Surgical Animal Models Research Articles

O98 NEW APPROACHES TARGETING THE RENIN-ANGIOTENSIN SYSTEM: BRAIN ACE2 ACTIVATION FOLLOWING BRAIN AMINOPEPTIDASE A BLOCKADE BY FIRIBASTAT IN SALT-DEPENDENT HYPERTENSION

Background and Objective: In the brain, aminopeptidase A (APA), a membrane-bound zinc metalloprotease, generates angiotensin III from angiotensin II. Brain angiotensin III exerts a tonic stimulatory effect on the control of blood pressure (BP) in hypertensive rats and increases vasopressin release. Blocking brain angiotensin III formation by the APA inhibitor prodrug RB150/firibastat normalizes arterial BP in hypertensive deoxycorticosterone acetate (DOCA)-salt rats. Ang II and Ang III have similar affinities for AT1 receptors and blocking brain AngIII formation by RB150 decreases arterial BP without inducing Ang II accumulation. Methods: We therefore hypothesized that another metabolic pathway of brain angiotensin II, such as the conversion of angiotensin II into angiotensin 1-7 (Ang 1-7) by angiotensin-converting enzyme 2 (ACE2) might be activated following brain APA inhibition. To answer this question, we use surgical animal models that could allow us to monitor awake blood pressure responses to intracerebroventricular (icv) injections and measure enzymatic activity. Results: We found that the intracerebroventricular administration of RB150/firibastat in conscious DOCA-salt rats both inhibited brain APA activity and induced an increase in brain ACE2 activity. Then, we showed that the decreases in BP and vasopressin release resulting from brain APA inhibition with RB150/firibastat were reduced if ACE2 was concomitantly inhibited by MLN4760, a potent ACE2 inhibitor, or if the Mas receptor (MasR) was blocked by A779, a MasR antagonist. Conclusions: Our findings suggest that in the brain, the increase in ACE2 activity resulting from APA inhibition by RB150/firibastat treatment, subsequently increasing Ang 1-7 and activating the MasR while blocking angiotensin III formation, contributes to the antihypertensive effect and the decrease in vasopressin release induced by RB150/firibastat. RB150/firibastat treatment constitutes an interesting therapeutic approach to improve BP control in hypertensive patients by inducing in the brain renin-angiotensin system, hyperactivity of the beneficial ACE2/Ang 1-7/MasR axis while decreasing that of the deleterious APA/Ang II/Ang III/ATI receptor axis.

Training in Endoscopic Endonasal Neurosurgical Procedures: A Systematic Review of Available Models

Abstract Background Proficiency in endoscopic endonasal neurosurgery (EEN) requires a unique skill set and is associated with a steep learning curve. Endoscopic simulation models present an opportunity for trainees to enhance their surgical skills and anatomical knowledge in a risk-free environment. To date, four main categories of training modalities have been recorded: cadaveric, synthetic, animal, and virtual reality (VR) models. Objective To analyze the features, advantages, and disadvantages of each EEN training model, describe the stages of simulation training, and propose future directions and an algorithm for EEN training. Methods A comprehensive search was performed including studies published before August 2023. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed in the search and selection of studies included. Terms for searching title and abstract were (“simulation”) AND (“endoscopic endonasal”) AND (“neurosurgery”). Articles were screened for duplicates. Results We identified 176 references, and 43 studies met the inclusion criteria. Twelve articles described cadaveric models, with 7 of them studying internal carotid artery injury management and 3 of them cerebrospinal leak management; 14 articles illustrated synthetic models, 1 article described animal models, and 16 articles outlined VR simulations. Conclusion Cadaveric models provide realistic hands-on surgical training with acceptable cost and remain the gold standard method for training. Synthetic models are most effective for preoperative surgical planning and animal models are best suited for testing of hemostatic techniques. VR simulations may become the primary training tool for novices to acquire basic anatomical knowledge as their role in advanced surgical planning is evolving.

Comparison of four in vitro test methods to assess nucleus pulposus replacement device expulsion risk.

