Threats to validity in the design and conduct of preclinical efficacy studies: a systematic review of guidelines for in vivo animal experiments

Preclinical assessment for translation to humans: The PATH approach for assessing supporting evidence for early-phase trials and innovative care

Early-phase trials and innovative care draw support from basic science, preclinical studies, and clinical research. Such evidential diversity presents a challenge for traditional ways of synthesizing evidence. In what follows, we review the limitations of existing approaches for communicating supporting evidence for early-phase trials. We then offer a structured approach, PATH (preclinical assessment for translation to humans). PATH is grounded in the premise that the case for administering novel strategies to patients requires connecting the dots between nine mechanistic steps supporting a clinical claim. Using PATH entails first parsing supporting evidence, assessing the strength of evidence at each step, and then assessing the strength of a chain of evidence linking drug administration to clinical effect. While PATH requires further refinement, the approach reduces some of the opacity, arbitrariness, and biases in current ways of presenting and assessing scientific support for early-phase trials and innovative care.

Identifying assessment criteria for in vitro studies: a method and item bank

To support the development of appraisal tools for assessing the quality of in vitro studies, we developed a method for literature-based discovery of study assessment criteria, used the method to create an item bank of assessment criteria of potential relevance to in vitro studies, and analyzed the item bank to discern and critique current approaches for appraisal of in vitro studies. We searched four research indexes and included any document that identified itself as an appraisal tool for in vitro studies, was a systematic review that included a critical appraisal step, or was a reporting checklist for in vitro studies. We abstracted, normalized, and categorized all criteria applied by the included appraisal tools to create an "item bank" database of issues relevant to the assessment of in vitro studies. The resulting item bank consists of 676 unique appraisal concepts from 67 appraisal tools. We believe this item bank is the single most comprehensive resource of its type to date, should be of high utility for future tool development exercises, and provides a robust methodology for grounding tool development in the existing literature. Although we set out to develop an item bank specifically targeting in vitro studies, we found that many of the assessment concepts we discovered are readily applicable to other study designs. Item banks can be of significant value as a resource; however, there are important challenges in developing, maintaining, and extending them of which researchers should be aware.

A bitter flavonoid gum from Dorema aucheri accelerate wound healing in rats: Involvement of Bax/HSP 70 and hydroxyprolin mechanisms

BACKGROUND

Dorema aucheri gum (DAG) is a bitter flavonoid gum widely used for numerous medicinal purposes including wound recovery. The present work investigates the acute toxicity and wound-healing effects of DAG in excisional skin injury in rats.

MATERIALS AND METHODS

Sprague Dawley rats (24) were clustered into four groups, each rat had a full-thickness excisional dorsal neck injury (2.00 cm) and addressed with 0.2 mL of the following treatments for 15 days: Group A (vehicle), rats addressed with normal saline; Group B, rats received intrasite gel; C and D, rats addressed with 250 and 500 mg/kg of DAG, respectively.

RESULTS

The results revealed the absence of any toxic signs in rats who received oral dosages of 2 and 5 g/kg of DAG. Wound healing was significantly accelerated following DAG treatments indicated by smaller open areas and higher wound contraction percentages compared to vehicle rats. Histological evaluation revealed higher fibroblast formation, collagen deposition, and noticeably lower inflammatory cell infiltration in granulated skin tissues of DAG-addressed rats compared to vehicle rats. DAG treatment caused significant modulation of immunohistochemical proteins (decreased Bax and increased HSP 70) and inflammatory mediators (reduced TNF-α, IL-6, and magnified IL-10), which were significantly varied compared to vehicle rats. Moreover, topical DAG treatment led to significant upregulation of the hydroxyproline (HDX) (collagen) and antioxidant content. At the same time, decreased the lipid peroxidation (MDA) levels in healed tissues obtained from DAG-treated rats.

CONCLUSION

The present wound contraction by DAG might be linked with the modulatory effect of its phytochemicals (polysaccharides, flavonoids, and phenolic) on the cellular mechanisms, which justify their folkloric use and provokes further investigation as therapeutic drug additives for wound contraction.

Applying EBM epistemology and the GRADE system to address practitioners' disagreements in medical malpractice allegations during COVID-19 pandemic

RATIONALE

The GRADE system of clinical recommendations has deontic implications and can discriminate between mandatory, prohibited, and merely permitted medical decisions.

AIMS AND OBJECTIVES

The recommendation categories of the GRADE framework map onto deontological imperatives that can lead to a better understanding and management of allegations of imprudence and appropriateness of treatments. Allegations made during the worst phase of COVID-19 pandemic are used as a case study for exploring the deontic implications of GRADE.

METHOD

Conceptual theoretical analysis, case study analysis, and argumentation in defence of hypotheses.

RESULTS

Strong GRADE recommendations for or against treatment are justified by high-quality evidence and can be construed as ethical obligations and prohibitions. In contrast, when evidence for benefit or harm is of lower quality, GRADE yields weak, discretionary recommendations. In such grey area cases, the absence of a duty to prescribe or refuse to prescribe a requested treatment is compatible with the privilege of considering unproven but possibly beneficial options in a private setting. This privilege, however, does not extend to healthcare policymakers, who have a duty to promote actions that serve the public and whose recommendations should not be guided by personal or idiosyncratic preferences or values.

CONCLUSION

If there is no prima facie evidence that a proposed treatment is harmful, doctors are not negligent in considering it in shared doctor-patient decision-making. But these clinical decisions under uncertainty do not transfer obligations to health authorities, who are not part of the decision-making process in clinical settings. The clinical decision-making process concerns particulars and is guided by contextual and specific reasons that do not fall within the scope of a general policy. Thus, in the context of a serious epidemic in which patients need and demand treatments, if the body of evidence is still changing and fragile, an attitude of tolerance and connivance may ensure a smoother transition to a more stable phase of progress, both in scientific and clinical medicine.

Boric Acid (Boron) Attenuates AOM-Induced Colorectal Cancer in Rats by Augmentation of Apoptotic and Antioxidant Mechanisms

Boric acid (BA) is a naturally occurring weak Lewis acid containing boron, oxygen, and hydrogen elements that can be found in water, soil, and plants. Because of its numerous biological potentials including anti-proliferation actions, the present investigates the chemopreventive possessions of BA on azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) in rats. Thirty laboratory rats were divided into 5 groups: negative control (A) received two subcutaneous inoculations of normal saline and nourished on 10% Tween 20; groups B-E had two injections of 15 mg/kg azoxymethane followed by ingestion of 10% Tween 20 (B, cancer control), inoculation with intraperitoneal 35 mg/kg 5-fluorouracil injection (C, reference group), or ingested with boric acid 30 mg/kg (D) and 60 mg/kg (E). The gross morphology results showed significantly increased total colonic ACF in cancer controls, while BA treatment caused a significant reduction of ACF values. Histopathological evaluation of colons from cancer controls showed bizarrely elongated nuclei, stratified cells, and higher depletion of the submucosal glands than that of BA-treated groups. Boric acid treatment up-surged the pro-apoptotic (Bax) expression and reduced anti-apoptotic (Bcl-2) protein expressions. Moreover, BA ingestion caused upregulation of antioxidant enzymes (GPx, SOD, CAT), and lowered MDA contents in colon tissue homogenates. Boric acid-treated rats had significantly lower pro-inflammatory cytokines (TNF-α and IL-6) and higher anti-inflammatory cytokines (IL-10) based on serum analysis. The colorectal cancer attenuation by BA is shown by the reduced ACF numbers, anticipated by its regulatory potentials on the apoptotic proteins, antioxidants, and inflammatory cytokines originating from AOM-induced oxidative damage.

