Comparison of Serial Blood Collection by Facial Vein and Retrobulbar Methods in C57BL/6 Mice

Venipuncture Site Influences Blood-drop Volume in C57BL/6 Mice

Many experiments require the collection of serial blood samples from mice. However, the size of mice limits the volume of blood that can be safely collected as a survival procedure. In IACUC protocols, investigators may report the amount of blood they collect from mice as a number of drops. Many institutions, including ours, use an anecdotal conversion factor (1drop of mouse blood = 25μL) to ensure that blood-collection volumes are compliant with institutional guidelines. To our knowledge, previous work has not experimentally determined the volume of a drop of mouse blood. In this 10-wk crossover experiment, 2 phlebotomists bled 30 C57BL/6J mice from 3 sites (facial, saphenous, and tail) using one or 2 different needle gauge sizes per site. Male and female mice were weighed weekly and divided among 5 groups (n = 6): left and right tail vein, left and right saphenous vein, and facial vein. A single blood drop from each site was weighed, and the volume of each drop was calculated using the average blood density determined from 8 mice terminally bled at the end of the study. Venipuncture site and side significantly influenced blood-drop weight and thus calculated volume. Facial vein puncture produced the largest drop volume (mean: 21.7μL), followed by the saphenous vein (mean: 9.97μL) and tail vein (mean: 4.96μL). Collection from the facial vein was associated with more hemorrhage and morbidity. Left-sided venipuncture was associated with slightly larger-volume blood drops, though the effect size of side was small. The results of this study may be useful in more accurately estimating blood loss via conversion of drops to volume. Our data indicate that blood collection from saphenous and tail veins minimizes blood loss relative to facial vein puncture and may optimize both serial collection of small-volume blood samples and animal welfare.

L-Ergothioneine slows the progression of age-related hearing loss in CBA/CaJ mice

The naturally occurring amino acid, l-ergothioneine (EGT), has immense potential as a therapeutic, having shown promise in the treatment of other disease models, including neurological disorders. EGT is naturally uptaken into cells via its specific receptor, OCTN1, to be utilized by cells as an antioxidant and anti-inflammatory. In our current study, EGT was administered over a period of 6 months to 25-26-month-old CBA/CaJ mice as a possible treatment for age-related hearing loss (ARHL), since presbycusis has been linked to higher levels of cochlear oxidative stress, apoptosis, and chronic inflammation. Results from the current study indicate that EGT can prevent aging declines of some key features of ARHL. However, we found a distinct sex difference for the response to the treatments, for hearing - Auditory Brainstem Responses (ABRs) and Distortion Product Otoacoustic Emissions (DPOAEs). Males exhibited lower threshold declines in both low dose (LD) and high dose (HD) test groups throughout the testing period and did not display some of the characteristic aging declines in hearing seen in Control animals. In contrast, female mice did not show any therapeutic effects with either treatment dose. Further confirming this sex difference, EGT levels in whole blood sampling throughout the testing period showed greater uptake of EGT in males compared to females. Additionally, RT-PCR results from three tissue types of the inner ear confirmed EGT activity in the cochlea in both males and females. Males and females exhibited significant differences in biomarkers related to apoptosis (Cas-3), inflammation (TNF-a), oxidative stress (SOD2), and mitochondrial health (PGC1a).These changes were more prominent in males as compared to females, especially in stria vascularis tissue. Taken together, these findings suggest that EGT has the potential to be a naturally derived therapeutic for slowing down the progression of ARHL, and possibly other neurodegenerative diseases. EGT, while effective in the treatment of some features of presbycusis in aging males, could also be modified into a general prophylaxis for other age-related disorders where treatment protocols would include eating a larger proportion of EGT-rich foods or supplements. Lastly, the sex difference discovered here, needs further investigation to see if therapeutic conditions can be developed where aging females show better responsiveness to EGT.