Nucleus replacement devices (NRDs) are not routinely used in clinic, predominantly due to the risk of device expulsion. Rigorous in vitro testing may enable failure mechanisms to be identified prior to clinical trials; however, current testing standards do not specify a particular expulsion test. Multiple methods have therefore been developed, complicating comparisons between NRD designs. Thus, this study assessed the effectiveness of four previously reported expulsion testing protocols; hula-hoop (Protocol 1), adapted hula-hoop (Protocol 2), eccentric cycling (Protocol 3), and ramp to failure (Protocol 4), applied to two NRDs, one preformed and one in situ curing. Nucleus material was removed from 40 bovine tail intervertebral disks. A NRD was inserted posteriorly into each cavity and the disks were subjected to one of four expulsion protocols. NRD response was dependent on both the NRD design and the loading protocol. Protocol 1 resulted in higher migration and earlier failure rates compared to Protocol 2 in both NRDs. The preformed NRD was more likely to migrate when protocols incorporated rotation. The NRDs had equal migration (60%) and expulsion (60%) rates when using unilateral bending and ramp testing. Combining the results of multiple tests revealed complimentary information regarding the NRD response. Adapted hula-hoop (Protocol 2) and ramp to failure (Protocol 4), combined with fluoroscopic analysis, revealed complimentary insights regarding migration and failure risk. Therefore, when adopting the surgical approach and animal model used in this study, it is recommended that NRD performance be assessed using both a cyclic and ramp loading protocol.

A magnesium screw with optimized geometry exhibits improved corrosion resistance and favors bone fracture healing

Stress-induced corrosion impairs the mechanical integrity of magnesium (Mg) and its alloys as potential orthopedic implants. Although there has been extensive work reporting the effects of stress on Mg corrosion in vitro, the geometric design principles of the Mg-based orthopedic devices still remain largely unknown. In this work, a numerical simulation model mimicking fractured bone fixation and surgical animal models were applied to investigate the effects of the geometric design of Mg screws on the stress distribution and the stress-induced degradation behavior. Finite element (FE) analysis was used for calculation of stress concentrations around the Mg screws, with different thread type, thread pitch, and thread width. Afterward, the Mg screws of the pre-optimization and post-optimization groups exhibiting the highest and lowest stress concentrations, respectively, were implanted in the fractured distal femora and back subcutaneous tissue of rabbits. Encouragingly, there was a significant difference between the pre-optimization and the post-optimization groups in the degradation rate of the stressed screw parts located around the fracture line. Interestingly, there was no significant difference between the two groups in the degradation rate of the non-stressed screw parts. Consistently, the Mg screw post-optimization exhibited a significantly lower degradation rate than that pre-optimization in the back subcutaneous implantation model, which generated stress in the whole screw body. The alteration in geometric design did not affect the corrosion rate of the Mg screws in an immersion test without load applied. Importantly, an accelerated new bone formation with less fibrous encapsulation around the screws was observed in the Mg group post-optimization relative to the Mg group pre-optimization and the poly (lactic acid) group. Geometry optimization may be a promising strategy to reduce stress-induced corrosion in Mg-based orthopedic devices. Statement of significanceStress concentrations influence corrosion characteristics of magnesium (Mg)-based implants. The geometric design parameters, including thread type, thread pitch, and thread width of the Mg screws, were optimized through finite element analysis to reduce stress concentrations in a fractured model. The Mg screws with triangular thread type, 2.25 mm pitch, and 0.3 mm thread width, exhibiting the lowest maximum von Mises stress, showed a significant decrease in the volume loss relative to the Mg screws pre-optimization. Compared with the Mg screw pre-optimization and the poly(lactic acid) screw, the Mg screw post-optimization favored new bone formation while inhibiting fibrous encapsulation. Collectively, optimization in the geometric design is a promising approach to reduce stress-induced corrosion in Mg-based implants.

Large animal models of pressure overload-induced cardiac left ventricular hypertrophy to study remodelling of the human heart with aortic stenosis.

