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Background: Eighty percent of hemodialysis patients start their dialysis with a tunneled hemodialysis catheter. Catheter related bacteremia is the second most common cause of death in these patients. Side holes near the tips of the tunneled cuffed central venous catheters are associated with accumulation of thrombus, which can lead to catheter dysfunction and, possibly, also to catheter-related infection. To assess the hypothesis that a catheter without side holes would be associated with less bacterial growth, this study compared the susceptibility of a side-hole-free catheter to accumulation of pathogenic bacteria at the catheter tip with that of two catheters which have side holes. Methods: Eight tunneled cuffed double-lumen central venous catheters were inserted into both jugular veins of four sheep; one side-hole-free and one control catheter with side holes at the tip in each animal. Staphylococcus aureus bacteria were then infused intravenously to cause bacteremia. Six hours later, the catheters were removed, the clots that accumulated in their tips were collected and cultured, and the bacterial colonies were counted after additional 12 h of incubation. Results: Bacteria grew on culture plates seeded with the clot homogenate obtained from the tips of all catheters. The colony counts from the catheters with side holes at the tip exceeded the colony counts of bacteria accumulated in the tips of the side-hole-free hemodialysis catheters by one or more orders of magnitude, with a difference of at least two orders of magnitude observed in three of the four intra-animal comparisons. Conclusions: In paired intra-animal post-inoculation comparison made in this limited study, fewer colony forming units of pathogenic bacteria accumulated at the tip of the side-hole-free catheters than at the tips of the catheters which have side holes. This may translate to a decreased rate of catheter-related blood stream infections in the side-hole-free catheters.

Background: Bipolar or “kissing” cartilage lesions formed on 2 opposite articular surfaces of the knee joint are commonly listed as exclusion criteria for advanced cartilage therapies. Purpose: To test, in a pilot large-animal study, whether autologous nasal chondrocyte (NC)–based tissue engineering, recently introduced for the treatment of focal cartilage injuries, could provide a solution for challenging kissing lesions. Study Design: Controlled laboratory study. Methods: Osteochondral kissing lesions were freshly introduced into the knee joints of 26 sheep and covered with NC-based grafts with a low or high hyaline-like extracellular matrix; a control group was treated with a cell-free scaffold collagen membrane (SCA). The cartilage repair site was assessed at 6 weeks and 6 months after implantation by histology, immunohistochemistry, and magnetic resonance imaging evaluation. Results: NC-based grafts, independently of their composition, induced partial hyaline cartilage repair with stable integrity in surrounding healthy tissue at 6 months after treatment. The SCA repaired cartilage to a similar degree to that of NC-based grafts. Conclusion: Kissing lesion repair, as evidenced in this sheep study, demonstrated the feasibility of the treatment of complex cartilage injuries with advanced biological methods. However, the potential advantages of an NC-based approach over a cell-free approach warrant further investigations in a more relevant preclinical model. Clinical Relevance: NC-based grafts currently undergoing phase II clinical trials have a high potential to replace existing cartilage therapies that show significant limitations in the quality and reproducibility of the repair method. We have brought this innovative concept to the next level by addressing a new clinical indication.

Background: Osteochondral defects, if left untreated, do not heal and can potentially progress toward osteoarthritis. Direct gene transfer of basic fibroblast growth factor 2 (FGF-2) with the clinically adapted recombinant adeno-associated viral (rAAV) vectors is a powerful tool to durably activate osteochondral repair processes. Purpose: To examine the ability of an rAAV-FGF-2 construct to target the healing processes of focal osteochondral injury over time in a large translational model in vivo versus a control gene transfer condition. Study Design: Controlled laboratory study. Methods: Standardized osteochondral defects created in the knee joints of adult sheep were treated with an rAAV human FGF-2 (hFGF-2) vector by direct administration into the defect relative to control (reporter) rAAV- lacZ gene transfer. Osteochondral repair was monitored using macroscopic, histological, immunohistological, and biochemical methods and by micro–computed tomography after 6 months. Results: Effective, localized prolonged FGF-2 overexpression was achieved for 6 months in vivo relative to the control condition without undesirable leakage of the vectors outside the defects. Such rAAV-mediated hFGF-2 overexpression significantly increased the individual histological parameter “percentage of new subchondral bone” versus lacZ treatment, reflected in a volume of mineralized bone per unit volume of the subchondral bone plate that was equal to a normal osteochondral unit. Also, rAAV-FGF-2 significantly improved the individual histological parameters “defect filling,”“matrix staining,” and “cellular morphology” and the overall cartilage repair score versus the lacZ treatment and led to significantly higher cell densities and significantly higher type II collagen deposition versus lacZ treatment. Likewise, rAAV-FGF-2 significantly decreased type I collagen expression within the cartilaginous repair tissue. Conclusion: The current work shows the potential of direct rAAV-mediated FGF-2 gene therapy to enhance osteochondral repair in a large, clinically relevant animal model over time in vivo. Clinical Relevance: Delivery of therapeutic (hFGF-2) rAAV vectors in sites of focal injury may offer novel, convenient tools to enhance osteochondral repair in the near future.

