Iron regulatory protein 1 is required for the propagation of inflammation in inflammatory bowel disease.

Inflammatory bowel diseases (IBDs) are complex disorders. Iron accumulates in the inflamed tissue of IBD patients, yet neither a mechanism for the accumulation nor its implication on the course of inflammation is known. We hypothesized that the inflammation modifies iron homeostasis, affects tissue iron distribution, and that this in turn perpetuates the inflammation. This study analyzed human biopsies, animal models, and cellular systems to decipher the role of iron homeostasis in IBD. We found inflammation-mediated modifications of iron distribution, and iron-decoupled activation of the iron regulatory protein (IRP) 1. To understand the role of IRP1 in the course of this inflammation-associated iron pattern, a novel cellular coculture model was established, which replicated the iron-pattern observed in vivo, and supported involvement of nitric oxide in the activation of IRP1 and the typical iron pattern in inflammation. Importantly, deletion of IRP1 from an IBD mouse model completely abolished both, the misdistribution of iron and intestinal inflammation. These findings suggest that IRP1 plays a central role in the coordination of the inflammatory response in the intestinal mucosa and that it is a viable candidate for therapeutic intervention in IBD.

Biocompatible Solutions: Evaluating the Safety of Repeated Intra-Articular Injections of pMPCylated Liposomes for Knee Osteoarthritis Therapy in Rat Models.

Knee osteoarthritis (OA) poses a significant health care burden globally, necessitating innovative therapeutic approaches. CCoat, a novel poly(2-[methacryloyloxy]ethyl phosphorylcholine) (pMPC)ylated liposome device, protects the cartilage surface of the joint from mechanical wear through an entropy-favored process. Two preclinical studies were performed to explore the safety of CCoat following repeated intra-articular (IA) injections into the knee joint (i.e., femorotibial joint) in Sprague-Dawley rats. The studies involved 2 or 3 IA injections, at an interval of 2 or 3 weeks, and an observation period of 1 or 13 weeks after the last injection. Assessments included clinical, histopathological, and immunofluorescent evaluations. In study 1, no mortality or abnormal clinical signs occurred. At 1 week post last injection, histopathology revealed minimal vacuolated macrophages beneath the synovial membrane, predominantly M2-like, indicating a nonadverse response. Immunofluorescent staining supported M2-like macrophage predominance. Study 2 confirmed these findings with no systemic effects over 13 weeks. Statistical analyses indicated no significant differences in body weight, clinical pathology, or organ weights compared with controls. Results affirming the safety of pMPCylated liposomes following repeated IA injections in rat. This novel lubricant coating approach shows promise in OA therapy, with this safety assessment supporting its potential clinical application.

Comprehensive Evaluation of the BeShape One Device: Assessing Thermal Safety in Noninvasive Body Contouring Using Advanced Techniques.

OBJECTIVES: This study aims to assess the thermal safety profile of the BeShape One Device, a noninvasive, high-intensity, non-focused ultrasound device designed for reducing waist circumference. This device possesses several features that distinguish it from other commercial ultrasound-based fat reduction devices. The study focuses on evaluating temperature-related physiological changes through thermal safety analysis and histopathology in a swine model. MATERIALS AND METHODS: The study utilized three types of applicators-active, demo, and modified-to comprehensively assess the device's impact on various skin layers. Five female Large White X Landrace swine were involved in the study, and the BeShape One Device was applied to designated treatment sites using a specific treatment protocol. The assessment included clinical observations, skin reaction evaluations, gross pathology, histopathological analyses, and advanced temperature measurement techniques, including needle thermocouples, thermal cameras, COMSOL modeling, and CEM43 analysis. RESULTS: Clinical observations indicated the animals' overall well-being throughout the study. Skin reactions, including erythema, edema, bruising, and crust formation, were temporary and resolved over time. Gross pathology revealed no treatment-related pathologies, except for a discoloration related to a tattoo procedure. Histopathological analyses at 30 and 90 days posttreatment demonstrated an absence of heat-related lesions in skin layers. Needle thermocouples and thermal camera measurements supported the device's ability to maintain consistent thermal homogeneity. COMSOL modeling and CEM43 analysis predicted no thermal damage to the skin, confirming the safety of the BeShape One Device. CONCLUSIONS: Under the experimental conditions, the BeShape One Device demonstrated a favorable safety profile. Clinically and histopathologically, no adverse effects were observed. The device's ability to achieve thermal homogeneity in skin layers was validated through advanced temperature measurement techniques. COMSOL modeling and CEM43 analysis further supported the conclusion that the device is safe, making it a promising option for noninvasive body contouring procedures.

