization of healthy pediatric tissue. In this study, we comprehensively characterized the planar biaxial tensile behaviour, extracellular matrix (ECM) composition and organization, and valvular interstitial cell (VIC) phenotypes of PVs from piglets to provide benchmarks for TEHVs. The piglet PV possessed an anisotropic and non-linear tension-strain profile from which material constants for a predictive constitutive model were derived. The ECM of the piglet PV possessed a trilayer organization populated by collagen, glycosaminoglycans, and elastin. Biochemical quantification of ECM content normalized to wet weight and DNA content of PV tissue revealed homogeneous distribution across sampled regions of the leaflet. Finally, VICs in the piglet PV were primarily quiescent vimentin-expressing fibroblasts, with a small proportion of activated α-smooth muscle actin-expressing myofibroblasts. Overall, piglet PV properties were consistent with those reported anecdotally for pediatric human PVs and distinct from those of adult porcine and human PVs, supporting the utility of the properties determined here to inform the design of tissue engineered pediatric PVs. STATEMENT OF SIGNIFICANCE: Heart valve tissue engineering has the potential to transform treatment for children born with defective pulmonary valves by providing living replacement tissue that can grow with the child. The design of tissue engineered heart valves is best informed by native valve properties, but native pediatric pulmonary valves have not been fully described to date. Here, we provide comprehensive characterization of the planar biaxial tensile behaviour, extracellular matrix composition and organization, and valvular interstitial cell phenotypes of pulmonary valves from piglets as a model for the native human pediatric valve. Together, these findings provide standards that inform engineered heart valve design towards generation of biomimetic pediatric pulmonary valves.

Comparative Analysis of Hepatic Gene Expression Profiles in Murine and Porcine Sepsis Models

Sepsis remains a huge unmet medical need for which no approved drugs, besides antibiotics, are on the market. Despite the clinical impact of sepsis, its molecular mechanism remains inadequately understood. Recent insights have shown that profound hepatic transcriptional reprogramming, leading to fatal metabolic abnormalities, might open a new avenue to treat sepsis. Translation of experimental results from rodents to larger animal models of higher relevance for human physiology, such as pigs, is critical and needs exploration. We performed a comparative analysis of the transcriptome profiles in murine and porcine livers using the following sepsis models: cecal ligation and puncture (CLP) in mice and fecal instillation (FI) in pigs, both of which induce polymicrobial septic peritonitis, and lipopolysaccharide (LPS)-induced endotoxemia in pigs, inducing sterile inflammation. Using bulk RNA sequencing, Metascape pathway analysis, and HOMER transcription factor motif analysis, we were able to identify key genes and pathways affected in septic livers. Conserved upregulated pathways in murine CLP and porcine LPS and FI generally comprise typical inflammatory pathways, except for ER stress, which was only found in the murine CLP model. Conserved pathways downregulated in sepsis comprise almost exclusively metabolic pathways such as monocarboxylic acid, steroid, biological oxidation, and small-molecule catabolism. Even though the upregulated inflammatory pathways were equally induced in the two porcine models, the porcine FI model more closely resembles the metabolic dysfunction observed in the CLP liver compared to the porcine LPS model. This comprehensive comparison focusing on the hepatic responses in mouse CLP versus LPS or FI in pigs shows that the two porcine sepsis models generally resemble quite well the mouse CLP model, with a typical inflammatory signature amongst the upregulated genes and metabolic dysfunction amongst the downregulated genes. The hepatic ER stress observed in the murine model could not be replicated in the porcine models. When studying metabolic dysfunction in the liver upon sepsis, the porcine FI model more closely resembles the mouse CLP model compared to the porcine LPS model.

Penicillin concentrations in oropharyngeal and frontal sinus tissue following enteral and intravenous administration measured by microdialysis in a porcine model

BACKGROUND

Penicillin may be administered enterally or intravenously for the treatment of bacterial infections within the oropharynx and the frontal sinuses. We aimed to assess and compare penicillin concentrations in oropharyngeal and frontal sinus tissues following enteral and intravenous administration in a porcine model.

METHOD

Twelve pigs were randomized to receive either enteral (0.8 g Penicillin V) or intravenous (1.2 g Penicillin G) penicillin. Microdialysis was used for sampling in oropharyngeal and frontal sinus tissues during a six-hour dosing interval. In addition, plasma samples were collected. The primary endpoints were time with drug concentration above the minimal inhibitory concentration (T>MIC) for two MIC targets: 0.125 (low target) and 0.5 (high target) μg/mL (covering Group A Streptococci, Fusobactarium necrophorum, Streptococcus pneumoniae and Hemophilus influenza) and attainment of these treatment targets for ≥50 % T>MIC.

RESULTS

For both the low and high MIC targets, intravenous administration resulted in higher T>MIC in oropharyngeal and frontal sinus tissues compared to enteral administration. In oropharyngeal tissue, the treatment target (≥50 % T>MIC) was achieved for both the low target (96 %) and high target (68 %) when penicillin was administrated intravenously. In frontal sinus tissue, the treatment target was reached for the low target (70 %), but not the high target (35 %) when administered intravenously. None of the two tissues reached the treatment targets when penicillin was administered enterally.