Pathologic cardiac hypertrophy is a common consequence of many cardiovascular diseases, including aortic stenosis (AS). AS is known to increase the pressure load of the left ventricle, causing a compensative response of the cardiac muscle, which progressively will lead to dilation and heart failure. At a cellular level, this corresponds to a considerable increase in the size of cardiomyocytes, known as cardiomyocyte hypertrophy, while their proliferation capacity is attenuated upon the first developmental stages. Cardiomyocytes, in order to cope with the increased workload (overload), suffer alterations in their morphology, nuclear content, energy metabolism, intracellular homeostatic mechanisms, contractile activity, and cell death mechanisms. Moreover, modifications in the cardiomyocyte niche, involving inflammation, immune infiltration, fibrosis, and angiogenesis, contribute to the subsequent events of a pathologic hypertrophic response. Considering the emerging need for a better understanding of the condition and treatment improvement, as the only available treatment option of AS consists of surgical interventions at a late stage of the disease, when the cardiac muscle state is irreversible, large animal models have been developed to mimic the human condition, to the greatest extend. Smaller animal models lack physiological, cellular and molecular mechanisms that sufficiently resemblance humans and in vitro techniques yet fail to provide adequate complexity. Animals, such as the ferret (Mustello purtorius furo), lapine (rabbit, Oryctolagus cunigulus), feline (cat, Felis catus), canine (dog, Canis lupus familiaris), ovine (sheep, Ovis aries), and porcine (pig, Sus scrofa), have contributed to research by elucidating implicated cellular and molecular mechanisms of the condition. Essential discoveries of each model are reported and discussed briefly in this review. Results of large animal experimentation could further be interpreted aiming at prevention of the disease progress or, alternatively, at regression of the implicated pathologic mechanisms to a physiologic state. This review summarizes the important aspects of the pathophysiology of LV hypertrophy and the applied surgical large animal models that currently better mimic the condition.

Standardized Pre-clinical Surgical Animal Model Protocol to Investigate the Cellular and Molecular Mechanisms of Ischemic Flap Healing

BackgroundSome of the most complex surgical interventions to treat trauma and cancer include the use of locoregional pedicled and free autologous tissue transfer flaps. While the techniques used for these reconstructive surgery procedures have improved over time, flap complications and even failure remain a significant clinical challenge. Animal models are useful in studying the pathophysiology of ischemic flaps, but when repeatability is a primary focus of a study, conventional in-vivo designs, where one randomized subset of animals serves as a treatment group while a second subset serves as a control, are at a disadvantage instigated by greater subject-to-subject variability. Our goal was to provide a step-by-step methodological protocol for creating an alternative standardized, more economical, and transferable pre-clinical animal research model of excisional full-thickness wound healing following a simulated autologous tissue transfer which includes the primary ischemia, reperfusion, and secondary ischemia events with the latter mimicking flap salvage procedure.ResultsUnlike in the most frequently used classical unilateral McFarlane’s caudally based dorsal random pattern skin flap model, in the herein described bilateral epigastric fasciocutaneous advancement flap (BEFAF) model, one flap heals under normal and a contralateral flap—under perturbed conditions or both flaps heal under conditions that vary by one within-subjects factor. We discuss the advantages and limitations of the proposed experimental approach and, as a part of model validation, provide the examples of its use in laboratory rat (Rattus norvegicus) axial pattern flap healing studies. ConclusionsThis technically challenging but feasible reconstructive surgery model eliminates inter-subject variability, while concomitantly minimizing the number of animals needed to achieve adequate statistical power. BEFAFs may be used to investigate the spatiotemporal cellular and molecular responses to complex tissue injury, interventions simulating clinically relevant flap complications (e.g., vascular thrombosis) as well as prophylactic, therapeutic or surgical treatment (e.g., flap delay) strategies in the presence or absence of confounding risk factors (e.g., substance abuse, irradiation, diabetes) or favorable wound-healing promoting activities (e.g., exercise). Detailed visual instructions in BEFAF protocol may serve as an aid for teaching medical or academic researchers basic vascular microsurgery techniques that focus on precision, tremor management and magnification.Graphical

Abstract P202: Changes In Cerebral Mitochondrial Function In Intrauterine Growth-Restricted Offspring Before The Development Of Hypertension And Cerebrovascular Dysfunction