Preclinical In-Vivo Safety and Toxicokinetics of D-PLEX100 in an Abdominal Surgery Incision Model in Juvenile Miniature Swine.

D-PLEX100 (D-PLEX) is a novel product candidate made of a polymer-lipid-based matrix (PLEX platform) which contains doxycycline that is being released at a constant rate for 30 days. D-PLEX was developed to prevent surgical site infections, which are a major global health challenge. Previous studies have shown its safety in adult humans, adult swine, and adult rabbits. The aim of this study was to assess the toxicity and safety of D-PLEX also in juvenile animals to support future clinical trials in pediatric patients. Yucatan miniature swine were selected as a model, primarily due to their relatively larger mass. D-PLEX or placebo (formulation without doxycycline) was administered locally to abdominal incisions, and the animal's safety parameters were followed for 9 months and compared to sham-control swine. There was no evidence of any systemic safety concern or local toxicity at the incision site in D-PLEX-treated animals. D-PLEX was detected after 1 month and was fully resorbed at the 3-month time point. The surgical incision sites were fully healed at the 6-month time point in all D-PLEX-treated animals. Toxicokinetic (TK) assessments revealed that doxycycline exhibited low Cmax and therefore minimal systemic exposure following a single dose of local administration. This study provides evidence for the safety of D-PLEX and PLEX-based formulation in juvenile miniature swine and supports its further testing in clinical pediatric population. In addition, it can be used as a reference for future preclinical studies aiming to evaluate the safety of other PLEX-based product candidates for the pediatric population.

Neural tissue tolerance to synthetic dural mater graft implantation in a rabbit durotomy model.

In neurosurgical interventions, effective closure of the dura mater is essential to prevent cerebrospinal fluid leakage and minimize post-operative complications. Biodegradable synthetic materials have the potential to be used as dura mater grafts owing to their regenerative properties and low immunogenicity. This study evaluated the safety of ArtiFascia, a synthetic dura mater graft composed of poly(l-lactic-co-caprolactone acid) and poly(d-lactic-co-caprolactone acid), in a rabbit durotomy model. Previously, ArtiFascia demonstrated positive local tolerance and biodegradability in a 12-month preclinical trial. Here, specialized stains were used to evaluate potential brain damage associated with ArtiFascia use. Histochemical and immunohistochemical assessments included Luxol Fast Blue, cresyl Violet, Masson's Trichrome, neuronal nuclei,, Glial Fibrillary Acidic Protein, and ionized calcium-binding adaptor molecule 1 stains. The stained slides were graded based on the brain-specific reactions. The results showed no damage to the underlying brain tissue for either the ArtiFascia or control implants. Neither inflammation nor neuronal loss was evident, corroborating the safety of the ArtiFascia. This approach, combined with previous histopathological analyses, strengthens the safety profile of ArtiFascia and sets a benchmark for biodegradable material assessment in dura graft applications. This study aligns with the Food and Drug Administration guidelines and offers a comprehensive evaluation of the potential neural tissue effects of synthetic dura mater grafts.

Saroglitazar suppresses the hepatocellular carcinoma induced by intraperitoneal injection of diethylnitrosamine in C57BL/6 mice fed on choline deficient, l-amino acid- defined, high-fat diet.

