Effects of triggers of senescence and senolysis in murine pancreatic cancer cells.

BACKGROUND: The combination of senescence triggers with senolytic drugs is considered a promising new approach to cancer therapy. Here, we studied the efficacy of the genotoxic agent etoposide (Eto) and irradiation in inducing senescence of Panc02 pancreatic cancer cells, and the capability of the Bcl-2 inhibitor navitoclax (ABT-263; Nav) to trigger senolysis. METHODS: Panc02 cells were treated with Eto or irradiated with 5-20 Gy before exposure to Nav. Cell survival, proliferation, and senescence were assessed by trypan blue staining, quantification of DNA synthesis, and staining of senescence-associated ß-galactosidase (SA-ß-Gal)-positive cells, respectively. Levels of mRNA were determined by real-time polymerase chain reaction, and protein expression was analyzed by immunoblotting. Panc02 cells were also grown as pancreatic tumors in mice, which were subsequently treated with Eto and Nav. RESULTS: Eto and irradiation had an antiproliferative effect on Panc02 cells that was significantly or tendentially enhanced by Nav. In vivo, Eto and Nav together, but not Eto alone, significantly reduced the proportion of proliferating cells. The expression of the senescence marker γH2AX and tumor infiltration with T-cells were not affected by the treatment. In vitro, almost all Eto-exposed cells and a significant proportion of cells irradiated with 20 Gy were SA-ß-Gal-positive. Application of Nav reduced the percentage of SA-ß-Gal-positive cells after irradiation but not after pretreatment with Eto. In response to triggers of senescence, cultured Panc02 cells showed increased protein levels of γH2AX and the autophagy marker LC3B-II, and higher mRNA levels of Cdkn1a, Mdm2, and PAI-1, while the effects of Nav were variable. CONCLUSIONS: In vitro and in vivo, the combination of senescence triggers with Nav inhibited tumor cell growth more effectively than the triggers alone. Our data also provide some evidence for senolytic effects of Nav in vitro.

Uncoupling protein 2 deficiency of non-cancerous tissues inhibits the progression of pancreatic cancer in mice.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is a disease of the elderly mostly because its development from preneoplastic lesions depends on the accumulation of gene mutations and epigenetic alterations over time. How aging of non-cancerous tissues of the host affects tumor progression, however, remains largely unknown. METHODS: We took advantage of a model of accelerated aging, uncoupling protein 2-deficient (Ucp2 knockout, Ucp2 KO) mice, to investigate the growth of orthotopically transplanted Ucp2 wild-type (WT) PDAC cells (cell lines Panc02 and 6606PDA) in vivo and to study strain-dependent differences of the PDAC microenvironment. RESULTS: Measurements of tumor weights and quantification of proliferating cells indicated a significant growth advantage of Panc02 and 6606PDA cells in WT mice compared to Ucp2 KO mice. In tumors in the knockout strain, higher levels of interferon-γ mRNA despite similar numbers of tumor-infiltrating T cells were observed. 6606PDA cells triggered a stronger stromal reaction in Ucp2 KO mice than in WT animals. Accordingly, pancreatic stellate cells from Ucp2 KO mice proliferated at a higher rate than cells of the WT strain when they were incubated with conditioned media from PDAC cells. CONCLUSIONS: Ucp2 modulates PDAC microenvironment in a way that favors tumor progression and implicates an altered stromal response as one of the underlying mechanisms.

Effects of Bile Duct Ligation and Ghrelin Treatment on the Colonic Barrier and Microbiome of Mice.

INTRODUCTION: Cholestatic liver disease (CLD) is associated with intestinal barrier dysfunction. The peptide hormone ghrelin may exert both hepatoprotective and barrier-strengthening effects. Here, we have evaluated these effects under the conditions of experimental cholestasis. METHODS: C57BL/6J mice with bile duct ligation (BDL) or sham surgery were treated with ghrelin or solvent for 9 days. Liver injury was assessed by histological and laboratory analyses. Paracellular macromolecule permeability and transmural electrical resistance (TMER) of colonic tissues were measured using a Ussing chamber. Expression of tight junction (TJ) genes was quantified by real-time PCR. Amplicon metagenomic sequencing was employed to analyze bacterial 16S rRNA from colonic stool samples. RESULTS: Mice with BDL exhibited weight loss and signs of severe liver injury. These changes were unaffected by ghrelin treatment. FITC-4-kDa-dextran flux was increased and TMER decreased after BDL. Treatment with ghrelin tended to reduce these effects. Furthermore, application of ghrelin was associated with higher mRNA levels of claudin-4, occludin, and ZO-1 in colonic tissues of mice with BDL. Reduced alpha-diversity of the microbiome was observed in solvent-treated mice with BDL but not in ghrelin-treated animals. CONCLUSION: Ghrelin treatment did not improve weight loss and liver damage but increased gene expression of colonic TJ proteins and restored the alpha-diversity of the microbiome. Since protective effects of ghrelin might be masked by the severity of the model, we suggest follow-up studies in models of milder CLD.

