Compensatory lung growth after bilobectomy in emphysematous rats

<div><p>Lung volume reduction surgery (LVRS) is an option for emphysematous patients who are awaiting lung transplantation. LVRS reduces nonfunctional portions of lung tissues and favors the compensatory lung growth (CLG) of the remaining lobes. This phenomenon diminishes dyspnea and improves both the respiratory mechanics and quality of life for the patients. An animal model of elastase-induced pulmonary emphysema was used to investigate the structural and functional lung response after LVRS. Bilobectomy was performed six weeks after elastase instillation. Two weeks after bilobectomy, CLG effects were evaluated by lung mechanics and histomorphometric analysis. After bilobectomy, the emphysematous animals presented decreased mean linear intercepts, increased elastic fiber proportion, and increased alveolar surface density, total volumes of airspace, tissue and respiratory region and absolute surface area. We conclude that bilobectomy promoted CLG in emphysematous animals, resulting in alveolar architecture repair.</p></div

Compensatory lung growth parameters.

<p>(<i>A)</i> Alveolar surface density (cm²/cm³) was lower in elastase group; (<i>B)</i> Total volume of respiratory region (mL) was higher in the Ela+LBX group; (<i>C)</i> Total volume of respiratory airspace (mL) was higher in the elastase groups and Sal+LBX; (<i>D)</i> Total volume of respiratory tissue (mL) was higher in the Sal+LBX group, but the Ela+Sham group showed lower TVrt than the other groups; (E) Absolute surface area (x10³ cm²) was higher in LBX animals. Values are expressed as mean ± SD. (*) vs. Sal+Sham; (#) vs. Sal+LBX; (†) vs. Ela+Sham; p < 0.05.</p

Morphometric parameters and images analysis in lung parenchyma.

<p>(<i>A)</i> Mean linear intercept (Lm_, μm); (<i>B)</i> Elastic fibers per tissue area (%); (<i>C)</i> Collagen fibers per tissue area (%); (D) Photomicrographs of the lung parenchyma stained by resorsin-fuchsin (400x); (E) Photomicrographs of the lung parenchyma stained by picrosirius (400x). Values are expressed as mean ± SD. (*) vs. Sal+Sham; (#) vs. Sal+LBX; (†) vs. Ela+Sham; (§) vs. Ela+LBX; p < 0.05.</p

Lung weight, lung volume, and hypertension index.

<p>(<i>A)</i> Lung weight (mg/g) was higher in both Sal+LBX and Ela+LBX groups; (<i>B)</i> Volume of the lower lobe (mL/kg) was higher in Sal+LBX and Ela+LBX; (C) Right ventricle to left ventricle + septum to body weight (x10⁷ mg/Kg). This index was higher in the Sal+LBX group. Values are expressed as mean ± SD. (*) vs. Sal+Sham; † vs. Ela+Sham; (§) vs. Ela+LBX; p < 0.05.</p

Inflammatory cells in bronchoalveolar lavage fluid and in lung tissue.

<p>(<i>A)</i> Total cells values in BALF (cells x10⁴/mL) were higher in the Ela+Sham group; (<i>B)</i> Macrophages in BALF (cells x10⁴/mL); (<i>C)</i> Neutrophils in BALF (cells x10⁴/mL); (<i>D)</i> The number of mononuclear cells in lung tissue (cells/mm²) was higher in elastase groups. (<i>E)</i> The number of polymorphonuclear cells in lung tissue (cells/mm²) was higher in the Ela+Sham group. Values are expressed as mean ± SD. (*) vs. Sal+Sham; (#) vs. Sal+LBX; (†) vs. Ela+Sham; p < 0.05.</p