Studying intramuscular fat deposition and muscle regeneration: insights from a comparative analysis of mouse strains, injury models, and sex differences

Intramuscular fat (IMAT) infiltration, pathological adipose tissue that accumulates between muscle fibers, is a shared hallmark in a diverse set of diseases including muscular dystrophies and diabetes, spinal cord and rotator cuff injuries, as well as sarcopenia. While the mouse has been an invaluable preclinical model to study skeletal muscle diseases, they are also resistant to IMAT formation. To better understand this pathological feature, an adequate pre-clinical model that recapitulates human disease is necessary. To address this gap, we conducted a comprehensive in-depth comparison between three widely used mouse strains: C57BL/6J, 129S1/SvlmJ and CD1. We evaluated the impact of strain, sex and injury type on IMAT formation, myofiber regeneration and fibrosis. We confirm and extend previous findings that a Glycerol (GLY) injury causes significantly more IMAT and fibrosis compared to Cardiotoxin (CTX). Additionally, females form more IMAT than males after a GLY injury, independent of strain. Of all strains, C57BL/6J mice, both females and males, are the most resistant to IMAT formation. In regard to injury-induced fibrosis, we found that the 129S strain formed the least amount of scar tissue. Surprisingly, C57BL/6J of both sexes demonstrated complete myofiber regeneration, while both CD1 and 129S1/SvlmJ strains still displayed smaller myofibers 21 days post injury. In addition, our data indicate that myofiber regeneration is negatively correlated with IMAT and fibrosis. Combined, our results demonstrate that careful consideration and exploration are needed to determine which injury type, mouse model/strain and sex to utilize as preclinical model especially for modeling IMAT formation.

Animal models of Takotsubo syndrome: bridging the gap to the human condition

Modelling human diseases serves as a crucial tool to unveil underlying mechanisms and pathophysiology. Takotsubo syndrome (TS), an acute form of heart failure resembling myocardial infarction, manifests with reversible regional wall motion abnormalities (RWMA) of the ventricles. Despite its mortality and clinical similarity to myocardial infarction, TS aetiology remains elusive, with stress and catecholamines playing central roles. This review delves into current animal models of TS, aiming to assess their ability to replicate key clinical traits and identifying limitations. An in-depth evaluation of published animal models reveals a variation in the definition of TS among studies. We notice a substantial prevalence of catecholamine-induced models, particularly in rodents. While these models shed light on TS, there remains potential for refinement. Translational success in TS research hinges on models that align with human TS features and exhibit the key features, including transient RWMA. Animal models should be comprehensively evaluated regarding the various systemic changes of the applied trigger(s) for a proper interpretation. This review acts as a guide for researchers, advocating for stringent TS model standards and enhancing translational validity.

Cumin (Cuminum cyminum L.) seeds accelerates wound healing in rats: Possible molecular mechanisms

Wound healing is a complex, intricate, and dynamic process that requires effective therapeutic management. The current study evaluates the wound healing potentials of methanolic extract of Cuminum cyminum L. seeds (CCS) in rats. Sprague Dawley (24) rats were distributed into four cages, wounds produced on the back of the neck, and received two daily topical treatments for 14 days: A, rats received normal saline; B, wounded rats treated with intrasite gel; C and D, rats received 0.2 mL of 250 and 500 mg/kg of CCS, respectively. After that, wound area and closure percentage were evaluated, and wound tissues were dissected for histopathological, immunohistochemical, and biochemical examinations. Acute toxicity trials of methanolic extract of CCS showed the absence of any physiological changes or mortality in rats. CCS application caused a significant reduction in wound size and a statistically elevated percentage of wound contraction than those of vehicle rats. CCS treatment caused significant up-regulation of collagen fiber, fibroblasts, and fewer inflammatory cells (inflammation) in granulation tissues. TGF-β1 (angiogenetic factor) was significantly more expressed in CCS-treated rats in comparison to normal saline-treated rats; therefore, more fibroblasts transformed into myofibroblasts (angiogenesis). CCS-treated rats showed remarkable antioxidant potentials (higher SOD and CAT enzymes) and decreased MDA (lipid peroxidation) levels in their wound tissue homogenates. Hydroxyproline amino acid (collagen) was significantly up-regulated by CCS treatment, which is commonly related to faster wound closure area. The outcomes suggest CCS as a viable new source of pharmaceuticals for wound treatment.

The intervention of cannabinoid receptor in chronic and acute kidney disease animal models: a systematic review and meta-analysis

AIM

Cannabinoid receptors are components of the endocannabinoid system that affect various physiological functions. We aim to investigate the effect of cannabinoid receptor modulation on kidney disease.

METHODS

PubMed, Web of Science databases, and EMBASE were searched. Articles selection, data extraction and quality assessment were independently performed by two investigators. The SYRCLE's RoB tool was used to assess the risk of study bias, and pooled SMD using a random-effect model and 95% CIs were calculated. Subgroup analyses were conducted in preselected subgroups, and publication bias was evaluated. We compared the effects of CB1 and CB2 antagonists and/or knockout and agonists and/or genetic regulation on renal function, blood glucose levels, body weight, and pathological damage-related indicators in different models of chronic and acute kidney injury.

RESULTS

The blockade or knockout of CB1 could significantly reduce blood urea nitrogen [SMD,- 1.67 (95% CI - 2.27 to - 1.07)], serum creatinine [SMD, - 1.88 (95% CI - 2.91 to - 0.85)], and albuminuria [SMD, - 1.60 (95% CI - 2.16 to - 1.04)] in renal dysfunction animals compared with the control group. The activation of CB2 group could significantly reduce serum creatinine [SMD, - 0.97 (95% CI - 1.83 to - 0.11)] and albuminuria [SMD, - 2.43 (95% CI - 4.63 to - 0.23)] in renal dysfunction animals compared with the control group.

CONCLUSIONS

The results suggest that targeting cannabinoid receptors, particularly CB1 antagonists and CB2 agonists, can improve kidney function and reduce inflammatory responses, exerting a renal protective effect and maintaining therapeutic potential in various types of kidney disease.

Development and application of a systematic and quantitative weighting framework to evaluate the quality and relevance of relative potency estimates for dioxin-like compounds (DLCs) for human health risk assessment

The toxic equivalency factors (TEFs) approach for dioxin-like chemicals (DLCs) is currently based on a qualitative assessment of a heterogeneous data set of relative estimates of potency (REPs) spanning several orders of magnitude with highly variable study quality and relevance. An effort was undertaken to develop a weighting framework to systematically evaluate and quantitatively integrate the quality and relevance for development of more robust TEFs. Six main-study characteristics were identified as most important in characterizing the quality and relevance of an individual REP for human health risk assessment: study type, study model, pharmacokinetics, REP derivation method, REP derivation quality, and endpoint. Subsequently, a computational approach for quantitatively integrating the weighting framework parameters was developed and applied to the REP2004 database. This was accomplished using a machine learning approach which infers a weighted TEF distribution for each congener. The resulting database, weighted for quality and relevance, provides REP distributions from >600 data sets (including in vivo and in vitro studies, a range of endpoints, etc.). This weighted database provides a flexible platform for systematically and objectively characterizing TEFs for use in risk assessment, as well as providing information to characterize uncertainty and variability. Collectively, this information provides risk managers with information for decision making.

Addressing the elephant in the T-maze: Developing experimental conduct guidelines for neuroscience

Personal view - no abstract.