The Inhibitory Response to PI3K/AKT Pathway Inhibitors MK-2206 and Buparlisib Is Related to Genetic Differences in Pancreatic Ductal Adenocarcinoma Cell Lines.

The aberrant activation of the phosphoinositide 3-kinase (PI3K)/ protein kinase B (AKT) pathway is common in pancreatic ductal adenocarcinomas (PDAC). The application of inhibitors against PI3K and AKT has been considered as a therapeutic option. We investigated PDAC cell lines exposed to increasing concentrations of MK-2206 (an AKT1/2/3 inhibitor) and Buparlisib (a pan-PI3K inhibitor). Cell proliferation, metabolic activity, biomass, and apoptosis/necrosis were evaluated. Further, whole-exome sequencing (WES) and RNA sequencing (RNA-seq) were performed to analyze the recurrent aberrations and expression profiles of the inhibitor target genes and the genes frequently mutated in PDAC (Kirsten rat sarcoma virus (KRAS), Tumor protein p53 (TP53)). MK-2206 and Buparlisib demonstrated pronounced cytotoxic effects and limited cell-line-specific effects in cell death induction. WES revealed two sequence variants within the direct target genes (PIK3CA c.1143C > G in Colo357 and PIK3CD c.2480C > G in Capan-1), but a direct link to the Buparlisib response was not observed. RNA-seq demonstrated that the expression level of the inhibitor target genes did not affect the efficacy of the corresponding inhibitors. Moreover, increased resistance to MK-2206 was observed in the analyzed cell lines carrying a KRAS variant. Further, increased resistance to both inhibitors was observed in SU.86.86 carrying two TP53 missense variants. Additionally, the presence of the PIK3CA c.1143C > G in KRAS-variant-carrying cell lines was observed to correlate with increased sensitivity to Buparlisib. In conclusion, the present study reveals the distinct antitumor effects of PI3K/AKT pathway inhibitors against PDAC cell lines. Aberrations in specific target genes, as well as KRAS and TP53, individually or together, affect the efficacy of the two PI3K/AKT pathway inhibitors.

Inhibitory Response to CK II Inhibitor Silmitasertib and CDKs Inhibitor Dinaciclib Is Related to Genetic Differences in Pancreatic Ductal Adenocarcinoma Cell Lines.

Casein kinase II (CK2) and cyclin-dependent kinases (CDKs) frequently interact within multiple pathways in pancreatic ductal adenocarcinoma (PDAC). Application of CK2- and CDK-inhibitors have been considered as a therapeutic option, but are currently not part of routine chemotherapy regimens. We investigated ten PDAC cell lines exposed to increasing concentrations of silmitasertib and dinaciclib. Cell proliferation, metabolic activity, biomass, and apoptosis/necrosis were evaluated, and bioinformatic clustering was used to classify cell lines into sensitive groups based on their response to inhibitors. Furthermore, whole exome sequencing (WES) and RNA sequencing (RNA-Seq) was conducted to assess recurrent mutations and the expression profile of inhibitor targets and genes frequently mutated in PDAC, respectively. Dinaciclib and silmitasertib demonstrated pronounced and limited cell line specific effects in cell death induction, respectively. WES revealed no genomic variants causing changes in the primary structure of the corresponding inhibitor target proteins. RNA-Seq demonstrated that the expression of all inhibitor target genes was higher in the PDAC cell lines compared to non-neoplastic pancreatic tissue. The observed differences in PDAC cell line sensitivity to silmitasertib or dinaciclib did not depend on target gene expression or the identified gene variants. For the PDAC hotspot genes kirsten rat sarcoma virus (KRAS) and tumor protein p53 (TP53), three and eight variants were identified, respectively. In conclusion, both inhibitors demonstrated in vitro efficacy on the PDAC cell lines. However, aberrations and expression of inhibitor target genes did not appear to affect the efficacy of the corresponding inhibitors. In addition, specific aberrations in TP53 and KRAS affected the efficacy of both inhibitors.