Background: The issue of side holes in the tips of the tunneled cuffed central venous catheters is complex and has been subject to longstanding debate. This study sought to compare the clotting potential of the side-hole-free Pristine hemodialysis catheter with that of a symmetric catheter with side holes. Methods: Both jugular veins of five goats were catheterized with the two different catheters. The catheters were left in place for 4 weeks and were flushed and locked with heparin thrice weekly. The aspirated intraluminal clot length was assessed visually prior to each flushing. In addition, the size and weight of the clot were recorded upon catheter extraction at the end of the 4-week follow-up Results: The mean intraluminal clot length observed during the entire study follow-up measured up to a mean of 0.66 cm in the GlidePath (95% CI, 0.14–1.18) and 0.19 cm in the Pristine hemodialysis catheter (95% CI, −0.33 to 0.71), the difference being statistically significant ( p = 0.026). On average, 0.01 g and 0.07 g of intraluminal clot were retrieved from the Pristine and GlidePath catheters, respectively ( p = 0.052). Conclusion: The Pristine hemodialysis catheter was largely superior to a standard side hole catheter in impeding clot formation, and, contrary to the side hole catheter, allowed for complete aspiration of the intraluminal clot.

Objective Regulatory guidelines for preclinical cartilage repair studies suggest large animal models (e.g., sheep, goat, [mini]-pig, or horse) to obtain results representative for humans. However, information about the 3-dimensional thickness of articular cartilage at different implantation sites in these models is limited. Design To identify the most suitable site for experimental surgery, cartilage thickness at the medial femoral condyle (MFC), lateral femoral condyle (LFC), and trochlea in ovine, caprine, and porcine cadaver stifle joints was systematically measured using hematoxylin-eosin staining of 6 µm paraffin sections and software-based image analysis. Results Regarding all ventral-dorsal regions of the MFC, goat showed the thickest articular cartilage (maximal mean thickness: 1299 µm), followed by sheep (1096 µm) and mini-pig (604 µm), with the highest values in the most ventral and dorsal regions. Also for the LFC, the most ventral regions showed the thickest cartilage in goat (maximal mean thickness: 1118 µm), followed by sheep (678 µm) and mini-pig (607 µm). Except for the mini-pig, however, the cartilage thickness on the LFC was consistently lower than that on the MFC. The 3 species also differed along the transversal measuring points on the MFC and LFC. In contrast, there were no consistent differences for the regional cartilage thickness of the trochlea among goat and sheep (≥780 µm) and mini-pig (≤500 µm). Conclusions Based on their cartilage thickness, experimental defects on goat and sheep MFC may be viable options for preclinical cartilage repair studies, in addition to well-established horse models.

Neuroendovascular procedures have led to breakthroughs in the treatment of ischemic stroke, intracranial aneurysms, and intracranial arteriovenous malformations. Due to these substantial successes, there is continuous development of novel and refined therapeutic approaches. Large animal models feature various conceptual advantages in translational research, which makes them appealing for the development of novel endovascular treatments. However, the availability and role of large animal models have not been systematically described so far. Based on comprehensive research in two databases, this systematic review describes current large animal models in neuroendovascular research including their primary use. It may therefore serve as a compact compendium for researchers entering the field or looking for opportunities to refine study concepts. It also describes particular applications for ischemic stroke and aneurysm therapy, as well as for the treatment of arteriovenous malformations. It focuses on most promising study designs and readout parameters, as well as on important pitfalls in endovascular translational research including ways to circumvent them.