Background: Preeclampsia (PE), new-onset gestational hypertension (HTN) affects 3-8% of all births in the USA. PE is the leading cause for intrauterine growth restriction (IUGR). IUGR children have increased risks of HTN and cerebrovascular disease (CVD) later in life. Prior studies in our lab show adult male IUGR rat offspring (OS) to develop HTN, CVD, and cerebral mitochondrial dysfunction (mtDys) at 17 weeks while female IUGR OS exhibit CVD. The role of mtDys in HTN is unknown and is the focus of our study. We hypothesize that IUGR OS will have mtDys prior to HTN. Methods: Our surgical PE animal model utilized the reduced-uterine-perfusion pressure (RUPP) surgery at GD 14. OS from NP served as controls (CON) while OS from RUPP mothers were IUGR. At 12 weeks, OS BP was measured alongside cerebral mtDys through mitochondrial fusion and fission, electron-transport chain (ETC) proteins, and respiration. Results: BP did not change between sexes or among IUGR and CON offspring. Male IUGR OS showed elevated mtRes (State 2: 199 ± 1.08 v. 76 ± 1.13 pmol/mg, p < .05; State 3: 555 ± 3.02 v. 245 ± 1.77 pmol/mg, p < .05; State 4: 346 ± 1.66 v. 85 ± 1.12 pmol/mg, p < .05). Female IUGR and CON OS had no changes in BP or mtRes. Male IUGR OS had increased mito-fusion proteins MFN-1 (176 ± 1.68 v. 100 ± .57 IU/protein/CON %, p < .05), MFN-2 (155 ± 1.36 v. 100 ± .74 IU/protein/CON %, p < .05) and OPA-1 (166 ± 1.99 v. 100 ± .73 IU/protein/CON %, p < .05). DRP-1 had no changes in males; females had no changes in fusion or fission. Male IUGR OS had changes in ETC proteins (CI: 8 ± 9.34 v. 100 ± .82 IU/protein/CON %, p < .05; CII: 23 ± .53 v. 100 ± .52 IU/protein/CON %, p < .05; CIII: 26 ± .23 v. 100 ± .41 IU/protein/CON %, p < .05), as did female IUGR OS (CI: 12 ± .24 v. 100 ± .86 IU/protein/CON %, p < .05; CII: 29 ± .39 v. 100 ± .61 IU/protein/CON %, p < .05; CIII: 39 ± .56 v. 100 ± .62 IU/protein/CON %, p < .05; CIV: 76 ± .74 v. 100 ± .73 IU/protein/CON %, p < .05) vs. CON OS. Summary: Male IUGR OS have elevated mtRes, changed ETC proteins, and fusion proteins that may lead to mtDys and HTN development. This study is clinically relevant because specific cerebral therapy for mtDys for IUGR OS may prevent HTN and CVD development. Future studies will examine changes in mtDys causing male HTN and protection from HTN in females.

Eucalyptol induces osteoblast differentiation through ERK phosphorylation in vitro and in vivo.

Eucalyptol (EU) is monoterpene oxide that is the main component of the essential oil extracted from aromatic plants such as Eucalyptus globules. EU has therapeutic effects such as antibacterial, anti-inflammatory and antioxidant in chronic diseases including inflammation disorder, respiratory disease, and diabetic disease. However, the effects of EU on osteoblast differentiation and bone diseases such as osteoporosis have not been studied. The present study investigated the effects of EU on osteoblast differentiation and bone formation. EU induces mRNA and protein expression of osteogenic genes in osteoblast cell line MC3T3-E1 and primary calvarial osteoblasts. EU also promoted alkaline phosphatase (ALP) activity and mineralization. Here, the osteoblast differentiation effect of EU is completely reversed by ERK inhibitor. These results demonstrate that osteoblast differentiation effect of EU is mediated by ERK phosphorylation. The efficacy of EU on bone formation was investigated using surgical bone loss-induced animal models. EU dose-dependently promoted bone regeneration in zebrafish caudal fin rays. In the case of ovariectomized mice, EU increased ERK phosphorylation and ameliorated bone loss of femurs. These results indicate that EU ameliorates bone loss by promoting osteoblast differentiation through ERK phosphorylation. We suggest that EU, plant-derived monoterpenoid, may be useful for preventing bone loss. KEY MESSAGES: Eucalyptol (EU) increases osteoblast differentiation in pre-osteoblasts. EU up-regulates the osteogenic genes expression via ERK phosphorylation. EU promotes bone regeneration in partially amputated zebrafish fin rays. Oral administration of EU improves ovariectomy-induced bone loss and increases ERK phosphorylation.