A Simple LC-MS/MS Method for the Quantification of PDA-66 in Human Plasma.

The treatment of cancer is one of the most important pharmacotherapeutic challenges. To this end, chemotherapy has for some time been complemented by targeted therapies against specific structures. PDA-66, a structural analogue of the inhibitor of serine-threonine kinase glycogen synthase kinase 3ß SB216763, has shown preclinical antitumour effects in various cell lines, with the key pathways of its anticancer activity being cell cycle modulation, DNA replication and p53 signalling. For the monitoring of anticancer drug treatment in the context of therapeutic drug monitoring, the determination of plasma concentrations is essential, for which an LC-MS/MS method is particularly suitable. In the present study, a sensitive LC-MS/MS method for the quantification of the potential anticancer drug PDA-66 in human plasma with a lower limit of quantification of 2.5 nM is presented. The method was successfully validated and tested for the determination of PDA-66 in mouse plasma and sera.

Pharmaceutical immunoglobulin G impairs anti-carcinoma activity of oxaliplatin in colon cancer cells.

BACKGROUND: Recent evidence proves that intravenous human immunoglobulin G (IgG) can impair cancer cell viability. However, no study evaluated whether IgG application benefits cancer patients receiving chemotherapeutics. METHODS: Influence of pharmaceutical-grade human IgG on the viability of a series of patient-derived colon cancer cell lines with and without chemotherapeutic intervention was determined. Cell death was analysed flow cytometrically. In addition, the influence of oxaliplatin and IgG on the ERK1/2-signalling pathway was evaluated by western blots. RESULTS: We evaluated the effects of pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, in combination with chemotherapeutics. We did not observe any significant effects of IgG on tumour cell viability directly; however, human IgG significantly impaired the anti-tumoral effects of oxaliplatin. Primary cancer cell lines express IgG receptors and accumulate human IgG intracellularly. Moreover, while oxaliplatin induced the activation of ERK1/2, the pharmaceutical IgG inhibited ERK1/2 activity. CONCLUSIONS: The present study demonstrates that pharmaceutical IgG, such as PRIVIGEN® IgG and Tonglu® IgG, can impair the anti-carcinoma activity of oxaliplatin. These data strongly suggest that therapeutic IgG as co-medication might have harmful side effects in cancer patients. The clinical significance of these preclinical observations absolutely advises further preclinical, as well as epidemiological and clinical research.

Remote Welfare Monitoring of Rodents Using Thermal Imaging.

Animal research has always played a crucial role in various medical and scientific breakthroughs. They offer, inter alia, insights into diseases mechanisms, genetic predisposition to a disease, and drug therapy. However, the use of animals for medical research is a cause of major controversies and debates in modern science. To warrant high bioethical standards, new directives have been being adopted to replace animal research whenever possible, to reduce the number of animals, and to refine the procedures to minimize stress and pain. Here, we present two new approaches, based on thermal imaging (a remote and passive technology), to assess respiratory rate (RR) as well as exploratory behavior and general activity in rodents. In animal research, these parameters are gold standards for welfare assessment. The approaches were validated in a study conducted with both rats and mice. To test the feasibility of our algorithm to estimate RR, thermal videos from anesthetized rodents were acquired. The capability of the second approach to monitor activity was tested with videos of Open Field tests. Regarding RR, a high agreement between thermal imaging and gold standard (electrocardiography-derived RR) was achieved. The mean relative error averaged 0.50 ± 0.15 breaths/min and 4.55 ± 2.94 breaths/min for rats and mice, respectively. The second approach was capable of monitoring and tracking the activity of the rodents very well. This paper demonstrates that thermal imaging is a promising and relevant alternative for monitoring of RR and activity in rodents, thus contributing to the remote assessment of animal welfare.

The Ambivalent Function of YAP in Apoptosis and Cancer.

