Model Introduction
The Acute Lung Injury (ALI) model is a biomedical model used to simulate pathological processes such as diffuse inflammatory alveolar infiltration, hemorrhage, pulmonary edema, and hyaline membrane formation caused by intrapulmonary or extrapulmonary pathogenic factors. The core principle lies in the activation of inflammatory response chains (such as alveolar macrophage activation) and oxidative stress injury by pathogenic factors, leading to increased permeability of the alveolar epithelial microvasculature. Its biological significance is to provide a stable experimental platform for studying the pathogenesis and pathological evolution of ALI, as well as screening preventive and therapeutic drugs.
Research Applications
This model is mainly used to simulate the lung injury process caused by Acute Respiratory Distress Syndrome (ARDS), sepsis, severe pneumonia, aspiration, major trauma, burns, and acute pancreatitis. In scientific research, it is widely applied to explore hypotheses such as inflammatory response mediation, imbalance of coagulation and fibrinolysis, redox imbalance, and cell apoptosis, and to evaluate the efficacy of potential therapeutic drugs and the mechanisms for preventing complications.
Experimental Design Key Points
Taking the Lipopolysaccharide (LPS) intratracheal instillation method as an example, the key experimental parameters are as follows:
- Experimental Subjects: 6-8 week old male mice.
- Anesthesia and Fixation: After intraperitoneal injection of anesthetic drugs, mice are fixed on a dissection table.
- Surgical Procedure: The trachea is exposed via a midline neck incision, and administration is performed via tracheal intubation.
- Dosage: LPS dose is 3 mg/kg.
- Modeling Operation: After instillation, the mice must be held upright and rotated vertically to ensure uniform distribution of the drug in the lungs.
Key Monitoring Indicators
- Pathological Evaluation (Gold Standard): Observation of alveolar interstitial edema, increased alveolar wall thickness, neutrophil infiltration, and patchy hemorrhage in lung tissue via H-E staining.
- Inflammatory Mediator Concentration:
- Cell Counts: Macrophage and neutrophil counts in Bronchoalveolar Lavage Fluid (BALF).
- Cytokines: Detection of concentrations of IL-1β, NLRP3, NF-κB, HIF-1α, TNF-α, etc.
- Lung Wet/Dry (W/D) Ratio: Assessment of the severity of pulmonary edema by measuring the ratio of lung tissue wet weight to dry weight after oven-drying (the more severe the injury, the higher the ratio/higher the water content).
- Protein Concentration: Determination of relevant protein content in BALF, reflecting alveolar-capillary permeability.
- Blood Gas Analysis: Monitoring changes in arterial partial pressure of oxygen to assess the lung’s oxygen-binding capacity (as a reference indicator).