BACKGROUND: Saroglitazar is a novel PPAR-α/γ agonist with predominant PPAR-α activity. In various preclinical models, saroglitazar has been shown to prevent & reverse symptoms of NASH. In view of these observations, and the fact that NASH is a progressive disease leading to HCC, we hypothesized that saroglitazar may prevent the development of HCC in rodents. METHODS: HCC was induced in C57BL/6 mice by a single intraperitoneal injection of 25 mg/kg diethylnitrosamine (DEN) at the age of 4 weeks and then feeding the animal a choline-deficient, L-amino acid- defined, high-fat diet (CDAHFD) for the entire study duration. Eight weeks after initiation of CDAHFD, saroglitazar (1 and 3 mg/kg) treatment was started and continued for another 27 weeks. RESULTS: Saroglitazar treatment significantly reduced the liver injury markers (serum ALT and AST), reversed hepatic steatosis and decreased the levels of pro-inflammatory cytokines like TNF-α in liver. It also resulted in a marked increase in serum adiponectin and osteopontin levels. All disease control animals showed hepatic tumors, which was absent in saroglitazar (3 mg/kg)- treatment group indicating 100% prevention of hepatic tumorigenesis. This is the first study demonstrating a potent PPARα agonist causing suppression of liver tumors in rodents, perhaps due to a strong anti-NASH activity of Saroglitazar that overrides its rodent-specific peroxisome proliferation activity. CONCLUSION: The data reveals potential of saroglitazar for chemoprevention of hepatocellular carcinoma in patients with NAFLD/NASH.

Results of the European Society of Toxicologic Pathology Survey on the Use of Artificial Intelligence in Toxicologic Pathology.

The European Society of Toxicologic Pathology (ESTP) initiated a survey through its Pathology 2.0 workstream in partnership with sister professional societies in Europe and North America to generate a snapshot of artificial intelligence (AI) usage in the field of toxicologic pathology. In addition to demographic information, some general questions explored AI relative to (1) the current status of adoption across organizations; (2) technical and methodological aspects; (3) perceived business value and finally; and (4) roadblocks and perspectives. AI has become increasingly established in toxicologic pathology with most pathologists being supportive of its development despite some areas of uncertainty. A salient feature consisted of the variability of AI awareness and adoption among the responders, as the spectrum extended from pathologists having developed familiarity and technical skills in AI, to colleagues who had no interest in AI as a tool in toxicologic pathology. Despite a general enthusiasm for these techniques, the overall understanding and trust in AI algorithms as well as their added value in toxicologic pathology were generally low, suggesting room for the need for increased awareness and education. This survey will serve as a basis to evaluate the evolution of AI penetration and acceptance in this domain.

COVID-eVax, an electroporated DNA vaccine candidate encoding the SARS-CoV-2 RBD, elicits protective responses in animal models.

The COVID-19 pandemic caused by SARS-CoV-2 has made the development of safe and effective vaccines a critical priority. To date, four vaccines have been approved by European and American authorities for preventing COVID-19, but the development of additional vaccine platforms with improved supply and logistics profiles remains a pressing need. Here we report the preclinical evaluation of a novel COVID-19 vaccine candidate based on the electroporation of engineered, synthetic cDNA encoding a viral antigen in the skeletal muscle. We constructed a set of prototype DNA vaccines expressing various forms of the SARS-CoV-2 spike (S) protein and assessed their immunogenicity in animal models. Among them, COVID-eVax-a DNA plasmid encoding a secreted monomeric form of SARS-CoV-2 S protein receptor-binding domain (RBD)-induced the most potent anti-SARS-CoV-2 neutralizing antibody responses (including against the current most common variants of concern) and a robust T cell response. Upon challenge with SARS-CoV-2, immunized K18-hACE2 transgenic mice showed reduced weight loss, improved pulmonary function, and lower viral replication in the lungs and brain. COVID-eVax conferred significant protection to ferrets upon SARS-CoV-2 challenge. In summary, this study identifies COVID-eVax as an ideal COVID-19 vaccine candidate suitable for clinical development. Accordingly, a combined phase I-II trial has recently started.