Background: The corrective procedures for meniscal injury are dependent on tear type, severity, and location. Vertical longitudinal tears are common in young and active individuals, but their natural progression and impact on osteoarthritis (OA) development are not known. Root tears are challenging and they often indicate poor outcomes, although the timing and mechanisms of initiation of joint dysfunction are poorly understood, particularly in large-animal and human models. Purpose/Hypothesis: In this study, vertical longitudinal and root tears were made in a large-animal model to determine the progression of joint-wide dysfunction. We hypothesized that OA onset and progression would depend on the extent of injury-based load disruption in the tissue, such that root tears would cause earlier and more severe changes to the joint. Study Design: Controlled laboratory study. Methods: Sham surgeries and procedures to create either vertical longitudinal or root tears were performed in juvenile Yucatan mini pigs through randomized and bilateral arthroscopic procedures. Animals were sacrificed at 1, 3, or 6 months after injury and assessed at the joint and tissue level for evidence of OA. Functional measures of joint load transfer, cartilage indentation mechanics, and meniscal tensile properties were performed, as well as histological evaluation of the cartilage, meniscus, and synovium. Results: Outcomes suggested a progressive and sustained degeneration of the knee joint and meniscus after root tear, as evidenced by histological analysis of the cartilage and meniscus. This occurred in spite of spontaneous reattachment of the root, suggesting that this reattachment did not fully restore the function of the native attachment. In contrast, the vertical longitudinal tear did not cause significant changes to the joint, with only mild differences compared with sham surgery at the 6-month time point. Conclusion: Given that the root tear, which severs circumferential connectivity and load transfer, caused more intense OA compared with the circumferentially stable vertical longitudinal tear, our findings suggest that without timely and mechanically competent fixation, root tears may cause irreversible joint damage. Clinical Relevance: More generally, this new model can serve as a test bed for experimental surgical, scaffold-based, and small molecule–driven interventions after injury to prevent OA progression.

Background: The isolated heart apparatus is over 100 years old, but remains a useful research tool today. While designs of many large animal systems have been described in the literature, trouble-shooting and refining such a model to yield a stable, workable system has not been previously described. This paper outlines the issues, in tabular form, that our group encountered in developing our own porcine isolated heart rig with the aim of assisting other workers in the field planning similar work. The paper also highlights some of the modern applications of the isolated heart apparatus. Methods Landrace pigs (50-80 kg) were used in a pilot project to develop the model. The model was then used in a study examining the effects of various cardioplegic solutions on function after reanimation of porcine hearts. During the two projects, non-protocol issues were documented as well as their solutions. These were aggregated in this paper. Results: Issues faced by the group without explicit literature solutions included pig size selection, animal acclimatisation, porcine transoesophageal echocardiography, cannulation and phlebotomy for cross-clamping, cardioplegia delivery, heart suspension and rig tuning. Conclusion: Prior recognition of issues and possible solutions faced by workers establishing a porcine isolated heart system will speed progress towards a useable system for research. The isolated heart apparatus remains applicable in transplant, ischaemia reperfusion, heart failure and organ preservation research.

Preclinical studies play an indispensable role in exploring the biological regulation of the musculoskeletal system. They are required in all drug development pipelines where both small and large animal models are needed to understand efficacy and side effects. This brief review highlights 4 aspects of human bone, longitudinal bone growth, intracortical remodeling, collagen/mineral interface, and age-related changes, and discusses how various animal models recapitulate (or don’t) these aspects of human skeletal physiology.

Background: The risk of anterior cruciate ligament (ACL) injury is 2 to 10 times greater in women than men. While the effect of sex on injury risk is well established, its effects on surgical outcomes remain controversial. Purpose/Hypothesis: To investigate whether the biomechanical outcomes of ACL reconstruction are affected by sex using an established porcine model that displays similar sex-specific differences in knee anatomy and ligament structural properties to humans. The hypothesis was that there will be sex differences in ACL reconstruction outcomes with regard to the graft structural properties, knee laxity, and cartilage damage. Study Design: Controlled laboratory study. Methods: A total of 41 adolescent Yucatan minipigs (23 male, 18 female) underwent unilateral ACL transection and ACL reconstruction using sex-matched bone–patellar tendon–bone allografts (with or without additional bioenhancement). Graft biomechanical and histological properties, knee laxity, and cartilage damage were assessed after 15 weeks. A 2-factor analysis of variance was used to investigate the effect of sex on all the measured outcomes after adjusting for the treatment effect. Results: After 15 weeks of healing, female pigs had a significantly lower mean normalized graft yield load (by 18.5% ± 7.7%; P = .023) and linear stiffness (by 11.9% ± 5.6%; P = .043) compared with male pigs. Female pigs had significantly greater side-to-side differences in anteroposterior knee laxity at 30° (by 1.4 ± 0.6 mm; P = .028) and 90° (by 1.8 ± 0.8 mm; P = .032). Female pigs had a lower graft vascular density (by 0.8 ± 0.3 [analog scoring]; P = .021) with similar cellular and collagen-based histologic scores in both sexes ( P > .6). Female pigs also had a significantly larger area of cartilage damage (by 43.3 ± 14.8 mm2; P = .014) after conventional ACL reconstruction compared with their male counterparts. Conclusion: Female pigs had significantly worse outcomes (ie, graft structural properties, knee laxity, and cartilage damage) compared with male pigs in this translational model after 15 weeks of healing. Clinical Relevance: These data suggest that further optimization of ACL injury treatments may be needed to accommodate each sex instead of using a “one fits all” approach to improve surgical outcomes, decrease incidence of reinjury, and decrease posttraumatic osteoarthritis risk after ACL reconstruction.