Yes-associated protein, a core regulator of the Hippo-YAP signaling pathway, plays a vital role in inhibiting apoptosis. Thus, several studies and reviews suggest that yes-associated protein is a good target for treating cancer. Unfortunately, more and more evidence demonstrates that this protein is also an essential contributor of p73-mediated apoptosis. This questions the concept that yes-associated protein is always a good target for developing novel anti-cancer drugs. Thus, the aim of this review was to evaluate the clinical relevance of yes-associated protein for cancer pathophysiology. This review also summarized the molecules, processes and drugs, which regulate Hippo-YAP signaling and discusses their effect on apoptosis. In addition, issues are defined, which should be addressed in the future in order to provide a solid basis for targeting the Hippo-YAP signaling pathway in clinical trials.

Binding versus Conventional Pancreaticojejunostomy in Preventing Postoperative Pancreatic Fistula: A Systematic Review and Meta-Analysis.

BACKGROUND: The aim of this study was to compare the safety and efficacy of a new technology, binding pancreaticojejunostomy (BPJ), with conventional pancreaticojejunostomy (CPJ) after pancreaticoduodenectomy in preventing postoperative pancreatic fistula (POPF). METHODS: Randomized controlled trials and observational studies were retrieved from literature searches. Pooled OR with 95% CI for dichotomous variables and weighted mean difference with 95% CI for continuous variables were calculated. Fixed-effect and random-effect models as well as subgroup analysis were used for sensitivity analysis. RESULTS: No statistically significant differences were found in the incidence of POPF, delayed gastric emptying, postpancreatectomy hemorrhage, reoperation, morbidity, mortality, operation time, intraoperative blood loss, blood transfusion, and hospital stay between 2 groups. However, the total costs of hospitalization and ordinary stay were higher in BPJ group (€10,513 ± €6,536 vs. €8,238 ± €4,687, p = 0.002; €7,946 ± €5,023 vs. €5,700 ± €2,902, p = 0.015, respectively). CONCLUSIONS: Our study showed BPJ was as safe as CPJ. However, no significant superiority was found in BPJ group regarding the incidence of POPF. The total costs of hospital stay were higher for patients undergoing BPJ. Surgeons can prefer to perform the digestive tract reconstruction of their choice.

Impact of diabetes type II and chronic inflammation on pancreatic cancer.

BACKGROUND: We explored if known risk factors for pancreatic cancer such as type II diabetes and chronic inflammation, influence the pathophysiology of an established primary tumor in the pancreas and if administration of metformin has an impact on tumor growth. METHODS: Pancreatic carcinomas were assessed in a syngeneic orthotopic pancreas adenocarcinoma model after injection of 6606PDA cells in the pancreas head of either B6.V-Lep(ob/ob) mice exhibiting a type II diabetes-like syndrome or normoglycemic mice. Chronic pancreatitis was then induced by repetitive administration of cerulein. Cell proliferation, cell death, inflammation and the expression of cancer stem cell markers within the carcinomas was evaluated by immunohistochemistry. In addition, the impact of the antidiabetic drug, metformin, on the pathophysiology of the tumor was assessed. RESULTS: Diabetic mice developed pancreatic ductal adenocarcinomas with significantly increased tumor weight when compared to normoglycemic littermates. Diabetes caused increased proliferation of cancer cells, but did not inhibit cancer cell necrosis or apoptosis. Diabetes also reduced the number of Aldh1 expressing cancer cells and moderately decreased the number of tumor infiltrating chloracetate esterase positive granulocytes. The administration of metformin reduced tumor weight as well as cancer cell proliferation. Chronic pancreatitis significantly diminished the pancreas weight and increased lipase activity in the blood, but only moderately increased tumor weight. CONCLUSION: We conclude that diabetes type II has a fundamental influence on pancreatic ductal adenocarcinoma by stimulating cancer cell proliferation, while metformin inhibits cancer cell proliferation. Chronic inflammation had only a minor effect on the pathophysiology of an established adenocarcinoma.

Risk factors for pancreatic ductal adenocarcinoma specifically stimulate pancreatic duct glands in mice.

