Alfaxalone and Dexmedetomidine as an Alternative to Gas Anesthesia for Micro-CT Lung Imaging in a Bleomycin-Induced Pulmonary Fibrosis Murine Model

Abstract

Micro-CT imaging could be considered a powerful non-invasive tool for accessing pulmonary fibrosis in mice. However, the choice of the anesthesia protocol plays a fundamental role to obtain robust and reproducible data, avoiding misinterpretations of the results. Inhaled anesthesia is commonly used for micro-CT lung imaging, but sometimes the standardization of the protocol may be challenging for routine activities in drug discovery. In this study we used micro-CT to evaluate the effects of two anesthetic protocols, consisting in Alfaxalone and Dexmedetomidine mixture, as injectable agents, and gaseous isoflurane, on vehicle and bleomycin-treated mice. No significant differences were highlighted between the protocols either for lung aeration degrees by micro-CT or histologic analyses in both the controls and bleomycin-treated groups. Our results support Alfaxalone and Dexmedetomidine mixture as a suitable and safe alternative compared to isoflurane for lung imaging. We also concluded that this injectable mixture may be applied for several imaging technologies and on different mice models.

Pivotal role of micro-CT technology in setting up an optimized lung fibrosis mouse model for drug screening

“…Micro-CT was performed longitudinally and the data were integrated with ex-vivo outcomes to select the best BLM regimen. Longitudinal imaging drastically reduced the number of mice per group and the intra-experimental variability, since the progression of the disease could be monitored in the same subjects [ 12 , 13 , 22 , 23 ]. All the BLM-treated groups showed decreased normo- and increased hypo-aerated tissue; however, at day 7, a significant difference with respect to the saline group in hypo-aerated tissue was revealed only in mice dosed three times with 6 μg BLM ( Fig 2E ).…”

“…Micro-CT has been well-documented to play an important role in decreasing intra-experimental variability, and, as a result, significantly reducing the number of animals used per experiment, in agreement with the 3R’s principles [ 11 ]. In particular, micro-CT technology has been used to quantify lung fibrosis progression, as well as the evaluation of the response to pharmacological treatments [ 6 , 11 – 13 ].…”

The importance of routine quality control for reproducible pulmonary measurements by in vivo micro-CT

“…Animals were lightly anesthetized with 2.5% isoflurane delivered in a box and vehicle (50 μl saline [0.9%]) was administered via oropharyngeal aspiration (OA) using a micropipette 42 . Twenty-one days after saline administration, mice were anesthetized with 2% isoflurane and underwent micro-CT imaging 10 , 14 .…”

“…However, timing, reliability and reproducibility of the data generated by micro-CT in preclinical studies present crucial issues in characterizing the human disease and profiling the putative drug candidate for a move into the clinic. Although standardized protocols for image acquisition and anesthesia are adopted to generate accurate and reproducible datasets 14 , other factors can potentially undermine either the intra- or the inter-experiment reproducibility of results.…”

The Importance of Routine Quality Control For Reproducible Pulmonary Measurements By in Vivo Micro-CT

“…However, timing, reliability and reproducibility of the data generated by micro-CT in preclinical studies present crucial issues in characterizing the human disease and pro ling the putative drug candidate for a move into the clinic. Although standardized protocols for image acquisition and anesthesia are adopted to generate accurate and reproducible datasets 14 , other factors can potentially undermine either the intraor the inter-experiment reproducibility of results.…”