A novel robotic tool is proposed to enable the surgical removal of tissue from inside the beating heart. The tool is manufactured using a unique metal MEMS process that provides the means to fabricate fully assembled devices that incorporate micron-scale features in a millimeter scale tool. The tool is integrated with a steerable curved concentric tube robot that can enter the heart percutaneously through peripheral vessels. Incorporating both irrigation and aspiration, the tissue removal system is capable of extracting substantial amounts of tissue under teleoperated control by first morselizing it and then transporting the debris out of the heart through the lumen of the robot. Tool design and robotic integration are described, and ex vivo and in vivo large animal experimental results are presented.

Objectives: We developed a large animal model for auricular reconstruction with engineered cartilage frameworks and evaluated the performance of porous polyethylene auricular implants in this model. Methods: Eighteen high-density porous polyethylene auricular frameworks were implanted subcutaneously in the infra-auricular areas of 9 sheep. The implants were harvested 17 weeks later for gross and histologic examination. The perioperative and postoperative courses were carefully documented. Results: Five implants became exposed, and 2 implants needed to be removed at 7 weeks. Additionally, 1 infected implant was removed at 2 weeks. Seromas developed in 2 implants because of drain failures and were drained successfully during the first postoperative week. There were no other surgical site complications. The remaining 10 implants had an acceptable cosmetic appearance at 17 weeks. Conclusions: The perioperative complication rate in the ovine porous polyethylene auricular implant model was higher than that reported for auricular reconstructions in humans. The implant exposures were likely caused by ischemia and excessive stress on the thin overlying skin, because vascularized flap coverage was not used. The histologic findings were comparable to the results reported for other animal models. This large animal model is appropriate for auricular reconstruction experiments, including engineered constructs.

In vivo preclinical testing of mechanical circulatory devices requires large animal models that provide reliable physiological and hemodynamic conditions by which to test the device and investigate design and development strategies. Large bovine species are commonly used for mechanical circulatory support device research. The animals used for chronic in vivo support require high-quality care and excellent surgical techniques as well as advanced methods of postoperative care. These techniques are constantly being updated and new methods are emerging. We report results of our double steel-wire closure technique in large bovine models used for Cleveland Clinic's continuous-flow total artificial heart development program. This is the first report of double-wire sternal fixation used in large bovine models.

Replacement of urinary bladder tissue with functional equivalents remains one of the most challenging problems of reconstructive urology over the last several decades. The gold standard treatment for urinary diversion after radical cystectomy is the ileal conduit or neobladder; however, this technique is associated with numerous complications including electrolyte imbalances, mucus production, and the potential for malignant transformation. Tissue engineering techniques provide the impetus to construct functional bladder substitutes de novo. Within this review, we have thoroughly perused the literature utilizing PubMed in order to identify clinical studies involving bladder reconstruction utilizing tissue engineering methodologies. The idea of urinary bladder regeneration through tissue engineering dates back to the 1950s. Many natural and synthetic biomaterials such as plastic mold, gelatin sponge, Japanese paper, preserved dog bladder, lyophilized human dura, bovine pericardium, small intestinal submucosa, bladder acellular matrix, or composite of collagen and polyglycolic acid were used for urinary bladder regeneration with a wide range of outcomes. Recent progress in the tissue engineering field suggest that in vitro engineered bladder wall substitutes may have expanded clinical applicability in near future but preclinical investigations on large animal models with defective bladders are necessary to optimize the methods of bladder reconstruction by tissue engineering in humans.

Research in the life sciences has been greatly advanced by the ability to directly visualize cells, tissues, and organs. Preclinical studies often involve many small and large animal experiments and, frequently, cell and organ transplantations. The rat is an excellent animal model for the development of transplantation and surgical techniques because of its small size and ability to breed in small spaces. Ten years ago, we established color-imaging transgenic rats and methods for the direct visualization of their tissues. Since then, our transgenic rats have been used throughout the various fields that are concerned with cell transplantation therapy. In this minireview, we summarize results from some of the groups that have used our transgenic rats at the bench level and in cell transplantation research.