CONCLUSION

Intravenous administrated penicillin in standard dosage is superior to enteral administration of penicillin in standard dosage in achieving clinically important T>MIC as the majority of targets were achieved following intravenously administration, while none of the targets were achieved following enteral administration. These results support the general notion of higher tissue concentrations following intravenous compared to enteral administration.

Fetal bone engraftment reconstitutes the immune system in pigs with severe combined immunodeficiency

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

A pilot pharmacokinetic and Metabolite identification study of Erinacine A in a Single landrace pig model

Erinacine A has been proven to have the ability to protect nerves and have the benefit of neurohealth. However, the pharmacokinetic and metabolites study of erinacine A in pigs, whose physiology and anatomy are similar to humans, have not been reported. In this study, 5 mg/kg of erinacine A was intravenously administered to the landrace pig. Blood, cerebrospinal fluid, and brain tissue samples were collected and analyzed by HPLC-QQQ/MS and UPLC-QTOF/MS. The results indicated the following pharmacokinetic parameters in plasma samples: with an area under the plasma concentration versus time curve (AUC) were 38.02 ± 0.03 mg∙min/L (AUC0-60) and 43.60 ± 0.06 mg∙min/L (AUC0-∞), clearance (CL) was 0.11 ± 0.00 L/min∙kg, volume of distribution (Vd) was 4.24 ± 0.00 L/kg, and terminal half-life (T1/2β) was 20.85 ± 0.03 min. In the cerebrospinal fluid samples, erinacine A was detected after 15 min and the highest concentration (5.26 ± 0.58 μg/L) was observed at 30 min. In the brain tissue sample, 77.45 ± 0.58 μg/L of erinacine A was found. In the study of metabolites, there were 6 identical metabolites in plasma and brain tissue. To our surprise, erinacine B was found to be the metabolite of erinacine A, and its concentration increased over time as erinacine A was metabolized. In summary, this study is the first to demonstrate that erinacine A can be found in the cerebrospinal fluid of landrace pigs. Additionally, the metabolite identification of erinacine A in landrace pigs is also investigated.

Generation of RAG2 Knockout Immune-Deficient Miniature Pigs

Recombination-activating genes (RAGs) play a crucial role in the V(D)J recombination process and the development of immune cells. The development of the immune system and its mechanisms in pigs exhibit greater similarity to those of humans compared to other animals, thus rendering pigs a valuable tool for biomedical research. In this study, we utilized CRISPR/Cas9 gene editing and somatic cell nuclear transfer technology to generate RAG2 knockout (KO) pigs. Furthermore, we evaluated the impact of RAG2 KO on the immune organs and immune cell development through morphological observations, blood analysis and flow cytometry technology. RAG2 KO cell lines were used as donors for cloning. The reconstructed embryos were transplanted into 4 surrogate sows, and after 116 days of gestation, 2 sows gave birth to 12 live piglets, all of which were confirmed to be RAG2 KO. The thymus and spleen sizes of RAG2 KO pigs were significantly smaller than those of wild-type (WT) pigs. Hematoxylin-eosin staining results revealed that the thymus and spleen tissue structures of RAG2 KO pigs were disorganized and lacked the characteristic structures, indicating that RAG2 KO leads to dysplasia of the thymus and spleen. Hematological analysis demonstrated that the total number of white blood cells and lymphocytes in the circulation of RAG2 KO pigs was significantly lower, while the number of eosinophils was higher. Flow cytometry results indicated that the proportions of mature T and B lymphocytes were significantly reduced compared to WT pigs. These findings successfully verified the immunodeficiency phenotype of RAG2 KO pigs. This study may provide experimental animals for the development of tumor models and humanized animals.

An experimental study of the heterogeneity and anisotropy of porcine meniscal ultimate tensile strength

Characterizing the ultimate tensile strength (UTS) of the meniscus is critical in studying knee damage and pathology. This study aims to determine the UTS of the meniscus with an emphasis on its heterogeneity and anisotropy. We performed tensile tests to failure on the menisci of six month old Yorkshire pigs at a low strain rate. Specimens from the anterior, middle and posterior regions of the meniscus were tested in the radial and circumferential directions. Then the UTS was obtained for each specimen and the data were analyzed statistically, leading to a comprehensive view of the variations in porcine meniscal strength. The middle region has the highest average strength in the circumferential (43.3 ± 4.7 MPa) and radial (12.6 ± 2.2 MPa) directions. This is followed by the anterior and posterior regions, which present similar average values (about 34.0MPa) in circumferential direction. The average strength of each region in the radial direction is approximately one-fourth to one-third of the value in the circumferential direction. This study is novel as it is the first work to focus on the experimental methods to investigate the heterogeneity and anisotropy only for porcine meniscus.

Genetic engineering drives the breakthrough of pig models in liver disease research

Compared with the widely used rodents, pigs are anatomically, physiologically, and genetically more similar to humans, making them high-quality models for the study of liver diseases. Here, we review the latest research progress on pigs as a model of human liver disease, including methods for establishing them and their advantages in studying cystic fibrosis liver disease, acute liver failure, liver regeneration, non-alcoholic fatty liver disease, liver tumors, and xenotransplantation. We also emphasize the importance of genetic engineering techniques, mainly the CRISPR/Cas9 system, which has greatly enhanced the utility of porcine models as a tool for substantially advancing liver disease research. Genetic engineering is expected to propel the pig as one of the irreplaceable animal models for future biomedical research.