Oral chronic toxicity and carcinogenicity study of alpha-glycosyl isoquercitrin (AGIQ) in Sprague Dawley rats.

alpha-Glycosyl isoquercitrin (AGIQ) is a flavonoid that possesses antioxidant and tumor suppressive capabilities and is marketed as a food additive in Japan. The aim of this study was to assess the potential for oral chronic toxicity and carcinogenicity of AGIQ in male and female Sprague Dawley rats following up to 5.0% dietary exposure. In the chronic toxicity study, rats were exposed to AGIQ or vehicle for one year with a 6-month interim termination point; for the carcinogenicity study, rats were treated for 24 months. No signs of AGIQ-related toxicity clinically or histologically were observed for up to one year except for yellow discoloration of bone. In the carcinogenicity study, a statistically significant increase in the incidence of malignant glioma of the brain or spinal cord was observed in female rats exposed to 5.0% AGIQ compared to those exposed to control feed. A Scientific Advisory Panel of experienced neuropathologists reviewed the gliomas (routine stains and glial cell markers) and concluded that the gliomas were a rare, spontaneous, rat-specific neoplasm: malignant microglial tumor. The lesions could not definitively be attributed to AGIQ exposure and have limited implications with respect to predicting human cancer risk.

Preclinical In-Vivo Safety of a Novel Thyrotropin-Releasing Hormone-Loaded Biodegradable Nanoparticles After Intranasal Administration in Rats and Primates.

Thyrotropin-releasing hormone (TRH) and TRH-like peptides carry a therapeutic potential for neurological conditions. Nanoparticles (NP) made of the biodegradable polymer, Poly(Sebacic Anhydride) (PSA), have been developed to carry TRH, intended for intranasal administration to patients. There is limited information on the safety of biodegradable polymers when given intranasally, and therefore, we have performed two preclinical safety and toxicity studies in cynomolgus monkeys and rats using TRH-PSA nanoparticles. The rats and monkeys were dosed intranasally for 42 days or 28 days, respectively, and several animals were followed for additional 14 days. Animals received either placebo, vehicle (PSA), or different concentrations of TRH-PSA. No systemic adverse effects were seen. Changes in T3 or T4 concentrations were observed in some TRH-PSA-treated animals, which did not have clinical or microscopic correlates. No effect was seen on TSH or prolactin concentrations. In the monkey study, microscopic changes in the nasal turbinates were observed, which were attributed to incidental mechanical trauma caused during administration. Taken together, the TRH-loaded PSA NPs have proven to be safe, with no local or systemic adverse effects attributed to the drug loaded nanoparticles. These findings provide additional support to the growing evidence of the safety of peptide-loaded NPs for intranasal delivery and pave the way for future clinical trials in humans.

Safety and efficacy of a novel robotic, fractional micro-coring device in a swine model.

Laser resurfacing may be accompanied by unwanted side effects. The micro coring technology, designed to remove small skin columns, was developed to avoid the thermal injury associated with lasers. However, very limited data are available on its pre-clinical efficacy and safety. The novel robotic, fractional micro-coring device, AimeTM, was tested on four pigs, each treated in 12 sites, at 6 time-points, over the course of 28 days. Macroscopic and microscopic evaluation was performed at each of the 6 time-points during the 28-day follow-up. Macroscopically, treatment resulted in erythema and mild edema that quickly resolved. Microscopically, there was progressive re-coverage of the tested sites with complete, well differentiated, newly formed epidermis, associated with efficient elimination of the underlying excised dermis, which was replaced by maturing fibroplasia. Some of the sites demonstrated complete healing already after 7 days. No significant adverse events were noted with the use of the device. The use of the micro-coring device AimeTM in a porcine model for skin fractional micro-excision and resurfacing was effective and safe. The comprehensive gradual healing process shown in this study with detailed histopathological images can also serve as a basis for future pre-clinical studies of fractional ablative devices.