Simple protocol for measuring CD11b+ GR-1+ (Ly6C+/Ly6G+) myeloid cells from a minimum volume of mouse peripheral blood

Myeloid-derived suppressor cells (MDSCs) comprise a heterogeneous population of myeloid origin and immature state, whose hallmark is the capacity to suppress T cells and other immune populations. In mice, the first approach to identify MDSCs relies in the measurement of their phenotypical markers: CD11b and GR-1. In addition, two main subtypes of MDSCs have been defined based on the expression of the following markers: CD11b+ Ly6G- Ly6C+ (monocytic-MDSCs, M-MDSCs) and CD11b+ Ly6G+ Ly6C+/low (polymorphonuclear-MDSCs, PMN-MDSCs). Since CD11b+ GR-1+ (Ly6C+/Ly6G+) MDSCs can increase significantly in peripheral blood during numerous acute or chronic processes, measuring alterations in the phenotypic markers CD11b and GR-1 could be important as a first step before assessing the suppressive function of the cells. In many cases it could be necessary to measure CD11b+ Gr-1+ cells from a minimum volume of peripheral blood cells without greatly affecting animal viability, since this approach would allow for further studies to be conducted on subsequent days, such as measuring parameters of the immune response or even survival in the context of the pathology under study. The following protocol describes a simple and optimized protocol for measuring the presence of CD11b+ GR-1+ (Ly6C+/Ly6G+) myeloid cells using 2+ channel flow cytometry, from a minimum volume of mouse peripheral blood obtained by facial vein puncture.

A Comparison of Blood Collection Techniques in Mice and their Effects on Welfare

Multiple methods are used to collect blood from mice; these methods have different effects on animal welfare. This study compared blood collection from facial, chin, and saphenous locations with regard to various parameters, including the time needed to collect blood, the number of attempts needed, success at completing the blood collection, volume of blood loss, weight changes in the mouse, presence of external lesions after blood collection and gross lesions at necropsy, physical signs during blood collection (vocalization, urination, and defecation), fecal corticosterone after blood collection, and blood chemistry values. While no one technique was clearly better for animal welfare, each technique had benefits and drawbacks.

Improving the Quality of EDTA-treated Blood Specimens from Mice

Nonterminal blood sampling in laboratory mice is a very common procedure. With the goal of improving animal welfare, different sampling sites and methods have been compared but have not achieved a consensus. Moreover, most of these studies overlooked the quality of blood specimens collected. The main preanalytical concern with EDTA-treated blood specimens for hematology analyses is platelet aggregation, which is known to cause analytical errors. Our objective was to find a nonterminal blood sampling method with minimal adverse effects on mice and few or no platelet aggregates. We tested and compared 2 collection sites, 4 sampling methods, and 3 antithrombotic drugs in 80 C57BL6/j male and female mice by evaluating platelet aggregates on blood smears and platelet, WBC, and RBC counts. In addition, the blood collection process was carefully evaluated, and adverse effects were recorded. Platelet aggregation was lower in specimens collected from the jugular vein than from the facial vein, with no effect of the sampling device or the presence of an antithrombotic additive. Highly aggregated specimens were significantly associated with lower platelet counts, whereas aggregation had no effect on WBC or RBC counts. Adverse events during sampling were significantly associated with more numerous platelet aggregates. The jugular vein is thus a satisfactory sampling site in mice in terms of both animal welfare and low platelet aggregation. Using antithrombotic agents appears to be unnecessary, whereas improving sampling conditions remains a key requirement to ensure the quality of EDTA-treated blood specimens from mice.