Pharmacological and surgical experimental animal models of induction of spermatogenesis disorders

Introduction. Experimental induction of spermatogenesis disorders is possible mainly by physical, pharmacological methods. However, not all methods can cause non-obstructive azoospermia.Objective. To evaluate and compare the effectiveness of induction of spermatogenesis disorders in rat models by applying ligatures to the spermatic cords and administration of cisplatin.Materials & methods. Seventy-three mature male rats (Wistar) were divided into 2 experimental groups and 1 control (n = 9) group: group 1 (n = 27) with ligature on the spermatic cord for 12 h (n = 9), 24 h (n = 9), 36 h (n = 9); group 2 (n = 37) with five-fold intraperitoneal administration of cisplatin at concentrations of 5 mg/kg, 3 mg/kg, 1 mg/kg. On days 0, 7, 14, 28 after the last day of induction of spermatogenesis disorders, epididymal semen analysis, blood test, total serum testosterone, pathomorphological examination of testes tissue, body weight, reproductive system organ weight were performed to assess model performance.Results. Ligation to the spermatic cords did not have a negative effect on the general condition of the animals (p < 0.05), blood test (p < 0.05); there was a decrease in the testicular weight (p < 0.05), the appendage of the testis (p < 0.05), prostate (p < 0.05), the weight of the seminal vesicles did not change (p > 0.05). In group 1, the number of epidermal spermatozoa decreased in all subgroups, statistically significant changes were recorded at 7 (exposure 24 h) and 28 (exposure 12, 36 h) days of research. Histologically, there was no significant inhibition of spermatogenesis, except for a decrease in the area, diameter of the seminal tubules on 7, 28 days after surgery (exposure 24, 36 h). In group 2, the survival of animals was noted only when using cisplatin at a dose of 1 mg/kg five times. Body weight decreased in all rats without recovery, thrombocytopenia recorded after 1 wk, leukocytopenia regressed by 2 wk of the study. A decrease in the weight of all reproductive organs was noted. Sperm concentration decreased at 1 wk and recovered at 28 wk. In the analysis of testicular biopsies: pronounced disorganization of the spermatogenic epithelium, a decrease in the absolute area and diameter of the seminal tubules.Conclusion. Ligation to the spermatic cord does not cause permanent inhibition of spermatogenesis. Cisplatin at a dose of 1 mg/kg causes persistent severe damage to the spermatogenic epithelium.

A novel pilot animal model for bone augmentation using osseous shell technique for preclinical in vivo studies.

Bone grafting is commonly used to reconstruct skeletal defects in the craniofacial region. Several bone augmentation models have been developed to evaluate bone formation using novel bone substitute materials. The aim of this study was to evaluate a surgical animal model for establishing a three-dimensional (3D) grafting environment in the animal's mandibular ramus for bone augmentation using the osseous shell technique, as in humans. Osteological survey of New Zealand white (NZW) rabbit skull (Oryctolagus cuniculus): Initial osteological and imaging surveys were performed on a postmortem skull for a feasibility assessment of the surgical procedure. Postmortem pilot surgery and cone beam computed tomography imaging: a 3D osseous defect was created in the mandibular ramus through a submandibular incision. The osseous shell plates were stabilized with osteosynthesis fixation screws, and defects were filled with particular bone grafting material. In vivo surgical procedure: surgeries were conducted in four 8-week-old NZW rabbits utilizing two osseous shell materials: xenogeneic human cortical plates and autogenous rabbit cortical plates. The created 3D defects were filled using xenograft and allograft bone grafting materials. The healed defects were evaluated for bone formation after 12 weeks using histological and cone beam computed tomography imaging analysis. Clinical analysis 12 weeks after surgery revealed the stability of the 3D grafted bone augmentation defects using the osseous shell technique. Imaging and histological analyses confirmed the effectiveness of this model in assessing bone formation. The proposed animal model is a promising model with the potential to study various bone grafting materials for augmentation in the mandibular ramus using the osseous shell technique without compromising the health of the animal. The filled defects could be analyzed for osteogenesis, quantification of bone formation, and healing potential using histomorphometric analysis, in addition to 3D morphologic evaluation using radiation imaging.