Objective: Patients with congenital and acquired heart diseases or arteriopathy require small-diameter vascular grafts for arterial reconstruction. Autologous veins are the most suitable graft, but when absent, an alternative is necessary. This work addresses the issue. Background: Tissue-engineering efforts to create such grafts by modifications of acellular natural scaffolds are considered a promising area. Methods: Homologous saphenous veins harvested from cadavers and organ donors were processed by decellularization with detergent and enzymatic digestion, followed by crosslinking by dye-mediated photooxidation. They were validated for acellularity, mechanical strength, and crosslink stability. In-vitro and in-vivo cytotoxicity and hemocompatibility studies were conducted. Collagen conformity was studied by Fourier transform infrared spectroscopy, and heat stability by differential scanning calorimetry. A limited large animal study was performed. Results: The processing method delivered biocompatible, hemocompatible, effectively crosslinked grafts, with high heat stability of 126 ℃, an enthalpy value of 183.5 J·g−1, and collagen conformity close to that of the native vein. The mechanical strength was 250% better than the native vein. The presence of extracellular matrix proteins allowed the acellular vein to become a triple-layered vascular structure in the sheep venous system. Conclusion: Crosslinking after decellularization by the dye-mediated photooxidation method could be reproduced in any human vein to obtain a small-diameter vascular grafts.

Background: There are limited large animal models for the research of novel anastomotic technologies. Subtotal colectomy requires the anastomosis of relatively remote segments of the alimentary tract that are different anatomically, histologically, and pose significant physiological challenge. The quest for a foreign material–free anastomotic line reintroduced nitinol compression anastomosis into clinical use in the last decade. Objective: To evaluate the safety, histological, and physiological parameters of side-to-side ileocolic nitinol compression anastomosis in a newly developed large animal model, mimicking the human subtotal colectomy. Intervention: Resection of the entire spiral colon with an ileocolic side-to-side compression anastomosis in 12 animals, compared to resection of a short ileal segment in 6 animals. All anastomoses were constructed by using a novel nitinol-based compression device. The animals were followed up to 30 days postoperatively and were reoperated and sacrificed. Results: All 12 animals underwent successful subtotal colectomy with side-to-side nitinol compression anastomosis. No signs of abdominal infection were found. The increase in the colectomized animals’ bodyweight over the postoperative course was significantly lower and the animals presented with longer periods of diarrhea. The histopathology revealed minimal inflammation and foreign body reaction with good alignment of the bowel wall layers in both groups. The anastomotic line width was shown to be reduced during the healing course of the compression anastomoses. Conclusions: Side-to-side nitinol compression anastomosis is safe and demonstrates favorable functional and histopathological features. The porcine model of subtotal colectomy can be used for further research of novel anastomotic technologies.

A large animal (sheep) model was used to compare nerve axon regeneration and return of muscle function after a median-to-ulnar nerve end-to-side neurorrhaphy technique with conventional, clinically established, methods of nerve repair and untreated controls. Three groups of sheep were allocated to end-to-side repair (12 animals), a conventional method of nerve repair (18 animals), or a control group (eight animals). After a year nerve repairs were assessed electrophysiologically and histologically, and the muscles supplied by the repaired nerves were assessed physiologically. There were no significant differences in the outcomes of nerve repair between different conventional techniques. Half of the end-to-side nerve repairs supported nerve regeneration. The functional outcomes of the end-to-side repairs were inferior to conventional techniques which were, in turn, inferior to controls. End-to-side neurorrhaphy supported nerve regeneration, but the reliability of this technique is called into question and its use as a clinical tool can only be recommended as a salvage procedure.

Background: Marrow stimulation techniques such as subchondral drilling are clinically important treatment options for symptomatic small cartilage defects. Little is known about whether they induce deleterious changes in the subchondral bone. Hypothesis: Subchondral drilling induces substantial alterations of the microarchitecture of the subchondral bone that persist for a clinically relevant postoperative period in a preclinical large animal model. Study Design: Controlled laboratory study. Methods: Standardized full-thickness chondral defects in the medial femoral condyles of 19 sheep were treated by subchondral drilling. Six months postoperatively, the formation of cysts and intralesional osteophytes was evaluated. A standardized methodology was developed to segment the ovine subchondral unit into reproducible volumes of interest (VOIs). Indices of bone structure were determined by micro–computed tomography (micro-CT). Results: Analysis of the microarchitecture revealed the absence of zonal stratification in the ovine subarticular spongiosa, permitting an unimpeded and simultaneous analysis of the entire subchondral trabecular network. Subchondral drilling led to the formation of subchondral bone cysts (63%) and intralesional osteophytes (26%). Compared with the adjacent unaffected subchondral bone, drilling induced significant alterations in nearly all parameters for the microarchitecture of the subchondral bone plate and the subarticular spongiosa, most importantly in bone volume, bone surface/volume ratio, trabecular thickness, separation, pattern factor, and bone mineral density (BMD) (all P ≤ .01). Conclusion: The data show that the ovine subchondral bone can be reliably evaluated using micro-CT with standardized VOIs. We report that subchondral drilling deteriorates the microarchitecture both of the subchondral bone plate and subarticular spongiosa and decreases BMD. These results suggest that the entire osteochondral unit is altered after drilling for an extended postoperative period. Clinical Relevance: The subchondral bone remains fragile after subchondral drilling for longer durations than previously expected. Further evaluations of structural subchondral bone parameters of patients undergoing marrow stimulation are warranted.