Evaluation and Correlation of Rabies Vaccine Potency Using the National Institute of Health, Rapid Focus Fluorescent Inhibition, and Passive Hemagglutination Tests

Rabies vaccine preparations are quantitatively assayed for potency using the in-vivo challenge National Institute of Health (NIH), the main test that consumes a high number of animals, takes a long time, and has wide variability. The Rapid focus fluorescent inhibition (RFFIT) and the passive hemagglutination (PHA) tests, the two serologically based tests, were also used for such purpose. In this study, we aimed to evaluate and correlate the potency of the NIH, RFFIT, and PHA tests according to the World Health Organization (WHO) validity criteria, aiming to validate the use of RFFIT or PHA test as a substitute to the NIH test for determining the potency of commercially available Rabies vaccine preparations. The results showed that, the three tests can be successfully used; however, a higher correlation between RFFIT and NIH than PHA and NIH was recorded (Pearson correlation = 1). The potency of rabies vaccine preparations using NIH, RFFIT, and PHA were 3.73, 3.51, and 4.50, respectively. NIH is the main test for the determination of vaccine potency carried out by conducting 25 experiments and consuming about 5,000 mice compared to 1,200 mice used with RFFIT and 1,000 mice used with PHA test. Taken together, we concluded that (i) in some tested preparations, both RFFIT and PHA tests gave comparable results, and they can be used interchangeably; (ii) RFFIT could successfully replace NIH test, but not PHA; (iii) RFFIT and PHA tests are faster, more accurate, more economic, and more sensitive than NIH; nevertheless, PHA needs further investigations; and (iv) both RFFIT and NIH tests complement and reinforce each other as they provide a comprehensive picture of the product potency.

Anisakis pegreffii Extract Induces Airway Inflammation with Airway Remodeling in a Murine Model System

Exposure of the respiratory system to the Anisakis pegreffii L3 crude extract (AE) induces airway inflammation; however, the mechanism underlying this inflammatory response remains unknown. AE contains allergens that promote allergic inflammation; exposure to AE may potentially lead to asthma. In this study, we aimed to establish a murine model to assess the effects of AE on characteristic features of chronic asthma, including airway hypersensitivity (AHR), airway inflammation, and airway remodeling. Mice were sensitized for five consecutive days each week for 4 weeks. AHR, lung inflammation, and airway remodeling were evaluated 24 h after the last exposure. Lung inflammation and airway remodeling were assessed from the bronchoalveolar lavage fluid (BALF). To confirm the immune response in the lungs, changes in gene expression in the lung tissue were assessed with reverse transcription-quantitative PCR. The levels of IgE, IgG1, and IgG2a in blood and cytokine levels in the BALF, splenocyte, and lung lymph node (LLN) culture supernatant were measured with ELISA. An increase in AHR was prominently observed in AE-exposed mice. Epithelial proliferation and infiltration of inflammatory cells were observed in the BALF and lung tissue sections. Collagen deposition was detected in lung tissues. AE exposure increased IL-4, IL-5, and IL-13 expression in the lung, as well as the levels of antibodies specific to AE. IL-4, IL-5, and IL-13 were upregulated only in LLN. These findings indicate that an increase in IL-4+ CD4+ T cells in the LLN and splenocyte resulted in increased Th2 response to AE exposure. Exposure of the respiratory system to AE resulted in an increased allergen-induced Th2 inflammatory response and AHR through accumulation of inflammatory and IL-4+ CD4+ T cells and collagen deposition. It was confirmed that A. pegreffii plays an essential role in causing asthma in mouse models and has the potential to cause similar effects in humans.

Comparison of murine retroorbital plexus and facial vein blood collection to mitigate animal ethics issues

Background

Blood collection is an important procedure used in animal experiments. Blood collection methods that reduce pain, injury, and stress in experimental animals are important with regard to animal ethics. Various comparative studies of blood collection methods have been reported; however, there are no comparative studies on serial blood collection considering animal ethics. To suggest simple methods that minimize pain during serial blood collection, we compared the retroorbital plexus (RP) and facial vein (FV) blood collection methods performed by both experienced and novice groups. The experienced and novice groups collected up to 0.4 mL of blood via the RP and FV methods every second day for 2 weeks. After blood collection, all mice were evaluated by corticosterone concentrations for stress, hematological, immunological, and histological analyses.

