PATHOLOGIES > COPD – respiratory diseases – pulmonary Emphysema
Current literature on pulmonary emphysema observed in animal models highlights the need to develop a fast, reliable and independent-observer assessment of histological analysis of pulmonary emphysema that cannot be satisfactorily achieved by conventional linear intercept and chord length evaluation methods.
BIOCELLVIA’S EMPHYSEMA VALIDATION ASSAY
- To overcome the limitations of conventional methods Biocellvia developed a digital approach of emphysema assessment based on fully automatic, fast, reliable and observer-independent delineation of the whole lung airspaces (alveolar ducts & alveoli) located in entire lung sections coupled to the evaluation of key morphometric airspace parameters: area, diameter, number and high airspace area frequency (figures 1 & 2).
Figure 1. Representative images of automatic delineation of airspace areas in parenchyma of entire histological sections of control and elastase treated lungs of mice. Bronchi and vessels were deleted automatically from original images (top images). After the delimitation of airspace areas throughout the entire lung section, the pixels of the alveolar parenchyma were colored blue and those of airspace areas in red (bottom images). Bars: 100 µm and 250 µm.
Figure 2. Representative images of airspace areas according to their size in control and elastase-treated mouse. Large bronchi and vessels were deleted automatically from the original images. Smaller airspaces were artificially colored in blue (16-32, 767 µm2) and higher (> 32,768 µm2) in brown-yellow. With regard to their size, ranged in 15 classes, the number of effectives per class the frequency of airspace areas was defined. Note that emphysema was characterized by a marked increase in the frequency of higher airspaces and in parallel by a significant decrease in the frequency of small airspaces. Scale bars: 1000 µm.
AIRSPACE MORPHOMETRIC PARAMETERS
- Mean airspace area, corresponding to the mean area of the whole airspaces (alveolar ducts & alveoli) contained in entire lung sections.
- Mean diameter of airspaces, corresponding to the mean value of the greatest airspace diameters (Feret’s diameter) of airspaces contained in entire lung sections.
- Frequency of high airspace areas, corresponding for each lung section to the sum of the frequencies of higher airspace areas.
- Mean number of airspaces, corresponding to the mean number of airspaces per mm2 of parenchyma lung tissue.
TOTALLY AUTOMATED QUANTITATIVE ANALYSIS OF EMPHYSEMA
The severity of emphysema is accurately assessed by evaluating the airspace morphometric parameters. The occurrence of emphysema is characterized by a significant increase of the mean area and diameter of airspaces as well as the frequency of high airspace areas associated with a significant decrease of the number of airspaces (figure 3). These morphological changes characterize the occurrence of emphysema in elastase-treated lungs.
All these morphometric parameters are acquired automatically in a very short time (<30 sec/entire lung section) and independently of the observer.
Figure 3. Assessment of airspace morphometric parameters in entire lung sections of control and elastase-treated mice. Elastase (2U) induced a statistically significant increase of area, diameter and high airspace area frequency of airspaces coupled with a significant statistically decrease of the number of airspaces. Data correspond to mean ± sem.* p<0.05, **p<0.01.
The implementation of multiple key morphometric parameters of airspaces provides new fundamental data which contribute to a better and deeper analysis of emphysema in COPD animal models. This new approach provides a total reliability and reproductibility for preclinical drug evaluation and consequently a robust support for decision-making.