The incidence of fetal alcohol syndrome has not been declining even though alcohol has been established as a teratogen and significant efforts have been made to educate women not to abuse alcohol during pregnancy. In addition to further educational efforts, strategies to prevent or mitigate the damages of prenatal alcohol exposure are now under development. Animal models will play a significant role in the effort to develop these strategies. Because prenatal alcohol exposure causes damage by multiple mechanisms, depending on dose, pattern, and timing of exposure, and because no species of animal is the same as the human, the choice of which animal model to use is complicated. To choose the best animal model, it is necessary to consider the specific scientific question that is being addressed and which model system is best able to addressthe question. Animal models that are currently in use include nonhuman primates, rodents (rats, mice, guinea pigs), large animal models (pig and sheep), the chick, and simple animals, including fish, insects, and round worms. Each model system has strengths and weaknesses, depending on the question being addressed. Simple animal models are useful in exploring basic science questions that relate to molecular biology and genetics that cannot be explored in higher-order animals, whereas higher-order animal models are useful in studying complex behaviors and validating basic science findings in an animal that is more like the human. Substantial progress in this field will require the judicious use of multiple scientific approaches that use different animal model systems.

BackgroundThe avascular portion of the meniscus cartilage in the knee does not have the ability to repair spontaneously.HypothesisCell-based therapy is able to repair a lesion in the swine meniscus.Study DesignControlled laboratory study.MethodsSixteen Yorkshire pigs were divided into four groups. A longitudinal tear was produced in the avascular portion of the left medial meniscus of 4 pigs. Autologous chondrocytes were seeded onto devitalized allogenic meniscal slices and were secured inside the lesion with two sutures. Identical incisions were created in 12 other pigs, which were used as three separate control groups: 4 animals treated with an unseeded scaffold, 4 were simply sutured, and 4 were left untreated. Meniscal samples were collected after 9 weeks, and the samples were analyzed grossly, histologically, and histomorphometrically.ResultsGross results showed bonding of the lesion margins in the specimens of the experimental group, whereas no repair was noted in any of the control group specimens. Histological and histomorphometrical analysis showed multiple areas of healing in the specimens of the experimental group.ConclusionsThis study demonstrated the ability of seeded chondrocytes to heal a meniscal tear.Clinical RelevanceCell-based therapy could be a potential tool for avascular meniscus repair.

Large animal toxicity studies, also called nonrodent studies, are very different from rodent (rat, mouse, guinea pig, and rabbit) studies in significant ways. The differences between the two study types, as well as the advantages and disadvantages of each, are evaluated in detail. Also examined are causes for selecting specific species, regulatory requirements for using nonrodent species, and an overview of major species characteristics for dogs, primates, pigs, and ferrets.

A Sunderland type IV traction injury to the C6 root of the sheep or lamb brachial plexus was used as a model for obstetric traction injury to the C5 root in humans. The injury was created and immediately repaired using interfascicular nerve autografts in a group of adult sheep and a group of newborn lambs. The animals were examined using electrophysiological and morphometric techniques 1 year after operation. It was found that the recovery of neuromuscular function was superior in the lambs. The implication is that nerves in newborn animals have a better potential for regeneration than that seen in older individuals. This is discussed with reference to the management of obstetric brachial plexus palsy.

Diagnosticiansshould be aware of the possibilities of these concurrent viralinfections in raccoons with neurologic disorders.Acknowledgements We thank G. Moser, B. Lehman, andS. Hindman for technical assistance. This work was sup-ported by grants from the Pennsylvania Department of Ag-riculture and the Laboratory of Large Animal Pathology,University of Pennsylvania.References

The safe experimental handling of animals infected with a new Risk Category 4 virus posed significant biosafety challenges. Novel approaches for restraining, handling and inoculating horses, cats and large fruit-eating bats with equine morbillivirus were developed. Equipment was designed to allow staff working in encapsulating suits access to all parts of a large animal room capable of accommodating seven horses individually. Procedures were developed for the safe handling, anesthesia and euthanasia of experimental animals and for the disposal of infected horse carcasses. Comprehensive staff training for this demanding work included safety consciousness, teamwork and training in first aid and emergency procedures.