Trace amine-associated receptor 1 (TAAR1) agonists for psychosis: protocol for a living systematic review and meta-analysis of human and non-human studies

BACKGROUND

There is an urgent need to develop more effective and safer antipsychotics beyond dopamine 2 receptor antagonists. An emerging and promising approach is TAAR1 agonism. Therefore, we will conduct a living systematic review and meta-analysis to synthesize and triangulate the evidence from preclinical animal experiments and clinical studies on the efficacy, safety, and underlying mechanism of action of TAAR1 agonism for psychosis.

METHODS

Independent searches will be conducted in multiple electronic databases to identify clinical and animal experimental studies comparing TAAR1 agonists with licensed antipsychotics or other control conditions in individuals with psychosis or animal models for psychosis, respectively. The primary outcomes will be overall psychotic symptoms and their behavioural proxies in animals. Secondary outcomes will include side effects and neurobiological measures. Two independent reviewers will conduct study selection, data extraction using predefined forms, and risk of bias assessment using suitable tools based on the study design. Ontologies will be developed to facilitate study identification and data extraction. Data from clinical and animal studies will be synthesized separately using random-effects meta-analysis if appropriate, or synthesis without meta-analysis. Study characteristics will be investigated as potential sources of heterogeneity. Confidence in the evidence for each outcome and source of evidence will be evaluated, considering the summary of the association, potential concerns regarding internal and external validity, and reporting biases. When multiple sources of evidence are available for an outcome, an overall conclusion will be drawn in a triangulation meeting involving a multidisciplinary team of experts. We plan trimonthly updates of the review, and any modifications in the protocol will be documented. The review will be co-produced by multiple stakeholders aiming to produce impactful and relevant results and bridge the gap between preclinical and clinical research on psychosis.

PROTOCOL REGISTRATION

PROSPERO-ID: CRD42023451628.

Structured tracking of alcohol reinforcement (STAR) for basic and translational alcohol research

There is inherent tension between methodologies developed to address basic research questions in model species and those intended for preclinical to clinical translation: basic investigations require flexibility of experimental design as hypotheses are rapidly tested and revised, whereas preclinical models emphasize standardized protocols and specific outcome measures. This dichotomy is particularly relevant in alcohol research, which spans a diverse range of basic sciences in addition to intensive efforts towards understanding the pathophysiology of alcohol use disorder (AUD). To advance these goals there is a great need for approaches that facilitate synergy across basic and translational areas of nonhuman alcohol research. In male and female mice, we establish a modular alcohol reinforcement paradigm: Structured Tracking of Alcohol Reinforcement (STAR). STAR provides a robust platform for quantitative assessment of AUD-relevant behavioral domains within a flexible framework that allows direct crosstalk between translational and mechanistically oriented studies. To achieve cross-study integration, despite disparate task parameters, a straightforward multivariate phenotyping analysis is used to classify subjects based on propensity for heightened alcohol consumption and insensitivity to punishment. Combining STAR with extant preclinical alcohol models, we delineate longitudinal phenotype dynamics and reveal putative neuro-biomarkers of heightened alcohol use vulnerability via neurochemical profiling of cortical and brainstem tissues. Together, STAR allows quantification of time-resolved biobehavioral processes essential for basic research questions simultaneous with longitudinal phenotyping of clinically relevant outcomes, thereby providing a framework to facilitate cohesion and translation in alcohol research.

Initial heritable genome editing: mapping a responsible pathway from basic research to the clinic

Following the Second Summit on Human Gene Editing in Hong Kong in 2018, where the birth of two girls with germline genome editing was revealed, the need for a responsible pathway to the clinical application of human germline genome editing has been repeatedly emphasised. This paper aims to contribute to the ongoing discussion on research ethics issues in germline genome editing by exploring key issues related to the initial applications of CRISPR in reproductive medicine. Following an overview of the current discussion on bringing germline genome editing into clinical practice, we outline the specific challenges associated with such interventions and the features that distinguish them from conventional clinical testing of new medical treatments. We then review proposed ethical requirements for initial heritable genome editing, such as the absence of reasonable alternatives, the existence of sufficient and reliable preclinical data, appropriate informed consent, requirements related to safety, and long-term follow-up.

Lung-on-chip microdevices to foster pulmonary drug discovery

Respiratory diseases account for unprecedented mortality owing to a lack of personalized or insufficient therapeutic interventions. Fostering pulmonary research into managing pulmonary threat requires a potential alternative approach that can mimick the in vivo complexities of the human body. The in vitro miniaturized bionic simulation of the lung holds great potential in the quest for a successful therapeutic intervention. This review discusses the emerging roles of lung-on-chip microfluidic simulator devices in fostering translational pulmonary drug discovery and personalized medicine. This review also explicates how the lung-on-chip model emulates the breathing patterns, elasticity, and vascularization of lungs in creating a 3D pulmonary microenvironment.

Preclinical efficacy in investigator's brochures: Stakeholders' views on measures to improve completeness and robustness

AIMS

Research ethics committees and regulatory agencies assess whether the benefits of a proposed early-stage clinical trial outweigh the risks based on preclinical studies reported in investigator's brochures (IBs). Recent studies have indicated that the reporting of preclinical evidence presented in IBs does not enable proper risk-benefit assessment. We interviewed different stakeholders (regulators, research ethics committee members, preclinical and clinical researchers, ethicists, and metaresearchers) about their views on measures to increase the completeness and robustness of preclinical evidence reporting in IBs.

METHODS

This study was preregistered (https://osf.io/nvzwy/). We used purposive sampling and invited stakeholders to participate in an online semistructured interview between March and June 2021. Themes were derived using inductive content analysis. We used a strengths, weaknesses, opportunities and threats matrix to categorize our findings.

RESULTS

Twenty-seven international stakeholders participated. The interviewees pointed to several strengths and opportunities to improve completeness and robustness, mainly more transparent and systematic justifications for the included studies. However, weaknesses and threats were mentioned that could undermine efforts to enable a more thorough assessment: The interviewees stressed that current review practices are sufficient to ensure the safe conduct of first-in-human trials. They feared that changes to the IB structure or review process could overburden stakeholders and slow drug development.

CONCLUSION

In principle, more robust decision-making processes align with the interests of all stakeholders and with many current initiatives to increase the translatability of preclinical research and limit uninformative or ill-justified trials early in the development process. Further research should investigate measures that could be implemented to benefit all stakeholders.

Organ Chips and Visualization of Biological Systems

Organ-on-a-chip (OOC) is an emerging frontier cross-cutting science and technology developed in the past 10 years. It was first proposed by the Wyss Institute for Biologically Inspired Engineering of Harvard Medical School. It consists of a transparent flexible polymer the size of a computer memory stick, with hollow microfluidic channels lined with living human cells. Researchers used bionics methods to simulate the microenvironment of human cells on microfluidic chips, so as to realize the basic physiological functions of corresponding tissues and organs in vitro. Transparent chip materials can perform real-time visualization and high-resolution analysis of various human life processes in a way that is impossible in animal models, so as to better reproduce the microenvironment of human tissue and simulate biological systems in vitro to observe drug metabolism and other life processes. It provides innovative research systems and system solutions for in vitro bionics of biological systems. It also has gradually become a new tool for disease mechanism research and new drug development. In this chapter, we will take the current research mature single-organ-on-a-chip and multi-organ human-on-a-chip as examples; give an overview of the research background and underlying technologies in this field, especially the application of in vitro bionic models in visualized medicine; and look forward to the foreseeable future development prospects after the integration of organ-on-chip and organoid technology.

