Characteristics of 3D-Printed Polycaprolactone Tracheal Scaffolds Implanted In Vivo

BACKGROUND: A 3D-printing technology using polycaprolactone (PCL) has shown promise for the development of patient-customized tracheal constructs. However, no studies have compared the mechanical properties of various grades of PCL using animal experiments under the same conditions. In this study, the mechanical properties and tissue reconstruction abilities of research-grade (RG) and medical-grade (MG) PCL scaffolds were compared in rabbit tracheal defect models. METHOD: Customized scaffolds for the rabbit's segmental defect was manufactured using an extrusion-based 3D printing system and two types of PCL. Six months after transplantation into trachea defected rabbits, transplanted areas were excised to evaluate its mechanical properties, and the reconstruction of the damaged tissue were analyzed through endoscope and tissue staining. And, the change in molecular weight of PCL before and after transplantation was compared using Gel permeation chromatography (GPC). Molecular weight changes PCL scaffolds before and after gamma radiation were also compared using GPC. RESULTS: The medical-grade PCL scaffold (MG) group showed superior ultimate stress, strain, and tissue reconstruction compared with the research-grade PCL scaffold (RG) group, demonstrating better strength, ductility, and mucosal tissue regeneration. However, MG PCL scaffold degrades more rapidly in the body, as indicated by a notable decrease in molecular weight and ultimate stress post-transplantation. Gamma sterilization, which is an essential process for implants, did not affect the molecular weight of PCL, demonstrating its effectiveness in sterilization. CONCLUSION: Our results highlight the substantial differences between RG and MG PCL scaffolds, emphasizing the need for researchers to thoroughly evaluate PCL properties before conducting animal studies or clinical trials to ensure the accurate prediction of experimental outcomes.