Endomicroscopic fluorescence lifetime imaging enables molecular detection and targeted sampling in the distal human lung

Molecular imaging and targeted sampling in the distal human lung have been enhanced by endomicroscopic fluorescence lifetime imaging microscopy (eFLIM) using a clinic-ready platform. This innovative approach enables real-time detection and sampling of bacteria and activated neutrophils in the alveolar space, crucial for accurate diagnosis and future therapeutic development in critically ill patients.

The study employed a multifunctional imaging and sampling catheter called Eyes on Target (EoT), which facilitated fluorescence intensity and lifetime imaging along with directed alveolar microlavage. The catheter's design allowed for real-time monitoring of three wash-free SmartProbes: NBD-PMX for Gram-negative bacteria, Merocy-Van for Gram-positive bacteria, and a neutrophil activation probe (NAP).

Preclinical trials in ventilated ex vivo human lungs demonstrated the effectiveness of this approach. The EoT successfully navigated to alveolar regions in all lung lobes, enabling probe-specific molecular detection. Increased fluorescence signals were observed in regions instilled with Escherichia coli, while Merocy-Van lifetime signatures selectively identified Staphylococcus aureus-infested areas. Additionally, activated neutrophils were detected throughout the tissue after NAP administration.

This platform's ability to recover cellular material and bacterial DNA from imaged regions opens up opportunities for downstream analysis. By combining eFLIM with eFLIM using Eyes on Target and molecular SmartProbes, researchers have developed a translatable approach for evaluating infection and inflammation at the alveolar level. This breakthrough holds promise for the clinical development of molecular imaging probes and therapeutics targeting pulmonary diseases.