Melanocyte-secreted fibromodulin constrains skin inflammation in mice injected with lupus serum.

Skin pigmentation has been linked to the development, prevalence, and severity of several immune-mediated diseases such as SLE. Here, we asked whether fibromodulin (FMOD), which is highly expressed in skin with light complexion, can explain the known differences in the magnitude of inflammation. C57 mice with different levels of pigmentation and FMOD were injected with human lupus serum to induce skin inflammation. Histopathologic studies revealed that black C57 FMOD+/+ that produce low levels of FMOD and white C57 FMOD -/- mice develop more severe inflammation compared with white FMOD +/+ mice. This study also revealed that dark pigmentation and FMOD deletion correlates with the increased numbers of Langerhans cells. Altogether, we identify low pigmentation and FMOD are linked to low severity of inflammation and approaches to promote FMOD expression should offer clinical benefit.

Safety and Performance Evaluation of Su2ura Approximation, a New Suturing Device, in Pigs.

One of the challenging aspects of minimal invasive surgery (MIS) is intracorporal suturing, which can be significantly time-consuming. Therefore, there is a rising need for devices that can facilitate the suturing procedure in MIS. Su2ura Approximation Device (Su2ura Approximation) is a novel device developed to utilize the insertion of anchors threaded with stitches to allow a single action placement of a suture. The objective of this study was to evaluate the long-term safety and tissue approximation of Su2ura Approximation in comparison to Endo Stitch + Surgidac sutures in female domestic pigs. All incision sites were successfully closed by both methods. Firm consolidation within and around the incision site was noted in several animals in both treatment groups, which corresponded histopathologically to islands of ectopic cartilage or bone spicules within the fibrotic scar. These changes reflect heterotopic ossification that is commonly seen in the healing of abdominal operation sites in pigs. No other abnormal findings were observed throughout the study period. In conclusion, the use of Su2ura Approximation under the present experimental conditions revealed no safety concerns.

Preclinical In Vivo Safety of Poly-Phosphorylated Superlubrication Vectors for the Treatment of Osteoarthritis.

Osteoarthritis (OA) can lead to a significant functional disability. Poly[2-(methacryloyloxy)ethyl phosphorylcholine] (pMPC) liposomes are a novel treatment modality for OA, intended to restore the natural lubrication properties of articular cartilage. Here, we report on two studies aimed to assess the local and systemic safety and toxicity of pMPCylated liposomes in comparison with physiological saline, in Sprague-Dawley (SD) rats and in sheep after a single intra-articular (IA) injection. The animals were sacrificed after 1 and 6 weeks (rats) and 3 and 6 weeks (sheep). No signs of toxicity or abnormal clinical findings were observed. Histopathological evaluation revealed no signs of reactivity or abnormal findings in the injected joints or in any other organs. In conclusion, a single IA injection of the pMPCylated liposomes demonstrated an excellent safety profile and did not result in local reactivity or systemic toxicity, thus supporting its further development for use in humans.

Toxicity and Local Tolerance of a Novel Spike Protein RBD Vaccine Against SARS-CoV-2, Produced Using the C1 Thermothelomyces Heterothallica Protein Expression Platform.

