A systematic review of the development and application of home cage monitoring in laboratory mice and rats

BACKGROUND

Traditionally, in biomedical animal research, laboratory rodents are individually examined in test apparatuses outside of their home cages at selected time points. However, the outcome of such tests can be influenced by various factors and valuable information may be missed when the animals are only monitored for short periods. These issues can be overcome by longitudinally monitoring mice and rats in their home cages. To shed light on the development of home cage monitoring (HCM) and the current state-of-the-art, a systematic review was carried out on 521 publications retrieved through PubMed and Web of Science.

RESULTS

Both the absolute (~ × 26) and relative (~ × 7) number of HCM-related publications increased from 1974 to 2020. There was a clear bias towards males and individually housed animals, but during the past decade (2011-2020), an increasing number of studies used both sexes and group housing. In most studies, animals were kept for short (up to 4 weeks) time periods in the HCM systems; intermediate time periods (4-12 weeks) increased in frequency in the years between 2011 and 2020. Before the 2000s, HCM techniques were predominantly applied for less than 12 h, while 24-h measurements have been more frequent since the 2000s. The systematic review demonstrated that manual monitoring is decreasing in relation to automatic techniques but still relevant. Until (and including) the 1990s, most techniques were applied manually but have been progressively replaced by automation since the 2000s. Independent of the year of publication, the main behavioral parameters measured were locomotor activity, feeding, and social behaviors; the main physiological parameters were heart rate and electrocardiography. External appearance-related parameters were rarely examined in the home cages. Due to technological progress and application of artificial intelligence, more refined and detailed behavioral parameters have been investigated in the home cage more recently.

CONCLUSIONS

Over the period covered in this study, techniques for HCM of mice and rats have improved considerably. This development is ongoing and further progress as well as validation of HCM systems will extend the applications to allow for continuous, longitudinal, non-invasive monitoring of an increasing range of parameters in group-housed small rodents in their home cages.

Pharmacokinetic evaluation of MFF in combinations with tacrolimus and cyclosporine. Findings of C0 and AUC

We hypothesized that area under the concentration time curve (AUC(0-12)) is more accurate pharmacokinetic predictor vs trough level of mycophenolic acid (C0).Study was performed at the University Hospital of Limoges (France) and included 238 renal recipients aged 22 to 82 years. Risk of nephropathy was evaluated by analyzing data of protocol biopsies according to the Banff 97 classification.Assessment of immunosuppressants' exposures was based on the calculation of the mean of AUC(0-12). The AUC(0-12) was estimated using a Bayesian estimator and a 3-point limited sampling strategy. Cyclosporine and tacrolimus analyses were performed using liquid chromatography-mass spectrometry method. The measurement of total mycophenolic acid was performed using a validated high-performance liquid chromatography method with ultraviolet detection. IBM SPSS 20.0 was used for statistical analysis.The most accurate dosing of mycophenolate mofetil (MMF) was observed in patients receiving MMF with tacrolimus, 70.6% of patients' AUC(0-12) exposures were within the therapeutic range. The highest rates of low dosing were observed in patients receiving MMF with cyclosporine, 30.9% of patients had AUC(0-12) exposures below the therapeutic range. The assessment of AUC(0-12) revealed 38% of chronic nephropathy cases, while C0 enables to identify only 20% of chronic nephropathy cases.Probability test results showed that more likely AUC(0-12) and C0 will be maintained within the therapeutic width if patients receive MMF with tacrolimus vs MMF with cyclosporine: 0.6320 vs 0.6410 for AUC(0-12) determination and 0.8415 vs 0.4827 for C0 determination.Combination of MMF with tacrolimus is dosed more precisely vs dosing of MMF with cyclosporine. 72 (70.6%) patients AUC(0-12) and 79 (77.5%) patients C0 out of 102 patients were within the therapeutic range. The AUC(0-12) monitoring of mycophenolic acid in patients receiving MMF with tacrolimus or in patients receiving MMF with cyclosporine enabled to identify more overdosing and possible risky cases.Study results show that standard MMF dosing without monitoring and with mycophenolic acid level within the therapeutic width is possible and demonstrates less risky cases in patients receiving MMF with tacrolimus, while patients receiving MMF with cyclosporine should be intensively monitored to achieve the highest safety. However, AUC(0-12) monitoring is advised showing better compliance vs C0 monitoring.