Pulmonary artery hypertension-induced vascular structure analysis using label-free fluorescence lifetime imaging

Pulmonary artery hypertension (PAH) is a chronic condition characterized by pathological remodeling of the vascular structures and poor clinical prognosis. Therefore, early interventional treatment is essential to slow disease progression, improve survival rates, and enhance quality of life. In animal models of pulmonary hypertension, analyzing the remodeling of the pulmonary artery tissue and collagen deposition usually involves computed tomography and tissue staining. However, computer tomography has limited specificity and sensitivity, while preparing stained samples is labor-intensive and time-consuming. Phasor-based fluorescence lifetime imaging microscopy (FLIM), which estimates the autofluorescence decays, provides a powerful technique for detecting disease progression in biological tissue samples without staining. Accordingly, the present study proposes an integrated method combining two-photon excited fluorescence microscopy (TPEFM), FLIM, and four-color quantization (FCQ) to examine changes in the collagen distribution and average wall thickness of the pulmonary arteries in the lung tissue of three mouse models: control, monocrotaline (MCT), and MCT + magnolol. The results show that magnolol treatment significantly reduces the arterial wall thickening compared to the MCT-only group, suggesting its potential efficacy in mitigating the progression of PAH. Overall, the proposed method effectively visualizes the vascular remodeling associated with PAH and enables the severity of the PAH-induced arterial wall thickening to be quantified by calculating the wall area percentage. It thus provides a valuable tool for assessing PAH progression and evaluating the effectiveness of potential therapeutic interventions.