Swellable and Thermally Responsive Hydrogel/Shape Memory Polymer Foam Composites for Sealing Lung Biopsy Tracts

Lung tissue biopsies can result in a leakage of blood (hemothorax) and air (pneumothorax) from the biopsy tract, which threatens the patient with a collapsed lung and other complications. We have developed a lung biopsy tract sealant based on a thiol-ene-crosslinked PEG hydrogel and polyurethane shape memory polymer (SMP) foam composite. After insertion into biopsy tracts, the PEG hydrogel component contributes to sealing through water-driven swelling, whereas the SMP foam contributes to sealing via thermal actuation. The gelation kinetics, swelling properties, and rheological properties of various hydrogel formulations were studied to determine the optimal formulation for composite fabrication. Composites were then fabricated via vacuum infiltration of the PEG hydrogel precursors into the SMP foam followed by thermal curing. After drying, the composites were crimped to enable insertion into biopsy tracts. Characterization revealed that the composites exhibited a slight delay in shape recovery compared to control SMP foams. However, the composites were still able to recover their shape in a matter of minutes. Cytocompatibility testing showed that leachable byproducts can be easily removed by washing and washed composites were not cytotoxic to mouse lung fibroblasts (L929s). Benchtop testing demonstrated that the composites can be easily deployed through a cannula, and the working time for deployment after exposure to water was 2 min. Furthermore, testing in an in vitro lung model demonstrated that the composites were able to effectively seal a lung biopsy tract and prevent air leakage. Collectively, these results show that the PEG hydrogel/SMP foam composites have the potential to be used as lung biopsy tract sealants to prevent pneumothorax post-lung biopsy.