Effects of Multimodal Therapy, Blinding, and Multi-laboratory Protocol Conduct on the Robustness of the Rat Model of Adjuvant Induced Arthritis

BACKGROUND/AIM

The aim of this study was to investigate the effects of multimodal therapy comprising buprenorphine (BUP) and indomethacin (IND) on key translational parameters in the rat adjuvant induced arthritis (AIA) model. Furthermore, we investigated the difference between visual assessment scores and histology scores generated by blinded and non-blinded assessors and the robustness and generalizability of results by conducting a multi-laboratory study.

MATERIALS AND METHODS

The experiment was terminated on day 26 after 11 days (days 15-25) of voluntarily ingested buprenorphine and 7 days of gavage delivered indomethacin treatment (days 19-25). The treatment effects were assessed on the last day of the study, relying on body weight assessment, serum concentrations of α1- acid glycoprotein, and assessment of affected hind paws swelling, in-life and post mortem.

RESULTS

Across two laboratories, the combined analgesic treatments had minimal effects on the measured model parameters indicating that multimodal treatment did not affect the translatability of the model. We found an improvement in clinical scores (a negative change in scores) in nearly all medicated animals when scored informed, whereas it was essentially 50:50 for the blinded scorings and no difference between the blinded and informed histological scoring.

CONCLUSION

The present results support the use of more effective analgesic treatment regimens and the good practice recommendations advocating blinding as a mandatory practice in conduct of preclinical in vivo efficacy studies. In spite of minor differences between results obtained at the two sites, there was good agreement between them indicating robustness of the AIA model.

International evidence-based guidelines on hypertension and type 2 diabetes mellitus: A systematic review

This systematic review provides a high-quality, comprehensive summary of recommendations on hypertension (HT) and type 2 diabetes mellitus (T2DM), accentuating patient blood pressure, HbA1c levels, patterns of drug treatment, management, and screening of these diseases. The overall objective of the review is to support adapting existing clinical practice guidelines in Indonesia, Vietnam, and Myanmar. The database PubMed and the web search engines Google and Google Scholar were searched from October to December 2019 for evidence-based guidelines covering the overall disease management in Europe, the United States of America, and low and middle-income countries (Indonesia, Vietnam, and Myanmar-IVM later on). Nine studies were selected for the review, seven concerning HT and five T2DM. Guidelines in IVM and Europe identified HT as increased blood pressure (BP; ≥140/90 mmHg). IVM guidelines also recommended commencing drug treatment if lifestyle interventions were not successful. Four international HT guidelines recommended monitoring BP every few months, and the other three guidelines gave recommendations based on the patient's current BP levels. All five T2DM guidelines recommended target HbA1c levels below 7%-6.5%, but only IVM guidelines included re-examination every 3-6 months. Metformin was recommended as the first choice of medical treatment, if not contraindicated. Amid the guidelines' recommendations, there were no major variations in the Class of recommendation and Level of evidence (except IVM guidelines where COR and LOE were missing). Revision and completion of IVM guidelines by this grading system would enhance evidence-based and informed decisions in clinical care.

In Silico Modeling Demonstrates that User Variability During Tumor Measurement Can Affect In Vivo Therapeutic Efficacy Outcomes

User measurement bias during subcutaneous tumor measurement is a source of variation in preclinical in vivo studies. We investigated whether this user variability could impact efficacy study outcomes, in the form of the false negative result rate when comparing treated and control groups. Two tumor measurement methods were compared; calipers which rely on manual measurement, and an automatic 3D and thermal imaging device. Tumor growth curve data were used to create an in silico efficacy study with control and treated groups. Before applying user variability, treatment group tumor volumes were statistically different to the control group. Utilizing data collected from 15 different users across 9 in vivo studies, user measurement variability was computed for both methods and simulation was used to investigate its impact on the in silico study outcome. User variability produced a false negative result in 0.7% to 18.5% of simulated studies when using calipers, depending on treatment efficacy. When using an imaging device with lower user variability this was reduced to 0.0% to 2.6%, demonstrating that user variability impacts study outcomes and the ability to detect treatment effect. Reducing variability in efficacy studies can increase confidence in efficacy study outcomes without altering group sizes. By using a measurement device with lower user variability, the chance of missing a therapeutic effect can be reduced and time and resources spent pursuing false results could be saved. This improvement in data quality is of particular interest in discovery and dosing studies, where being able to detect small differences between groups is crucial.

Understanding the importance of quality control and quality assurance in preclinical PET/CT imaging

The fundamental principle of experimental design is to ensure efficiency and efficacy of the performed experiments. Therefore, it behoves the researcher to gain knowledge of the technological equipment to be used. This should include an understanding of the instrument quality control and assurance requirements to avoid inadequate or spurious results due to instrumentation bias whilst improving reproducibility. Here, the important role of preclinical positron emission tomography/computed tomography and the scanner's required quality control and assurance is presented along with the suggested guidelines for quality control and assurance. There are a multitude of factors impeding the continuity and reproducibility of preclinical research data within a single laboratory as well as across laboratories. A more robust experimental design incorporating validation or accreditation of the scanner performance can reduce inconsistencies. Moreover, the well-being and welfare of the laboratory animals being imaged is prime justification for refining experimental designs to include verification of instrumentation quality control and assurance. Suboptimal scanner performance is not consistent with the 3R principle (Replacement, Reduction, and Refinement) and potentially subjects animals to unnecessary harm. Thus, quality assurance and control should be of paramount interest to any scientist conducting animal studies. For this reason, through this work, we intend to raise the awareness of researchers using PET/CT regarding quality control/quality assurance (QC/QA) guidelines and instil the importance of confirming that these are routinely followed. We introduce a basic understanding of the PET/CT scanner, present the purpose of QC/QA as well as provide evidence of imaging data biases caused by lack of QC/QA. This is shown through a review of the literature, QC/QA accepted standard protocols and our research. We also want to encourage researchers to have discussions with the PET/CT facilities manager and/or technicians to develop the optimal designed PET/CT experiment for obtaining their scientific objective. Additionally, this work provides an easy gateway to multiple resources not only for PET/CT knowledge but for guidelines and assistance in preclinical experimental design to enhance scientific integrity of the data and ensure animal welfare.

How failure to falsify in high-volume science contributes to the replication crisis

The number of scientific papers published every year continues to increase, but scientific knowledge is not progressing at the same rate. Here we argue that a greater emphasis on falsification - the direct testing of strong hypotheses - would lead to faster progress by allowing well-specified hypotheses to be eliminated. We describe an example from neuroscience where there has been little work to directly test two prominent but incompatible hypotheses related to traumatic brain injury. Based on this example, we discuss how building strong hypotheses and then setting out to falsify them can bring greater precision to the clinical neurosciences, and argue that this approach could be beneficial to all areas of science.

Practical considerations for navigating the regulatory landscape of non-clinical studies for clinical translation of radiopharmaceuticals

Background

The development of radiopharmaceuticals requires extensive evaluation before they can be applied in a diagnostic or therapeutic setting in Nuclear Medicine. Chemical, radiochemical, and pharmaceutical parameters must be established and verified to ensure the quality of these novel products.

Main body

To provide supportive evidence for the expected human in vivo behaviour, particularly related to safety and efficacy, additional tests, often referred to as “non-clinical” or “preclinical” are mandatory. This document is an outcome of a Technical Meeting of the International Atomic Energy Agency. It summarises the considerations necessary for non-clinical studies to accommodate the regulatory requirements for clinical translation of radiopharmaceuticals. These considerations include non-clinical pharmacology, radiation exposure and effects, toxicological studies, pharmacokinetic modelling, and imaging studies. Additionally, standardisation of different specific clinical applications is discussed.

