Lung implantable devices: the issue with granulation tissue

Abstract

After decades of development and experience, lung implantable devices have proven to be invaluable in the management of respiratory diseases and complications. Unfortunately, granulation tissue hyperplasia remains a common and challenging complication, compromising implant function through obstruction, migration and increased susceptibility to infection, ultimately requiring frequent reinterventions. Reinterventions often involve bronchoscopy for tissue debulking or device replacement, all of which significantly affect patient wellbeing and healthcare resources. Granulation tissue hyperplasia results from an imbalance in the interactions between the host and the implant. While most patients achieve implant integration, persistent stressors cause chronic inflammation leading to granulation tissue hyperplasia. While several studies have provided insights, the disease endotype remains largely undefined. Variability in incidence and severity across devices and patient populations complicates characterisation. Surface factors, including implant material, adsorbed proteins and the colonising microorganisms, as well as geometrical and biomechanical mismatches with the airways may contribute to pathological tissue responses. Future research aimed at gaining a fundamental understanding of the stressors and biological mechanisms driving granulation tissue hyperplasia is essential for preventing and treating this complication. Ultimately, the goal is to reduce morbidity and improve the longevity of implants and treatment benefit.

FIGURE 1

Illustrative endoscopic photographs depicting granulation tissue hyperplasia following a) airway stent and b) endobronchial valve implantation.

FIGURE 2

Overview of potential factors contributing to granulation tissue hyperplasia in response to treatment with lung implantable devices. Figure created using BioRender.com.