Coronavirus disease 2019 (COVID-19) has caused the ongoing COVID-19 pandemic and there is a growing demand for safe and effective vaccines. The thermophilic Thermothelomyces heterothallica filamentous fungal host, C1-cell, can be utilized as an expression platform for the rapid production of large quantities of antigens for developing vaccines. The aim of this study was to evaluate the local tolerance and the systemic toxicity of a C1-cell expressed receptor-binding domain (C1-RBD) vaccine, following repeated weekly intramuscular injections (total of 4 administrations), in New Zealand White rabbits. The animals were sacrificed either 3 days or 3 weeks following the last dose. No signs of toxicity were observed, including no injection site reactions. ELISA studies revealed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific immunoglobulin G antibodies in the sera of C1-RBD-treated animals starting from day 13 post injection, that were further elevated. Histopathology evaluation and immunohistochemical staining revealed follicular hyperplasia, consisting of B-cell type, in the spleen and inguinal lymph nodes of the treated animals that were sustained throughout the recovery phase. No local or systemic toxicity was observed. In conclusion, the SARS-CoV-2 C1-RBD vaccine candidate demonstrated an excellent safety profile and a lasting immunogenic response against receptor-binding domain, thus supporting its further development for use in humans.

Scientific and Regulatory Policy Committee Points to Consider for Medical Device Implant Site Evaluation in Nonclinical Studies.

Nonclinical implantation studies are a common and often critical step for medical device safety assessment in the bench-to-market pathway. Nonclinical implanted medical devices or drug-device combination products require complex macroscopic and microscopic pathology evaluations due to the physical presence of the device itself and unique tissue responses to device materials. The Medical Device Implant Site Evaluation working group of the Society of Toxicologic Pathology's (STP) Scientific and Regulatory Policy Committee (SRPC) was tasked with reviewing scientific, technical, and regulatory considerations for these studies. Implant site evaluations require highly specialized methods and analytical schemes that should be designed on a case-by-case basis to address specific study objectives. Existing STP best practice recommendations can serve as a framework when performing nonclinical studies under Good Laboratory Practices and help mitigate limitations in standards and guidances for implant evaluations (e.g., those from the International Organization for Standardization [ISO], ASTM International). This article integrates standards referenced by sponsors and regulatory bodies with practical pathology evaluation methods for implantable medical devices and combination products. The goal is to ensure the maximum accuracy and scientific relevance of pathology data acquired during a medical device or combination drug-device implantation study.

Self-regulating novel iron oxide nanoparticle-based magnetic hyperthermia in swine: biocompatibility, biodistribution, and safety assessments.

Studies demonstrating the successful and safe application of magnetic hyperthermia in large animals are scarce. A therapeutic approach for advanced cancer comprising multicore encapsulated iron oxide (IO) Sarah Nanoparticles (SaNPs), that uniquely self-regulate their temperature, was developed thus overcoming the safety challenges of hyperthermia. SaNPs are intravenously injected and accumulate in tumor tissue, leading to selective heating upon exposure to an external alternating magnetic field (AMF). A series of studies were conducted in healthy swine to assess SaNPs' safety, alone or combined with AMF application. Administration of single high (up to 22 mg IO/kg) or low (3.6 mg IO/kg) SaNP doses had no adverse effects, including no infusion reactions. Vital signs remained stable with no significant clinical pathology changes, and no treatment-associated toxicities. Biodistribution analysis indicated that SaNPs predominantly accumulate in the lungs and clear in a dose- and time-dependent manner. In minipigs that received a single SaNP no-observed-adverse-effect-level (NOAEL)-based dose (3.6 mg IO/kg) with AMF, the average percentage remaining in vital organs after 90 days was 13.7%. No noticeable clinical signs were noted during the 87 to 92-day observation period following irradiation, and no inflammation, necrosis, nor thermal damage were found in the histopathology evaluation. In another minipig, ~ 90 days after three recurrent high doses (14 mg IO/kg), without AMF, almost half of the injected SaNPs were cleared with no residual detrimental effects. We demonstrate that the approach is safe and well tolerated in swine, opening potential avenues as a novel therapeutic modality for cancer patients.

rVSV-ΔG-SARS-CoV-2-S vaccine: repeated intramuscular (IM) toxicity, local tolerance, immunogenicity and biodistribution study in NZW rabbits.