Comparison of Pain-Like behaviors in two surgical incision animal models in C57BL/6J mice

BackgroundManagement of pain post-surgery is crucial for tissue healing in both veterinary and human medicine. Overuse of some analgesics such as opioids may lead to addictions and worsen pain syndromes (opioid-induced hyperalgesia), while underuse of it may affect the welfare of the patient. Therefore, the importance of using surgery models in laboratory animals is increasing, with the goal of improving our understanding of pain neurobiology and developing safer analgesics. MethodsWe compared the widely used plantar incision model with the laparotomy surgery model and measured pain-related behaviors using both spontaneous and evoked responses in female and male C57BL/6J mice. Additionally, we assessed conditioned place preference (CPP) and sucrose preference tests to measure pain-induced motivation for the analgesic ketoprofen and anhedonia-like behavior. ResultsLaparotomized mice showed increased abdominal sensitivity while paw-incised mice showed increased paw thermal and mechanical sensitivity up to seven days post-surgery. Laparotomy surgery reduced all spontaneous behaviors in our study however this effect dissipated by 24 h post-laparotomy. On the other hand, paw incision only reduced the percentage of cage hanging in a sex-dependent manner at 6 h post-incision. We also showed that both surgery models increased conditioned place preference for ketoprofen while preference for sucrose was only reduced at 24 h post-laparotomy. Laporatomy, but not paw incision, induced a decrease in body weight at 24 h post-surgery. Neither surgery model affected fluid intake. ConclusionOur results indicate that post-surgery hypersensitivity and behavioral deficits may differ by the incision site. Furthermore, factors associated with the surgery including length of the incision, duration of the anesthesia, and the layers that received stitches may affect subsequent spontaneous behaviors. These findings may help to improve drug development or the choice of the effective analgesic, depending on the surgery type.

Temporomandibular joint osteoarthritis: A review of animal models induced by surgical interventions.

The pathological mechanism of temporomandibular joint osteoarthritis (TMJOA) is still unclear. Animal models induced by surgical interventions are one of the most ideal tools to imitate human pathological conditions. This review aims to define the similarities and differences of different surgical animal models. Articles of TMJOA surgical animal models were collected including anterior disc displacement, disc perforation, and discectomy. We analyzed their experiments strategies based on comparing preoperative selection, intraoperative methodology, and postoperative manifestations. No matter which surgical intervention is selected, abnormal stress forces the whole joint to remodel its structure so that it could adapt to functional requirements, resulting in TMJOA eventually. However, anterior disc displacement needs more than 16 weeks to obtain typical manifestations, where the methodology is complicated. The course of perforation and discectomy is around 12-16 weeks, but they could cause excessive damage to the TMJ structure. All surgical interventions can cause TMJOA, but the extent of pathology varies from each other. This review will assist future experiments to better understand the pathogenesis of TMJOA and choose the most appropriate model.

Loss of cardiac myosin light chain kinase contributes to contractile dysfunction in right ventricular pressure overload.

Nearly 1 in every 100 children born have a congenital heart defect. Many of these defects primarily affect the right heart causing pressure overload of the right ventricle (RV). The RV maintains function by adapting to the increased pressure; however, many of these adaptations eventually lead to RV hypertrophy and failure. In this study, we aim to identify the cellular and molecular mechanisms of these adaptions. We utilized a surgical animal model of pulmonary artery banding (PAB) in juvenile rats that has been shown to accurately recapitulate the physiology of right ventricular pressure overload in young hearts. Using this model, we examined changes in cardiac myocyte protein expression as a result of pressure overload with mass spectrometry 4 weeks post‐banding. We found pressure overload of the RV induced significant downregulation of cardiac myosin light chain kinase (cMLCK). Single myocyte calcium and contractility recordings showed impaired contraction and relaxation in PAB RV myocytes, consistent with the loss of cMLCK. In the PAB myocytes, calcium transients were of smaller amplitude and decayed at a slower rate compared to controls. We also identified miR‐200c, which has been shown to regulate cMLCK expression, as upregulated in the RV in response to pressure overload. These results indicate the loss of cMLCK is a critical maladaptation of the RV to pressure overload and represents a novel target for therapeutic approaches to treat RV hypertrophy and failure associated with congenital heart defects.

Ultrasound-guided rectus sheath injection in pig cadavers – a pilot study

The rectus sheath block is a locoregional technique used to desensitize ventromedial aspects of the abdominal wall in dogs and humans. This technique has not yet been described in pigs, which represent an accepted surgical animal model.