Results

We found that the FV methods reduced the collection time, pain, distress, tissue damage and lasting harms without anesthesia. Corticosterone concentrations in the peripheral blood were decreased in mice subjected FV methods compare with those subjected to RP methods. The proportion of granulocytes and monocytes, such as macrophages in the peripheral blood and spleen, was decreased in mice subjected to FV methods compared with that in mice subjected to RP methods in both experienced and novice groups. White blood cells were infiltrated in RP areas with severe tissue damage and inflammation.

Conclusions

With respect to animal ethics, we suggest that the FV method, a simple and fast technique that can easily be performed by both experienced and novice researchers, is suitable for serial blood collection.

The Impact of Common Recovery Blood Sampling Methods, in Mice (Mus Musculus), on Well-Being and Sample Quality: A Systematic Review

Blood sampling is often performed in laboratory mice. Sampling techniques have the potential to cause pain, distress and impact on lifetime cumulative experience. In spite of institutions commonly providing guidance to researchers on these methods, and the existence of published guidelines, no systematic evaluation of the evidence on this topic exists. A systematic search of Medline, Scopus, and Web of Science was performed, identifying 27 studies on the impact of recovery blood sample techniques on mouse welfare and sample quality. Studies were appraised for quality using the SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) risk of bias tool. In spite of an acceptable number of studies being located, few studies examined the same pairwise comparisons. Additionally, there was considerable heterogeneity in study design and outcomes, with many studies being at a high risk of bias. Consequently, results were synthesised using the Synthesis Without Meta-analysis (SWiM) reporting guidelines. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was utilised for assessment of certainty in the evidence. Due to the heterogeneity and GRADE findings, it was concluded that there was not enough high-quality evidence to make any recommendations on the optimal method of blood sampling. Future high-quality studies, with standardised outcome measures and large sample sizes, are required.

Hypothalamus-pituitary-adrenal axis imbalance and inflammation contribute to sex differences in separation- and restraint-induced depression

Whether social contact contributes to the underlying mechanisms of depression and the observed sex differences is unclear. In this study, we subjected young male and female mice to separation- and restraint-induced stress for 4 weeks and assessed behaviors, neurotransmitter levels, hormones, and inflammatory cytokines. Results showed that, compared with controls, male mice exposed to stress displayed significant decreases in body weight and sucrose preference after 1 week. In the fourth week, they exhibited a higher degree of anxiety (open field test) and depressive-like behavior (forced swim test). Moreover, the males showed significant decreases in monoamine neurotransmitters, including norepinephrine and dopamine in striatum, and an increase in pro-inflammatory cytokines, such as tumor necrosis factor α and interleukin 1β in serum. In contrast, females showed persistent loss of weight during stress and displayed significant decreases in sucrose preference after stress. Importantly, the females but not males showed activation of the hypothalamus-pituitary-adrenal (HPA) axis, with significantly higher levels adrenocorticotropic hormone. Additionally, mRNA level of c-fos and AVP showed there was significant interaction between stress and sex. Finally, we conclude that an imbalance of the HPA axis and inflammation might be important contributors to sex differences in separation/restraint-induced depressive behavior and that changes might be mediated by c-fos and AVP.

Thromboelastography testing in mice following blood collection from facial vein and cardiac puncture

: Blood collection is critical for mouse research studies particularly in hemostatic testing. Cardiac puncture; a standard effective method requires anesthesia and is a terminal procedure while facial vein technique allows multiple collections. Thromboelastography (TEG) is a global hemostasis test, provides a dynamic real-time picture of coagulation. However, TEG experiments in mice require large number of animals and may not allow pre/postinterventions assessment. In this study, we aimed to investigate the feasibility of facial vein sampling for TEG analysis as an alternative to cardiac puncture and examined the impact on coagulation results. Blood samples were obtained from a total of 10 C57BL/6 and CD-1 mice via cardiac puncture and a total of another eight mice of similar strains via facial vein sampling. We compared TEG parameters in both methods using descriptive statistics and the Student t test. Results show no significant difference in any of the TEG parameters between cardiac and facial vein blood indicating the two methods are comparable. Facial vein sampling provides a less costly alternative to cardiac puncture. It is a suitable blood collection method for pre/postinterventions or follow-up studies and it better addresses reduction and refinement goals in mouse studies. A larger study to evaluate the sex or strain and genetic background differences will be valuable.