Undesired pharmacologic activities of novel drugs or biologies may limit development of a therapeutic prior to the characterization of any toxicologic effects. In rodent species, general pharmacology assays have traditionally been used to screen new agents for pharmacologic effects on the central and peripheral nervous systems, the autonomic nervous system and smooth muscles, the respiratory and cardiovascular systems, the digestive system, and the physiologic mechanisms of water and electrolyte balance. In large animal species, such as dogs and nonhuman primates, smaller numbers of animals per study limit their use for screening assays, but these species may play an important role in more detailed mechanistic studies. For drugs and biologies that must be tested in nonhuman primates because of species-specific action of the test agent, functional pharmacologic data are often collected during acute or subacute toxicity studies. This requires careful experimental design to minimize any impact pharmacologic effects or instrumentation may have on the assessment of toxicity. In addition, with many new therapies targeted at immunologic diseases, the pharmacologic effect of therapeutics on the immune system presents new challenges for pharmacologic profiling. The application of pharmacology assays by organ system in both rodent and large animal species are discussed, as well as practical issues in assessing pharmacology endpoints in the context of toxicity studies.

Although sodium iodate (NaIO3)-induced retinal injury model has been widely used in rodents, its application in large animal species has encountered variation in retinal toxicity. NaIO3 induced retinal degeneration and functional changes in sheep, but not in swine. In monkeys, administration of NaIO3 via a carotid artery affected only the cell function of ipsilateral retinal pigment epithelium. The aim of the present study was to identify the dosage and route of NaIO3 administration resulting in morphologic and functional retinal changes in cynomolgus monkeys. Separate groups of animals received NaIO3 intravenously in three different dosing paradigms. Vehicle control animals received phosphate-buffered saline. At selected time points following dosing, flash electroretinograms (ERGs) were recorded followed by necropsy. The eyes were examined microscopically post-necropsy and the levels of circulating microRNA-183 cluster were evaluated in the blood samples collected on days 1, 4, and 5 postdose. A statistically significant reduction in both scotopic a-wave and scotopic and photopic b-wave signals ( p < 0.05) were observed between the ERG signals acquired from NaIO3-treated and vehicle control animals, coupled with time-dependent elevations in plasma miR-183 cluster. Mild to moderate retinal degeneration was observed in the outer layer of the retina, which correlated well with the functional and clinical observations. There were no statistically significant differences in scotopic oscillatory potentials. These findings suggest that intravenous injection of sublethal NaIO3 markedly damaged the cone and rod photoreceptors both functionally and morphologically, and plasma miR-183 reflected the retinal toxicity in those animals with moderate retinal damage.

Freeze-thawed muscle grafts (FTMG) have been suggested as an alternative to nerve grafts in reconstruction of peripheral nerve defects. This study compares the results of immediate and delayed nerve repair with freeze-thawed muscle graft in a large animal model. Under general anaesthesia, ten adult sheep underwent excision of 3 cm of the right median nerve. Five had immediate nerve reconstruction with FTMGs (Group A) and five were repaired after 4 weeks (Group B). At 6 months, both the right (repaired) and left (“control”) median nerves of each sheep were assessed. Nerve blood flow distal to the graft in both groups of repaired nerves was approximately 60% of that in their respective control nerves. Peak nerve conduction velocities were significantly slower in the repaired nerves. The mean fibre diameters of the immediate and delayed repairs were 5.06 and 3.90 μ respectively compared to a control mean of 8.58 μ. G-ratios confirmed that the repaired nerves in both groups were well myelinated. The authors conclude that the FTMG can be used in delayed as well as immediate nerve reconstruction with minimal impairment of final results.

IntroductionTo study the efficacy of novel regenerative strategies is necessary to develop new models that do not implement annulus fibrosus (AF) damage. We hypothesize an ideal preclinical model t...