Diabetes mellitus type 2 and chronic pancreatitis are regarded as risk factors for pancreatic cancer. Pancreatic duct glands (PDGs) were recently described as a new compartment of the major duct in humans and mice. To evaluate the influence of diabetes and chronic pancreatitis on PDGs, cerulein was injected i.p., repetitively over 10 weeks, in mice exhibiting obesity and a type 2 diabetes-like syndrome (B6.V-Lep(ob/ob)) and in lean littermates. By using 5-bromo-2'-deoxyuridine (BrdU), a label-retaining cell population was characterized in PDGs. Cerulein administration led to more BrdU(+) cells in PDGs of obese mice compared with lean mice. The observed increase was specific to PDGs, because BrdU incorporation in cells of the pancreatic duct was not increased. In addition, the expression of distinct tumor markers in PDGs was characterized by Muc5ac, S100P, regenerating islet-derived 3ß, 14-3-3 σ, and prostate stem cell antigen immunochemistry. Type 2 diabetes-like syndrome, accompanied by chronic pancreatitis, enhanced nuclear localization of S100P. Both risk factors for pancreatic cancer also induced the production of Muc5ac and the nuclear localization of S100P [corrected]. These results demonstrate that diabetes and chronic pancreatitis jointly enhance BrdU incorporation and production of pancreatic cancer-specific proteins in PDGs. The observed alterations suggest that pancreatic tumors might originate from the newly discovered histomorphological structures, called PDGs, which could represent a target for future anticancer therapies.

Diabetes increases pancreatitis induced systemic inflammation but has little effect on inflammation and cell death in the lung.

Acute pancreatitis (AP) can lead to a systemic inflammatory response that often results in acute lung injury and single or multiple organ failure. In a previous study we demonstrated that diabetes aggravates the local pathophysiological process during AP. In this study we explore, if diabetes also increases pancreatitis induced systemic inflammation and causes lung injury. Acute pancreatitis was induced in untreated and streptozotocin-treated diabetic mice by injection of cerulein. Systemic inflammation was studied by IL-6 ELISA in blood plasma and white blood cell count. Lung inflammation and lung injury were quantified by chloroacetate esterase staining, evaluation of the alveolar cellularity index and cleaved caspase-3 immunohistochemistry. In normoglycaemic mice AP increased the IL-6 concentration in plasma and caused lymphocytopenia. Diabetes significantly increased the IL-6 concentration in plasma and further reduced the number of lymphocytes during AP, whereas diabetes had little effect on these parameters in the absence of pancreatitis. However, diabetes only marginally increased lung inflammation and did not lead to cell death of the lung epithelium during AP. We conclude that diabetes increases parameters of systemic inflammation during AP, but that this increase is insufficient to cause lung injury.

Comparing animal well-being between bile duct ligation models.

A prevailing animal model currently used to study severe human diseases like obstructive cholestasis, primary biliary or sclerosing cholangitis, biliary atresia, and acute liver injury is the common bile duct ligation (cBDL). Modifications of this model include ligation of the left hepatic bile duct (pBDL) or ligation of the left bile duct with the corresponding left hepatic artery (pBDL+pAL). Both modifications induce cholestasis only in the left liver lobe. After induction of total or partial cholestasis in mice, the well-being of these animals was evaluated by assessing burrowing behavior, body weight, and a distress score. To compare the pathological features of these animal models, plasma levels of liver enzymes, bile acids, bilirubin, and within the liver tissue, necrosis, fibrosis, inflammation, as well as expression of genes involved in the synthesis or transport of bile acids were assessed. The survival rate of the animals and their well-being was comparable between pBDL+pAL and pBDL. However, surgical intervention by pBDL+pAL caused confluent necrosis and collagen depositions at the edge of necrotic tissue, whereas pBDL caused focal necrosis and fibrosis in between portal areas. Interestingly, pBDL animals had a higher survival rate and their well-being was significantly improved compared to cBDL animals. On day 14 after cBDL liver aspartate, as well as alanine aminotransferase, alkaline phosphatase, glutamate dehydrogenase, bile acids, and bilirubin were significantly elevated, but only glutamate dehydrogenase activity was increased after pBDL. Thus, pBDL may be primarily used to evaluate local features such as inflammation and fibrosis or regulation of genes involved in bile acid synthesis or transport but does not allow to study all systemic features of cholestasis. The pBDL model also has the advantage that fewer mice are needed, because of its high survival rate, and that the well-being of the animals is improved compared to the cBDL animal model.