Conclusion

This document is intended as a guide for radiopharmaceutical scientists, Nuclear Medicine specialists, and regulatory professionals to bring innovative diagnostic and therapeutic radiopharmaceuticals into the clinical evaluation process in a safe and effective way.

Acute axon damage and demyelination are mitigated by 4-aminopyridine (4-AP) therapy after experimental traumatic brain injury

Damage to long axons in white matter tracts is a major pathology in closed head traumatic brain injury (TBI). Acute TBI treatments are needed that protect against axon damage and promote recovery of axon function to prevent long term symptoms and neurodegeneration. Our prior characterization of axon damage and demyelination after TBI led us to examine repurposing of 4-aminopyridine (4-AP), an FDA-approved inhibitor of voltage-gated potassium (Kv) channels. 4-AP is currently indicated to provide symptomatic relief for patients with chronic stage multiple sclerosis, which involves axon damage and demyelination. We tested clinically relevant dosage of 4-AP as an acute treatment for experimental TBI and found multiple benefits in corpus callosum axons. This randomized, controlled pre-clinical study focused on the first week after TBI, when axons are particularly vulnerable. 4-AP treatment initiated one day post-injury dramatically reduced axon damage detected by intra-axonal fluorescence accumulations in Thy1-YFP mice of both sexes. Detailed electron microscopy in C57BL/6 mice showed that 4-AP reduced pathological features of mitochondrial swelling, cytoskeletal disruption, and demyelination at 7 days post-injury. Furthermore, 4-AP improved the molecular organization of axon nodal regions by restoring disrupted paranode domains and reducing Kv1.2 channel dispersion. 4-AP treatment did not resolve deficits in action potential conduction across the corpus callosum, based on ex vivo electrophysiological recordings at 7 days post-TBI. Thus, this first study of 4-AP effects on axon damage in the acute period demonstrates a significant decrease in multiple pathological hallmarks of axon damage after experimental TBI.

Applications of Model-Based Target Pharmacology Assessment in Defining Drug Design and DMPK Strategies: GSK Experiences

Many critical decisions faced in early discovery require a thorough understanding of the dynamic behavior of pharmacological pathways following target engagement. From fundamental decisions on the optimal target to pursue and the ultimate drug product profile (combination of modality, potency, and compound properties) expected to elicit the desired clinical outcome to tactical program decisions such as what chemical series to pursue, what chemical properties require optimization, and what compounds to synthesize and progress, all demand detailed consideration of pharmacodynamics. Model-based target pharmacology assessment (mTPA) is a computational approach centered around large-scale virtual exploration of pharmacokinetic and pharmacodynamic models built early in discovery to guide these decisions. The present work summarizes several examples (use cases) from programs at GlaxoSmithKline that demonstrate the utility of mTPA throughout the drug discovery lifecycle.

A Structured Approach to Optimizing Animal Model Selection for Human Translation: The Animal Model Quality Assessment

Animal studies in pharmaceutical drug discovery are common in preclinical research for compound evaluation before progression into human clinical trials. However, high rates of drug development attrition have prompted concerns regarding animal models and their predictive translatability to the clinic. To improve the characterization and evaluation of animal models for their translational relevance, the authors developed a tool to transparently reflect key features of a model that may be considered in both the application of the model but also the likelihood of successful translation of the outcomes to human patients. In this publication, we describe the rationale for the development of the Animal Model Quality Assessment tool, the questions used for the animal model assessment, and a high-level scoring system for the purpose of defining predictive translatability. Finally, we provide an example of a completed Animal Model Quality Assessment for the adoptive T-cell transfer model of colitis as a mouse model to mimic inflammatory bowel disease in humans.

Melatonin and the cardiovascular system in animals: systematic review and meta-analysis

Melatonin, a hormone released by the pineal gland, demonstrates several effects on the cardiovascular system. Herein, we performed a systematic review and meta-analysis to verify the effects of melatonin in an experimental model of myocardial infarction. We performed a systematic review according to PRISMA recommendations and reviewed MEDLINE, Embase, and Cochrane databases. Only articles in English were considered. A systematic review of the literature published between November 2008 and June 2019 was performed. The meta-analysis was conducted using the RevMan 5.3 program provided by the Cochrane Collaboration. In total, 858 articles were identified, of which 13 were included in this review. The main results of this study revealed that melatonin benefits the cardiovascular system by reducing infarct size, improving cardiac function according to echocardiographic and hemodynamic analyses, affords antioxidant effects, improves the rate of apoptosis, decreases lactate dehydrogenase activity, enhances biometric analyses, and improves protein levels, as analyzed by western blotting and quantitative PCR. In the meta-analysis, we observed a statistically significant decrease in infarct size (mean difference [MD], -20.37 [-23.56, -17.18]), no statistical difference in systolic pressure (MD, -1.75 [-5.47, 1.97]), a statistically significant decrease in lactate dehydrogenase in animals in the melatonin group (MD, -4.61 [-6.83, -2.40]), and a statistically significant improvement in the cardiac ejection fraction (MD, -8.12 [-9.56, -6.69]). On analyzing potential bias, we observed that most studies presented a low risk of bias; two parameters were not included in the analysis, and one parameter had a high risk of bias. Melatonin exerts several effects on the cardiovascular system and could be a useful therapeutic target to combat various cardiovascular diseases.

Mesenchymal stromal cell extracellular vesicles as therapy for acute and chronic respiratory diseases: A meta-analysis

Preclinical studies suggest mesenchymal stromal cell extracellular vesicles (MSC-EVs) reduce inflammation and improve organ function in lung diseases; however, an objective analysis of all available data is needed prior to translation. Using rigorous meta-research methods, we determined the effectiveness of MSC-EVs for preclinical respiratory diseases and identified experimental conditions that may further refine this therapy. A systematic search of MEDLINE/Embase identified 1167 records. After screening, 52 articles were included for data extraction and evaluated for risk of bias and quality of reporting in study design. A random effects meta-analysis was conducted for acute lung injury (ALI; N = 23), bronchopulmonary dysplasia (BPD; N = 8) and pulmonary arterial hypertension (PAH; N = 7). Subgroup analyses identified EV methods/characteristics that may be associated with improved efficacy. Data is presented as standardized mean differences (SMD) or risk ratios (RR) with 95% confidence intervals (CI). For ALI, MSC-EVs markedly reduced lung injury (SMD -4.33, CI -5.73 to -2.92), vascular permeability (SMD -2.43, CI -3.05 to -1.82), and mortality (RR 0.39, CI 0.22 to 0.68). Small EVs were more consistently effective than large EVs whereas no differences were observed between tissue sources, immunocompatibility or isolation techniques. For BPD, alveolarization was improved by MSC-EVs (SMD -1.45, CI -2.08 to -0.82) with small EVs more consistently beneficial then small/large EVs. In PAH, right ventricular systolic pressure (SMD -4.16, CI -5.68 to -2.64) and hypertrophy (SMD -2.80, CI -3.68 to -1.91) were significantly attenuated by EVs. In BPD and PAH, EVs isolated by ultracentrifugation demonstrated therapeutic benefit whereas tangential flow filtration (N = 2) displayed minimal efficacy. Lastly, risk of bias and quality of reporting for experimental design were consistently unclear across all studies. Our findings demonstrate clear potential of MSC-EVs to be developed as therapy for acute and chronic lung diseases. However, greater transparency in research design and direct comparisons of isolation technique and EV subtypes are needed to generate robust evidence to guide clinical translation. Protocol Registration: PROSPERO CRD42020145334.