Background: Treatment of osteochondritis dissecans (OCD) of the knee is challenging, and evidence for stage-dependent treatment options is lacking. Basic science approaches utilizing animal models have provided insight into the etiology of OCD but have yet to produce a reliable and reproducible large animal model of the disease on which to test new surgical strategies. Purpose/Hypotheses: The purpose of this study was to develop an animal model featuring an OCD-like lesion in terms of size, location, and International Cartilage Repair Society (ICRS) grading. The hypothesis was that surgical creation of an osteochondral defect followed by placement of a barrier between parent bone and progeny fragment would generate a reproducible OCD-like lesion. Study Design: Controlled laboratory study. Methods: Bilateral osteochondral lesions were created in the medial femoral condyles of 9 Yucatan minipigs. After lesion creation, a biodegradable membrane was interposed between the progeny and parent bone. Five different treatment groups were evaluated at 2 weeks: a control with no membrane (ctrl group; n = 4), a slowly degrading nanofibrous poly(∊-caprolactone) membrane (PCL group; n = 4), a fenestrated PCL membrane with 1.5-mm holes covering 25% of surface area (fenPCL group; n = 4), a collagen membrane (Bio-Gide) (CM group; n = 3), and a fenestrated CM (fenCM group; n = 3). Five unperturbed lateral condyles (1 from each treatment group) served as sham controls. After euthanasia on day 14, the lesion was evaluated by gross inspection, fluoroscopy, micro–computed tomography (micro-CT), and histology. To quantify changes between groups, a scoring system based on gross appearance (0-2), fluoroscopy (0-2), and micro-CT (0-6) was established. Micro-CT was used to quantify bone volume per total volume (BV/TV) in a defined region surrounding and inclusive of the defect. Results: The no scaffold group showed healing of the subchondral bone at 2 weeks, with continuity of subchondral bone elements. Conversely, condyles treated with PCL or CM showed substantial remodeling, with loss of bone in both the progeny fragment and surrounding parent bone. When these membranes were fenestrated (fenPCL and fenCM groups), bone loss was less severe. Histological analysis showed no integration in the cartilage layer in any treatment group, while fibrous tissue formed between the parent and progeny fragments. Micro-CT showed significant differences in mean BV/TV between the PCL (27.4% ± 2.3%) and the sham (47.7% ± 1.4%) or no scaffold (54.9% ± 15.1%) groups ( P < .01 and P < .05, respectively). In addition, a significant difference in bone loss was evident between the PCL and fenPCL groups (mean BV/TV, 46.6% ± 15.2%; P < .05), as well as between the PCL and fenCM (mean BV/TV, 50.9% ± 3.5%) and fenPCL groups ( P < .01). Grading by 6 blinded reviewers using an OCD scoring system with 3 subcategories showed a significant difference between control and PCL groups. Conclusion: This study successfully developed a large animal model of OCD-like lesions in the knee joint of Yucatan minipigs. The lesions generated matched characteristics of an ICRS grade 3 OCD lesion in humans. These findings set the stage for ongoing model refinement as well as exploration of novel interventional therapies to restore function and bone and cartilage patency in individuals affected by this rare but significant disease. Clinical Relevance: This developed model will serve as a platform on which to further investigate the natural course as well as emerging treatment options for OCD.

Herbal drugs are more and more used both in human and veterinary medicine to mitigate and prevent minor diseases and to support conventional medicine using allopathic drugs. Nevertheless, ‘natural product’ does not mean lack of adverse effects, and many people and veterinarians do not know enough about the adverse reactions that can occur following the administration of such drugs in domestic animals. Moreover, herbal products can interact with each other when administered concomitantly or can agonize or antagonize the effects of synthetic drugs administered as primary therapy. The use of non-conventional medicines (NCM) should be considered as a veterinary practise. In this paper, the herbal drugs most utilized in domestic animals, both pets and large animals, are reviewed, as their use is increasing, despite the prejudices of the academic world and some of the adverse effects and interactions that can occur in domestic animals.

Agricultural injury occurrence was determined among 1,096 working farm women in Texas and Louisiana. The 1-year cumulative incidence was 4.8%. Lower extremities were the body parts most frequently injured. The leading external causes were contact with foreign object, followed by falls and overdoing/lifting. The seasonal pattern of injury was consistent with warm weather. The factors predictive of increased injury risk in multiple logistic regression included large animal farm type, greater time commitment, recurrent or persistent back conditions or weakness during the previous 12 months, hauling goods to market, and driving a tractor more than 52 days per year. Most women consulted a physician as a result of the injury. Resolving the problem of preventable farm-related injuries will require a major and coordinated effort aimed not only at farm women themselves but also at multiple variables that profoundly affect the underlying conditions and behaviors that lead to farm-related injuries.

With a view of obtaining an antihuman hemolytic amboceptor on a large scale, I immunized a goat with thoroughly washed human corpuscles. I obtained a serum of a titre of 0.01 cubic centimeter, that is, capable of complete hemolysis with I cubic centimeter of a one per cent, suspension of washed human corpuscles in the presence of 0.01 cubic centimeter of normal goat's or guinea-pig's serum. The reactivating property of normal goat's serum for this ambocepter was found to be somewhat superior to that of guinea-pig's complement. As it would be of great economical value for complement fixation tests to utilize an amboceptor and complement from such a large animal as a goat, instead of using an amboceptor from rabbits and complement from guinea-pigs, I tested the amboceptor and complement from goats as to the possibility of using them in complement fixation tests in general. It was soon found that no complement-fixation phenomenon can be obtained by using them (antihuman amboceptor from this immune goat and c...