A Non-Invasive Method for Generating the Cyclic Loading-Induced Intra-Articular Cartilage Lesion Model of the Rat Knee.

The pathophysiology of primary osteoarthritis (OA) remains unclear. However, a specific subclassification of OA in relatively younger age groups is likely correlated with a history of articular cartilage damage and ligament avulsion. Surgical animal models of OA of the knee play an important role in understanding the onset and progression of post-traumatic OA and aid in the development of novel therapies for this disease. However, non-surgical models have been recently considered to avoid traumatic inflammation that could affect the evaluation of the intervention. In this study, an intra-articular cartilage lesion rat model induced by in vivo cyclic compressive loading was developed, which allowed researchers to (1) determine the optimal magnitude, speed, and duration of load that could cause focal cartilage damage; (2) assess post-traumatic spatiotemporal pathological changes in chondrocyte vitality; and (3) evaluate the histological expression of destructive or protective molecules that are involved in the adaptation and repair mechanisms against joint compressive loads. This report describes the experimental protocol for this novel cartilage lesion in a rat model.

A Cardiac Protection of Germinated Brown Rice During Cardiopulmonary Bypass Surgery and Simulated Myocardial Ischemia.

PurposeThe potential cardio-protective property of germinated brown rice (GBR) has been revealed by ameliorating risk factors related to cardiovascular diseases. This study hypothesized that the combination of GBR and cardioplegic solution could protect the cardiomyocytes exposed to simulated ischemic reperfusion injury in vitro study and preserve cardiac function during cardiopulmonary bypass surgery in animal models.MethodsPrimary porcine cardiomyocytes were isolated and experimented cell viability against simulated ischemic reperfusion injury. In a cardiac surgical animal model, six pigs were randomly assigned to receive the two types of cardioplegic solution: i) St. Thomas cardioplegic solution (20 cc/kg); and ii) St. Thomas cardioplegic solution plus GBR (1 mg/kg). During open-heart surgery, the aorta was cross-clamped for 20 minutes, followed by reperfusion for 1 hour. Cardiopulmonary bypass parameters were recorded until the end of the procedure. Furthermore, hemodynamic parameters and arterial blood gas characteristics of animals among groups were monitored at different time points, including baseline before cardiopulmonary bypass (T1), during cardiopulmonary bypass (T2), during aortic clamp on (T3), and aortic clamp off (T4).ResultsPrimarily, GBR cotreatment with cardioplegic solution essentially resulted in the improvement of cell viability in primary porcine cardiomyocytes against simulated ischemic reperfusion induction. The findings from cardiac surgery demonstrated that mean arterial pressure and heart rate are constantly stable in cardioplegic solution combined with the GBR group, while the trend of potassium and lactase concentration was decreased in the animals receiving GBR group. Consistently, all parameters from arterial blood gas showed better outcomes in animals receiving GBR; however, there were no statistically significant differences between groups, except hepatic enzymes.ConclusionTherefore, GBR might exert cardio-protective effects against ischemic reperfusion injury in the porcine cardiac surgery model due to anti-inflammatory response. These protective actions of GBR may explain the benefits gained from applying GBR products as a possible therapeutic supplement on cardiac diseases.

Proximal Perineural Femoral Nerve Injection in Pigs Using an Ultrasound-Guided Lateral Subiliac Approach-A Cadaveric Study.

Simple SummaryDesensitizing the femoral nerve improves pain control in several species undergoing pelvic limb surgeries. Despite possible advantages, this method has not yet been described in pigs, although they make an accepted surgical animal model. We developed an approach for femoral nerve blockade using ultrasound guidance in pigs which could be useful for pain control in pigs undergoing pelvic limb surgery.Desensitizing the femoral nerve (FN) improves pain control in several species undergoing pelvic limb surgeries. Despite its advantages, this method has not yet been described in pigs, although they make an accepted surgical animal model. Based on anatomical dissections, first performed in two pig cadavers, an ultrasound-guided access for localization and perineural infiltration of the FN trunk at the iliopsoas compartment level was specified. The FN was found running between the psoas major and medial portion of iliac muscle. Ultrasonographically, the FN appeared as a hypoechogenic round–oval structure surrounded by a hyperechogenic rim. Technical feasibility and accuracy were assessed in six additional pig cadavers by injecting 0.15 mL kg−1 methylene blue dye bilaterally in direct proximity to the nerve. The needle was inserted caudoventral to the coxal tuber, traversing the ultrasound plane as it progressed towards the FN in dorsomedial direction. Staining of the nerve was evaluated by dissection. The injection was considered effective if the nerve was stained in its entire circumference over a length of 2 cm. FNs of all investigated individuals could be successfully stained. This ultrasound-guided subiliac approach allows feasible and accurate access to the FN and may be useful in producing a successful blockade in vivo.