Ethical challenges for a new generation of early-phase pediatric gene therapy trials

After decades of setbacks, gene therapy (GT) is experiencing major breakthroughs. Five GTs have received US regulatory approval since 2017, and over 900 others are currently in development. Many of these GTs target rare pediatric diseases that are severely life-limiting, given a lack of effective treatments. As these GTs enter early-phase clinical trials, specific ethical challenges remain unresolved in three domains: evaluating risks and potential benefits, selecting participants fairly, and engaging with patient communities. Drawing on our experience as clinical investigators, basic scientists, and bioethicists involved in a first-in-human GT trial for an ultrarare pediatric disease, we analyze these ethical challenges and offer points to consider for future GT trials.

A review of pre-clinical models for Gulf War Illness

Gulf War Illness (GWI) is a chronic multisymptomatic disorder that afflicts over 1/3rd of the 1991 GW veterans. It spans multiple bodily systems and presents itself as a syndrome exhibiting diverse symptoms including fatigue, depression, mood, and memory and concentration deficits, musculoskeletal pain and gastrointestinal distress in GW veterans. The etiology of GWI is complex and many factors, including chemical, physiological, and environmental stressors present in the GW arena, have been implicated for its development. It has been over 30 years since the end of the GW but, GWI has been persistent in suffering veterans who are also dealing with paucity of effective treatments. The multifactorial aspect of GWI along with genetic heterogeneity and lack of available data surrounding war-time exposures have proved to be challenging in developing pre-clinical models of GWI. Despite this, over a dozen GWI animal models exist in the literature. In this article, following a brief discussion of GW history, GWI definitions, and probable causes for its pathogenesis, we will expand upon various experimental models used in GWI laboratory research. These animal models will be discussed in the context of their attempts at mimicking GW-related exposures with regards to the variations in chemical combinations, doses, and frequency of exposures. We will discuss their advantages and limitations in modeling GWI followed by a discussion of behavioral and molecular findings in these models. The mechanistic data obtained from these preclinical studies have offered multiple molecular pathways including chronic inflammation, mitochondrial dysfunction, oxidative stress, lipid disturbances, calcium homeostatic alterations, changes in gut microbiota, and epigenetic modifications, amongst others for explaining GWI development and its persistence. Finally, these findings have also informed us on novel druggable targets in GWI. While, it has been difficult to conceive a single pre-clinical model that could express all the GWI signs and exhibit biological complexity reflective of the clinical presentation in GWI, animal models have been critical for identifying molecular underpinnings of GWI and evaluating treatment strategies for GWI.

Robust preclinical evidence in somatic cell genome editing: A key driver of responsible and efficient therapeutic innovations

Somatic cell genome editing (SCGE) is highly promising for therapeutic innovation. This study demonstrates that the majority of 46 preclinical SCGE studies discussed in reviews as particularly promising for clinical translation do not report on key elements for robust and confirmatory research practices: randomization, blinding, sample size calculation, data handling, pre-registration, multi-centric study design, and independent confirmation. We present the here-examined reporting standards and the new National Institutes of Health (NIH) funding criteria for SCGE research as a viable solution to protect this promising field from backlashes. We argue that the implementation of the novel methodological standards provides the opportunity for SCGE research to become a lighthouse example for trustworthy and useful translational research.

Species variations in tenocytes' response to inflammation require careful selection of animal models for tendon research

For research on tendon injury, many different animal models are utilized; however, the extent to which these species simulate the clinical condition and disease pathophysiology has not yet been critically evaluated. Considering the importance of inflammation in tendon disease, this study compared the cellular and molecular features of inflammation in tenocytes of humans and four common model species (mouse, rat, sheep, and horse). While mouse and rat tenocytes most closely equalled human tenocytes’ low proliferation capacity and the negligible effect of inflammation on proliferation, the wound closure speed of humans was best approximated by rats and horses. The overall gene expression of human tenocytes was most similar to mice under healthy, to horses under transient and to sheep under constant inflammatory conditions. Humans were best matched by mice and horses in their tendon marker and collagen expression, by horses in extracellular matrix remodelling genes, and by rats in inflammatory mediators. As no single animal model perfectly replicates the clinical condition and sufficiently emulates human tenocytes, fit-for-purpose selection of the model species for each specific research question and combination of data from multiple species will be essential to optimize translational predictive validity.

Internal consistency and compatibility of the 3Rs and 3Vs principles for project evaluation of animal research

Using animals for research raises ethical concerns that are addressed in project evaluation by weighing expected harm to animals against expected benefit to society. A harm-benefit analysis (HBA) relies on two preconditions: (a) the study protocol is scientifically suitable and (b) the use of (sentient) animals and harm imposed on them are necessary for achieving the study's aims. The 3Rs (Replace, Reduce and Refine) provide a guiding principle for evaluating whether the use of animals, their number and the harm imposed on them are necessary. A similar guiding principle for evaluating whether a study protocol is scientifically suitable has recently been proposed: the 3Vs principle referring to the three main aspects of scientific validity in animal research (construct, internal and external validity). Here, we analyse the internal consistency and compatibility of these two principles, address conflicts within and between the 3Rs and 3Vs principles and discuss their implications for project evaluation. We show that a few conflicts and trade-offs exist, but that these can be resolved either by appropriate study designs or by ethical deliberation in the HBA. In combination, the 3Vs, 3Rs and the HBA thus offer a coherent framework for a logically structured evaluation procedure to decide about the legitimacy of animal research projects.

Pre-Clinical Common Data Elements for Traumatic Brain Injury Research: Progress and Use Cases

Traumatic brain injury (TBI) is an extremely complex condition due to heterogeneity in injury mechanism, underlying conditions, and secondary injury. Pre-clinical and clinical researchers face challenges with reproducibility that negatively impact translation and therapeutic development for improved TBI patient outcomes. To address this challenge, TBI Pre-clinical Working Groups expanded upon previous efforts and developed common data elements (CDEs) to describe the most frequently used experimental parameters. The working groups created 913 CDEs to describe study metadata, animal characteristics, animal history, injury models, and behavioral tests. Use cases applied a set of commonly used CDEs to address and evaluate the degree of missing data resulting from combining legacy data from different laboratories for two different outcome measures (Morris water maze [MWM]; RotorRod/Rotarod). Data were cleaned and harmonized to Form Structures containing the relevant CDEs and subjected to missing value analysis. For the MWM dataset (358 animals from five studies, 44 CDEs), 50% of the CDEs contained at least one missing value, while for the Rotarod dataset (97 animals from three studies, 48 CDEs), over 60% of CDEs contained at least one missing value. Overall, 35% of values were missing across the MWM dataset, and 33% of values were missing for the Rotarod dataset, demonstrating both the feasibility and the challenge of combining legacy datasets using CDEs. The CDEs and the associated forms created here are available to the broader pre-clinical research community to promote consistent and comprehensive data acquisition, as well as to facilitate data sharing and formation of data repositories. In addition to addressing the challenge of standardization in TBI pre-clinical studies, this effort is intended to bring attention to the discrepancies in assessment and outcome metrics among pre-clinical laboratories and ultimately accelerate translation to clinical research.

