# Repetitive invasive lung function maneuvers do not accentuate experimental fibrosis in mice

## TL;DR

This study shows that repeated lung function tests in mice do not worsen lung fibrosis and can reduce the number of animals needed for research.

## Contribution

The study demonstrates the feasibility of repetitive invasive lung function maneuvers in mice without exacerbating fibrosis.

## Key findings

- Repetitive lung function maneuvers were well tolerated in mice.
- The maneuvers did not worsen experimental lung fibrosis.
- This approach supports the 3R principle by reducing animal use.

## Abstract

Assessment of lung function is an important clinical tool for the diagnosis and monitoring of chronic lung diseases, including idiopathic pulmonary fibrosis (IPF). In mice, lung function maneuvers use algorithm-based ventilation strategies including forced oscillation technique (FOT), negative pressure-driven forced expiratory (NPFE) and pressure–volume (PV) maneuvers via the FlexiVent system. This lung function test (LFT) is usually performed as end-point measurement only, requiring several mice for each time point to be analyzed. Repetitive lung function maneuvers would allow monitoring of a disease process within the same individual while reducing the numbers of laboratory animals. However, its feasibility in mice and impact on developing lung fibrosis has not been studied so far. Using orotracheal cannulation without surgical exposure of the trachea, we examined the tolerability to repetitive lung function maneuvers (up to four times) in one and the same mouse, both under healthy conditions and in a model of AdTGF-β1 induced lung fibrosis. In essence, we found that repetitive invasive lung function maneuvers were well tolerated and did not accentuate experimental lung fibrosis in mice. This study contributes to the 3R principle aiming to reduce the numbers of experimental animals used in biomedical research.