Sex Matters-Insights from Testing Drug Efficacy in an Animal Model of Pancreatic Cancer.

Preclinical studies rarely test the efficacy of therapies in both sexes. The field of oncology is no exception in this regard. In a model of syngeneic, orthotopic, metastasized pancreatic ductal adenocarcinoma we evaluated the impact of sex on pathological features of this disease as well as on the efficacy and possible adverse side effects of a novel, small molecule-based therapy inhibiting KRAS:SOS1, MEK1/2 and PI3K signaling in male and female C57BL/6J mice. Male mice had less tumor infiltration of CD8-positive cells, developed bigger tumors, had more lung metastasis and a lower probability of survival compared to female mice. These more severe pathological features in male animals were accompanied by higher distress at the end of the experiment. The evaluated inhibitors BI-3406, trametinib and BKM120 showed synergistic effects in vitro. This combinatorial therapy reduced tumor weight more efficiently in male animals, although the drug concentrations were similar in the tumors of both sexes. These results underline the importance of sex-specific preclinical research and at the same time provide a solid basis for future studies with the tested compounds.

Contribution of protein Z and protein Z-dependent protease inhibitor in generalized Shwartzman reaction.

OBJECTIVE: Sepsis, a leading cause of mortality in critically ill patients, is closely linked to the excessive activation of coagulation and inflammation. Protein Z, a cofactor for the protein Z-dependent protease inhibitor, enhances the inhibition of coagulation factor Xa, and protein Z-dependent protease inhibitor inhibits factor XIa in a protein Z-independent fashion. The functions of protein Z and protein Z-dependent protease inhibitor in the inflammatory and coagulant responses to septic illness have not been evaluated. DESIGN: For induction of generalized Shwartzman reaction, dorsal skinfold chamber-equipped mice were challenged twice with lipopolysaccharide (0.05 mg/kg on day -1 and 5 mg/kg body weight 24 hr later). Time-matched control animals received equal volumes of saline. SETTING: University research laboratory. SUBJECTS, INTERVENTIONS, AND MEASUREMENTS: Using intravital fluorescence microscopy in protein Z-dependent protease inhibitor deficient (ZPI) and protein Z deficient (PZ) mice, as well as their wild-type littermates (ZPI, PZ), kinetics of light/dye-induced thrombus formation and microhemodynamics were assessed in randomly chosen venules. Plasma concentrations of chemokine (C-X-C motif) ligand 1, interleukin-6, and interleukin-10 were measured. Liver and lung were harvested for quantitative analysis of leukocytic tissue infiltration and thrombus formation. MAIN RESULTS: After induction of generalized Shwartzman reaction, all mice showed significant impairment of microhemodynamics, including blood flow velocity, volumetric blood flow, and functional capillary density, as well as leukocytopenia and thrombocytopenia. Thrombus formation time was markedly prolonged after induction of generalized Shwartzman reaction in all mice, except of ZPI mice, which also had a significantly higher fraction of occluded vessels in liver sections. PZ mice developed the highest concentrations of interleukin-6 and interleukin-10 in response to generalized Shwartzman reaction and showed greater leukocytic tissue infiltration than their wild-type littermates. CONCLUSIONS: In this murine model of generalized Shwartzman reaction, protein Z-dependent protease inhibitor deficiency enhanced the thrombotic response to vascular injury, whereas protein Z deficiency increased inflammatory response.

Robustness of a multivariate composite score when evaluating distress of animal models for gastrointestinal diseases.

The fundament of an evidence-based severity assessment in laboratory animal science is reliable distress parameters. Many readouts are used to evaluate and determine animal distress and the severity of experimental procedures. Therefore, we analyzed four distinct parameters like the body weight, burrowing behavior, nesting, and distress score in the four gastrointestinal animal models (pancreatic ductal adenocarcinoma (PDA), pancreatitis, CCl4 intoxication, and bile duct ligation (BDL)). Further, we determined the parameters' robustness in various experimental subgroups due to slight variations like drug treatment or telemeter implantations. We used non-parametric bootstrapping to get robust estimates and 95% confidence intervals for the experimental groups. It was found that the performance of the readout parameters is model-dependent and that the distress score is prone to experimental variation. On the other hand, we also found that burrowing and nesting can be more robust than, e.g., the body weight when evaluating PDA. However, the body weight still was highly robust in BDL, pancreatitis, and CCl4 intoxication. To address the complex nature of the multi-dimensional severity space, we used the Relative Severity Assessment (RELSA) procedure to combine multiple distress parameters into a score and mapped the subgroups and models against a defined reference set obtained by telemeter implantation. This approach allowed us to compare the severity of individual animals in the experimental subgroups using the maximum achieved severity (RELSAmax). With this, the following order of severity was found for the animal models: CCl4 < PDA ≈ Pancreatitis < BDL. Furthermore, the robustness of the RELSA procedure and outcome was externally validated with a reference set from another laboratory also obtained from telemeter implantation. Since the RELSA procedure reflects the multi-dimensional severity information and is highly robust in estimating the quantitative severity within and between models, it can be deemed a valuable tool for laboratory animal severity assessment.