Preclinical Research Reporting in Shock: Room for Improvement

ABSTRACT

The ARRIVE (Animals in Research: Reporting In Vivo Experiments) guidelines were endorsed by the Shock Society in 2012, but to date there has been no systematic evaluation of research reporting quality for Shock. We systematically assessed 100 randomly selected animal-based research articles published between 2014 and 2018 for reporting quality and statistical practice, compared with 40 pre-ARRIVE studies. More than half of surveyed papers omitted verifiable ethical oversight information and basic animal descriptive information. Few papers reported best-practice methods, such as sample size justification (10%), randomization (43%), randomization method (7%), blinding (23%). Only one paper reported effect sizes to interpret study results. Most troubling was inadequate reporting of welfare-related information (anesthesia, analgesia, humane endpoints, euthanasia). Almost a decade after ARRIVE endorsement, our findings show that reporting deficiencies have persisted with little sign of correction. There is a clear need for investigators to increase transparency of research methods reporting, and drastically improve skills in experimental design. Improvement in standards and greater attention paid to reporting will lead to improvement in reproducibility, replicability, and research quality. It is incumbent upon the research community to improve reporting practices; accurate and transparent reporting is integral to producing rigorous and ethical science.

Epidemiology and reporting characteristics of preclinical systematic reviews

In an effort to better utilize published evidence obtained from animal experiments, systematic reviews of preclinical studies are increasingly more common-along with the methods and tools to appraise them (e.g., SYstematic Review Center for Laboratory animal Experimentation [SYRCLE's] risk of bias tool). We performed a cross-sectional study of a sample of recent preclinical systematic reviews (2015-2018) and examined a range of epidemiological characteristics and used a 46-item checklist to assess reporting details. We identified 442 reviews published across 43 countries in 23 different disease domains that used 26 animal species. Reporting of key details to ensure transparency and reproducibility was inconsistent across reviews and within article sections. Items were most completely reported in the title, introduction, and results sections of the reviews, while least reported in the methods and discussion sections. Less than half of reviews reported that a risk of bias assessment for internal and external validity was undertaken, and none reported methods for evaluating construct validity. Our results demonstrate that a considerable number of preclinical systematic reviews investigating diverse topics have been conducted; however, their quality of reporting is inconsistent. Our study provides the justification and evidence to inform the development of guidelines for conducting and reporting preclinical systematic reviews.

Current Status and Limitations of Myocardial Infarction Large Animal Models in Cardiovascular Translational Research

Establishing an appropriate disease model that mimics the complexities of human cardiovascular disease is critical for evaluating the clinical efficacy and translation success. The multifaceted and complex nature of human ischemic heart disease is difficult to recapitulate in animal models. This difficulty is often compounded by the methodological biases introduced in animal studies. Considerable variations across animal species, modifications made in surgical procedures, and inadequate randomization, sample size calculation, blinding, and heterogeneity of animal models used often produce preclinical cardiovascular research that looks promising but is irreproducible and not translatable. Moreover, many published papers are not transparent enough for other investigators to verify the feasibility of the studies and the therapeutics' efficacy. Unfortunately, successful translation of these innovative therapies in such a closed and biased research is difficult. This review discusses some challenges in current preclinical myocardial infarction research, focusing on the following three major inhibitors for its successful translation: Inappropriate disease model, frequent modifications to surgical procedures, and insufficient reporting transparency.

The Road Not Mapped: The Neuroethics Roadmap on Research with Nonhuman Primates

We have arrived at an inflection point, a moment in history when the sentience, consciousness, intelligence, agency, and even the moral agency of many nonhuman animals can no longer be questioned without ignoring centuries of accumulated scientific knowledge. Nowhere is this more true than in our understanding of nonhuman primates (NHPs). A neuroethics committed to probing the ethical implications of brain research must be able to respond to and anticipate the challenges ahead as brain projects globally prepare to increase the use of NHPs in research. This requires adopting a less anthropocentric focus that includes nonhuman animals within its scope. But the Neuroethics Roadmap represents a missed opportunity to critically examine the future direction of research with NHPs in an ethically-responsive neuroscience.

Mesenchymal Stromal Cell-derived Extracellular Vesicles in Preclinical Animal Models of Tumor Growth: Systematic Review and Meta-analysis

BACKGROUND

Mesenchymal stromal cell derived extracellular vesicles (MSC-EVs) have been implicated in the regulation of tumor growth. Studies remain preclinical with effects ranging from inhibition of tumor growth to cancer progression. A systematic review and meta-analysis is needed to clarify the effect of MSC-EVs on tumor growth to facilitate potential translation to clinical trials.

METHODS

A systematic search of the literature (MEDLINE, Embase, and BIOSIS databases to June 1, 2019) identified all pre-clinical controlled studies investigating the effect of MSC-EVs on tumor growth. Study selection and data extraction were performed in duplicate. Potential risk of bias was assessed using the SYRCLE tool. A random effects meta-analysis of reduction in tumor weight/volume (primary outcome) was performed.

RESULTS

We identified 29 articles and 22 reported data on tumor responses that were included for meta-analysis. Studies were associated with unclear risk of bias in a large proportion of domains in accordance with the SYRCLE tool for determining risk of bias in preclinical studies. A high risk of bias was not identified in any study. MSC-EVs had a mixed response on tumor progression with some studies reporting inhibition of tumor growth and others reporting tumor progression. Overall, MSC-EVs exerted a non-significant reduction in tumor growth compared to controls (standardized mean difference (SMD) -0.80, 95 % CI -1.64 to 0.03, p = 0.06, I² = 87 %). Some studies reported increased tumor growth which aligned with their stated hypothesis and some interrogated mechanisms in cancer biology. EVs isolated from MSCs that overexpressed anti-tumor RNAs were associated with significant tumor reduction in meta-analysis (SMD - 2.40, 95 % CI -3.36 to -1.44, p < 0.001). Heterogeneity between studies was observed and included aspects of study design such as enrichment of MSC-EVs with specific anti-tumor molecules, tissue source of MSCs, method of EV isolation, characterization of MSCs and EVs, dosage and administration schedules, and tissue type and source of tumor cells studied.

CONCLUSIONS

MSC-EVs are associated with mixed effects on tumor growth in animal models of cancer. In studies where anti-tumor RNAs are packaged in EVs, a significant reduction in tumor growth was observed. Reducing heterogeneity in study design may accelerate our understanding of the potential effects of MSC-EVs on cancer. [274 words] Forest plot of MSC-EV effect on tumor growth accordinggenetic modification of EVs in animal studies identified from a systematicreview of the literature. All cohorts from studies with multiple interventiongroups are presented separately with control groups divided equally among thegroups. M, modified; H, hypoxia.

Persistence of CRISPR/Cas9 gene edited hematopoietic stem cells following transplantation: A systematic review and meta-analysis of preclinical studies

Gene editing blood‐derived cells is an attractive approach to cure selected monogenic diseases but remains experimental. A systematic search of preclinical controlled studies is needed to determine the persistence of edited cells following reinfusion. All studies identified in our systematic search (to 20 October 2020) examining the use of CRISPR/Cas9 gene editing in blood‐derived cells for transplantation were included. Meta‐analysis was performed to determine the engraftment and persistence of gene edited cells. A total of 3538 preclinical studies were identified with 15 published articles meeting eligibility for meta‐analysis. These in vivo animal studies examined editing of hemoglobin to correct sickle cell disease (eight studies), inducing resistance to acquired immunodeficiency syndrome (two studies), and six other monogenic disorders (single studies). CRISPR‐Cas9 edited hematopoietic stem and progenitor cells demonstrated equivalent early engraftment compared to controls in meta‐analysis but persistence of gene‐edited cells was reduced at later time points and in secondary transplant recipients. Subgroup analysis in studies targeting the hemoglobin gene revealed a significant reduction in the persistence of gene‐edited cells whether homology‐directed repair or nonhomologous end‐joining were used. No adverse side effects were reported. Significant heterogeneity in study design and outcome reporting was observed and the potential for bias was identified in all studies. CRISPR‐Cas9 gene edited cells engraft similarly to unedited hematopoietic cells. Persistence of gene edited cells, however, remains a challenge and improved methods of targeting hematopoietic stem cells are needed. Reducing heterogeneity and potential risk of bias will hasten the development of informative clinical trials.