BriLife®, a vector-based vaccine that utilizes the recombinant vesicular stomatitis virus (VSV) platform to express and present the spike antigen of SARS-CoV-2, is undergoing testing in a phase 2 clinical trial in Israel. A nonclinical repeated-dose (GLP) toxicity study in New Zealand white rabbits was performed to evaluate the potential toxicity, local tolerance, immunogenicity and biodistribution of the vaccine. rVSV-ΔG-SARS-CoV-2-S (or vehicle) was administered intramuscularly to two groups of animals (106, 107 PFU/animal, n = 10/sex/group) on three occasions, at 2-week intervals, followed by a 3-week recovery period. Systemic clinical signs, local reactions, body weight, body temperature, food consumption, ophthalmology, urinalysis, clinical pathology, C-reactive protein, viremia and antibody levels were monitored. Gross pathology was performed, followed by organs/tissues collection for biodistribution and histopathological evaluation. Treatment-related changes were restricted to multifocal minimal myofiber necrosis at the injection sites, and increased lymphocytic cellularity in the iliac and mesenteric lymph nodes and in the spleen. These changes were considered related to the inflammatory reaction elicited, and correlated with a trend for recovery. Detection of rVSV-ΔG-SARS-CoV-2-S vaccine RNA was noted in the regional iliac lymph node in animals assigned to the high-dose group, at both termination time points. A significant increase in binding and neutralizing antibody titers was observed following vaccination at both vaccine doses. In view of the findings, it was concluded that the rVSV-ΔG-SARS-CoV-2-S vaccine is safe. These results supported the initiation of clinical trials.

Preliminary nonclinical safety and immunogenicity of an rVSV-ΔG-SARS-CoV-2-S vaccine in mice, hamsters, rabbits and pigs.

rVSV-ΔG-SARS-CoV-2-S is a clinical stage (Phase 2) replication competent recombinant vaccine against SARS-CoV-2. To evaluate the safety profile of the vaccine, a series of non-clinical safety, immunogenicity and efficacy studies were conducted in four animal species, using multiple doses (up to 108 Plaque Forming Units/animal) and dosing regimens. There were no treatment-related mortalities or any noticeable clinical signs in any of the studies. Compared to unvaccinated controls, hematology and biochemistry parameters were unremarkable and no adverse histopathological findings. There was no detectable viral shedding in urine, nor viral RNA detected in whole blood or serum samples seven days post vaccination. The rVSV-ΔG-SARS-CoV-2-S vaccination gave rise to neutralizing antibodies, cellular immune responses, and increased lymphocytic cellularity in the spleen germinal centers and regional lymph nodes. No evidence for neurovirulence was found in C57BL/6 immune competent mice or in highly sensitive type I interferon knock-out mice. Vaccine virus replication and distribution in K18-human Angiotensin-converting enzyme 2-transgenic mice showed a gradual clearance from the vaccination site with no vaccine virus recovered from the lungs. The nonclinical data suggest that the rVSV-ΔG-SARS-CoV-2-S vaccine is safe and immunogenic. These results supported the initiation of clinical trials, currently in Phase 2.

Microscope-Based Automated Quantification of Liver Fibrosis in Mice Using a Deep Learning Algorithm.

In preclinical studies that involve animal models for hepatic fibrosis, accurate quantification of the fibrosis is of utmost importance. The use of digital image analysis based on deep learning artificial intelligence (AI) algorithms can facilitate accurate evaluation of liver fibrosis in these models. In the present study, we compared the quantitative evaluation of collagen proportionate area in the carbon tetrachloride model of liver fibrosis in the mouse by a newly developed AI algorithm to the semiquantitative assessment of liver fibrosis performed by a board-certified toxicologic pathologist. We found an excellent correlation between the 2 methods of assessment, most evident in the higher magnification (×40) as compared to the lower magnification (×10). These findings strengthen the confidence of using digital tools in the toxicologic pathology field as an adjunct to an expert toxicologic pathologist.