Chem-inspired synthesis of injectable metal–organic hydrogels for programmable drug carriers, hemostasis and synergistic cancer treatment

Metal-organic hydrogels (MOGs) are emerging as alternatives to metal–organic frameworks owing to advantages such as porous microstructure and flexibility, particularly in the biomedical field. In this work, injectable MOGs were developed at room temperature with zinc ions as the metal nods and 4,5-imidazole dicarboxylic acid as the organic ligand modulator by a phase-transfer strategy. The resulting MOGs enabled the programmable encapsulation and pH-responsive release of various water-soluble and water-insoluble drugs, and biomacromolecules. The prepared MOGs exhibit a microporous nanofibrous structure with low mechanical strength, and shear-thinning, injectable, and self-healing properties. Notably, high-mechanical strength self-supporting hydrogels were obtained after injection into a saline solution. This resulted in the rapid hemostatic effect of the prepared MOGs in different surgical animal models. To illustrate their drug delivery applications, doxorubicin and glucose oxidase were encapsulated into the MOGs, demonstrating the glucose–pH dual-responsive release. The drug-loaded MOGs efficiently suppressed tumor growth by the synergetic effect of tumor vascular obstruction, nutrition starvation, and chemotherapy. The injectable MOGs with controllable rheological and drug-carrying properties have promising potential for drug delivery and other biomedical applications.

A novel serine protease inhibitor as potential treatment for dry eye syndrome and ocular inflammation

Dry eye syndrome (DES), a multifactorial disorder which leads to ocular discomfort, visual disturbance and tear film instability, has a rising prevalence and limited treatment options. In this study, a newly developed trypsin-like serine protease inhibitor (UAMC-00050) in a tear drop formulation was evaluated to treat ocular inflammation. A surgical animal model of dry eye was employed to investigate the potential of UAMC-00050 on dry eye pathology. Animals treated with UAMC-00050 displayed a significant reduction in ocular surface damage after evaluation with sodium fluorescein, compared to untreated, vehicle treated and cyclosporine-treated animals. The concentrations of IL-1α and TNF-α were also significantly reduced in tear fluid from UAMC-00050-treated rats. Additionally, inflammatory cell infiltration in the palpebral conjunctiva (CD3 and CD45), was substantially reduced. An accumulation of pro-MMP-9 and a decrease in active MMP-9 were found in tear fluid from animals treated with UAMC-00050, suggesting that trypsin-like serine proteases play a role in activating MMP-9 in ocular inflammation in this animal model. Comparative qRT-PCR analyses on ocular tissue indicated the upregulation of tryptase, urokinase plasminogen activator receptor (uPAR) and protease-activated receptor 2 (PAR2). The developed UAMC-00050 formulation was stable up to 6 months at room temperature in the absence of light, non-irritating and sterile with compatible pH and osmolarity. These results provide a proof-of-concept for the in vivo modifying potential of UAMC-00050 on dry eye pathology and suggest a central role of trypsin-like serine proteases and PAR2 in dry eye derived ocular inflammation.

A quantitative study to examine the effect of controlling abnormal joint instability in a mouse model of anterior cruciate ligament tibial displacement and cartilage degeneration

Purpose: Osteoarthritis (OA) is a gradually progressing disease that results in articular cartilage degradation and loss across the full-thickness of the cartilage. To analyze the onset of OA or its degeneration mechanism, surgical joint instability animal models are used in experimental studies. Smaller rodent animal models such as rats and mice are preferred for preliminary screening because of the cost-benefit and ease of modification of their genotypes. Both the anterior cruciate ligament transection (ACLT) and destabilized medial meniscus (DMM) models are common rodent animal models of knee OA produced in the laboratory.