Reporting experimental studies on animals - The problems with translating of outcomes to clinical benefits. Methodological and statistical considerations: The example of pulmonary hypertension

The variability inherent in animal models and the methods used to define drug response can lead to highly divergent results when evaluating new drug candidates. Several guidelines exist for high-quality and comprehensive reporting of experiments with animals. The present survey makes a quantitative demonstration of whether compliance with good preclinical practice guidelines can affect the results and reduce risk of over- or underestimation of treatment benefit. This meta-analysis was performed on more than 400 animal studies concerning pulmonary hypertension, where a wide range of potential therapeutic agents have been recently positively assessed in preclinical experiments. The experiments were reviewed according to the selected methodological and statistical items being recommended to report in papers. A quantitative evaluation was performed of their impact on effect size, which defined the efficacy of particular drug candidates. In addition, the paper also examines whether the quality score calculated for the papers included in the analysis changed over the previous 25 years. In conclusion, some information in experimental studies is often missed or incomplete, which complicates the correct evaluation and comprehension of obtained results. This in turn could subsequently increase the potential hazards involved in translating positive experimental outcomes to possible clinical benefits in patients.

Translational Intracerebral Hemorrhage Research: Has Current Neuroprotection Research ARRIVEd at a Standard for Experimental Design and Reporting?

One major aim of preclinical intracerebral hemorrhage (ICH) research is to develop and test potential neuroprotectants. Published guidelines for experimental design and reporting stress the importance of clearly and completely reporting results and methodological details to ensure reproducibility and maximize information availability. The current review has two objectives: first, to characterize current ICH neuroprotection research and, second, to analyze aspects of translational design in preclinical ICH studies. Translational design is the adoption and reporting of experimental design characteristics that are thought to be clinically relevant and critical to reproducibility in animal studies (e.g., conducting and reporting experiments according to the STAIR and ARRIVE guidelines, respectively). Given that ICH has no current neuroprotective treatments and an ongoing reproducibility crisis in preclinical research, translational design should be considered by investigators. We conducted a systematic review of ICH research from 2015 to 2019 using the PubMed database. Our search returned 281 published manuscripts studying putative neuroprotectants in animal models. Contemporary ICH research predominantly uses young, healthy male rodents. The collagenase model is the most commonly used. Reporting of group sizes, blinding, and randomization are almost unanimous, but group size calculations, mortality and exclusion criteria, and animal model characteristics are infrequently reported. Overall, current ICH neuroprotection research somewhat aligns with experimental design and reporting guidelines. However, there are areas for improvement. Because failure to consider translational design is associated with inflation of effect sizes (and possibly hindered reproducibility), we suggest that researchers, editors, and publishers collaboratively consider enhanced adherence to published guidelines.

Gap Analysis of Swine-Based Hemostasis Research: "Houses of Brick or Mansions of Straw?"

INTRODUCTION

Hemorrhage control is the top priority in far-forward care. Preclinical studies are essential for determining safety and efficacy before novel therapeutics can be tested in humans. Unfortunately, poor methodological quality jeopardizes translational potential.

METHODS

We systematically reviewed 136 recent publications describing swine models of hemostasis and hemorrhage reduction to assess compliance with established standards for scientific reporting. Quality measures were summarized by descriptive statistics; randomization was assessed by using baseline group differences to test the uniform distribution assumption for observed P-values.

RESULTS

Most articles did not report information essential to assess study validity and reliability of experimental results. Studies claiming random allocation showed clear evidence of systematic bias. Sample sizes were small, but nearly all studies reported statistically significant effects in the direction of "benefit." Excessive hypothesis testing increased the risk of false positives.

CONCLUSIONS

Methodological quality was poor. Although funding agencies actively promote good scientific practice, investigators have been slow to comply. Poorly executed and reported animal research is an ethical and translational issue, wasting animals and potentially harming patients. To properly assess the therapeutic benefit of novel interventions, investigators must rely less on rote hypothesis testing, develop skills in experimental design and quantitative analysis, and comply with best-practice reporting guidelines.

Preclinical Studies of MSC-Derived Extracellular Vesicles to Treat or Prevent Graft Versus Host Disease: a Systematic Review of the Literature

INTRODUCTION

Treating and preventing graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplant (HCT) remains a significant challenge. The use of mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) appears promising and a systematic review of preclinical studies is needed to accelerate the design of translational studies.

METHODS

We identified 4 eligible studies from a systematic review performed on December 1, 2018. In brief, eligible studies included the treatment or prevention of GVHD in animal models and the use of MSC-EVs. Study design and outcome data were extracted and reporting was evaluated using the SYRCLE tool to identify potential bias.

RESULTS

Two studies assessed the efficacy of MSC-EVs in treatment of GVHD and 2 studies address prevention. Mice treated with MSC-EVs showed improved median survival, GVHD clinical scores and histology scores as compared to untreated mice with GVHD. Prophylactic treatment with MSC-EVs attenuated GVHD severity and improved median survival as compared to no treatment or saline.

CONCLUSION

Our systematic review provides important insight regarding the potential of MSC-EVs to treat or prevent GVHD. Although few studies were identified, improved survival and attenuated histologic findings of GVHD were observed in mice after MSC-EV administration for the treatment and prevention of GVHD. Dosing of EVs and route of administration remain inconsistent, however, and scalability of EV isolation for clinical studies remains a challenge. Standardized outcome reporting is needed to pool results for metanalysis. Graphical abstract.

Facilitation of risk assessment with evidence-based methods - A framework for use of systematic mapping and systematic reviews in determining hazard, developing toxicity values, and characterizing uncertainty

Systematic review tools and approaches developed for clinical medicine are often difficult to apply "off the shelf" in order to meet the needs of chemical risk assessments. To address such, we propose an approach that can be used by practitioners for using evidence-based methods to facilitate the risk assessment process. The framework builds on and combines efforts conducted to date by a number of agencies and researchers; the novelty is in combining these efforts with a practical understanding of risk assessment, and translating such into a 'step-by-step' guide. The approach relies on three key components: problem formulation, systematic evidence mapping, and systematic review, applied using a stepwise approach. Unique to this framework is the consideration of exposure in selecting, prioritizing, and evaluating data (e.g., dose-relevance, routes of exposure, etc.). Using the proposed step-by-step process, critical appraisal of individual studies (e.g., formal and structured assessment of both relevance and reliability) and integration efforts are considered in context of specified risk assessment objectives (e.g., mode of action, dose-response) as well as chemical-specific considerations. The resulting framework provides a logical approach of how evidence-based methods can be used to facilitate risk assessment, and elevates the use of systematic methods beyond hazard identification to directly facilitating transparent and objective selection of candidate studies and/or datasets used to quantitatively characterize risk, and to better use the underlying process to inform the approaches used to develop toxicity values.