Towards substitution of invasive telemetry: An integrated home cage concept for unobtrusive monitoring of objective physiological parameters in rodents.

This study presents a novel concept for a smart home cage design, tools, and software used to monitor the physiological parameters of mice and rats in animal-based experiments. The proposed system focuses on monitoring key clinical parameters, including heart rate, respiratory rate, and body temperature, and can also assess activity and circadian rhythm. As the basis of the smart home cage system, an in-depth analysis of the requirements was performed, including camera positioning, imaging system types, resolution, frame rates, external illumination, video acquisition, data storage, and synchronization. Two different camera perspectives were considered, and specific camera models, including two near-infrared and two thermal cameras, were selected to meet the requirements. The developed specifications, hardware models, and software are freely available via GitHub. During the first testing phase, the system demonstrated the potential of extracting vital parameters such as respiratory and heart rate. This technology has the potential to reduce the need for implantable sensors while providing reliable and accurate physiological data, leading to refinement and improvement in laboratory animal care.

Melatonin restores muscle regeneration and enhances muscle function after crush injury in rats.

The goal of this study was to provide evidence that melatonin improves muscle healing following blunt skeletal muscle injury. For this purpose, we used 56 rats and induced an open muscle injury. After injury, all animals received either daily melatonin or vehicle solution intraperitoneally. Subsequent observations were performed at day 1, 4, 7, and 14 after injury. After assessment of fast twitch and tetanic muscle force, we analyzed leukocyte infiltration, satellite cell number, and cell apoptosis. We further quantified the expression of the melatonin receptor and the activation of extracellular-signal-regulated kinase (ERK). Chronic treatment with melatonin significantly increased the twitch and tetanic force of the injured muscle at day 4, 7, and 14. At day 1, melatonin significantly reduced the leukocyte infiltration and significantly increased the number of satellite cells when compared to the control group. Consistent with this observation, melatonin significantly reduced the number of apoptotic cells at day 4. Furthermore, phosphorylation of ERK reached maximal values in the melatonin group at day 1 after injury. Additionally, we detected the MT1a receptor in the injured muscle and showed a significant up-regulation of the MT1a mRNA in the melatonin group at day 4. These data support the hypothesis that melatonin supports muscle restoration after muscle injury, inhibits apoptosis via modulation of apoptosis-associated signaling pathways, increases the number of satellite cells, and reduces inflammation.

3D-printed lightweight dorsal skin fold chambers from PEEK reduce chamber-related animal distress.

The dorsal skinfold chamber is one of the most important in vivo models for repetitive longitudinal assessment of microcirculation and inflammation. This study aimed to refine this model by introducing a new lightweight chamber made from polyetheretherketone (PEEK). Body weight, burrowing activity, distress, faecal corticosterone metabolites and the tilting angle of the chambers were analysed in mice carrying either a standard titanium chamber or a PEEK chamber. Data was obtained before chamber preparation and over a postoperative period of three weeks. In the early postoperative phase, reduced body weight and increased faecal corticosterone metabolites were found in mice with titanium chambers. Chamber tilting and tilting-related complications were reduced in mice with PEEK chambers. The distress score was significantly increased in both groups after chamber preparation, but only returned to preoperative values in mice with PEEK chambers. In summary, we have shown that light chambers reduce animal distress and may extend the maximum dorsal skinfold chamber observation time. Chambers made of PEEK are particularly suitable for this purpose: They are autoclavable, sufficiently stable to withstand rodent bites, inexpensive, and widely available through 3D printing.