Comparison of sublingual, facial and retro-bulbar blood sampling in mice in relation to animal welfare and blood quality

INTRODUCTION

Repeated blood sampling is a common procedure in laboratory mice, but at present it is unknown which technique has the least impact on the animals when large or repeated blood samples are required. Retro-bulbar sinus puncture is a reliable technique but has been shown to cause many changes in the animals, why sublingual and facial vein puncture have been suggested as suitable alternatives. This study investigated 1) which of the three blood sampling techniques had the least impact on nest building activity, level of faecal corticosterone metabolites, body weight, fur status, and macroscopic changes, 2) whether the blood sampling techniques gave rise to variation in blood quality between blood samples, and 3) whether sublingual and facial vein puncture should be performed with or without anaesthesia in female C57BL/6 mice.

METHOD

Three hundred and sixty C57BL/6 female mice divided into five batches were included in the study and randomized to a short (blood sampling on Day 8, 9 and 10) or a long protocol (blood sampling on Day 8, 15 and 22). Each protocol consisted of six identical groups: sublingual vein puncture (SVP), sublingual vein puncture in isoflurane (SVPiso), facial vein puncture (FVP), facial vein puncture in isoflurane (FVPiso), retro-bulbar sinus puncture (RBP), and a control group (CONTROL) with only scruffing being performed. At baseline (Day 2) nest building activity (NBA) was assessed and faecal pellets collected for evaluation of faecal corticosterone metabolites (FCM). The day after each blood sampling day NBA and FCM were reassessed.

RESULTS AND CONCLUSION

None of the blood sampling techniques proved to be superior to the others in any of the measured parameters. Finally, sublingual and facial vein puncture performed under anaesthesia gave rise to variation in the quality of the blood. A refinement of all three techniques are therefore warranted.

The Aryl Hydrocarbon Receptor (AhR) Mediates the Counter-Regulatory Effects of Pelargonidins in Models of Inflammation and Metabolic Dysfunctions

Pelargonidins are anthocyanidins thought to be beneficial for the human health, although controversies exist over the doses needed and the unclear mechanism of action, along with poor systemic bioavailability. One putative target of pelargonidins is the aryl hydrocarbon receptor (AhR). A synthetic pelargonidin (Mt-P) was synthesized by the methylation of the pelargonidin (the natural compound indicated as P). Mt-P transactivated the AhR with an EC50 of 1.97 µM and was ~2-fold more potent than the natural compound. In vitro Mt-P attenuated pro-inflammatory activities of Raw264.7 macrophage cells in an AhR-dependent manner. In vivo, administration of the Mt-P in Balb/c mice resulted in a dose-dependent attenuation of signs and symptoms of colitis induced by TNBS. A dose of 5 mg/kg Mt-P, but not the natural compound P, reversed intestinal inflammation and increased expression of Tnf-α, Ifn-ƴ, and Il-6, while promoted the expansion of regulatory T cells and M2 macrophages. In C57BL/6J mice fed a high fat diet (HFD), Mt-P attenuated body weight gain, intestinal and liver inflammation, and ameliorated insulin sensitivity, while worsened liver steatosis by up-regulating the liver expression of Cd36 and Apo100b. These effects were abrogated by AhR gene ablation. Mt-P is a synthetic pelargonidin endowed with robust AhR agonist activity that exerts beneficial effects in murine models of inflammation and metabolic dysfunction.